ORCID Profile
0000-0003-2665-9850
Current Organisations
Centre for Addiction and Mental Health
,
Australian National University
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Publisher: Elsevier BV
Date: 10-2011
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2011.08.011
Abstract: The current study investigated the size and flexible control of visual span among patients with schizophrenia during visual search performance. Visual span is the region of the visual field from which one extracts information during a single eye fixation, and a larger visual span size is linked to more efficient search performance. Therefore, a reduced visual span may explain patients' impaired performance on search tasks. The gaze-contingent moving window paradigm was used to estimate the visual span size of patients and healthy participants while they performed two different search tasks. In addition, changes in visual span size were measured as a function of two manipulations of task difficulty: target-distractor similarity and stimulus familiarity. Patients with schizophrenia searched more slowly across both tasks and conditions. Patients also demonstrated smaller visual span sizes on the easier search condition in each task. Moreover, healthy controls' visual span size increased as target discriminability or distractor familiarity increased. This modulation of visual span size, however, was reduced or not observed among patients. The implications of the present findings, with regard to previously reported visual search deficits, and other functional and structural abnormalities associated with schizophrenia, are discussed.
Publisher: Elsevier BV
Date: 03-2020
Publisher: American Psychological Association (APA)
Date: 10-2019
DOI: 10.1037/EDU0000322
Publisher: Elsevier BV
Date: 04-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2001
DOI: 10.1097/00001756-200112210-00052
Abstract: Previous studies suggest that there is a dopamine lowering process during major depressive episodes (MDE). To investigate this, we measured the dopamine transporter binding potential (DAT BP) in the striatum of depressed and healthy subjects using [(11)C]RTI-32 PET. The DAT, a predominantly presynaptic receptor, decreases in density after chronic dopamine depletion and the BP is proportional to receptor density. In all striatal regions, subjects with MDE had significantly lower DAT BP. Low striatal DAT BP in MDE is consistent with a downregulation of DAT in response to a dopamine lowering process. There was also a strong, highly significant, inverse correlation between striatal DAT BP and neuropsychological tests of dopamine-implicated symptoms in patients (i.e. patients with lower DAT BP performed better). Lower DAT BP itself reduces extracellular clearance of dopamine. Patients who did not decrease their striatal DAT BP failed to compensate for low dopamine and showed greater impairment on dopamine related tests.
Publisher: Informa UK Limited
Date: 2007
DOI: 10.1080/02699050701785054
Abstract: The prevalence and profile of adults with a history of traumatic brain injury (TBI) has not been studied in large North American forensic mental health populations. This study investigated how adults with a documented history of TBI differed with the non-TBI forensic population with respect to demographics, psychiatric diagnoses and history of offences. A retrospective chart review of all consecutive admissions to a forensic psychiatry programme in Toronto, Canada was conducted. Information on history of TBI, psychiatric diagnoses, living environments and types of criminal offences were obtained from medical records. History of TBI was ascertained in 23% of 394 eligible patient records. Compared to those without a documented history of TBI, persons with this history were less likely to be diagnosed with schizophrenia but more likely to have alcohol/substance abuse disorder. There were also differences observed with respect to offence profiles. This study provides evidence to support routine screening for a history of TBI in forensic psychiatry.
Publisher: Elsevier BV
Date: 12-2002
DOI: 10.1016/S0920-9964(01)00406-6
Abstract: We investigated whether the caudate nuclei volume (CNV) of 15 first episode psychosis patients increased after 5 years of treatment with either atypical antipsychotics or low doses of typical antipsychotics. Caudate volumes were measured from magnetic resonance imaging (MRI) scans in 15 patients and 10 healthy controls. Both groups demonstrated a significant 9% decline in caudate volume. We were unable to replicate previous reports of caudate enlargement in patients receiving antipsychotic treatment.
Publisher: Elsevier BV
Date: 1998
DOI: 10.1016/S0003-9993(98)90215-5
Abstract: Review the existing literature on the incidence, neurobiological and psychosocial correlates, and methods of assessment and treatment of depression following traumatic brain injury (TBI). Computerized database searches of the English-language literature from Index Medicus, Psychological Abstracts, Excerpta Medica, and Cumulative Index of Nursing and Allied Health Literature. Given the relatively small number of publications specifically related to TBI and depression, all studies appearing in the peer-reviewed literature were included in the review. In addition, studies examining depression and other neurologic diseases (eg, stroke) were also reviewed as to the potential applicability of the theoretical model or methodology used. Depression occurs with sufficient frequency to be considered a significant consequence after TBI. Depression can impede the achievement of optimal functional outcome, whether in the acute or chronic stages of recovery. It appears that a combination of neuroanatomic, neurochemical, and psychosocial factors is responsible for the onset and maintenance of depression. Its treatment is typically psychopharmacologic, with best results obtained from nontricyclic antidepressants. These results have not been confirmed in double-blind clinical trials, however. Future research should use comprehensive, integrative models of depression that include demographic, biologic, and psychosocial factors enhanced functional neuroimaging techniques controlled studies of psychopharmacologic and other interventions and prospective designs with long-term follow-up.
Publisher: Medical Journals Sweden AB
Date: 2018
Abstract: To design and preliminarily test a questionnaire intended to measure patient treatment burden resulting from participation in cognitive assessments and interventions. An expert consensus process was used to develop the concept of patient treatment burden and to determine the first set of questionnaire items and administration protocol. The pilot questionnaire was administered to 20 patients with mild to severe acquired brain injuries on completion of a 2-h or longer neuropsychological assessment. Following preliminary testing, the questionnaire was revised and re-evaluated by a second expert panel and content validity was assessed. Burden was defined as psychologically and/or physically aversive symptoms in response to cognitive assessment or intervention. The first questionnaire contained 21 items assigned to 3 categories: physical, cognitive, and emotional. Eighty-five percent of patients endorsed symptom level increases, with "tired/fatigued" the most frequently endorsed item (80% of patients). Instructions and test items were easily understood, and the questionnaire was quick to administer. Content validity ratio (CVR) of the revised questionnaire yielded 23 acceptable items and a subset met the highest CVR threshold (>0.78). This patient-reported outcome will ultimately help patients give voice to aversive experiences, and help clinicians and researchers to monitor and adapt assessments/treatments appropriately. Future steps in development are described.
Publisher: Wiley
Date: 25-10-2013
DOI: 10.1002/HIPO.22189
Abstract: Spatial memory is impaired among persons with schizophrenia (SCZ). However, different strategies may be used to solve most spatial memory and navigation tasks. This study investigated the hypothesis that participants with schizophrenia-spectrum disorders (SSD) would demonstrate differential impairment during acquisition and retrieval of target locations when using a hippoc al-dependent spatial strategy, but not a response strategy, which is more associated with caudate function. Healthy control (CON) and SSD participants were tested using the 4-on-8 virtual maze (4/8VM), a virtual navigation task designed to differentiate between participants' use of spatial and response strategies. Consistent with our predictions, SSD participants demonstrated a differential deficit such that those who navigated using a spatial strategy made more errors and took longer to locate targets. In contrast, SSD participants who spontaneously used a response strategy performed as well as CON participants. The differential pattern of spatial-memory impairment in SSD provides only indirect support for underlying hippoc al dysfunction. These findings emphasize the importance of considering in idual strategies when investigating SSD-related memory and navigation performance. Future cognitive intervention protocols may harness SSD participants' intact ability to navigate using a response strategy and/or train the deficient ability to navigate using a spatial strategy to improve navigation and memory abilities in participants with SSD.
Publisher: American Medical Association (AMA)
Date: 04-2008
DOI: 10.1001/ARCHPSYC.65.4.378
Abstract: Neural plasticity in the human cortex involves a reorganization of synaptic connections in an effort to adapt to a changing environment. In schizophrenia, dysfunctional neural plasticity has been proposed as a key pathophysiological mechanism. To evaluate neural plasticity in unmedicated and medicated patients with schizophrenia compared with healthy subjects. Neural plasticity can be evaluated from the motor cortex in healthy subjects using transcranial magnetic stimulation through a paradigm known as use-dependent plasticity. This paradigm involves several steps: (1) measuring the spontaneous direction of transcranial magnetic stimulation-induced thumb movements (2) training subjects to practice thumb movements opposite to this baseline direction for 30 minutes and (3) measuring the direction of transcranial magnetic stimulation-induced thumb movement after training. Previous experiments have shown that in healthy subjects, posttraining transcranial magnetic stimulation-induced movements occur in a vector commensurate with the practiced movements, which may be associated with time-limited reorganization of motor circuits. All of the participants were recruited and evaluated at the Centre for Addiction and Mental Health. Fourteen medicated and 6 unmedicated patients with schizophrenia and 20 healthy subjects were recruited. It was anticipated that patients with schizophrenia would demonstrate attenuated motor reorganization in the direction of training. Both medicated and unmedicated patients with schizophrenia demonstrated significantly reduced motor reorganization compared with healthy subjects. It is possible that in schizophrenia, these deficits in neural plasticity are related to disturbances of gamma-aminobutyric acid, N-methyl-D-aspartate neurotransmission, or dopamine that may potentially account for the aberrant motor performance of these patients.
Publisher: Informa UK Limited
Date: 2009
DOI: 10.1080/02699050902970794
Abstract: To evaluate the extent to which the Personality Assessment Inventory (PAI) is confounded by symptoms that are transdiagnostic between psychopathology and neurological sequelae. Sixty-one adults with moderate-to-severe traumatic brain injury (TBI) completed the PAI over the first year post-injury. Items that discriminated brain-injured in iduals from a normative s le were identified using effect size analyses and were then subjected to principal components analysis (PCA) with varimax rotation. To explore whether the items identified in the PCA may be considered transdiagnostic in nature, an expert rating task and correlations with objective outcome measures were employed. Effect sizes analyses identified 21 items that discriminated adults with TBI from the normative s le. Eight items associated with component 1 of the PCA were considered to be transdiagnostic. These items reflected health concerns and thinking problems from the Somatic Complaints, Depression and Schizophrenia scales. Items belonging to the other components reflected behaviours that are commonly associated with TBI, but not considered transdiagnostic. Using a comprehensive and multi-modal approach, results demonstrated good convergent validity for a small sub-set of items as being transdiagnostic. Overall, the findings support the PAI as a useful measure of psychiatric and emotional disturbances among persons with TBI.
Publisher: American Medical Association (AMA)
Date: 04-2002
DOI: 10.1001/ARCHPSYC.59.4.347
Abstract: Cortical inhibition (CI) deficits have been proposed as a pathophysiologic mechanism in schizophrenia. This study employed 3 transcranial magnetic stimulation (TMS) paradigms to assess CI in patients with schizophrenia. Paired-pulse TMS involves stimulating with a lower-intensity pulse a few milliseconds before a higher-intensity pulse, thereby inhibiting the size of the motor evoked potential produced by the higher-intensity pulse. In the cortical silent period paradigm, inhibition is reflected by the silent period duration (ie, the duration of electromyographic activity cessation following a TMS-induced motor evoked potential). Transcallosal inhibition involves stimulation of the contralateral motor cortex several milliseconds prior to stimulation of the ipsilateral motor cortex, inhibiting the size of the motor evoked potential produced by ipsilateral stimulation. We measured CI using these 3 paradigms in 15 unmedicated patients with schizophrenia (14 medication-naive and 1 medication-free for longer than 1 year) (13 were in the transcallosal inhibition paradigm), 15 medicated patients with schizophrenia (11 taking olanzapine, 1 risperidone, 1 quetiapine, 1 methotrimeprazine + perphenazine, 1 quetiapine + loxapine), and 15 healthy controls. Unmedicated patients demonstrated significant CI deficits compared with healthy controls across all inhibitory paradigms whereas medicated patients did not (at all inhibitory intervals, paired-pulse TMS: controls = 59.9%, medicated = 44.3%, unmedicated = 28.7% cortical silent period: controls = 55.0 milliseconds, medicated = 60.4 milliseconds, unmedicated = 39.7 milliseconds transcallosal inhibition: controls = 33.6%, medicated = 23.7%, unmedicated = 10.4% P<.05). These results suggest that schizophrenia is associated with deficits in CI and that antipsychotic medications may increase CI.
Publisher: Informa UK Limited
Date: 02-06-2017
DOI: 10.1080/07448481.2017.1322090
Abstract: We modeled design factors influencing the intent to use a university mental health service. Between November 2012 and October 2014, 909 undergraduates participated. Using a discrete choice experiment, participants chose between hypothetical c us mental health services. Latent class analysis identified three segments. A Psychological/Psychiatric Service segment (45.5%) was most likely to contact c us health services delivered by psychologists or psychiatrists. An Alternative Service segment (39.3%) preferred to talk to peer-counselors who had experienced mental health problems. A Hesitant segment (15.2%) reported greater distress but seemed less intent on seeking help. They preferred services delivered by psychologists or psychiatrists. Simulations predicted that, rather than waiting for standard counseling, the Alternative Service segment would prefer immediate access to E-Mental health. The Usual Care and Hesitant segments would wait 6 months for standard counseling. E-Mental Health options could engage students who may not wait for standard services.
Publisher: Elsevier BV
Date: 03-2023
Publisher: Springer Science and Business Media LLC
Date: 26-08-2021
Publisher: Elsevier BV
Date: 05-2022
Publisher: American Society of Civil Engineers (ASCE)
Date: 06-2017
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.APMR.2008.09.551
Abstract: To examine the influence of cognitive reserve-related moderator variables on recovery trajectories during the first year after traumatic brain injury (TBI). Using mixed effects models, we measured (1) the level of cognitive function at 2 and 12 months postinjury and (2) the trajectories of cognitive recovery during the first 12 months postinjury. Repeated-measures design with neuropsychological testing at 2, 5, and 12 months postinjury. Large, urban inpatient neurorehabilitation program. Patients (N=75) with moderate-to-severe TBI. Not applicable. neuropsychological composite scores including simple speed of processing, complex speed of processing, memory, untimed executive functions, and attention span. Primary predictors: age, estimated premorbid intelligence quotient (IQ), and years of education. Only age significantly moderated trajectories. Decreasing age significantly enhanced recovery of speed of processing, both simple (2-12mo postinjury, P<.001) and complex (2-12mo postinjury, P<.05 5-12mo postinjury, P<.005). Decreasing age and increasing estimated premorbid IQ were associated with higher performance at 2 and 12mo postinjury for simple speed of processing (premorbid IQ, 2 and 12mo), complex speed of processing (age, 2 and 12mo), untimed executive functions (premorbid IQ, 2 and 12mo), and memory (premorbid IQ, 2 and 12mo). Recovery of speed of processing (both simple and complex) was favorably moderated by younger age. Older age is associated with more neuronal loss and less integrity of white matter, and speed of processing is associated with white matter networks. The recuperative effects of younger age may therefore be attributable to greater reserve capacity (as indexed by white matter integrity). Lower age and higher estimated premorbid IQ were associated with higher functioning on a variety of cognitive outcomes. This may reflect the buffering effects of reserve capacity or premorbid differences in age and IQ-related cognitive functioning. Implications for rehabilitation and recovery mechanisms are discussed.
Publisher: Elsevier BV
Date: 04-2013
Publisher: Copernicus GmbH
Date: 08-04-2022
Abstract: Abstract. In the modern northern Indian Ocean, biological productivity is intimately linked to near-surface oceanographic dynamics forced by the South Asian, or Indian, monsoon. In the late Pleistocene, this strong seasonal signal is transferred to the sedimentary record in the form of strong variance in the precession band (19–23 kyr), because precession dominates low-latitude insolation variations and drives seasonal contrast in oceanographic conditions. In addition, internal climate system feedbacks (e.g. ice-sheet albedo, carbon cycle, topography) play a key role in monsoon variability. Little is known about orbital-scale monsoon variability in the pre-Pleistocene, when atmospheric CO2 levels and global temperatures were higher. In addition, many questions remain open regarding the timing of the initiation and intensification of the South Asian monsoon during the Miocene, an interval of significant global climate change that culminated in bipolar glaciation. Here, we present new high-resolution ( kyr) records of export productivity and sediment accumulation from International Ocean Discovery Program Site U1443 in the southernmost part of the Bay of Bengal spanning the late Miocene (9 to 5 million years ago). Underpinned by a new orbitally tuned benthic isotope stratigraphy, we use X-ray fluorescence-derived biogenic barium variations to discern productivity trends and rhythms. Results show strong eccentricity-modulated precession-band productivity variations throughout the late Miocene, interpreted to reflect insolation forcing of summer monsoon wind strength in the equatorial Indian Ocean. On long timescales, our data support the interpretation that South Asian monsoon winds were already established by 9 Ma in the equatorial sector of the Indian Ocean, with no apparent intensification over the latest Miocene.
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.CLINPH.2008.03.031
Abstract: The neural correlates of inhibitory deficits for emotional semantic material in persons with major depressive disorder (MDD) were investigated. In iduals (n=15) with a diagnosis of MDD or MDD in partial remission, and healthy controls (n=14) underwent recording of event-related brain potentials (ERPs) while performing a computerized emotional Stroop task. There were no group performance differences on the emotional Stroop task. However, the analysis of ERP waveforms revealed a larger negative wave peaking at about 170ms over the left than the right hemisphere only in controls a negative displacement (N450) at parietal sites for positive and negative words only for persons with MDD in both groups, processing negative and positive words was associated with a positive displacement that peaked at about 450ms and was larger over the left lateral frontal region and, the N450 modulation correlated with negative automatic thinking and depressive symptoms. The electrophysiological data reveal early changes in neural activity associated with word processing as well as valence-related changes in the N450 component at parietal sites in MDD. This valence-related increase in N450 litude at parietal sites may reflect an automatic capture of attention by words with emotional valence.
Publisher: SAGE Publications
Date: 21-01-2008
Abstract: It has been previously demonstrated that unmedicated persons with schizophrenia have deficits in cortical inhibition (CI) as indexed with transcranial magnetic stimulation (TMS). This inhibition is largely mediated by cortical GABAergic mechanisms. It has also been demonstrated that these inhibitory deficits may be normalized with the use of atypical antipsychotic medications. The purpose of this study, therefore, was to examine the effects of clozapine on TMS measures of CI and to compare these effects to unmedicated persons with schizophrenia and healthy subjects. We used two TMS inhibitory paradigms: short interval intra-cortical inhibition (SICI) and the cortical silent period (CSP) to evaluate CI in 10 clozapine-treated persons with schizophrenia, 6 unmedicated persons with schizophrenia and 10 healthy subjects. Clozapine-treated persons with schizophrenia had significantly longer CSPs compared with healthy subjects and unmedicated persons with schizophrenia. There were no significant differences in SICI between groups, however, the severity of psychotic symptoms was correlated with reduced SICI across all persons with schizophrenia. Our findings suggest that clozapine treatment is associated with greater CI in persons with schizophrenia and this increase may be related to potentiation of cortical GABAergic receptor mediated inhibitory neurotransmission. Our results also confirm previous findings suggesting that deficits in CI are related to the severity of psychotic symptoms in persons with schizophrenia.
Publisher: Informa UK Limited
Date: 03-1994
Publisher: Springer Science and Business Media LLC
Date: 2003
Abstract: Previous research has found that pedophilic men referred for clinical assessment of their sexual behavior are more likely to report that they suffered head injuries before their 13th birthday than are nonpedophilic men referred for the same purpose. This study investigated whether pedophilic patients are also more likely to report head injuries after their 13th birthday. The 685 participants represented all patients with usable data from a consecutive series of men referred to a clinical laboratory specializing in phallometric assessment of erotic preferences. In addition to phallometric testing, participants were administered a brief neuropsychological test battery and a companion interview, which included questions on head injury, drug abuse, and childhood diagnosis of attention-deficit/hyperactivity disorder. The results showed that the pedophilic patients reported more head injuries before age 13 than did the nonpedophilic patients, but they did not report more head injuries after age 13. The association between pedophilia and childhood head injuries could mean either that subtle brain damage after birth increases a boy's risk of pedophilia, or that neurodevelopmental problems before birth increase a boy's accident-proneness along with his risk of pedophilia. Additional analyses showed that self-reported head injuries before age 13 were associated with attentional problems and with left-handedness in contrast, head injuries after age 13 were associated with drug abuse and promiscuity. These analyses suggest that, among patients with primary presenting complaints of sexual rather than cognitive problems, childhood head injuries cluster with neuropsychological phenomena, whereas later head injuries cluster with lifestyle variables.
Publisher: Informa UK Limited
Date: 15-05-2023
Publisher: American Psychiatric Association Publishing
Date: 11-2002
DOI: 10.1176/JNP.14.4.406
Abstract: Transcranial magnetic stimulation (TMS) is a new investigational technique used to explore various neural processes and treat a variety of neuropsychiatric illnesses. The most notable advantage of TMS is its ability to directly stimulate the cortex with little effect on intervening tissue. Single-pulse stimulation techniques can measure cortical inhibition, facilitation, connectivity, reactivity, and cortical plasticity, providing valuable insights into the cortical physiology. Repetitive TMS (rTMS) is currently being used to investigate cognitive processes and as a treatment tool in disorders such as depression and schizophrenia. Both TMS and rTMS are safe and well tolerated. The most serious side effect of high-frequency rTMS is seizures. TMS represents an exciting new frontier in neuroscience research, providing insights into the pathophysiology and treatment of various neuropsychiatric disorders.
Publisher: American Psychiatric Association Publishing
Date: 06-2004
DOI: 10.1176/APPI.AJP.161.6.985
Abstract: The effect of antipsychotic medication on neurocognitive function remains controversial, especially since most previous work has compared the effects of novel antipsychotic medications with those of high doses of conventional medications. This study compares the neurocognitive effects of olanzapine and low doses of haloperidol in patients with first-episode psychosis. Patients with a first episode of schizophrenia, schizoaffective disorder, or schizophreniform disorder (N=167) were randomly assigned to double-blind treatment with olanzapine (mean modal dose= 9.63 mg/day) or haloperidol (mean modal dose=4.60 mg/day) for the 12-week acute phase of a 2-year study. The patients were assessed with a battery of neurocognitive tests at baseline and 12 weeks after beginning treatment. An unweighted neurocognitive composite score, composed of measures of verbal fluency, motor functions, working memory, verbal memory, and vigilance, improved significantly with both haloperidol and olanzapine treatment (effect sizes of 0.20 and 0.36, respectively, no significant difference between groups). A weighted composite score developed from a principal-component analysis of the same measures improved to a significantly greater degree with olanzapine, compared with haloperidol. Anticholinergic use, extrapyramidal symptoms, and estimated IQ had little effect on the statistical differentiation of the medications, although duration of illness had a modest effect. The correlations of cognitive improvement with changes in clinical characteristics and with side effects of treatment were significant for patients who received haloperidol but not for patients who received olanzapine. Olanzapine has a beneficial effect on neurocognitive function in patients with a first episode of psychosis. However, in a comparison of the effects of olanzapine and low doses of haloperidol, the difference in benefit is small.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2017
DOI: 10.1038/S41598-017-16528-6
Abstract: The variability of seawater temperature through time is a critical measure of climate change, yet its reconstruction remains problematic in many regions. Mg/Ca and oxygen isotope ( δ 18 O C ) measurements in foraminiferal carbonate shells can be combined to reconstruct seawater temperature and δ 18 O ( δ 18 O SW ). The latter is a measure of changes in local hydrology (e.g., precipitation/evaporation, freshwater inputs) and global ice volume. But diagenetic processes may affect foraminiferal Mg/Ca. This restricts its potential in many places, including the Mediterranean Sea, a strategic region for deciphering global climate and sea-level changes. High alkalinity/salinity conditions especially bias Mg/Ca temperatures in the eastern Mediterranean (eMed). Here we advance the understanding of both western Mediterranean (wMed) and eMed hydrographic variability through the penultimate glacial termination (TII) and last interglacial, by applying the clumped isotope ( Δ 47 ) paleothermometer to planktic foraminifera with a novel data-processing approach. Results suggest that North Atlantic cooling during Heinrich stadial 11 (HS11) affected surface-water temperatures much more in the wMed (during winter/spring) than in the eMed (during summer). The method’s paired Δ 47 and δ 18 O C data also portray δ 18 O SW . These records reveal a clear HS11 freshwater signal, which attenuated toward the eMed, and also that last interglacial surface warming in the eMed was strongly lified by water-column stratification during the deposition of the organic-rich (sapropel) interval known as S5.
Publisher: Springer Science and Business Media LLC
Date: 08-2001
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.SCHRES.2014.01.001
Abstract: Schizophrenia is associated with abnormalities in using meaningful stimuli to activate or prime related concepts in semantic long-term memory. A neurophysiological index of this activation is the N400, an event-related brain potential (ERP) waveform elicited by meaningful stimuli, which is normally reduced (made less negative) by relatedness between the eliciting stimulus and preceding ones (N400 semantic priming). Schizophrenia patients exhibit N400 semantic priming deficits, suggesting impairment in using meaningful context to activate related concepts. To address whether this abnormality is a trait-like marker of liability to schizophrenia or, alternatively, a biomarker of the illness itself, we tested for its presence in schizophrenia patients' unaffected biological relatives. We recorded ERPs from 12 unaffected first-degree relatives of schizophrenia patients, 12 schizophrenia patients, and 12 normal control participants (NCPs) who viewed prime words each followed at 300- or 750-ms stimulus-onset asynchrony (SOA) by an unrelated or related target word, or a nonword, in a lexical-decision task. As expected, across SOAs, NCPs exhibited smaller (less negative) N400 litudes for related versus unrelated targets. The same pattern held in relatives, whose N400 litudes for related and unrelated targets did not differ from NCPs'. In contrast, consistent with previous results, schizophrenia patients exhibited larger N400 litudes than NCPs (and relatives) for related targets, such that patients' N400 litudes for related and unrelated targets did not differ. N400 litudes for unrelated targets did not differ between the three groups. Thus, N400 semantic priming deficits in a visual word-pair paradigm may be an illness biomarker for schizophrenia.
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.JPSYCHIRES.2007.10.013
Abstract: The present investigation sought to identify which brain regions distinguish pedophilic from nonpedophilic men, using unbiased, automated analyses of the whole brain. T1-weighted magnetic resonance images (MRIs) were acquired from men who demonstrated illegal or clinically significant sexual behaviors or interests (n = 65) and from men who had histories of nonsexual offenses but no sexual offenses (n = 62). Sexual interest in children was assessed by participants' admissions of pedophilic interest, histories of committing sexual offenses against children, and psychophysiological responses in the laboratory to erotic stimuli depicting children or adults. Automated parcellation of the MRIs revealed significant negative associations between pedophilia and white matter volumes of the temporal and parietal lobes bilaterally. Voxel-based morphometry corroborated the associations and indicated that the regions of lower white matter volumes followed, and were limited to, two major fiber bundles: the superior fronto-occipital fasciculus and the right arcuate fasciculus. No significant differences were found in grey matter or in cerebrospinal fluid (CSF). Because the superior fronto-occipital and arcuate fasciculi connect the cortical regions that respond to sexual cues, these results suggest (1) that those cortical regions operate as a network for recognizing sexually relevant stimuli and (2) that pedophilia results from a partial disconnection within that network.
Publisher: American Psychological Association (APA)
Date: 2004
Publisher: Cambridge University Press (CUP)
Date: 24-04-2007
DOI: 10.1017/S0033291707000530
Abstract: Within Beck's cognitive model of depression, little is known about the mechanism(s) by which activated self-schemas result in the production of negative thoughts. Recent research has demonstrated that inhibitory dysfunction is present in depression, and this deficit is likely valence-specific. However, whether valence-specific inhibitory deficits are associated with increased negative cognition and whether such deficits are specific to depression per se remains unexamined. The authors posit the theory that inhibitory dysfunction may influence the degree to which activated self-schemas result in the production of depressive cognition. In iduals with major depressive disorder (MDD, n =43) versus healthy ( n =36) and non-depressed anxious ( n =32) controls were assessed on the Prose Distraction Task (PDT), a measure of cognitive inhibition, and the Stop-Signal Task (SST), a measure of motor response inhibition. These two tasks were modified in order to present emotionally valenced semantic stimuli (i.e. negative, neutral, positive). Participants with MDD demonstrated performance impairments on the PDT, which were most pronounced for negatively valenced adjectives, relative to both control groups. Moreover, these impairments correlated with self-report measures of negative thinking and rumination. Conversely, the performance of the MDD participants did not differ from either control group on the SST. Implications of these findings for understanding the mechanisms underlying the development and maintenance of depressive cognition are discussed.
Publisher: Elsevier BV
Date: 10-2008
DOI: 10.1016/J.SCHRES.2008.05.001
Abstract: The current study investigated whether impaired visual attention among patients with schizophrenia can be accounted for by poor perceptual organization and impaired search selectivity. Twenty-three patients with schizophrenia and 22 healthy control participants completed a conjunctive visual search task where the relative frequency of the two types of distractors was manipulated. It has been shown that, when the total number of items in a display is fixed, search performance depends on the relative frequency of the types of distractors (i.e., as the ratio becomes more discrepant search time decreases). This modulation of search efficiency reflects participants' ability to group items by their perceptual similarity and then search only the smaller group of items that share a feature with the target. Results show that patients modulate their response time normally as a function of the distractor ratio--that is, they benefit from the presence of a smaller distractor subset in the display. This suggests that patients with schizophrenia, group items according to their perceptual similarity and flexibly deploy their attention to the smaller subset of distractors on each trial. These results demonstrate that search selectivity as a function of the relative frequency of distractors is unimpaired among patients with schizophrenia.
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.PSCYCHRESNS.2017.07.007
Abstract: Different strategies may be spontaneously adopted to solve most navigation tasks. These strategies are associated with dissociable brain systems. Here, we use brain-imaging and cognitive tasks to test the hypothesis that in iduals living with Schizophrenia Spectrum Disorders (SSD) have selective impairment using a hippoc al-dependent spatial navigation strategy. Brain activation and memory performance were examined using functional magnetic resonance imaging (fMRI) during the 4-on-8 virtual maze (4/8VM) task, a human analog of the rodent radial-arm maze that is amenable to both response-based (egocentric or landmark-based) and spatial (allocentric, cognitive mapping) strategies to remember and navigate to target objects. SSD (schizophrenia and schizoaffective disorder) participants who adopted a spatial strategy performed more poorly on the 4/8VM task and had less hippoc al activation than healthy comparison participants using either strategy as well as SSD participants using a response strategy. This study highlights the importance of strategy use in relation to spatial cognitive functioning in SSD. Consistent with a selective-hippoc al dependent deficit in SSD, these results support the further development of protocols to train impaired hippoc al-dependent abilities or harness non-hippoc al dependent intact abilities.
Publisher: American Geophysical Union (AGU)
Date: 04-2017
DOI: 10.1002/2016GC006753
Publisher: American Geophysical Union (AGU)
Date: 11-2018
DOI: 10.1029/2018PA003412
Publisher: Frontiers Media SA
Date: 2013
Publisher: Springer Publishing Company
Date: 2012
DOI: 10.1891/0889-8391.26.4.381
Abstract: The cognitive model of depression specifies the role of schema-driven negative processing biases in the onset and maintenance of depression. Research has shown that cognitive reactivity, or the ease with which negative thinking patterns are activated by mild changes in negative mood, is related to relapse and recurrence. The goal of this study was to examine cognitive reactivity following a mood prime in in iduals vulnerable to depression. Formerly (n = 28) and never (n = 36) depressed in iduals were assessed on two measures of negative cognition, the Automatic Thoughts Questionnaire (ATQ) and Dysfunctional Attitudes Scale (DAS), before and after participating in a sad or neutral mood induction procedure (MIP). The negative mood induction resulted in increased belief in negative automatic thoughts across groups however, only the formerly depressed participants assigned to this condition demonstrated increased DAS scores. Importantly, in iduals who completed the neutral mood induction did not exhibit increases in negative cognition, providing evidence against the possibility that the MIP itself may lead to increases in negative cognition. These findings are discussed in relation to understanding the role of negative cognition and vulnerability to depression.
Publisher: American Psychological Association (APA)
Date: 11-2008
DOI: 10.1037/A0013500
Abstract: This study frames anomalous functional brain organization in schizophrenia (SCZ) within an evolutionary model of brain development, the dual trends theory (DTT). The DTT argues that neural architecture develops along 2 separate pathways: the dorsal archicortical trend and the ventral paleocortical trend. The DTT dovetails with visual system organization, which is also composed of 2 independent pathways: a dorsal stream dedicated to visuomotor action and a ventral stream dedicated to perceptual processing. The present study examined the integrity of these pathways using a size-contrast visual illusion. Prior research has shown that, normally, perceptual estimations of object size are susceptible to visual illusions, whereas goal-directed actions are resistant. The authors hypothesized that, unlike control participants, SCZ patients' actions would be susceptible to the illusion, reflecting dorsal stream dysfunction. Here, 42 SCZ patients and 42 healthy controls grasped and estimated the size of target blocks in control and illusion conditions. During estimation, both groups were equally perturbed by the illusion however, grasping movements of patients alone were influenced by the illusion. These results suggest disrupted dorsal brain circuitry in SCZ but relatively intact ventral circuitry.
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.SCHRES.2011.05.026
Abstract: The current study investigated visual guidance and saccadic selectivity during visual search among patients with schizophrenia (SCZ). Data from a previous study (Elahipanah, A., Christensen, B.K., & Reingold, E.M., 2008. Visual selective attention among persons with schizophrenia: The distractor ratio effect. Schizophr. Res. 105, 61-67.) suggested that visual guidance for the less frequent distractors in a conjunction search display (i.e., the distractor ratio effect) is intact among SCZ patients. The current study investigated the distractor ratio effect among SCZ patients when: 1) search is more demanding, and 2) search involves motion perception. In addition, eye tracking was employed to directly study saccadic selectivity for the different types of distractors. Twenty-eight SCZ patients receiving a single antipsychotic medication and 26 healthy control participants performed two conjunction search tasks: a within-dimension (i.e., colour × colour) search task and a cross-dimension (i.e., motion × colour) search task. In each task the relative frequency of distractors was manipulated across 5 levels. Despite slower search times, patients' eye movement data indicated unimpaired visual guidance in both tasks. However, in the motion × colour conjunction search task, patients displayed disproportionate difficulty detecting the moving target when the majority of distractors were also moving. Results demonstrate that bottom-up attentional guidance is unimpaired among patients with SCZ however, patients' impairment in motion discrimination impedes their ability to detect a moving target against noisy backgrounds.
Publisher: American Psychological Association (APA)
Date: 09-2005
Publisher: Wiley
Date: 23-08-2017
DOI: 10.1111/EIP.12470
Abstract: To understand what service features would sustain patient engagement in early intervention mental health treatment. Mental health patients, family members of in iduals with mental illness and mental health professionals completed a survey consisting of 18 choice tasks that involved 14 different service attributes. Preferences were ascertained using importance and utility scores. Latent class analysis revealed segments characterized by distinct preferences. Simulations were carried out to estimate utilization of hypothetical clinical services. Overall, 333 patients and family members and 183 professionals (N = 516) participated. Respondents were distributed between a Professional segment (53%) and a Patient segment (47%) that differed in a number of their preferences including for appointment times, in idual vs group sessions and mode of after-hours support. Members of both segments shared preferences for many of the service attributes including having crisis support available 24 h per day, having a choice of different treatment modalities, being offered help for substance use problems and having a focus on improving symptoms rather than functioning. Simulations predicted that 60% of the Patient segment thought patients would remain engaged with a Hospital service, while 69% of the Professional segment thought patients would be most likely to remain engaged with an E-Health service. Patients, family members and professionals shared a number of preferences about what service characteristics will optimize patient engagement in early intervention services but erged on others. Providing effective crisis support as well as a range of treatment options should be prioritized in the future design of early intervention services.
Publisher: American Psychological Association (APA)
Date: 09-2016
DOI: 10.1037/NEU0000280
Abstract: Schizophrenia is associated with poor spatial attention. However, although this deficit undermines the perception of target information, it may be helpful for ignoring irrelevant inputs. The present study examined whether event-related brain potential (ERP) indices of visual spatial attention predicted the magnitude of the brain response to interference in schizophrenia. ERPs were recorded in 16 schizophrenia patients and 20 healthy control participants who had to indicate whether the target E was global or local in compound letter stimuli. The nontarget could be either highly similar to the target (i.e., a global E composed of local Ss and vice versa) and thus produce more interference, or it could be dissimilar (i.e., a global E composed of local Hs and vice versa) and generate less interference. Both groups' responses were slowed by interference. Voltage litudes of the P1, and of ERP interference effects from 300-500 ms after stimulus onset, were significantly smaller in schizophrenia patients than in healthy participants when the target was global. In patients, larger P1 litudes were correlated with larger interference effects and with more severe symptoms of attentional deficits and conceptual disorganization. Schizophrenia participants thus exhibited abnormal ERPs to interference despite normal behavioral performance. Schizophrenia patients likely pay less attention to stimuli in general however, the impact of this impairment on target detection is compensated by relatively greater inattention to irrelevant components of the stimuli, and this explains why they are not more influenced by interference than healthy participants at the behavioral level. (PsycINFO Database Record
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 07-2021
Publisher: Frontiers Media SA
Date: 2013
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1016/J.SCHRES.2021.08.025
Abstract: We present a novel account of delusion propensity that integrates the roles of working memory (WM), decision criteria, and information gathering biases. This framework emphasises the role of aberrant correlation detection, which leads to the spurious perception of relationships between one's experiences. The frequency of such outcomes is moderated by the scaling of one's decision criteria which, for reasons discussed, must also account for WM capacity. The proposed dysregulated correlation detection account posits that propensity for delusional ideation is influenced by disturbances in this mechanism. Hypotheses were tested using a novel task that required participants (N = 92) to identify correlation between binary manipulations of simple shapes, presented as sequential pairs. Decision criteria and correlation detection were assessed under a Signal Detection Theory framework, while WM capacity was assessed through the Automated Operation Span Task and delusion propensity was measured using the Peters Delusion Inventory. Structural equation modeling was conducted to evaluate the proposed model. Consistent with the central hypothesis, an interaction between decision criteria and WM was found to contribute significantly to delusion propensity through its effect on correlation detection accuracy. Greater delusion propensity was observed among participants with more liberal decision criteria, which was also in accordance with hypotheses. At the same time, the total effect of WM on delusion propensity was not found to be significant. These findings provide preliminary support for the proposed dysregulated correlation detection account of propensity for delusional ideation.
Publisher: American Psychological Association (APA)
Date: 11-2003
Publisher: American Psychological Association (APA)
Date: 2010
DOI: 10.1037/A0017523
Abstract: The current study investigated one possible mechanism of impaired visual attention among patients with schizophrenia: a reduced visual span. Visual span is the region of the visual field from which one can extract information during a single eye fixation. This study hypothesized that schizophrenia-related visual search impairment is mediated, in part, by a smaller visual span. To test this hypothesis, 23 patients with schizophrenia and 22 healthy controls completed a visual search task where the target was pseudorandomly presented at different distances from the center of the display. Response times were analyzed as a function of search condition (feature vs. conjunctive), display size, and target eccentricity. Consistent with previous reports, patient search times were more adversely affected as the number of search items increased in the conjunctive search condition. It was important however, that patients' conjunctive search times were also impacted to a greater degree by target eccentricity. Moreover, a significant impairment in patients' visual search performance was only evident when targets were more eccentric and their performance was more similar to healthy controls when the target was located closer to the center of the search display. These results support the hypothesis that a narrower visual span may underlie impaired visual search performance among patients with schizophrenia.
Publisher: Informa UK Limited
Date: 25-10-2018
Publisher: Elsevier BV
Date: 10-2008
DOI: 10.1016/J.SCHRES.2008.07.008
Abstract: There is uncertainty regarding the onset timing of the cognitive deficiencies of schizophrenia. We investigated whether conversion to psychosis and/or olanzapine altered the neuropsychological course of subjects within the first-ever double blind medication study of the putative schizophrenia first episode prodrome. Sixty participants in a double blind trial of olanzapine as a treatment for putative prodromal states were assessed at entry (pre-randomization), and again at 6 and 12 months (if they remained non-psychotic), or at any of these points prior to psychosis followed by post-psychosis and 6 months post-psychosis assessments. Participants who converted to psychosis did not differ from placebo non-converters in pre-randomization global neuropsychological status. Early converters did not differ from later converters in entry neuropsychological status. Subjects who converted after 6 months did not show neuropsychological declines during the initial, pre-psychosis, 6 months. Neuropsychological course did not differ between converters to psychosis and non-converters, or between olanzapine and placebo-assigned subjects. Neither the onset of frank psychosis nor olanzapine treatment of the prodrome significantly alters neuropsychological course in persons considered to be at high risk at their initial (pre-psychosis) assessment. These findings suggest that the neuropsychological deficiencies associated with psychotic conditions largely pre-exist the first frank psychotic episode.
Publisher: Informa UK Limited
Date: 05-2013
DOI: 10.1080/13854046.2013.780640
Abstract: Schizophrenia (SCZ)-related verbal memory impairment is hypothesized to be mediated, in part, by frontal lobe (FTL) dysfunction. However, little research has contrasted the performance of SCZ patients with that of patients exhibiting circumscribed frontal lesions. The current study compared verbal episodic memory in patients with SCZ and focal FTL lesions (left frontal, LF right frontal, RF and bi-frontal, BF) on a four-trial list learning task consisting of three lists of varying semantic organizational structure. Each dependent variable was examined at two levels: scores collapsed across all four trials and learning scores (i.e., trial 4-trial 1). Performance deficits were observed in each patient group across most dependent measures at both levels. Regarding patient group differences, SCZ patients outperformed LF/BF patients (i.e., either learning scores or scores collapsed across trial) on free recall, primacy, primary memory, secondary memory, and subjective organization, whereas they only outperformed RF patients on the semantically blocked list on recency and primary memory. Collectively, these results indicate that the pattern of memory performance is largely similar between patients with SCZ and those with RF lesions. These data support tentative arguments that verbal episodic memory deficits in SCZ may be mediated by frontal dysfunction in the right hemisphere.
Publisher: Springer Science and Business Media LLC
Date: 08-09-2018
Publisher: Wiley
Date: 22-12-2014
DOI: 10.1111/JNP.12056
Abstract: Recent models of schizophrenia suggest deficient use of contextual response cues when confronted with countermanding emotional cues. It is important to clinically validate these models by testing patients diagnosed with schizophrenia on tasks with competing emotional and contextual response determinants. Control and schizophrenia groups completed a novel task that elicited motor responses consistent with, or in opposition to, pre-potent emotional actions (i.e., approach vs. avoidance). An analogous non-emotional task was also used to examine cue-conflict impairment more generally. The groups demonstrated statistically equivalent performance decrements on incongruent versus congruent trials on both tasks. However, within the schizophrenia group, the incongruency effect was significantly greater in the emotional versus non-emotional task. These data suggest that, while patients with schizophrenia were able to employ contextual response cues to override competing emotional responses, they were slower to resolve emotional versus non-emotional response conflict. When patients were sub ided according to the presence or absence of disorganized symptoms, this effect was confined to patients with disorganized symptoms.
Publisher: Springer Science and Business Media LLC
Date: 08-2005
DOI: 10.1007/S10508-005-4344-7
Abstract: A s le of 404 adult men underwent assessment following illegal or clinically significant sexual behaviors or interests. Patients' assessments included: administration of a modified version of the Edinburgh Handedness Inventory recording of patients' phallometric (penile) responses to erotic stimuli depicting adults, pubescent children, and prepubescent children of both sexes and a tabulation of the numbers of patients' victims, ages 0-11, 12-14, 15-16, and 17 and older, of both sexes. In Study 1, patients' right-handedness scores correlated negatively with their phallometric responses to stimuli depicting prepubescent children and positively with stimuli depicting adults, replicating the pattern described in a previous report (Cantor et al., 2004). Unlike the previous study, however, patients' handedness scores did not significantly correlate with their numbers of prepubescent victims. To explore this discrepancy, Study 2 combined the patients from this replication s le with those in the previously reported s le, categorizing them by the sex and age group of greatest erotic interest to them. The odds of non-right-handedness in men offending predominantly against prepubescent children were approximately two-fold higher than that in men offending predominantly against adults and three-fold higher after eliminating those men with intrafamilial (i.e., incest) offenses. Handedness differences between men erotically interested in males versus females were not statistically significant. These results indicate that the rates of non-right-handedness in pedophilia are much larger than previously suggested and are comparable to the rates observed in pervasive developmental disorders, such as autism, suggesting a neurological component to the development of pedophilia and hebephilia.
Publisher: SAGE Publications
Date: 06-2023
DOI: 10.1177/00048674231175618
Abstract: We assessed the mental health effects of Australia’s 2019–2020 bushfires 12–18 months later, predicting psychological distress and positive psychological outcomes from bushfire exposure and a range of demographic variables, and seeking insights to enhance disaster preparedness and resilience planning for different profiles of people. We surveyed 3083 bushfire-affected and non-affected Australian residents about their experiences of bushfire, COVID-19, psychological distress (depression, anxiety, stress, post-traumatic stress disorder) and positive psychological outcomes (resilient coping, wellbeing). We found high rates of distress across all participants, exacerbated by severity of bushfire exposure. For people who were bushfire-affected, being older, having less financial stress, and having no or fewer pre-existing mental disorders predicted both lower distress and higher positive outcomes. Being male or having less income loss also predicted positive outcomes. Severity of exposure, higher education and higher COVID-19-related stressors predicted both higher distress and higher positive outcomes. Pre-existing physical health diagnosis and previous bushfire experience did not significantly predict distress or positive outcomes. To promote disaster resilience, we recommend investment in mental health, particularly for younger adults and for those in rural and remote areas. We also recommend investment in mechanisms to protect against financial distress and the development of a broader definition of bushfire-related impacts than is currently used to capture brushfires’ far-reaching effects.
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.SCHRES.2006.11.015
Abstract: Compliance with antipsychotic treatment is a well-recognized concern in the ongoing management of in iduals with schizophrenia. The present investigation incorporated the Medication Event Monitoring System (MEMS) to evaluate compliance in a group of outpatients (N=52) with schizophrenia or schizoaffective disorder. Evaluating compliance as a dichotomous variable and using a threshold of 80%, the rate of noncompliance as measured by MEMS was 52%, considerably higher than self-report (3%), clinician rating (24%) and pill count (25%). The ability of treating clinicians to predict compliance/noncompliance was limited: 13 of 31 (42%) subjects they rated as compliant were noncompliant while 4 of 9 (44%) rated as noncompliant were actually compliant according to MEMS. Factors most consistently associated with noncompliance were higher total symptom scores and dosing complexity i.e., greater than once daily. Based on MEMS data, the overall mean level of compliance was 66% however, it remains unclear as to what threshold is associated with a compromise in clinical response. More sophisticated measurement tools such as MEMS may assist us in better understanding how level and pattern of antipsychotic noncompliance, factors that at present remain poorly understood, impact on symptom exacerbation.
Publisher: Informa UK Limited
Date: 22-01-2008
DOI: 10.1080/13803390701300524
Abstract: Estimation of premorbid IQ in traumatic brain injury (TBI) is clinically and scientifically valuable because it permits the quantification of the cognitive impact of injury. This is achieved by comparing performances on tests of current ability to estimates of premorbid IQ, thereby enabling current capacity to be interpreted in light of preinjury ability. However, the validity of premorbid IQ tests that are commonly used for TBI has been questioned. In the present study, we examined the psychometric properties of a recently developed test, the Wechsler Test of Adult Reading (WTAR), which has yet to be examined for TBI. The cognitive performance of a group of 24 patients recovering from TBI (with a mean Glasgow Coma Scale score in the severely impaired range) was measured at 2 and 5 months postinjury. On both occasions, patients were administered three tests that have been used to measure premorbid IQ (the WTAR and the Vocabulary and Matrix Reasoning subtests of the Wechsler Adult Intelligence Scale 3rd Edition, WAIS-III) and three tests of current ability (Symbol Digit Modalities Test-Oral and Similarities and Block Design subtests of the WAIS-III). We found that performance significantly improved on tests of current cognitive ability, confirming recovery. In contrast, stable performance was observed on the WTAR from Assessment 1 (M = 34.25/50) to Assessment 2 (M = 34.21/50 r = .970, p < .001). Mean improvement across assessments was negligible (t = -0.086, p = .47 Cohen's d = -.005), and minimal in idual participant change was observed (modal scaled score change = 0). WTAR scores were also highly similar to scores on a demographic estimate of premorbid IQ. Thus, converging evidence--high stability during recovery from TBI and similar IQ estimates to those of a demographic equation suggests that the WTAR is a valid measure of premorbid IQ for TBI. Where word pronunciation tests are indicated (i.e., in patients for whom English is spoken and read fluently), these results endorse the use of the WTAR for patients with TBI.
Publisher: Elsevier BV
Date: 2003
DOI: 10.1016/S0091-3057(02)01028-6
Abstract: The effect of catecholamine depletion, achieved by per-oral administration of 5250 mg alpha-methyl-para-tyrosine (AMPT) given in the 29 h prior to [11C]raclopride positron emission tomography (PET) was studied on measures of dopamine (DA) release, mood, and attention. Neostriatal DA levels in vivo were estimated by comparing the neostriatal DA D(2) receptor binding potential (D(2)RBP) before and after catecholamine depletion using PET and the radiotracer [11C]raclopride. Six healthy subjects completed the protocol. The AMPT treatment increased D(2)RBP significantly by 13.3+/-5.9% (average+/-standard deviation) and decreased plasma levels of the DA metabolite homovanillic acid (HVA) by 62+/-17%, and levels of the norepinephrine (NE) metabolite 3-methoxy-4-hydroxyphenethyleneglycol (MHPG) by 66+/-5%. Catecholamine depletion resulted in decreased happiness, euphoria, energy, talkativeness, vigor, and attentiveness, and in increased sleepiness, fatigue, sedation, and eye blink rate (EBR). These changes were not correlated with the D(2)RBP increments. The results of this study are overall consistent with previous findings by our group using the same methodology in a different cohort of six healthy subjects.
Publisher: American Psychiatric Association Publishing
Date: 08-2001
DOI: 10.1176/APPI.AJP.158.8.1326
Abstract: The authors investigated the relationship between anxiety--a facet of the Revised NEO Personality Inventory dimension of neuroticism--and serotonin 5-HT(1A) receptor binding potential. Positron emission tomography with [(11)C]WAY-100635 was used to estimate regional 5-HT(1A) binding potential in 19 healthy volunteers who completed the Revised NEO Personality Inventory. Correlation coefficients were calculated to determine the degree of association between 5-HT(1A) binding potential and personality inventory measures. There was a significant negative correlation between 5-HT(1A) binding potential and anxiety in four regions: the dorsolateral prefrontal cortex, anterior cingulate cortex, parietal cortex, and occipital cortex. The inverse relationship between 5-HT(1A) receptor binding potential and anxiety is consistent with 1) animal models that have shown higher anxiety in mice lacking 5-HT(1A) receptors and 2) clinical trial data that have demonstrated antianxiety properties of partial 5-HT(1A) agonists.
Publisher: American Medical Association (AMA)
Date: 06-2010
Publisher: Elsevier BV
Date: 03-2019
Publisher: Informa UK Limited
Date: 18-07-2014
DOI: 10.1080/02699931.2014.935297
Abstract: Adaptive emotional responding relies on dual automatic and effortful processing streams. Dual-stream models of schizophrenia (SCZ) posit a selective deficit in neural circuits that govern goal-directed, effortful processes versus reactive, automatic processes. This imbalance suggests that when patients are confronted with competing automatic and effortful emotional response cues, they will exhibit diminished effortful responding and intact, possibly elevated, automatic responding compared to controls. This prediction was evaluated using a modified version of the face-vignette task (FVT). Participants viewed emotional faces (automatic response cue) paired with vignettes (effortful response cue) that signalled a different emotion category and were instructed to discriminate the manifest emotion. Patients made less vignette and more face responses than controls. However, the relationship between group and FVT responding was moderated by IQ and reading comprehension ability. These results replicate and extend previous research and provide tentative support for abnormal conflict resolution between automatic and effortful emotional processing predicted by dual-stream models of SCZ.
Publisher: Elsevier BV
Date: 07-2005
DOI: 10.1016/J.SCHRES.2005.01.009
Abstract: Clinicians frequently use a crossover approach in switching antipsychotics, although historically there has been a lack of data addressing the question of switch strategies. To establish if there is now empiric evidence that may guide clinicians in this regard, a MEDLINE search to April 2004 was carried out to identify published, randomized and controlled trials that have addressed this topic. A total of 404 articles were identified in the search, which resulted in the identification of four reports meeting the criteria. The four studies evaluated switching strategies to one of three atypical antipsychotics: aripiprazole, olanzapine (two reports), and ziprasidone. The switching process itself could be sub ided as follows: discontinuation (abrupt vs. gradual) and, replacement (abrupt vs. gradual). Meta-analyses confirmed a lack of difference in outcome, regardless of approach. While a crossover approach does not appear to increase adverse events, the available empiric evidence does not support its clinical superiority on various outcome measures. The existing data therefore argue against the position that a crossover approach in switching antipsychotics represents a 'safer' means of preventing clinical deterioration during the switch.
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.PSYCHRES.2019.05.032
Abstract: Spatial memory is core to wayfinding and everyday memory. Interestingly, in iduals with schizophrenia using spatial navigation strategies (cognitive mapping) are impaired, whereas those using response-based (e.g., single-landmark) strategies show relatively intact memory performance. We observed abnormal brain communication in schizophrenia participants who used a spatial strategy during a virtual-reality navigation task, particularly between temporal and frontal brain regions. In contrast, schizophrenia participants using a response strategy recruited similar brain systems to healthy participants, but to a greater extent to support memory performance. These findings highlight that strategy use is an important consideration for understanding memory systems and navigation in schizophrenia.
Publisher: Physicians Postgraduate Press, Inc
Date: 15-11-2002
DOI: 10.4088/JCP.V63N1106
Abstract: It has been suggested that transiently high dopamine-2 (D(2)) receptor occupancy by antipsychotic medication may be sufficient for inducing an antipsychotic response. We treated patients experiencing their first episode of schizophrenia with a single daily dose of quetiapine to achieve a transient daily peak of D(2) receptor blockade, to determine if this would lead to an antipsychotic response. Fourteen patients with a DSM-IV diagnosis of schizophrenia or schizophreniform or schizoaffective disorder were treated with quetiapine titrated to a single daily dose (mean +/- SD dose at the time of the positron emission tomography [PET] scan = 427 +/- 69 mg) for 12 weeks. Peak D(2) occupancy approximately 2 hours postdose and trough D(2) occupancy approximately 20 hours postdose were determined using PET and [(11)C]raclopride. Clinical symptoms and side effects were measured at baseline and every 2 weeks during the treatment phase. Quetiapine administration led to a mean peak D(2) occupancy of 62% +/- 10% 2 hours postdose, which declined to 14% +/- 8% approximately 20 hours postdose. Ten (71%) of 14 patients responded to treatment with quetiapine, scoring "much improved" or greater on the Clinical Global Impressions-Improvement scale. Plasma drug levels and peak D(2) occupancy were highly correlated (r = 0.84 p =.003), as were prolactin and plasma drug levels when measured 2.5 hours after drug administration (r = 0.60 p <.05). Mean weight gain for the 10 subjects who completed the 12-week study was 4.2 +/- 4.6 kg (9.3 +/- 10.2 lb). No clinically relevant motor side effects occurred during the trial. Patients with a first episode of schizophrenia responded to treatment with a single daily dose of quetiapine despite only transiently high D(2) receptor occupancy. Our findings raise the question of whether continuously high D(2) blockade is necessary for obtaining an antipsychotic response. Future studies aimed at evaluating the relative merits of "transiently high" versus "continuously high" D(2) occupancy are warranted.
Publisher: Oxford University Press (OUP)
Date: 08-2002
Abstract: The present study was designed to investigate the time-course of neural activity underlying the disruption of response monitoring in patients with schizophrenia. Event-related brain potentials were recorded from 12 patients with schizophrenia and from 12 age-matched controls while they performed a computerized version of the Stroop color-naming task. In control participants, but not in patients with schizophrenia, intrusion errors elicited an error-related negativity (ERN) that peaked at approximately 40 ms after the response and was maximum over the central region of the scalp. Brain electrical source analysis revealed an anterior cingulate generator for the ERN. Patients also showed reduced error-related slowing of response time following intrusion errors. These findings provide neuro-physiological evidence indicating that deficits in error monitoring in schizophrenia arise from a disruption of error-detection processes, possibly attributable to anterior cingulate dysfunction.
Publisher: Elsevier BV
Date: 11-2008
DOI: 10.1016/J.SCHRES.2008.05.031
Abstract: Cognitive control (CC), the capacity to flexibly direct resources to a goal by selecting and integrating relevant contextual information, is impaired among persons with schizophrenia-spectrum disorders. CC is achieved, in part, through shifting one's cognitive set towards stimuli of task relevance. Set-shifting deficits typically result in perseverative errors, like those captured by the Wisconsin Card Sorting Test (WCST). However, a disadvantage of the WCST is that it confounds the potential sources of perseverative errors. The Dimensional Change Card Sorting Task (DCCS), in contrast, allows for the decomposition of perseverative errors by systematically varying the shape and/or color of stimuli across pre-switch, switch and post-switch trials. Using these techniques previous research has evaluated the separable contributions of negative priming, positive priming, and extra dimensional shifting to the production of perseverative errors. In the current study, college students scoring high on the Schizotypal Personality Questionnaire (High-SPQ Raine, A., 1991. The SPQ: a scale for the assessment of schizotypal personality based on DSM-III-R criteria. Schizophr. Bull. 17 (4), 555-564.) and average scoring in iduals (Ave-SPQ) were administered the DCCS to investigate schizotypal-related mechanisms underlying set-shifting abnormalities. Relative to Ave-SPQ, High-SPQ participants showed more perseverative responses that were restricted to the positive priming post-switch condition. Possible mechanisms of this impairment, including depletion of cognitive resources and differences in strategy commitment, are discussed.
Publisher: Elsevier BV
Date: 09-2003
DOI: 10.1016/S0920-9964(02)00433-4
Abstract: Apathy is considered one of the negative symptoms of schizophrenia, but its natural history and relationship to other clinical characteristics have not been systematically studied. The purpose of this cross-sectional study was to measure the level of apathy in schizophrenia and its relation to other symptoms and functional outcome. Twenty-eight patients with schizophrenia, and receiving antipsychotic treatment, were assessed with the Apathy Evaluation Scale (AES). The mean level of apathy of patients with schizophrenia, as rated by the AES, was significantly higher than that of matched healthy control subjects. In the patients, apathy was not significantly correlated with positive symptoms or depressive symptoms. It was significantly correlated with the item "emotional withdrawal" on the negative subscale of the Positive and Negative Syndrome Scale (PANSS), but was not correlated with the overall negative subscale score. Apathy was more highly associated with functional outcome than were other symptom measures, and it was independently associated with functional outcome above and beyond other negative symptoms. It was not associated with observed interest in playing a video game or performance on a simulated clerical task.
Publisher: SAGE Publications
Date: 04-2000
DOI: 10.1177/070674370004500303
Abstract: To introduce and discuss an evolutionary model of frontal lobe functioning (the dual cytoarchitectonic trends theory [DTT]) and its application to understanding the neurobiology of schizophrenia and anxiety disorders. An introduction to the DTT with respect to neural architecture, connectivity, and function is presented. In addition, neurobiologic, neuropathologic, clinical, and cognitive research supporting the application of this model to schizophrenia and anxiety disorders is reviewed. Traditional neuropsychologic models of acquired brain damage have been limited in their ability to explain frontal lobe dysfunction and its consequences in relation to psychopathology. The DTT offers an appropriately general neural-systems framework that may be better able to account for the ersity of symptoms, widespread neuropathology, and developmental abnormalities that are associated with most forms of psychopathology. Research investigating the neurobiology of psychopathology would benefit from adopting models of brain dysfunction that are consistent with neurodevelopmental pathology and evolution. Such efforts would likely lead to a greater understanding of neurobiologic mechanisms and, ultimately, better treatment strategies.
Publisher: Elsevier BV
Date: 08-2011
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.APMR.2008.10.002
Abstract: To ascertain patterns of cognitive recovery during the first year after traumatic brain injury (TBI). Specifically, differential recovery across cognitive domains was investigated. Prospective, longitudinal, naturalistic, 1-year follow-up study. Large, urban inpatient neurorehabilitation program. Patients (N=75) with moderate to severe TBI. Not applicable. Patients with TBI were followed over the course of 1 year, during which participants' neuropsychological status was repeatedly evaluated at 3 time points (2, 5, and 12 months postinjury). Multilevel modeling results were consistent with previous research, demonstrating that recovery in the first year postinjury is asymptotic in nature, with more accelerated recovery occurring during the first 5 to 6 months. Importantly, results also suggest that recovery is not uniform across cognitive domains. From 2 to 5 months postinjury, steeper recovery curves were revealed for indices of memory, speeded executive function, verbal abstraction, and manual dexterity relative to untimed tests of executive function and word knowledge. Recovery trajectories did not significantly vary as a function of cognitive domain over the course of the last 5 to 12 months. These results are the first to explore trajectories of recovery directly as a function of multiple cognitive domains. They are expected to have implications for rehabilitative efforts as well as our understanding of the architecture of natural recovery after TBI.
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.PSYCHRES.2022.114817
Abstract: The aim of the study was to measure and compare prejudice towards people with specific mental illnesses between mental health professionals and the general population, and examine personality, ideological, and attitudinal antecedents of prejudice. To do so, we also aimed to validate three shortened scales of prejudice. A s le of mental health professionals (N = 299) and a s le from the general population (N = 427) completed shortened versions of the Prejudice towards People with Mental Illness, Prejudice towards People with Schizophrenia, and Prejudice towards People with Depression scales. They also completed measures of validity criteria and demographics. The scales demonstrated construct validity in both s les. Although prejudice was highest towards people with schizophrenia and lowest towards people with depression, mental health professionals demonstrated significantly less prejudice overall than the general population. Prejudice was associated with higher social dominance orientation, right wing authoritarianism, ethnocentrism, conservatism, and generalized prejudice, and lower agreeableness, openness to experience, and contact. These antecedents of prejudice were better predictors than any demographic or profession-related variables examined. This study contributes increased knowledge of the structure and correlates of prejudice towards people with mental disorders. This knowledge should inform more nuanced and effective interventions, therapy, and training.
Publisher: American Psychological Association (APA)
Date: 07-2005
DOI: 10.1037/0033-2909.131.4.555
Abstract: General intelligence has been the most commonly studied neuropsychological characteristic of sexual offenders for over 70 years. Results, however, have been highly inconsistent. To assess whether sexual offenders score lower in IQ than nonsexual offenders and to explore which sexual offense characteristics relate to IQ, the authors reanalyzed all reports providing sufficient information. Data spanned 236 s les, comprising 25,146 sexual offenders and controls. The literature contained sufficient information to permit comparison of adult versus juvenile sexual offenders, offenders targeting children versus adults, offenders targeting their own versus unrelated children, and offenders targeting boys versus girls. Results confirm the association between IQ and sexual offending and suggest that previous discrepancies are attributable to how many pedophilic in iduals were in each s le.
Publisher: Elsevier BV
Date: 04-2001
Abstract: Anorexia nervosa (AN) is one of the most common chronic illnesses afflicting adolescent girls and is associated severe medical complications. The structural abnormalities found in the brain of adolescents with AN are among the earliest and most striking physical consequences. In the past, it had been assumed that the brain abnormalities found in patients with AN reverse with weight-recovery. Recent evidence has shown that not all of these changes are completely reversible with weight recovery. To date, very little is known about the functional significance of these brain abnormalities. Several studies have shown that cognitive dysfunction is also a common feature of AN. Although current evidence suggests that there may be some degree of improvement in cognition with weight-recovery, it is unclear whether cognition recovers fully or equally across all neuropsychological domains. Furthermore, it remains unknown whether the reported functional consequences are associated with these structural brain changes. This article will review the current literature on structural brain abnormalities and cognitive dysfunction in adolescents with AN.
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.SCHRES.2010.11.018
Abstract: Substitution tests are sensitive to cognitive impairment and reliably discriminate patients with schizophrenia from healthy in iduals better than most other neuropsychological instruments. However, due to their multifaceted nature, substitution test scores cannot pinpoint the specific cognitive deficits that lead to poor performance. The current study investigated eye movements during performance on a substitution test in order to better understand what aspect of substitution test performance underlies schizophrenia-related impairment. Twenty-five patients with schizophrenia and 25 healthy in iduals performed a computerized version of the Symbol Digit Modalities Test while their eye movements were monitored. As expected, patients achieved lower overall performance scores. Moreover, analysis of participants' eye movements revealed that patients spent more time searching for the target symbol every time they visited the key area. Patients also made more visits to the key area for each response that they made. Regression analysis suggested that patients' impaired performance on substitution tasks is primarily related to a less efficient visual search and, secondarily, to impaired memory.
Publisher: American Psychological Association (APA)
Date: 05-2010
DOI: 10.1037/A0018313
Abstract: Enhanced understanding of cognitive deficits, and the neurobiological abnormalities that mediate them, can be achieved through translational research that employs comparable experimental approaches across species. This study employed a multiple-systems framework derived from the rodent literature to investigate visual-spatial memory abilities associated with schizophrenia. Using the bin task, a human analog of rodent maze tasks, everyday objects were hidden in visually identical bins. Following a 1-min filled delay, participants with schizophrenia-spectrum disorders (n = 30) and healthy community controls (n = 30) were asked to identify both the object hidden and bin used on the basis of its spatial location. Three dimensions of visual-spatial memory were contrasted: (a) memory for spatial locations versus memory for objects, (b) allocentric (viewpoint independent) versus egocentric (body-centered) spatial representations, and (c) event (working) memory versus reference memory. Most pronounced was a differential deficit in memory for spatial locations under allocentric (p = .005, d = -0.77) but not egocentric viewing conditions (p = .298, d = -0.28) in the schizophrenia group relative to healthy controls. Similarly, schizophrenia-related spatial memory deficits were pronounced under demands for event memory (p = .004, d = -0.77) but not reference memory (p = .171, d = -0.33). These results support a heuristic of preferential deficits in hippoc al-mediated forms of memory in schizophrenia. Moreover, the task provides a useful paradigm for translational research and the pattern of deficits suggests that persons with schizophrenia may benefit from mnemonic approaches favoring egocentric representations and consistency when interacting with our visual-spatial world.
Publisher: Elsevier BV
Date: 2006
DOI: 10.1016/J.BIOPSYCH.2005.06.022
Abstract: Neurocognitive deficits are severe in first-episode psychosis. Patients (N = 263) with first-episode psychosis (schizophrenia, schizoaffective, or schizophreniform disorders) were randomly assigned to double-blind treatment with olanzapine (mean 11.30 mg/day) or haloperidol (mean 4.87 mg/day) for 104 weeks. A neurocognitive battery was administered at baseline (n = 246) and 12 (n = 167), 24 (n = 126), 52 (n = 89), and 104 (n = 46) weeks during treatment. Weighted principal component and unweighted composite scores were derived from in idual tests. Both treatment groups demonstrated significant improvement on both composite scores. On the basis of the weighted composite score, olanzapine had greater improvement than haloperidol only at 12 (p = .014) and 24 (p = .029) weeks. For the unweighted composite, olanzapine had significantly better improvement compared with haloperidol only at week 12 (p = .044). At week 12 only, olanzapine improved performance on the Digit Symbol and Continuous Performance Test significantly more than haloperidol. Both antipsychotic agents appeared to improve neurocognitive functioning among first-episode psychosis patients with schizophrenia. A significantly greater benefit in terms of neurocognitive improvement was found with olanzapine than with haloperidol at weeks 12 and 24.
Publisher: American Psychiatric Association Publishing
Date: 02-2016
DOI: 10.1176/APPI.PS.201400306
Abstract: Early intervention services (EISs) for mental illness may improve outcomes, although treatment engagement is often a problem. Incorporating patients' preferences in the design of interventions improves engagement. A discrete-choice conjoint experiment was conducted in Canada to identify EIS attributes that encourage treatment initiation. Sixteen four-level attributes were formalized into a conjoint survey, completed by patients, family members, and mental health professionals (N=562). Participants were asked which EIS option people with mental illness would contact. Latent-class analysis identified respondent classes characterized by shared preferences. Randomized first-choice simulations predicted which hypothetical options, based on attributes, would result in maximum utilization. Participants in the conventional-service class (N=241, 43%) predicted that in iduals would contact traditional services (for ex le, hospital location and staffed by psychologists or psychiatrists). Membership was associated with being a patient or family member and being male. Participants in the convenient-service class (N=321, 57%) predicted that people would contact services promoting easy access (for ex le, self-referral and access from home). Membership was associated with being a professional. Both classes predicted that people would contact services that included short wait times, direct contact with professionals, patient autonomy, and psychological treatment information. The convenient-service class predicted that people would use an e-health model, whereas the conventional-service class predicted that people would use a primary care or clinic-hospital model. Provision of a range of services may maximize EIS use. Professionals may be more apt to adopt EISs in line with their beliefs regarding patient preferences. Considering several perspectives is important for service design.
Publisher: American Academy of Pediatrics (AAP)
Date: 08-2008
Abstract: OBJECTIVE. Abnormalities in cognitive function and brain structure have been reported in acutely ill adolescents with anorexia nervosa, but whether these abnormalities persist or are reversible in the context of weight restoration remains unclear. Brain structure and cognitive function in female subjects with adolescent-onset anorexia nervosa assessed at long-term follow-up were studied in comparison with healthy female subjects, and associations with clinical outcome were investigated. PATIENTS AND METHODS. Sixty-six female subjects (aged 21.3 ± 2.3 years) who had a diagnosis of adolescent-onset anorexia nervosa and treated 6.5 ± 1.7 years earlier in a tertiary care hospital and 42 healthy female control subjects (aged 20.7 ± 2.5 years) were assessed. All participants underwent a clinical examination, magnetic resonance brain scan, and cognitive evaluation. Clinical data were analyzed first as a function of weight recovery (n = 14, & % ideal body weight n = 52, ≥85% ideal body weight) and as a function of menstrual status (n = 18, absent/irregular menses n = 29, oral contraceptive pill n = 19, regular menses). Group comparisons were made across structural brain volumes and cognitive scores. RESULTS. Compared with control subjects, participants with anorexia nervosa who remained at low weight had larger lateral ventricles. Twenty-four–hour urinary free-cortisol levels were positively correlated with volumes of the temporal horns of the lateral ventricles and negatively correlated with volumes of the hippoc i in clinical participants. Participants who were amenorrheic or had irregular menses showed significant cognitive deficits across a broad range of many domains. CONCLUSIONS. Female subjects with adolescent-onset anorexia nervosa showed abnormal cognitive function and brain structure compared with healthy in iduals despite an extended period since diagnosis. To our knowledge, this is the first study to report a specific relationship between menstrual function and cognitive function in this patient population. Possible mechanisms underlying neural and cognitive deficits with anorexia nervosa are discussed. Additional examination of the effects of estrogen on cognitive function in female subjects with anorexia nervosa is necessary.
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.BRAINRESREV.2007.09.006
Abstract: Dysfunctional cortical inhibition (CI) has been suggested as a mechanism through which symptoms of schizophrenia (SCZ) are mediated. Cortical inhibition refers to a neurophysiological process in which gamma-aminobutyric acid (GABA) inhibitory interneurons selectively attenuate the activity of other neurons (e.g., pyramidal neurons) in the cortex. Here we review the neuroanatomic and neurophysiological evidence suggesting CI deficits among persons with SCZ. We also review genetic studies that have linked CI deficits to a polymorphism in the alpha(7)-nicotinic cholinergic receptor, thereby positing that a specific genetic mechanism underlies SCZ-related GABA interneuron dysfunction. We will conclude by reviewing the role of CI as a mechanism mediating the therapeutic action of antipsychotic medications.
Publisher: Elsevier BV
Date: 04-2004
Publisher: American Geophysical Union (AGU)
Date: 08-2019
DOI: 10.1029/2019PA003652
Publisher: Springer Science and Business Media LLC
Date: 2002
Abstract: The present study investigated whetherhead injuries in childhood might increase the risk of pedophilia in males. The subjects were 1206 patients referred to a clinical sexology service for assessment of their erotic preferences. These were classified, on the basis of phallometric test results, as pedophilic (n = 413) or nonpedophilic (n = 793). Information regarding early head injuries, other signs of possible neurodevelopmental problems, and parental histories of psychiatric treatment were collected with self-administered questionnaires. The results showed that childhood accidents that resulted in unconsciousness were associated with pedophilia and with lower levels of intelligence and education. These associations were statistically significant for accidents that occurred before the age of 6, but not for accidents that occurred between the ages of 6 and 12. These results are compatible with the hypothesis that neurodevelopmental perturbations in early childhood may increase the risk of pedophilia. They are also, however, compatible with the alternative explanation that prior neurodevelopmental problems lead to accident-proneness and head injury, on the one hand, and to pedophilia, on the other, and that head injury has no causal influence on pedophilia. A secondary finding was that the pedophiles were more likely to report that their mothers had undergone psychiatric treatment. This finding suggests that pedophilia may be influenced by genetic factors, which are manifested in women as an increased risk of psychiatric problems, and in their sons, as an increased risk of erotic interest in children.
Publisher: Wiley
Date: 08-2002
DOI: 10.1113/JPHYSIOL.2002.017673
Abstract: Transcranial magnetic stimulation can be used to non-invasively study inhibitory processes in the human motor cortex. Interhemispheric inhibition can be measured by applying a conditioning stimulus to the motor cortex resulting in inhibition of the contralateral motor cortex. Transcranial magnetic stimulation can also be used to demonstrate ipsilateral cortico-cortical inhibition in the motor cortex. At least two different ipsilateral cortico-cortical inhibitory processes have been identified: short interval intracortical inhibition and long interval intracortical inhibition. However, the relationship between interhemispheric inhibition and ipsilateral cortico-cortical inhibition remains unclear. This study examined the relationship between interhemispheric inhibition, short interval intracortical inhibition and long interval intracortical inhibition. First, the effect of test stimulus intensity on each inhibitory process was studied. Second, the effects of interhemispheric inhibition on short interval intracortical inhibition and long interval intracortical inhibition on interhemispheric inhibition were examined. Motor evoked potentials were recorded from the right first dorsal interosseous muscle in 11 right-handed healthy volunteers. For interhemispheric inhibition, conditioning stimuli were applied to the right motor cortex and test stimuli to the left motor cortex. For short interval intracortical inhibition and long interval intracortical inhibition, both conditioning stimuli and test stimuli were applied to the left motor cortex. With increasing test stimulus intensities, long interval intracortical inhibition and interhemispheric inhibition decreased, while short interval intracortical inhibition increased. Moreover, short interval intracortical inhibition was significantly reduced in the presence of interhemispheric inhibition. Interhemispheric inhibition was significantly reduced in the presence of long interval intracortical inhibition when matched for test motor evoked potential litude but the difference was not significant when matched for test pulse intensity. These findings suggest that both interhemispheric inhibition and long interval intracortical inhibition are predominately mediated by low threshold cortical neurons and may share common inhibitory mechanisms. In contrast, the mechanisms mediating short interval intracortical inhibition are probably different from those mediating long interval intracortical inhibition and interhemispheric inhibition although these systems appear to interact.
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.CLINPH.2012.09.029
Abstract: Elicited by any meaningful stimulus, the N400 event-related potential (ERP) component is reduced when the stimulus is related to a preceding one. This N400 semantic priming effect has been used to probe abnormal semantic relationship processing in clinical disorders, and suggested as a possible biomarker for treatment studies. Validating N400 semantic priming effects as a clinical biomarker requires characterizing their test-retest reliability. We assessed test-retest reliability of N400 semantic priming in 16 healthy adults who viewed the same related and unrelated prime-target word pairs in two sessions one week apart. As expected, N400 litudes were smaller for related versus unrelated targets across sessions. N400 priming effects ( litude differences between unrelated and related targets) were highly correlated across sessions (r=0.85, P<0.0001), but smaller in the second session due to larger N400s to related targets. N400 priming effects have high reliability over a one-week interval. They may decrease with repeat testing, possibly because of motivational changes. Use of N400 priming effects in treatment studies should account for possible magnitude decreases with repeat testing. Further research is needed to delineate N400 priming effects' test-retest reliability and stability in different age and clinical groups, and with different stimulus types.
Publisher: Springer Science and Business Media LLC
Date: 05-2001
Publisher: Springer Science and Business Media LLC
Date: 09-05-2006
DOI: 10.1007/S00221-006-0472-0
Abstract: It has been suggested that the therapeutic effects of repetitive transcranial magnetic stimulation (rTMS) are mediated through changes in cortical inhibition (CI). However, in healthy human subjects the effects of rTMS on CI have been inconsistent. Therefore, this study sought to improve on the methodological limitations of previous studies by exploring several different rTMS-stimulus conditions on inhibition in the human motor cortex. In the first experiment, 12 healthy control subjects were randomly assigned to receive regular 1, 10 or 20 Hz rTMS in a counterbalanced order with sessions separated by at least 1 week. In the second experiment, 10 of these 12 subjects received priming rTMS (600 stimuli at 6 Hz followed by 600 stimuli at 1 Hz). Cortical inhibition was indexed using short-interval intracortical inhibition (SICI) and cortical silent period (CSP). Corticospinal excitability was indexed using motor threshold and MEP litude. We found no significant overall change in SICI, although there was a significant correlation between changes in SICI with baseline SICI. Subjects with greater SICI at baseline tended to have reduction in SICI post-rTMS, whereas subjects with less SICI tended to have increase in SICI post-rTMS. There was also a significant lengthening of the CSP with higher stimulation frequencies compared to lower stimulation frequencies. These findings suggest that rTMS increases CI, particularly in subjects with reduced baseline inhibition, a finding consistent with the concept of homeostatic plasticity. Baseline physiological characteristics may be further explored as a method to select patients who may benefit from rTMS treatment.
Publisher: Annual Reviews
Date: 03-01-2018
DOI: 10.1146/ANNUREV-MARINE-121916-063242
Abstract: Climate sensitivity represents the global mean temperature change caused by changes in the radiative balance of climate it is studied for both present/future (actuo) and past (paleo) climate variations, with the former based on instrumental records and/or various types of model simulations. Paleo-estimates are often considered informative for assessments of actuo-climate change caused by anthropogenic greenhouse forcing, but this utility remains debated because of concerns about the impacts of uncertainties, assumptions, and incomplete knowledge about controlling mechanisms in the dynamic climate system, with its multiple interacting feedbacks and their potential dependence on the climate background state. This is exacerbated by the need to assess actuo- and paleoclimate sensitivity over different timescales, with different drivers, and with different (data and/or model) limitations. Here, we visualize these impacts with idealized representations that graphically illustrate the nature of time-dependent actuo- and paleoclimate sensitivity estimates, evaluating the strengths, weaknesses, agreements, and differences of the two approaches. We also highlight priorities for future research to improve the use of paleo-estimates in evaluations of current climate change.
Publisher: Hogrefe Publishing Group
Date: 2012
DOI: 10.1027/0227-5910/A000110
Abstract: Background: Our laboratory recently confronted this issue while conducting research with undergraduate students at the University of Waterloo (UW). Although our main objective was to examine cognitive and genetic features of in iduals with schizotypal personality disorder (SPD), the study protocol also entailed the completion of various self-report measures to identify participants deemed at increased risk for suicide. Aims and Methods: This paper seeks to review and discuss the relevant ethical guidelines and legislation that bear upon a psychologist’s obligation to further assess and intervene when research participants reveal that they are at increased risk for suicide. Results and Conclusions: In the current paper we argue that psychologists are ethically impelled to assess and appropriately intervene in cases of suicide risk, even when such risk is revealed within a research context. We also discuss how any such obligation may potentially be modulated by the research participant’s expectations of the role of a psychologist, within such a context. Although the focus of the current paper is on the ethical obligations of psychologists, specifically those practicing within Canada, the relevance of this paper extends to all regulated health professionals conducting research in nonclinical settings.
Publisher: Cambridge University Press (CUP)
Date: 19-03-2013
DOI: 10.1017/S0033291713000445
Abstract: Several psychological and neurobiological models imply that patients with schizophrenia (SCZ) are more inclined to utilize emotional cues as response determinants to the detriment of more task-appropriate cognitive or contextual cues. However, there is a lack of behavioural data from human clinical studies to support this assertion. Therefore, it is important to evaluate the performance of persons with SCZ using tasks designed to index the resolution between competing emotional and cognitive determinants of goal-directed behaviour. The current study employed a list-method, emotional directed-forgetting (DF) paradigm designed to invoke inhibitory mechanisms necessary to override emotional memory enhancement for successful task completion. Four psycholinguistically matched lists were constructed that were comprised of five negative, five positive, and five neutral words. Compared with healthy controls, in iduals with SCZ showed a reduced DF effect overall. When broken down according to valence, this effect was only observed for negative words, which, in turn, resulted from reduced forgetting of list 1 words following the forget cue. These results indicate that in iduals with SCZ were less able to engage strategic inhibitory mechanisms for the purpose of overriding recall of negative stimuli when tasks demand call for such action. Thus, our data support the theoretical assertion that SCZ patients have difficulty utilizing cognitive or contextual cues as determinants of goal-directed behaviour in the face of countermanding emotional cues.
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.SCHRES.2006.03.033
Abstract: Blocking dopamine (DA) D(2) receptors is the sine qua non of antipsychotic activity. However, it is this same process that accounts for their liability to produce extrapyramidal symptoms (EPS) and hyperprolactinemia. It remains unclear, though, whether there are other negative consequences that might result from DA D(2) blockade. For ex le, previous research has demonstrated a robust relationship between DA and both cognition and mood. The present study was designed to evaluate the impact of DA D(2) antagonism on each of these domains. Healthy participants (N = 59) were randomized to receive a single oral dose of 1, 3 or 5 mg of haloperidol or placebo. Participants were tested on cognitive and mood measures at baseline, 4 and 24 h post-administration of medication. In terms of cognition, the greatest negative impact was on sustained attention, reaction time and speed of information processing, with the effect on sustained attention reaching statistical significance. For mood, the greatest negative impact occurred on measures of contentment, anger and confusion, with the effect on contentment reaching statistical significance. Global effects for both cognition and mood domains were greatest at 4 h post-administration of haloperidol and dose-dependent. The present results suggest that DA D(2) blockade, as induced by haloperidol, produces important deficits that extend beyond motor or endocrine changes.
Publisher: Wiley
Date: 29-10-2021
DOI: 10.1002/EAT.23634
Abstract: Self‐worth contingent on shape/weight is a diagnostic criterion and key maintaining factor for eating disorders. However, the role of other contingencies of self‐worth (i.e., domains in which self‐worth is invested) is largely unknown. Moreover, research has relied on self‐ratings of contingency strength, which are subject to distortion through socially desirable responding and limited self‐awareness, and may have limitations in terms of ecological validity. To overcome these limitations, the present study investigated a broad range of contingencies of self‐worth in relation to eating disorder pathology and employed a choice‐based conjoint (CBC) approach for assessing these contingencies. Young women and men from the community ( N = 428) completed a CBC task to assess the domains in which self‐worth is invested, the Eating Disorder Examination Questionnaire (EDE‐Q) to assess eating disorder symptomatology, and the Balanced Inventory of Desirable Responding to assess socially desirable responding. Beta regression analyses showed that CBC thinness and athletic competence predicted higher scores on all EDE‐Q scales. CBC muscularity and facial attractiveness predicted higher scores, while coping ability and quality of relationships predicted lower scores, on various aspects of eating disorder symptoms. CBC social acceptance predicted lower eating disorder symptoms in males only. The findings suggest that a broader range of contingencies of self‐worth beyond shape/weight are relevant to eating disorder pathology and should be considered as potential underlying mechanisms and treatment targets. In addition, this first use of the CBC method in eating disorder research provides initial support for its validity and utility.
Publisher: American Psychological Association (APA)
Date: 03-2008
DOI: 10.1037/1040-3590.20.1.76
Abstract: The correlation between a short-form (SF) test and its full-scale (FS) counterpart is a mainstay in the evaluation of SF validity. However, in correcting for overlapping error variance in this measure, investigators have overattenuated the validity coefficient through an intuitive misapplication of P. Levy's (1967) formula. The authors of the present article clarify that such corrections should be based on subtest-level versus FS-level data. Additionally, the authors propose a simple, modified equation incorporating FS-level scores that provides liberal and conservative validity measures for comparison across estimation methods, and they demonstrate its use in both a normative (N = 2,450) and clinical psychiatric (N = 216) s le.
Publisher: Informa UK Limited
Date: 06-10-2018
Publisher: Elsevier BV
Date: 12-2004
Publisher: Springer Science and Business Media LLC
Date: 11-07-2012
Publisher: Springer Science and Business Media LLC
Date: 13-07-2002
DOI: 10.1007/S00213-002-1166-3
Abstract: Bupropion is thought to treat major depression by blocking the dopamine transporter (DAT) because bupropion appears to have a selective affinity for the DAT. The validity of this mechanism has been questioned because the affinity of bupropion for the DAT is quite low. To determine the occupancy of bupropion for the DAT during clinical treatment of patients with depression. Positron emission tomography with [(11)C]-RTI32 was used to determine the striatal DAT binding potential (BP) of eight depressed patients before and during treatment with bupropion. BP is proportional to available receptor density (receptors not blocked by drug). Occupancy is the percent change in BP. Eight healthy subjects were similarly studied in a test-retest design. No significant difference in DAT BP was found after bupropion treatment in comparison to the test-retest data. The occupancy after bupropion treatment was 14% (confidence interval 6-22%) as compared to 7% in the test-retest condition. Bupropion treatment occupies less than 22% of DAT sites. This raises the question as to whether a DAT occupancy of less than 22% is therapeutic or whether there is another mechanism involved during treatment with bupropion.
Publisher: Springer Science and Business Media LLC
Date: 07-08-2003
DOI: 10.1007/S00213-003-1548-1
Abstract: Previous studies suggest that antipsychotic medications may alter cortical inhibition (CI). The current study was designed to determine if typical or atypical antipsychotics indeed alter CI in healthy subjects using three CI paradigms as measured with transcranial magnetic stimulation (TMS): short interval intracortical inhibition (SICI), cortical silent period (CSP) and transcallosal inhibition (TCI). CI was measured before, 6 and 24 h after being randomly assigned to receive a single dose of 2 mg haloperidol (n=8), 10 mg olanzapine (n=10) or placebo (n=9). There was no significant effect on any measure of CI at 6 and 24 h after receiving olanzapine, haloperidol or placebo. Moreover, no significant change in the motor threshold was observed across the three medication groups. Therefore, single administration of an antipsychotic has no effect on CI or resting motor threshold. Whether chronic, repeated administration of antipsychotics has effects on CI requires further investigation.
Publisher: SAGE Publications
Date: 12-1992
DOI: 10.2466/PR0.1992.71.3.745
Abstract: 66 cognitively intact geriatric medical patients (ages 70 to 99 M = 77 yr.) were given the Logical Memory subtests of the Wechsler Memory Scale—Revised to extend normative data. 43 women and 23 men, 35 white and 31 black persons made up this urban geriatric s le. A review of patients' medical histories and Mattis' Dementia Rating scores of 129 or greater were used to ensure a s le of cognitively intact patients. Analyses showed that Logical Memory scores were uncorrelated with education, race, sex, or age.
Publisher: Informa UK Limited
Date: 31-05-2018
DOI: 10.1080/13546805.2018.1479248
Abstract: Introduction Working-memory (WM) is a core cognitive deficit among in iduals with Schizophrenia Spectrum Disorders (SSD). However, the underlying cognitive mechanisms of this deficit are less known. This study applies a modified version of the Corsi Block Test to investigate the role of proactive interference in visuospatial WM (VSWM) impairment in SSD. Methods Healthy and SSD participants completed a modified version of the Corsi Block Test involving both high (typical ascending set size from 4 to 7 items) and low (descending set size from 7 to 4 items) proactive interference conditions. Results The results confirmed that the SSD group performed worse overall relative to a healthy comparison group. More importantly, the SSD group demonstrated greater VSWM scores under low (Descending) versus high (Ascending) proactive interference this pattern is opposite to that of healthy participants. Conclusions This differential pattern of performance supports that proactive interference associated with the traditional administration format contributes to VSWM impairment in SSD. Further research investigating associated neurocognitive mechanisms and the contribution of proactive interference across other domains of cognition in SSD is warranted.
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.IJPSYCHO.2015.01.006
Abstract: Recent research has shown that patients with schizophrenia (SCZ) exhibit reduced directed forgetting (DF) for negative words, suggesting impaired ability to instantiate goal-directed inhibition in order to suppress a competing, emotion-driven responses (i.e., emotional memory enhancement). However, disrupted inhibition is not the only possible mechanism by which patients could manifest reduced emotional DF. Therefore, the primary objective of the current study was to use event-related brain potential (ERP) recordings to investigate alternative hypotheses. ERPs were recorded while patients and controls completed an item-method DF paradigm using negative and neutral words. The N2 indexed goal-directed inhibition of to-be-forgotten items. The late positive potential (LPP) indexed emotional memory enhancement for negative study items. The P300 indexed selective rehearsal of to-be-remembered items. The SCZ group exhibited a reduced DF effect overall, but this was not modulated by emotion. N2 litude at anterior sites was larger for forget versus remember cues in the control group only, but this effect was not modulated by emotion. LPP litude was greater for negative versus neutral words in both groups, independent of region. P300 litude at posterior sites was greater for remember versus forget cues in the control group only. These data suggest that reduced DF in SCZ may be due, in part, to both diminished goal-directed inhibition of to-be-forgotten items and reduced selective rehearsal of to-be-remembered items. However, these data do not support the hypothesis that goal-directed, inhibitory processes are disrupted by competing, emotion-driven processes in SCZ. Patients' ERP data also suggested that they did not exhibit disproportionately heightened encoding of emotional stimuli, nor did they have deficient selective rehearsal of to-be-remembered emotional items.
Publisher: Springer Science and Business Media LLC
Date: 02-12-2020
Publisher: American Psychological Association (APA)
Date: 04-2022
DOI: 10.1037/EMO0000764
Abstract: One of the fundamental factors maintaining social anxiety is biased attention toward threatening facial expressions. Typically, this bias has been conceptualized as driven by an overactive bottom-up attentional system however, this potentially overlooks the role of top-down attention in being able to modulate this bottom-up bias. Here, the role of top-down mechanisms in directing attention toward emotional faces was assessed with a modified dot-probe task, in which participants were given a top-down cue ("happy" or "angry") to attend to a happy or angry face on each trial, and the cued face was either presented with a face of the other emotion (angry, happy) or a neutral face. This study found that social anxiety was not associated with differences in shifting attention toward cued angry faces. However, participants with higher levels of social anxiety were selectively impaired in attentional shifting toward a cued happy face when it was paired with an angry face, but not when paired with a neutral face. The results indicate that top-down attention can be used to orient attention to emotional faces, but that higher levels of social anxiety are associated with selective deficits in top-down control of attention in the presence of threat. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Publisher: Elsevier BV
Date: 07-2005
DOI: 10.1016/J.JPSYCHIRES.2004.10.001
Abstract: Magnetic resonance imaging (MRI) studies measuring basal ganglia volumes in first episode patients suggest that treatment with typical neuroleptics leads to alteration in these brain structures. However, caudate nuclei volumes (CNV) of untreated first-episode patients may even be smaller than in healthy controls. We investigated whether CNV of newly diagnosed neuroleptic-naive psychotic patients differ as compared to an age- and sex-matched healthy control group to detect possible treatment effects early in the course of this illness. Magnetic resonance images were acquired in 37 un-medicated psychotic patients and 37 healthy controls. Ten of the patients were re-examined after 12 weeks of treatment with the second generation antipsychotic quetiapine. Regions of interest (ROI) delineating the caudate nuclei bilaterally were drawn manually using Brain Image software. The neuroleptic-naive patients showed a mean CNV of 8.40 cc (SD=1.01) and the controls of 8.55 cc (SD=1.16). There was no significant difference between groups (F=.600 P=.441). In contrast to previous studies in patients treated with typical neuroleptics, this cross-sectional MRI study did not find significant differences in CNV of neuroleptic-naive first-episode patients compared to healthy controls.
Publisher: Oxford University Press (OUP)
Date: 09-2001
Abstract: To investigate the effects of the home environment, socioeconomic status (SES), and health status on cognitive functioning in a s le of children with HIV-1 infection in a cross-sectional study. Forty-three caregivers and their children (2.5 to 12 years) participated. Caregivers completed two self-report measures of the home environment that included questions regarding the organization of the environment, play materials, parental involvement, variety of stimulation, and parental attitudes toward the provision of a cognitively stimulating environment. Cognitive functioning was assessed using a standardized intelligence (IQ) test. Children's medical charts were reviewed for HIV-1 classification status (CDC, 1994), CD4 cell counts, and current medication. This study revealed two primary findings. First, measures of the home environment mediated the association between SES and child IQ. Second, measures of the home environment had a stronger association with child IQ during the advanced stages of disease than earlier stages of disease. The home environment is associated with cognitive functioning among children with HIV-1 infection. Moreover, interventions aimed at enhancing the quality of the home environment may have a positive impact on these children's cognitive development.
Publisher: Elsevier BV
Date: 12-2006
DOI: 10.1016/J.SCHRES.2006.06.041
Abstract: Clinically defined prodromal diagnostic criteria identify at-risk in iduals with a 35-40% likelihood of developing a psychotic disorder within a year. The time course and predictive value of cognitive deficits in the development of psychosis has not been established. A comprehensive neurocognitive battery and clinical assessments were administered to 37 subjects meeting Criteria of Prodromal States (COPS) criteria for being at risk for psychosis, and two comparison groups: 59 first episode and 47 healthy subjects. Subjects were also evaluated at 6-month and 1-year follow-up periods. Primary analyses used a neurocognitive composite score derived from in idual neurocognitive measures, including measures of vigilance, verbal memory, working memory, and processing speed. At-risk subjects performed more poorly than healthy subjects (t=2.93, P=0.01), but better than first episode subjects (t=4.72, p<0.0001). At-risk subjects were particularly impaired on measures of vigilance and processing speed. Cognitive composite scores were significantly lower in at-risk subjects who progressed to psychosis (N=11 z=-1.2), while those at-risk subjects who did not progress to psychosis (N=17) performed better (z=-0.5), and not significantly different from controls. Poor CPT performance combined with better WAIS-R digit symbol performance predicted progression to psychosis. Severity of neurocognitive deficits was not related to duration of prodrome or to time to development of psychosis and neurocognitive function improved in all subjects except those who progressed to psychosis. Neurocognitive impairment emerges early in the course of psychotic illness. Performance on tests of neurocognition may prove to be an early risk predictor for subsequent development of psychotic disorders.
Publisher: Cold Spring Harbor Laboratory
Date: 28-09-2022
DOI: 10.1101/2022.09.27.509805
Abstract: Neural noise is an inherent property of all nervous systems. However, the mechanisms by which such random and fluctuating neural activity influences perception are still unclear. To elucidate the relationship between neural noise and perceptual performance we require techniques that can safely manipulate neural noise in humans. Transcranial random noise stimulation (tRNS), a form of electrical brain stimulation, has been proposed to increase neural noise according to principles of stochastic resonance (SR) where small to moderate intensities of tRNS improve performance, while higher intensities are detrimental. To date, high intensity (i.e., mA) tRNS effects on neural noise levels have not been directly quantified, nor have the detrimental effects proposed by SR been demonstrated in early visual processing. For this purpose, we applied a maximum current intensity of 3mA high-frequency tRNS to the visual cortex (V1) during an orientation discrimination task across increasing external visual noise levels, and fit the perceptual template model to contrast thresholds to quantify intrinsic mechanisms related to noise underlying changes in perceptual performance. We found that tRNS generally worsened perceptual performance by increasing observer’s internal noise and reducing the ability to filter external noise compared to sham. While most observers experienced detrimental effects, others demonstrated improved perceptual performance (i.e., reduced internal noise and better noise filtering). Preliminary evidence suggests that in idual baseline internal noise levels may drive the observed beneficial or detrimental observer responses to tRNS. These findings have important implications for the application of tRNS to investigate the impact of internal noise and noise filtering processes on perception.
Publisher: Wiley
Date: 24-05-2004
Publisher: Elsevier BV
Date: 09-2023
Publisher: Oxford University Press (OUP)
Date: 07-06-2023
Abstract: Action-effect predictions are believed to facilitate movement based on its association with sensory objectives and suppress the neurophysiological response to self- versus externally generated stimuli (i.e. sensory attenuation). However, research is needed to explore theorized differences in the use of action-effect prediction based on whether movement is uncued (i.e. volitional) or in response to external cues (i.e. stimulus-driven). While much of the sensory attenuation literature has examined effects involving the auditory N1, evidence is also conflicted regarding this component’s sensitivity to action-effect prediction. In this study (n = 64), we explored the influence of action-effect contingency on event-related potentials associated with visually cued and uncued movement, as well as resultant stimuli. Our findings replicate recent evidence demonstrating reduced N1 litude for tones produced by stimulus-driven movement. Despite influencing motor preparation, action-effect contingency was not found to affect N1 litudes. Instead, we explore electrophysiological markers suggesting that attentional mechanisms may suppress the neurophysiological response to sound produced by stimulus-driven movement. Our findings demonstrate lateralized parieto-occipital activity that coincides with the auditory N1, corresponds to a reduction in its litude, and is topographically consistent with documented effects of attentional suppression. These results provide new insights into sensorimotor coordination and potential mechanisms underlying sensory attenuation.
Publisher: Elsevier BV
Date: 12-2009
DOI: 10.1016/J.PSYCHRES.2008.10.018
Abstract: Tasks measuring reasoning biases and social cognition were originally applied to the study of schizophrenia in order to shed light on the cognitive underpinnings of positive symptoms. However, the empirical evidence for overlap between these tasks, and their association with positive symptoms, remains preliminary. In the current study we explore these associations using multivariate methodology, with primary interest in two commonly studied paradigms: jumping to conclusions (JTC) and theory of mind (ToM). We also included measures of memory, executive function and fluency performance, in order to relate the cognitive constructs to more traditional neuropsychological constructs. Forty-six schizophrenia inpatients were administered JTC, ToM, verbal fluency, executive functioning, and verbal memory tasks. A principal component analysis resulted in three components interpreted as Memory, Elaboration and Flexibility. ToM loaded with verbal fluency on the Elaboration component, whereas JTC loaded with executive functioning on the Flexibility component. The negative susbscale of the Positive and Negative Syndrome Scale (PANSS) correlated with the Elaboration component, but no other component-subscale correlations reached significance. Implications of these results are that impairments in elaboration may underlie the commonly observed correlation between ToM and negative symptoms, but argue against a common neurocognitive system for JTC, ToM and positive symptoms.
Publisher: Springer Science and Business Media LLC
Date: 06-10-2000
Abstract: Dopamine D2 receptor upregulation in the striatum is regularly seen in response to the administration of traditional antipsychotics in animal experiments. This is associated with hyperactivity and, for this reason, D2 receptor upregulation has long been postulated as central to tar e dyskinesia (TD). Using positron emission tomography (PET), the present study attempted to determine whether antipsychotic-induced D2 receptor up-regulation also occurs in humans. The long-term effects of traditional and novel antipsychotics on dopamine D2 receptors were investigated in nine subjects meeting DSM-IV criteria for schizophrenia who were deemed eligible for temporary treatment washout. Subjects had been treated with traditional antipsychotics (haloperidol n=3, perphenazine n=1) and novel antipsychotics (risperidone n=3, olanzapine n=2) in the moderate to high dosage range. Fourteen days after treatment withdrawal, the binding potentials (BPs) of dopamine D2 receptors were measured using 11[C] raclopride. The obtained BPs were compared to the BPs from antipsychotic-naive control subjects with schizophrenia. There was a significant increase in the D2 BP in both groups combined that reached 34%. The increases in the D2 BPs in the groups treated with conventional and novel antipsychotics were 37% and 31%, respectively. Significantly, the patients showing the highest degree of D2 receptor upregulation (98%) developed severe and persistent TD shortly after being started on a new antipsychotic with low affinity for D2 receptors. This study demonstrates for the first time, using in vivo neuroreceptor imaging, that dopamine D2 receptor binding is increased after long-term treatment with antipsychotics in humans. The data suggest that both traditional and novel antipsychotics with high affinity for dopamine D2 receptors are associated with a substantial increase in D2 receptor binding. The present data in humans agree well with animal data that implicate D2 receptor-mediated mechanisms in motor hyperactivity.
Publisher: Frontiers Media SA
Date: 14-10-2021
DOI: 10.3389/FPUBH.2021.682402
Abstract: The 2019–20 bushfire season in south-eastern Australia was one of the most severe in recorded history. Bushfire smoke-related air pollution reached hazardous levels in major metropolitan areas, including the Australian Capital Territory (ACT), for prolonged periods of time. Bushfire smoke directly challenges human health through effects on respiratory and cardiac function, but can also indirectly affect health, wellbeing and quality of life. Few studies have examined the specific health effects of bushfire smoke, separate from direct effects of fire, and looked beyond physical health symptoms to consider effects on mental health and lifestyle in Australian communities. This paper describes an assessment of the health impacts of this prolonged exposure to hazardous levels of bushfire smoke in the ACT and surrounding area during the 2019–20 bushfire season. An online survey captured information on demographics, health (physical and mental health, sleep) and medical advice seeking from 2,084 adult participants (40% male, median age 45 years). Almost all participants (97%) experienced at least one physical health symptom that they attributed to smoke, most commonly eye or throat irritation, and cough. Over half of responders self-reported symptoms of anxiety and/or feeling depressed and approximately half reported poorer sleep. Women reported all symptoms more frequently than men. Participants with existing medical conditions or poorer self-rated health, parents and those directly affected by fire (in either the current or previous fire seasons) also experienced poorer physical, mental health and/or sleep symptoms. Approximately 17% of people sought advice from a medical health practitioner, most commonly a general practitioner, to manage their symptoms. This study demonstrated that prolonged exposure to bushfire smoke can have substantial effects on health. Holistic approaches to understanding, preventing and mitigating the effects of smoke, not just on physical health but on mental health, and the intersection of these, is important. Improved public health messaging is needed to address uncertainty about how in iduals can protect their and their families health for future events. This should be informed by identifying subgroups of the population, such as those with existing health conditions, parents, or those directly exposed to fire who may be at a greater risk.
Publisher: American Psychiatric Association Publishing
Date: 06-2005
DOI: 10.1176/APPI.AJP.162.6.1203
Abstract: Postmortem and structural imaging studies suggest that patients with schizophrenia have disrupted cerebellar activity. It has been speculated that these abnormalities mediate disorganized thought processes and psychosis. The authors' goal was to use transcranial magnetic stimulation to measure cerebellar inhibition, a proxy of cerebellar activity, as the principal output of the cerebellum is inhibitory. Cerebellar inhibition was accomplished by delivering a magnetic cerebellar conditioning stimulus 5-15 msec before a magnetic test stimulus to the motor cortex. The cerebellar conditioning stimulus inhibits the size of the motor evoked potential produced by the test stimulus by approximately 50%. Ten patients with schizophrenia and 10 healthy comparison subjects completed the cerebellar inhibition protocol. Patients with schizophrenia demonstrated significant deficits in cerebellar inhibition compared with healthy subjects. The authors conclude that deficits in cerebellar inhibitory activity in schizophrenia may be the result of an abnormality in the cerebellum or disrupted cerebellar-thalamic-cortical connectivity.
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.APMR.2008.08.210
Abstract: To evaluate the efficacy of cognitive behavior therapy (CBT), adapted to meet the unique needs of in iduals with acquired brain injury (ABI), and modified for both group and telephone delivery. Matched-controlled trial, with multiple measurements across participants, including pretreatment baseline assessment plus posttreatment and 1-month follow-up. Outpatient community brain injury center. Participants (N=20) with chronic ABI. Ten were assigned to the CBT treatment group and 10 to education control. All were experiencing significant emotional distress at the onset of the study. Eleven sessions of CBT (or education control), including 1 introductory in idual session plus 10 further sessions administered in either group format or by telephone. The CBT was designed to decrease psychologic distress and improve coping. Specific adaptations were made to the CBT in order to better accommodate in iduals with cognitive difficulties. Primary outcome measures included the Symptom Checklist-90-Revised (SCL-90-R) and the Depression Anxiety Stress Scales (DASS-21). Secondary outcome measures included the Community Integration Questionnaire (CIQ) and the Ways of Coping Scale, Revised. Significant CBT treatment effects (in both group and telephone formats) were observed on the SCL-90-R and the DASS-21, whereas no significant effects were observed in the education control group. No significant effects of treatment were observed on the CIQ or Ways of Coping Scale, Revised. Results suggest that adapted CBT-administered by telephone or in a face-to-face group setting-can significantly improve emotional well-being in chronic ABI.
Publisher: SAGE Publications
Date: 07-2005
DOI: 10.1177/070674370505000806
Abstract: Response to typical antipsychotic medication has been associated with achieving a level of striatal dopamine D 2 receptor occupancy in the range of 65% to 70%. We undertook this study to determine whether response to the atypical antipsychotic olanzapine occurs at lower levels of D 2 receptor occupancy. Eighteen patients who presented with a first episode of psychosis were randomized to receive olanzapine 5 mg daily or haloperidol 2 mg daily in a double-blind design. We acquired positron emission tomography (PET) scans using the D 2 ligand [ 11 C]raclopride within the first 15 days of treatment to determine the percentage of D 2 receptors occupied by the medication. According to response, dosage was then adjusted to a maximum dosage of 20 mg daily of either drug. PET scans were repeated after 10 to 12 weeks of treatment. At the first PET scan, the 8 olanzapine-treated patients had significantly lower D 2 receptor occupancies (mean 63.4%, SD 7.3) than those observed in the 10 patients treated with haloperidol (mean 73.0%, SD 6.1). When patients were rescanned following dosage adjustment, mean D 2 receptor occupancies were greater than 70% in both groups. D 2 receptor occupancies did not differ significantly between the olanzapine-treated group (mean 72.0%, SD 5.7) and the haloperidol-treated group (mean 78.7%, SD 7.6). These results suggest that, in patients being treated for a first episode of psychosis, olanzapine has its antipsychotic effect at approximately the same levels of D 2 receptor occupancy as are achieved with low dosages of haloperidol.
Publisher: American Psychological Association (APA)
Date: 06-2007
DOI: 10.1037/1040-3590.19.2.236
Abstract: An eight-subtest short form (SF8) of the Wechsler Adult Intelligence Scale, Third Edition (WAIS-III), maintaining equal representation of each index factor, was developed for use with psychiatric populations. Data were collected from a mixed inpatient/outpatient s le (99 men and 101 women) referred for neuropsychological assessment. Psychometric analyses revealed an optimal SF8 comprising Vocabulary, Similarities, Arithmetic, Digit Span, Picture Completion, Matrix Reasoning, Digit Symbol Coding, and Symbol Search, scored by linear scaling. Expanding on previous short forms, the current SF8 maximizes the breadth of information and reduces administration time while maintaining the original WAIS-III factor structure.
Publisher: CMA Joule Inc.
Date: 2010
DOI: 10.1503/JPN.080039
Publisher: SAGE Publications
Date: 30-08-2020
Abstract: A significant percentage of college students discontinue mental health treatment prematurely. Using a discrete choice experiment, 909 students chose between experimentally manipulated descriptions of mental health services, selecting the option that would encourage them to stay in treatment. Latent class analysis identified three groups. The community class (36.7%) would remain in treatment at community walk-in clinics. The c us class (27.3%) would be more likely to remain in an on-c us student health service. The residence class, 36.0% of participants, would be most likely to remain in treatments at their residence. All classes would be more likely to remain in services including the option of medication, psychotherapy, or alternative treatments such as diet and exercise. Simulations predicted that most students would trade in idual treatment for more cost-effective groups if students who had experienced mental health problems recommended these services and access to text messages and telephone help was included.
Publisher: Informa UK Limited
Date: 1996
Publisher: Elsevier BV
Date: 05-2003
DOI: 10.1016/S1388-2457(03)00038-5
Abstract: The transcranial magnetic stimulation (TMS)-induced contralateral silent period (CSP) refers to a period of interruption of voluntary muscle activity measured in tonically active muscles. The length of the CSP is generally interpreted to reflect cortical inhibition. The determination of the return of voluntary motor activity is typically accomplished via visual inspection of the electromyography (EMG) waveform and may be subject to inaccuracy on the part of the rater. To present and evaluate an automated method (AM) to determine the CSP. The CSP of 11 healthy controls was recorded using stimulus intensities 20 and 50% above the resting motor threshold (RMT). The mean CSP duration obtained by the two raters using visual inspection and our automated approach were compared. The interclass correlation coefficient (ICC) between the two raters and the AM was 0.99 at 150% of RMT and was 0.97 at 120% of RMT. The level of pre-stimulus EMG litude and s ling rate did not affect agreement between the AM and more conventional visually guided methods. Our study demonstrates that this AM is a simple, objective and reliable approach for CSP determination. The CSP is an important neurophysiological measure of cortical inhibition and its determination by our AM provides a more objective and automated approach compared to visually guided methods.
Publisher: Springer Science and Business Media LLC
Date: 25-11-2014
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.BANDC.2014.10.009
Abstract: Previous studies from the human, rodent, and computational research have identified the hippoc us as a core structure mediating pattern separation. However, these investigations have generally focused on the role of distinct subregions of the hippoc us. Less well-understood is how the human hippoc us interacts with other brain regions to support pattern separation. The purpose of this study was to identify the functional networks connected to the hippoc us during delayed matching-to-s le pattern separation tasks promoting either spatial or temporal interference. Results revealed that the hippoc us was functionally connected to two distinct networks. The first network was characterized by correlated activation with the hippoc us primarily in bilateral temporal regions. This network was differentially related to spatial and temporal conditions, suggesting hippoc al connectivity to this network is modulated by interference type. A secondary network was characterized by correlations between the left hippoc us and several other sparsely distributed brain regions, including bilateral cerebellum and frontal and temporal cortices. This network was not modulated by interference type, suggesting that it may be a domain-general pattern separation network. We suggest that the hippoc us may play a role in integrating information from these networks to support performance on pattern separation tasks.
Publisher: Springer Science and Business Media LLC
Date: 20-07-2020
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.SCHRES.2011.08.002
Abstract: N400, an event-related brain potential (ERP) waveform elicited by meaningful stimuli, is normally reduced (made less negative) by relatedness between the eliciting stimulus and preceding ones (N400 semantic priming). Schizophrenia patients' N400 semantic priming deficits suggest impairment in using meaningful context to activate related concepts in semantic memory. We aimed to examine the degree to which this impairment can be ameliorated by task instructions that more explicitly require processing of stimulus meaning. We recorded ERPs from 16 schizophrenia patients and 16 controls who viewed prime words each followed at 750-ms stimulus-onset asynchrony by an unrelated or related target word, or a nonword, in a non-semantic task (indicating whether a letter occurred in the target) compared to an explicit semantic task (judging prime-target relatedness). Consistent with previous work, controls exhibited greater N400 semantic priming (larger litude reductions for related versus unrelated targets) in the semantic task than in the orthographic task. Schizophrenia patients showed this same pattern, although their N400 semantic priming effects were smaller than controls' across tasks. Nevertheless, patients' priming effects increased as much as did controls' from the orthographic to the semantic task. Thus, connections among related concepts in schizophrenia patients' semantic memory appear grossly intact, such that, given a meaningful stimulus, they can make use of explicit cues to activate related concepts at a neurophysiological level, although their ability to do so remains less than normal. These data provide support for further research on semantic-cueing strategies for cognitive remediation of verbal memory in schizophrenia.
Publisher: Informa UK Limited
Date: 12-2013
DOI: 10.1080/13803395.2013.857389
Abstract: This study builds upon our previous work indicating that impaired hippoc al-dependent forms of memory are core to schizophrenia. Using a virtual-reality courtyard task, we presented participants with schizophrenia spectrum disorders (SSD n = 20) and a healthy community comparison group (n = 20) with objects to remember within a town square, followed by a recognition test of the location of objects from either the same viewpoint or a shifted viewpoint relative to initial presentation. The SSD group demonstrated a relative deficit under shifted- compared to same-view conditions. These findings provide further support for deficient hippoc al-dependent cognition in SSD.
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.BRS.2011.12.002
Abstract: Repetitive transcranial magnetic stimulation (rTMS) has shown promise as a treatment for refractory auditory hallucinations (AH) in Schizophrenia. Most previous studies have examined the effect of low frequency, left-sided stimulation (LFL) (1 Hz) to the temporoparietal cortex (TPC). Priming stimulation (6 Hz) prior to LFL stimulation (hereby simply referred to as priming) has been shown to enhance the neurophysiological effects of LFL rTMS alone and, as such, may lead to greater attenuation of AH. Therefore, this study evaluated the efficacy of priming rTMS and LFL rTMS compared to sham rTMS using MRI targeting of Heschl's gyrus (HG) within the TPC of subjects with SCZ experiencing refractory auditory hallucinations (AH). Subjects between the ages of 18 and 65 were recruited from a tertiary care university hospital. Fifty-four subjects with medication resistant AH were randomized to receive LFL, priming, or sham rTMS for 20 treatments. The primary outcome was reduction of hallucinatory symptoms as indexed by response rates on the Psychotic Symptoms Rating Scale (PSYRATS). The response rates did not differ among the three treatment groups using an intention to treat analysis. The response rates did not differ in any of the secondary outcome measures. The treatment was well tolerated with minimal adverse effects including no changes in cognition during the study. These findings suggest that neither priming nor LFL rTMS of Heschl's gyrus are effective at ameliorating refractory AH in schizophrenia. ClinicalTrials.gov Identifier: NCT01386918.
No related grants have been discovered for Bruce Christensen.