ORCID Profile
0000-0001-7841-018X
Current Organisations
Deakin University
,
Universidad de Granada
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Publisher: Royal College of Psychiatrists
Date: 08-2015
DOI: 10.1192/BJP.BP.114.152223
Abstract: In iduals with cocaine and gambling addictions exhibit cognitive flexibility deficits that may underlie persistence of harmful behaviours. We investigated the neural substrates of cognitive inflexibility in cocaine users v. pathological gamblers, aiming to disambiguate common mechanisms v. cocaine effects. Eighteen cocaine users, 18 pathological gamblers and 18 controls performed a probabilistic reversal learning task during functional magnetic resonance imaging, and were genotyped for the DRD2/ANKK Taq1A polymorphism. Cocaine users and pathological gamblers exhibited reduced ventrolateral prefrontal cortex (PFC) signal during reversal shifting. Cocaine users further showed increased dorsomedial PFC (dmPFC) activation relative to pathological gamblers during perseveration, and decreased dorsolateral PFC activation relative to pathological gamblers and controls during shifting. Preliminary genetic findings indicated that cocaine users carrying the DRD2/ANKK Taq1A1+ genotype may derive unique stimulatory effects on shifting-related ventrolateral PFC signal. Reduced ventrolateral PFC activation during shifting may constitute a common neural marker across gambling and cocaine addictions. Additional cocaine-related effects relate to a wider pattern of task-related dysregulation, reflected in signal abnormalities in dorsolateral and dmPFC.
Publisher: Wiley
Date: 2016
DOI: 10.1111/JPC.13029
Abstract: Autism spectrum disorder (ASD) is a neurodevelopmental disorder with reported prevalence of more than 1/100. In Australia, paediatricians are often involved in diagnosing ASD and providing long-term management. However, it is not known how paediatricians diagnose ASD. This study aimed to investigate whether the way Australian paediatricians diagnose ASD is in line with current recommendations. Members of the Australian Paediatric Research Network were invited to answer questions about their ASD diagnostic practice in a multi-topic survey and also as part of a study about parents needs around the time of a diagnosis of ASD. The majority of the 124 paediatricians who responded to the multi-topic survey and most who responded to the parent needs survey reported taking more than one session to make a diagnosis of ASD. Most paediatricians included information from preschool, child care or school when making a diagnosis, and over half included information from speech pathology or psychology colleagues more than 50% of the time. The main reasons for not including assessment information in the diagnostic process were service barriers such as no regular service available or long waiting lists. More than 70% reported ordering audiology and genetic tests more than half of the time. Not all paediatricians are following current recommendations for diagnosing ASD more than 50% of the time. While there are good reasons why current diagnostic approaches may fall short of expected standards, these need to be overcome to ensure diagnostic validity and optimal services for all children and their families.
Publisher: American Psychological Association (APA)
Date: 2014
DOI: 10.1037/NEU0000007
Abstract: Cocaine dependence often co-occurs with personality disorders from Clusters B and C, which are inherently associated with some of the executive dysfunctions found in addiction. We address the question of whether the comorbidity between cocaine dependence and different types of personality disorders is associated with differential profiles of executive deficits compatible with their personality dysfunction. We predicted that the comorbidity with Cluster B disorders would be associated with inhibition and shifting deficits, whereas the comorbidity with Cluster C disorders would be associated with working memory deficits. We tested 107 participants (22 cocaine users with Cluster B disorders, 15 cocaine users with Cluster C disorders, 36 cocaine users without comorbidities, and 34 controls) using tests of working memory, attention, inhibition, and shifting. Groups were statistically matched on IQ and had no Axis I comorbidities (other than substance-related). Based on the performance of the control group, we obtained z-score composite measures of working memory, attention/inhibition, shifting, and global executive impairment. We tested group differences in these composite measures using univariate analyses of variance and Sidak tests corrected for multiple comparisons. Cocaine users with Cluster B disorders had poorer attention/inhibition, whereas cocaine users with comorbid Cluster C disorders had poorer working memory. Cluster B and noncomorbid cocaine users (but not Cluster C users) differed from controls on the global executive impairment measure. The comorbidity between cocaine dependence and personality disorders from Clusters B and C is associated with executive function deficits that are compatible with their respective personality dysfunctions.
Publisher: Elsevier BV
Date: 10-2011
Publisher: Springer Science and Business Media LLC
Date: 13-03-2013
DOI: 10.1007/S00213-013-3040-X
Abstract: The co-occurrence of cocaine dependence and personality disorders may contribute to frontal systems-related behavioral symptoms in cocaine users. This study aims to characterize apathy, disinhibition, and dysexecutive symptoms in cocaine users with comorbid personality disorders. Thirty-nine participants meeting criteria for cocaine dependence and personality disorders, 35 participants meeting criteria for cocaine dependence without comorbidities, and 29 controls matched for age, education, and IQ completed the Frontal Systems Behavior Scale (FrSBe), which provides present and retrospective assessments (of the period preceding cocaine use) about apathy, disinhibition, and dysexecutive symptoms. Additionally, relatives of cocaine patients (34 relatives from comorbid patients and 31 relatives from noncomorbid patients) completed the informant version of the FrSBe. We used one-way ANOVAs to investigate present-moment differences between the groups and related s les t tests to quantify changes between pre-disorder and present-moment symptoms. Cocaine users with personality disorders self-reported higher present-moment apathy and disinhibition symptoms than noncomorbid users and controls. Informant ratings showed that comorbid users exhibited pre-disorder elevations in apathy, disinhibition and dysexecutive symptoms, and that these symptoms did not significantly change between the pre-disorder and the present-moment assessments. In contrast, noncomorbid users exhibited increased apathy, disinhibition, and dysexecutive symptoms at present-moment compared with pre-disorder measures. The co-occurrence of cocaine dependence and personality disorders is associated with elevated frontal systems-related behavioral symptoms. Comorbid and noncomorbid users differ in frontal symptoms' trajectories, with the former showing pre-disorder stable elevations and the latter showing lower baseline symptoms but greater addiction-related elevations.
Publisher: Wiley
Date: 29-03-2015
DOI: 10.1111/ADB.12242
Abstract: Neural biomarkers for the active detrimental effects of cocaine dependence (CD) are lacking. Direct comparisons of brain connectivity in cocaine-targeted networks between CD and behavioural addictions (i.e. pathological gambling, PG) may be informative. This study therefore contrasted the resting-state functional connectivity networks of 20 in iduals with CD, 19 in iduals with PG and 21 healthy in iduals (controls). Study groups were assessed to rule out psychiatric co-morbidities (except alcohol abuse and nicotine dependence) and current substance use or gambling (except PG). We first examined global connectivity differences in the corticolimbic reward network and then utilized seed-based analyses to characterize the connectivity of regions displaying between-group differences. We examined the relationships between seed-based connectivity and trait impulsivity and cocaine severity. CD compared with PG displayed increased global functional connectivity in a large-scale ventral corticostriatal network involving the orbitofrontal cortex, caudate, thalamus and amygdala. Seed-based analyses showed that CD compared with PG exhibited enhanced connectivity between the orbitofrontal and subgenual cingulate cortices and between caudate and lateral prefrontal cortex, which are involved in representing the value of decision-making feedback. CD and PG compared with controls showed overlapping connectivity changes between the orbitofrontal and dorsomedial prefrontal cortices and between amygdala and insula, which are involved in stimulus-outcome learning. Orbitofrontal-subgenual cingulate cortical connectivity correlated with impulsivity and caudate/amygdala connectivity correlated with cocaine severity. We conclude that CD is linked to enhanced connectivity in a large-scale ventral corticostriatal-amygdala network that is relevant to decision making and likely to reflect an active cocaine detrimental effect.
Publisher: Wiley
Date: 17-04-2014
DOI: 10.1111/ADB.12143
Abstract: Cocaine addiction involves persistent deficits to unlearn previously rewarded response options, potentially due to neuroadaptations in learning-sensitive regions. Cocaine-targeted prefrontal systems have been consistently associated with reinforcement learning and reversal deficits, but more recent interspecies research has raised awareness about the contribution of the cerebellum to cocaine addiction and reversal. We aimed at investigating the link between cocaine use, reversal learning and prefrontal, insula and cerebellar gray matter in cocaine-dependent in iduals (CDIs) varying on levels of cocaine exposure in comparison with healthy controls (HCs). Twenty CDIs and 21 HCs performed a probabilistic reversal learning task (PRLT) and were subsequently scanned in a 3-Tesla magnetic resonance imaging scanner. In the PRLT, subjects progressively learn to respond to one predominantly reinforced stimulus, and then must learn to respond according to the opposite, previously irrelevant, stimulus-reward pairing. Performance measures were errors after reversal (reversal cost), and probability of maintaining response after errors. Voxel-based morphometry was conducted to investigate the association between gray matter volume in the regions of interest and cocaine use and PRLT performance. Severity of cocaine use correlated with gray matter volume reduction in the left cerebellum (lobule VIII), while greater reversal cost was correlated with gray matter volume reduction in a partially overlapping cluster (lobules VIIb and VIII). Right insula/inferior frontal gyrus correlated with probability of maintaining response after errors. Severity of cocaine use detrimentally impacted reversal learning and cerebellar gray matter.
Publisher: Cold Spring Harbor Laboratory
Date: 08-01-2021
DOI: 10.1101/2021.01.06.425653
Abstract: There is evidence to suggest a disruption of gamma-aminobutyric acid (GABA) in autism spectrum disorder (ASD), but findings are mixed. Concurrent electroencephalography and transcranial magnetic stimulation (TMS-EEG) provides a novel method by which to probe GABA-mediated cortical inhibition. With a particular focus on GABAB-ergic mechanisms, we investigated the N100 peak of the TMS evoked potential (TEP), as well as long interval cortical inhibition (LICI EEG ) in adults with ASD (n = 23 12 female) without intellectual disability, and a neurotypical comparison group (n =22 12 female) matched for age, sex, and IQ. Seventy-five single-(spTMS) and 75 paired-(ppTMS 100 ms inter-stimulus-interval) pulses were applied to the right primary motor cortex (M1), right temporoparietal junction (TPJ), and right dorsolateral prefrontal cortex (DLPFC) while EEG was recorded from 20 scalp electrodes. Additionally, electromyography (EMG) was used to investigate corticospinal inhibition following ppTMS to M1 (LICI EMG ). There were no group differences in the N100 litude or latency following spTMS. LICI outcomes following ppTMS, as measured by either EEG or EMG, also did not differ between groups. These findings were further supported by Bayesian analyses, which provided weak-moderate support for the null hypothesis. Data presented here reflect adults without intellectual disability, and the generalisability of these results is therefore limited. The findings of this study argue against GABAB-ergic impairment in adults with ASD without intellectual disability, at least at the cortical regions examined. Further research investigating these mechanisms in ASD at various ages, with varying degrees of symptomatology, and at different brain sites is an important factor in understating the role of GABA in the neuropathophysiology of ASD.
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.BRS.2019.02.013
Abstract: The prefrontal cortex regulates behavioural adaptation in response to feedback. However, the causal role of different prefrontal regions remains unclear, based on indirect evidence derived from functional neuroimaging. Neuroimaging studies show dorsomedial prefrontal activation during feedback monitoring, whereas the ventrolateral prefrontal cortex engages during behavioural adaptation (shifting). We used high-definition transcranial direct current stimulation (HD-tDCS) to elucidate the roles of the ventrolateral prefrontal cortex (vlPFC) and the dorsomedial prefrontal cortex (dmPFC) in behaviour change, using a probabilistic reversal learning task (PRLT). Fifty-two healthy adults were randomly assigned to receive cathodal HD-tDCS to inhibit the vlPFC or the dmPFC versus sham stimulation, prior to completing the PRLT. The outcome measures were the number of perseverative errors and the electroencephalography (EEG) signals of feedback-related negativity (FRN) in the PRLT. We hypothesised that inhibition of the vlPFC would be specifically associated with more perseverative errors and weaker FRNs. We found that vlPFC inhibition was associated with higher perseverative errors compared to sham and dmPFC stimulation conditions. Although there were no statistically significant differences in FRN litudes, the effect sizes indicate an association between inhibition of the vlPFC and lower FRN litudes. Our findings support a causal role of the vlPFC on feedback-based behavioural adaptation, which is critical for adaptive goal-driven behaviour.
Publisher: Wiley
Date: 11-07-2016
DOI: 10.1111/ADB.12422
Abstract: Cocaine addiction is characterized by impaired self-awareness about cognitive and motivational deficits, leading to poor treatment outcomes. However, there is still limited understanding of the neurophysiological underpinnings of this impairment. We aimed to establish if impaired self-awareness is underpinned by brain structural phenotypes among cocaine-dependent in iduals (CDI). Sixty-five CDI and 65 designated informants completed the Frontal Systems Behavior Scale, and a subs le of 40 CDI were scanned via magnetic resonance imaging. We applied multiple regression models to establish the association between levels of self-awareness indexed by Frontal Systems Behavior Scale's discrepancy scores (i.e. informant ratings minus self-reports of apathy, disinhibition and dysexecutive deficits) and gray matter volumes indexed by magnetic resonance imaging voxel-based measures within five brain regions of interest: anterior cingulate cortex, orbitofrontal cortex (OFC), striatum, insula and dorsolateral prefrontal cortex (DLPFC). We also examined the neural underpinnings of underestimation versus overestimation of deficits, by splitting the CDI group according to the positive or negative value of their discrepancy scores. We found that poorer self-awareness of apathy deficits was associated with greater gray matter volume in the dorsal striatum, and poorer self-awareness of disinhibition deficits was associated with greater gray matter volume in the OFC in the whole s le. More underestimation and more overestimation of executive deficits were linked to lower DLPFC volume. We show that impaired self-awareness of cognitive and motivational deficits in cocaine addiction has a neural underpinning, implicating striatum, OFC and DLPFC structural phenotypes.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.DRUGALCDEP.2013.02.008
Abstract: In iduals with cocaine dependence and co-occurring personality disorders are more likely to have increased impulsivity, dysfunctional beliefs, executive dysfunction and brain structural abnormalities by virtue of the conjoint impact of both pathologies. We recruited 32 cocaine dependent patients with comorbid Cluster B personality disorders, 44 cocaine dependent patients without comorbidities and 34 non-drug-using controls. They completed the UPPS-P impulsivity scale, the Personality Belief Questionnaire, and executive function tests of working memory, attention/response inhibition and shifting. A subs le (n=61) was also scanned using Magnetic Resonance Imaging. We used univariate ANOVAs for group comparisons, and tested the association between impulsivity, executive control and personality dysfunction and diagnoses using correlation and multivariate logistic regression analyses. Cocaine dependent patients with personality disorders had elevated negative urgency and borderline beliefs, decreased inhibition and attention regulation, and reduced temporal pole gray matter with respect to the rest of the s le. Trait and cognitive measures correctly classified 73% of comorbid patients (60% sensitivity and 82% specificity). The co-occurrence of cocaine dependence and personality disorders is associated with negative-mood impulsivity and beliefs, executive dysfunction and temporal pole attrition.
Publisher: Wiley
Date: 14-02-2017
DOI: 10.1111/ADD.13751
Abstract: Gambling disorder is characterized by poor regulation of negative emotions and impulsive behaviours. This study aimed to (1) compare gambling disorder patients (GDPs) and healthy controls (HCs) in self‐report and brain activation measures of emotion regulation and (2) establish its relationship with negative emotion‐driven impulsivity. Two cross‐sectional case–control studies including GDPs and HCs. GDPs and HCs were recruited from specialized gambling clinics in Andalusia (Spain), where they were following out‐patient treatment, and from the community, respectively. Study 1 included 41 GDPs and 45 HCs [All males M age = 35.22, 33.22 standard deviation (SD) = 11.16, 8.18 respectively]. Study 2 included 17 GDPs and 21 HCs (16/20 males M age = 32.94, 31.00 SD = 7.77, 4.60 respectively). In study 1, we compared both groups on suppression and re‐appraisal emotion regulation strategies [Emotion Regulation Questionnaire (ERQ)]. In study 2, we compared GDPs with HCs on brain activation associated with down‐regulation of negative emotions in a cognitive re‐appraisal task, measured with functional magnetic resonance imaging (fMRI). In both studies, we correlated the measures of emotion regulation with mood‐related impulsivity indicated by negative urgency (UPPS‐P impulsive behaviour scale). GDPs relative to HCs showed higher levels of emotional suppression [ F = 4.525 P = 0.036 means difference M HCs –M GDPs = −2.433, 95% confidence interval (CI) = −4.706, −0.159] and higher activation of the premotor cortex and middle frontal gyrus during negative emotion regulation in the fMRI task [ P ≤ 0.005, cluster size (CS) 50 voxels]. Negative urgency correlated positively with emotional suppression ( r = 0.399, 95% CI = 0.104, 0.629, one‐tailed P = 0.005) and middle frontal gyrus activation during negative emotion regulation ( P ≤ 0.005, CS 50) in GDPs. Gambling disorder is associated with greater use of emotional suppression and stronger pre‐motor cortex and middle frontal gyrus activation for regulating negative emotions, compared with healthy controls. Emotional suppression use and middle frontal gyrus activation during negative emotion regulation are linked with negative emotion‐driven impulsivity in this disorder.
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.ADDBEH.2014.06.001
Abstract: Cocaine addiction and pathological gambling are commonly associated with steeper (impulsive) discounting of delayed rewards, which promotes ongoing drug and gambling behaviors. However, it is yet unclear whether impulsive delay discounting is a stable trait in cocaine and gambling disorders during abstinence, and whether it is significantly impacted by dysfunctional personality beliefs. The aim of this study was to compare the delay discounting rates of four groups: 47 cocaine users with comorbid personality disorders, 41 cocaine users without psychiatric comorbidities, 28 pathological gamblers without psychiatric comorbidities, and 36 healthy comparison in iduals. We also examined the association between dysfunctional personality beliefs and delay discounting rates. Participants completed the Kirby Delay Discounting Questionnaire and the Beck Personality Belief Questionnaire as part of a larger battery. We used non-parametric tests to compare discounting rates between the groups, and bivariate correlation analyses to examine the association between beliefs and discounting rates within each of the groups. We found that discounting rates were significantly higher in in iduals with disordered gambling compared to controls. Specifically in cocaine users with Cluster B personality disorders, higher discounting rates were associated with the intensity of "dependent" dysfunctional beliefs (e.g., "I am needy and weak"). Conclusion:We conclude that impulsive delay discounting is increased in gambling relative to controls and linked to personality beliefs in cocaine users with Cluster B personality disorders.
Publisher: Wiley
Date: 22-09-2015
DOI: 10.1111/ADD.13076
Abstract: To contrast functional connectivity on ventral and dorsal striatum networks in cocaine dependence relative to pathological gambling, via a resting-state functional connectivity approach and to determine the association between cocaine dependence-related neuroadaptations indexed by functional connectivity and impulsivity, compulsivity and drug relapse. Cross-sectional study of 20 in iduals with cocaine dependence (CD), 19 in iduals with pathological gambling (PG) and 21 healthy controls (HC), and a prospective cohort study of 20 CD followed-up for 12 weeks to measure drug relapse. CD and PG were recruited through consecutive admissions to a public clinic specialized in substance addiction treatment (Centro Provincial de Drogodependencias) and a public clinic specialized in gambling treatment (AGRAJER), respectively HC were recruited through community advertisement in the same area in Granada (Spain). Seed-based functional connectivity in the ventral striatum (ventral caudate and ventral putamen) and dorsal striatum (dorsal caudate and dorsal putamen), the Kirby delay-discounting questionnaire, the reversal-learning task and a dichotomous measure of cocaine relapse indicated with self-report and urine tests. CD relative to PG exhibit enhanced connectivity between the ventral caudate seed and subgenual anterior cingulate cortex, the ventral putamen seed and dorsomedial pre-frontal cortex and the dorsal putamen seed and insula (P≤0.001, kE=108). Connectivity between the ventral caudate seed and subgenual anterior cingulate cortex is associated with steeper delay discounting (P≤0.001, kE=108) and cocaine relapse (P≤0.005, kE=34). Cocaine dependence-related neuroadaptations in the ventral striatum of the brain network are associated with increased impulsivity and higher rate of cocaine relapse.
Publisher: Springer Science and Business Media LLC
Date: 13-04-2014
DOI: 10.1007/S00213-014-3563-9
Abstract: One of the key outstanding challenges in cocaine dependence research is determining who is at risk of relapsing during treatment. We examined whether cognitive decision-making profiles predict objectively (hair) indexed cocaine relapse at 3-month follow-up. Thirty-three cocaine-dependent patients commencing outpatient treatment in a public clinic performed baseline decision-making assessments with the original and variant versions of the Iowa Gambling Task, and provided a 3-cm hair s le 3 months afterwards. Based on Iowa Gambling Tasks' performance cut-offs, 5 patients had intact decision-making skills, 17 patients showed impaired sensitivity to reward or punishment (impairment in one of the tasks), and 9 patients showed insensitivity to future consequences (impairment in both tasks). Based on a 0.3 ng/mg cocaine cut-off, 23 patients were classified as relapsers and 10 as non-relapsers at the 3-month follow-up. Eighty percent of patients with intact decision-making were abstinent at follow-up, whereas 90% of patients with insensitivity to future consequences had relapsed. The two subgroups (relapsers and non-relapsers) showed no significant differences on drug use, comorbidities, or psychosocial function, and significantly differed on verbal but not performance IQ. A regression model including decision-making scores and verbal IQ predicted abstinence status with high sensitivity (95%) and moderately high specificity (81%). These preliminary findings demonstrate that decision-making profiles are associated with cocaine relapse. Moreover, combined decision-making and IQ assessments provide optimal predictive values over stimulant relapse, yielding significant opportunities for clinical translation.
Publisher: Wiley
Date: 14-09-2012
DOI: 10.1111/J.1369-1600.2012.00497.X
Abstract: Cocaine dependence is associated with pronounced elevations of negative affect and deficient regulation of negative emotions. We aimed to investigate the neural substrates of negative emotion regulation in cocaine-dependent in iduals (CDI), as compared to non-drug-using controls, using functional magnetic resonance imaging (fMRI) during a re-appraisal task. Seventeen CDI abstinent for at least 15 days and without other psychiatric co-morbidities and 18 intelligence quotient-matched non-drug-using controls participated in the study. Participants performed the re-appraisal task during fMRI scanning: they were exposed to 24 blocks of negative affective or neutral pictures that they should Observe (neutral pictures), Maintain (sustain the emotion elicited by negative pictures) or Suppress (regulate the emotion elicited by negative pictures through previously trained re-appraisal techniques). Task-related activations during two conditions of interest (Maintain>Observe and Suppress>Maintain) were analyzed using the general linear model in SPM8 software. We also performed psychophysiological interaction (PPI) seed-based analyses based on one region from each condition: the dorsolateral prefrontal cortex (dlPFC-Maintain>Observe) and the inferior frontal gyrus (IFG-Suppress>Maintain). Results showed that cocaine users had increased right dlPFC and bilateral temporoparietal junction activations during Maintain>Observe, whereas they showed decreased right IFG, posterior cingulate cortex, insula and fusiform gyrus activations during Suppress>Maintain. PPI analyses showed that cocaine users had increased functional coupling between the dlPFC and emotion-related regions during Maintain>Observe, whereas they showed decreased functional coupling between the right IFG and the amygdala during Suppress>Maintain. These findings indicate that CDI have dysfunctional corticolimbic activation and connectivity during negative emotion experience and re-appraisal.
Publisher: Cold Spring Harbor Laboratory
Date: 04-2022
DOI: 10.1101/2022.03.30.22273215
Abstract: Corpus callosum anomalies are commonly noted in autism spectrum disorder (ASD). Given the complexity of its microstructural architecture, with crossing fibers projecting throughout, we applied fixel-based analysis to probe white matter micro- and macrostructure within this region. As ASD is a neurodevelopmental condition with noted abnormalities in brain growth, age was also investigated. Data for participants with (N=54) and without (N=50) ASD, aged 5-34 years, were obtained from the Autism Brain Imaging Data Exchange-II (ABIDE-II). Within each site, indices of fiber density (FD), fiber cross-section (FC), and combined fiber density and cross-section (FDC) were compared between those groups. Young adolescents with ASD (age = 11.19 ± 7.54) showed reduced macroscopic FC and FDC compared to age-matched neurotypical controls (age = 10.04 ± 4.40). Reduced FD and FDC was noted in a marginally older ASD (age 13.87 ± 3.15) cohort compared to matched controls (age = 13.85 ± 2.90). Among the oldest cohorts, a non-significant trend indicated reduced FD in older adolescents/young adults with ASD (age = 17.07 ± 3.56) compared to controls (age = 16.55 ± 2.95). There was a positive correlation between age and callosal mean FC and FDC in the youngest cohort. When stratified by diagnosis, this finding remained only for the ASD s le. White matter aberration appears greatest among younger ASD cohorts. In older adolescents and young adults, less of the corpus callosum seems affected. This supports the suggestion that some early neuropathophysiological indicators in ASD may dissipate with age.
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.DRUGALCDEP.2012.03.008
Abstract: The aim of this study was to compare the cognitive performance of cocaine dependent in iduals (CDI) with that of pathological gamblers (PG). Cocaine dependence and pathological gambling share neurobiological vulnerabilities related to addiction, but PG are relatively free of the toxic consequences, such that any additional deficits observed in CDI may be interpreted as pertaining to specific drug effects. We used a case-control observational design contrasting multiple measures of impulsivity (UPPS-P trait impulsivity, delay discounting) and executive measures of response inhibition (Stroop) and working memory performance (N-back) between groups of CDI (n=29), PG (n=23), and healthy controls (n=20). We conducted one-way ANOVAs, followed by planned pairwise tests and calculations of Cohen's d to estimate significant differences between the groups. CDI, as compared to PG, had elevated scores on UPPS-P Negative Urgency and poorer performance on working memory (2-back). PG had steeper delay-discounting rates. Both groups had elevated Positive Urgency and poorer Stroop inhibition compared to controls. Peak amount of cocaine use was negatively correlated with working memory and response inhibition performance. We found cocaine-related specific elevations in Negative Urgency and working memory deficits, putatively identified as cocaine neurotoxicity effects. Other aspects of impulsivity (Positive Urgency, Stroop inhibition) were increased across CDI and PG groups and may reflect vulnerability factors for addiction.
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.EURONEURO.2013.04.012
Abstract: Cocaine dependence often co-occurs with Cluster B personality disorders. Since both disorders are characterized by emotion regulation deficits, we predicted that cocaine comorbid patients would exhibit dysfunctional patterns of brain activation and connectivity during reappraisal of negative emotions. We recruited 18 cocaine users with comorbid Cluster B personality disorders, 17 cocaine users without comorbidities and 21 controls to be scanned using functional magnetic resonance imaging (fMRI) during performance on a reappraisal task in which they had to maintain or suppress the emotions induced by negative affective stimuli. We followed region of interest (ROI) and whole-brain approaches to investigate brain activations and connectivity associated with negative emotion experience and reappraisal. Results showed that cocaine users with comorbid personality disorders had reduced activation of the subgenual anterior cingulate cortex during negative emotion maintenance and increased activation of the lateral orbitofrontal cortex and the amygdala during reappraisal. Amygdala activation correlated with impulsivity and antisocial beliefs in the comorbid group. Connectivity analyses showed that in the cocaine comorbid group the subgenual cingulate was less efficiently connected with the amygdala and the fusiform gyri and more efficiently connected with the anterior insula during maintenance, whereas during reappraisal the left orbitofrontal cortex was more efficiently connected with the amygdala and the right orbitofrontal cortex was less efficiently connected with the dorsal striatum. We conclude that cocaine users with comorbid Cluster B personality disorders have distinctive patterns of brain activation and connectivity during maintenance and reappraisal of negative emotions, which correlate with impulsivity and dysfunctional beliefs.
Publisher: UNED - Universidad Nacional de Educacion a Distancia
Date: 03-09-2015
Publisher: Wiley
Date: 06-10-2015
DOI: 10.1111/ADB.12318
Abstract: Cocaine dependence frequently co-occurs with personality disorders, leading to increased interpersonal problems and greater burden of disease. Personality disorders are characterised by patterns of thinking and feeling that ert from social expectations. However, the comorbidity between cocaine dependence and personality disorders has not been substantiated by measures of brain activation during social decision-making. We applied functional magnetic resonance imaging to compare brain activations evoked by a social decision-making task-the Ultimatum Game-in 24 cocaine dependents with personality disorders (CDPD), 19 cocaine dependents without comorbidities and 19 healthy controls. In the Ultimatum Game participants had to accept or reject bids made by another player to split monetary stakes. Offers varied in fairness (in fair offers the proposer shares ~50 percent of the money in unfair offers the proposer shares <30 percent of the money), and participants were told that if they accept both players get the money, and if they reject both players lose it. We contrasted brain activations during unfair versus fair offers and accept versus reject choices. During evaluation of unfair offers CDPD displayed lower activation in the insula and the anterior cingulate cortex and higher activation in the lateral orbitofrontal cortex and superior frontal and temporal gyri. Frontal activations negatively correlated with emotion recognition. During rejection of offers CDPD displayed lower activation in the anterior cingulate cortex, striatum and midbrain. Dual diagnosis is linked to hypo-activation of the insula and anterior cingulate cortex and hyper-activation of frontal-temporal regions during social decision-making, which associates with poorer emotion recognition.
Publisher: Oxford University Press (OUP)
Date: 06-09-2014
Abstract: High impulsivity is common to substance and gambling addictions. Despite these commonalities, there is still substantial heterogeneity on impulsivity levels within these diagnostic groups, and variations in impulsive levels predict higher severity of symptoms and poorer outcomes. We addressed the question of whether impulsivity scores can yield empirically driven subgroups of addicted in iduals that will exhibit different clinical presentations and outcomes. We applied latent class analysis (LCA) to trait (UPPS-P impulsive behavior scale) and cognitive impulsivity (Stroop and d2 tests) scores in three predominantly male addiction diagnostic groups: Cocaine with Personality Disorders, Cocaine Non-comorbid, and Gambling and analyzed the usefulness of the resulting subgroups to differentiate personality beliefs and relevant outcomes: Craving, psychosocial adjustment, and quality of life. In accordance with impulsivity scores, the three addiction diagnostic groups are best represented as two separate classes: Class 1 characterized by greater trait impulsivity and poorer cognitive impulsivity performance and Class 2 characterized by lower trait impulsivity and better cognitive impulsivity performance. The two empirically derived classes showed significant differences on personality features and outcome variables (Class 1 exhibited greater personality dysfunction and worse clinical outcomes), whereas conventional diagnostic groups showed non-significant differences on most of these measures. Trait and cognitive impulsivity scores differentiate subgroups of addicted in iduals with more versus less severe personality features and clinical outcomes.
Publisher: Springer Science and Business Media LLC
Date: 21-02-2018
DOI: 10.1007/S10803-018-3503-3
Abstract: Deficits in cognitive flexibility are thought to underpin the core symptom of repetitive and restricted patterns of behaviour in autism spectrum disorder (ASD). Studies investigating this relationship, however, report inconsistent results. This is partly due to the variable nature of measures used to assess the construct of flexibility. The main purpose of this study was to investigate whether ASD traits differentially predict cognitive flexibility performance on lab-based neurocognitive measures relative to behavioural self-reports in a non-clinical s le of young adults. Our results indicate that ASD traits exclusively predict performance on behavioural self-reports of cognitive flexibility. These findings highlight the possibility that behavioural self-reports are a better index than lab-based neurocognitive measures to capture cognitive flexibility impairments in in iduals with ASD.
Publisher: Frontiers Media SA
Date: 20-05-2014
Publisher: BMJ
Date: 07-2021
DOI: 10.1136/BMJOPEN-2020-046830
Abstract: There are no well-established biomedical treatments for the core symptoms of autism spectrum disorder (ASD). A small number of studies suggest that repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique, may improve clinical and cognitive outcomes in ASD. We describe here the protocol for a funded multicentre randomised controlled clinical trial to investigate whether a course of rTMS to the right temporoparietal junction (rTPJ), which has demonstrated abnormal brain activation in ASD, can improve social communication in adolescents and young adults with ASD. This study will evaluate the safety and efficacy of a 4-week course of intermittent theta burst stimulation (iTBS, a variant of rTMS) in ASD. Participants meeting criteria for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition ASD (n=150, aged 14–40 years) will receive 20 sessions of either active iTBS (600 pulses) or sham iTBS (in which a sham coil mimics the sensation of iTBS, but no active stimulation is delivered) to the rTPJ. Participants will undergo a range of clinical, cognitive, epi/genetic, and neurophysiological assessments before and at multiple time points up to 6 months after iTBS. Safety will be assessed via a structured questionnaire and adverse event reporting. The study will be conducted from November 2020 to October 2024. The study was approved by the Human Research Ethics Committee of Monash Health (Melbourne, Australia) under Australia’s National Mutual Acceptance scheme. The trial will be conducted according to Good Clinical Practice, and findings will be written up for scholarly publication. Australian New Zealand Clinical Trials Registry (ACTRN12620000890932).
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.DRUGALCDEP.2013.04.031
Abstract: Based on previous evidence of a MAOA gene*cocaine use interaction on orbitofrontal cortex volume attrition, we tested whether the MAOA low activity variant and cocaine use severity are interactively associated with impulsivity and behavioral indices of orbitofrontal dysfunction: emotion recognition and decision-making. 72 cocaine dependent in iduals and 52 non-drug using controls (including healthy in iduals and problem gamblers) were genotyped for the MAOA gene and tested using the UPPS-P Impulsive Behavior Scale, the Iowa Gambling Task and the Ekman's Facial Emotions Recognition Test. To test the main hypothesis, we conducted hierarchical multiple regression analyses including three sets of predictors: (1) age, (2) MAOA genotype and severity of cocaine use, and (3) the interaction between MAOA genotype and severity of cocaine use. UPPS-P, Ekman Test and Iowa Gambling Task's scores were the outcome measures. We computed the statistical significance of the prediction change yielded by each consecutive set, with 'a priori' interest in the MAOA*cocaine severity interaction. We found significant effects of the MAOA gene*cocaine use severity interaction on the emotion recognition scores and the UPPS-P's dimensions of Positive Urgency and Sensation Seeking: Low activity carriers with higher cocaine exposure had poorer emotion recognition and higher Positive Urgency and Sensation Seeking. Cocaine users carrying the MAOA low activity show a greater impact of cocaine use on impulsivity and behavioral measures of orbitofrontal cortex dysfunction.
Publisher: Springer Science and Business Media LLC
Date: 21-11-2021
Publisher: Elsevier BV
Date: 03-2020
Publisher: Springer Science and Business Media LLC
Date: 17-05-2016
DOI: 10.1007/S12311-016-0788-7
Abstract: The cerebellum appears to play a key role in the development of internal rules that allow fast, predictive adjustments to novel stimuli. This is crucial for adaptive motor processes, such as those involved in walking, where cerebellar dysfunction has been found to increase variability in gait parameters. Motor adaptation is a process that results in a progressive reduction in errors as movements are adjusted to meet demands, and within the cerebellum, this seems to be localised primarily within the right hemisphere. To examine the role of the right cerebellar hemisphere in adaptive gait, cathodal transcranial direct current stimulation (tDCS) was administered to the right cerebellar hemisphere of 14 healthy adults in a randomised, double-blind, crossover study. Adaptation to a series of distinct spatial and temporal templates was assessed across tDCS condition via a pressure-sensitive gait mat (ProtoKinetics Zeno walkway), on which participants walked with an induced 'limp' at a non-preferred pace. Variability was assessed across key spatial-temporal gait parameters. It was hypothesised that cathodal tDCS to the right cerebellar hemisphere would disrupt adaptation to the templates, reflected in a failure to reduce variability following stimulation. In partial support, adaptation was disrupted following tDCS on one of the four spatial-temporal templates used. However, there was no evidence for general effects on either the spatial or temporal domain. This suggests, under specific conditions, a coupling of spatial and temporal processing in the right cerebellar hemisphere and highlights the potential importance of task complexity in cerebellar function.
No related grants have been discovered for Natalia Albein Urios.