ORCID Profile
0000-0003-0971-2007
Current Organisation
University of South Australia
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Hindawi Limited
Date: 2016
DOI: 10.1155/2016/9485079
Abstract: Little is known about the long-lasting effect of use of illicit stimulant drugs on learning of new motor skills. We hypothesised that abstinent in iduals with a history of primarily meth hetamine and ecstasy use would exhibit normal learning of a visuomotor tracking task compared to controls. The study involved three groups: abstinent stimulant users ( n = 21 27 ± 6 yrs) and two gender-matched control groups comprising nondrug users ( n = 16 22 ± 4 yrs) and cannabis users ( n = 16 23 ± 5 yrs). Motor learning was assessed with a three-minute visuomotor tracking task. Subjects were instructed to follow a moving target on a computer screen with movement of the index finger. Metacarpophalangeal joint angle and first dorsal interosseous electromyographic activity were recorded. Pattern matching was assessed by cross-correlation of the joint angle and target traces. Distance from the target (tracking error) was also calculated. Motor learning was evident in the visuomotor task. Pattern matching improved over time (cross-correlation coefficient) and tracking error decreased. However, task performance did not differ between the groups. The results suggest that learning of a new fine visuomotor skill is unchanged in in iduals with a history of illicit stimulant use.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.DRUGALCDEP.2017.05.017
Abstract: Despite evidence that cannabinoid receptors are located in movement-related brain regions (e.g., basal ganglia, cerebral cortex, and cerebellum), and that chronic cannabis use is associated with structural and functional brain changes, little is known about the long-term effect of cannabis use on human movement. The aim of the current study was to investigate balance and walking gait in adults with a history of cannabis use. We hypothesised that cannabis use is associated with subtle changes in gait and balance that are insufficient in magnitude for detection in a clinical setting. Cannabis users (n=22, 24±6years) and non-drug using controls (n=22, 25±8years) completed screening tests, a gait and balance test (with a motion capture system and in-built force platforms), and a clinical neurological examination of movement. Compared to controls, cannabis users exhibited significantly greater peak angular velocity of the knee (396±30 versus 426±50°/second, P=0.039), greater peak elbow flexion (53±12 versus 57±7°, P=0.038) and elbow range of motion (33±13 versus 36±10°, P=0.044), and reduced shoulder flexion (41±19 versus 26±16°, P=0.007) during walking gait. However, balance and neurological parameters did not significantly differ between the groups. The results suggest that history of cannabis use is associated with long-lasting changes in open-chain elements of walking gait, but the magnitude of change is not clinically detectable. Further research is required to investigate if the subtle gait changes observed in this population become more apparent with aging and increased cannabis use.
Publisher: Public Library of Science (PLoS)
Date: 29-12-2014
Publisher: Elsevier BV
Date: 10-2021
Publisher: EMBO
Date: 04-10-2019
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.PARKRELDIS.2016.02.019
Abstract: The sonographic appearance of the substantia nigra is abnormally bright and enlarged (hyperechogenic) in young adults with a history of illicit stimulant use. The abnormality is a risk factor for Parkinson's disease. The aim of the current study was to identify the type of illicit stimulant drug associated with substantia nigra hyperechogenicity and to determine if in iduals with a history of illicit stimulant use exhibit clinical signs of parkinsonism. We hypothesised that use of hetamines (primarily meth hetamine) is associated with substantia nigra hyperechogenicity and clinical signs of parkinsonism. The area of echogenic signal in the substantia nigra was measured in abstinent human hetamine users (n = 27 33 ± 8 years) and in three control groups comprising a) 'ecstasy' users (n = 19 23 ± 3 years), b) cannabis users (n = 30 26 ± 8 years), and c) non-drug users (n = 37 25 ± 7 years). A subset of subjects (n = 55) also underwent a neurological examination comprising the third and fifth part of the Unified Parkinson's Disease Rating Scale. Area of substantia nigra echogenicity was significantly larger in the hetamine group (0.276 ± 0.080 cm(2)) than in the control groups (0.200 ± 0.075, 0.190 ± 0.049, 0.191 ± 0.055 cm(2), respectively P < 0.002). The score on the clinical rating scale was also significantly higher in the hetamine group (8.4 ± 8.1) than in pooled controls (3.3 ± 2.8 P = 0.002). Illicit use of hetamines is associated with abnormal substantia nigra morphology and subtle clinical signs of parkinsonism. The results support epidemiological findings linking use of hetamines, particularly meth hetamine, with increased risk of developing Parkinson's disease later in life.
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.DRUGALCDEP.2019.107595
Abstract: Illicit stimulant use is associated with long-lasting changes in movement and movement-related brain regions. The aim of our study was to investigate the prevalence of movement dysfunction in this population. We hypothesized that prevalence of self-reported movement dysfunction is higher among stimulant users than non-stimulant users. Three groups of adults completed a survey containing questions about demographics, health, drug use, and movement. The groups consisted of ecstasy users with no history of meth hetamine use (ecstasy group, n = 190, 20 ± 3 yrs.), meth hetamine users (meth hetamine group, n = 331, 23 ± 5 yrs.), and non-stimulant users (control group, n = 228, 25 ± 8 yrs.). Movement data was analyzed with logistic regression. In the unadjusted logistic regression model, group had a significant effect on fine hand control, tremor, and voice/speech questions, but not on other movement domain questions. The prevalence of tremor and abnormal fine hand control was significantly higher in the ecstasy and meth hetamine groups than in the control group (p < 0.018), and changes in voice/speech was more prevalent in the ecstasy group than in the control group (p = 0.015). Age and use of cannabis and hallucinogens were confounding variables. However, inspection of chi-square tables suggests that the effect of these parameters on the movement data is likely to be minor. The prevalence of self-reported tremor and changes in fine hand control and voice/speech is significantly higher in stimulant users than in non-stimulant users. Inclusion of these common and noticeable changes in body function may aid public health c aigns that target prevention or harm minimization.
Publisher: Elsevier
Date: 2016
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.CLINPH.2019.02.005
Abstract: The study aim was to determine if use of illicit hetamines or ecstasy is associated with abnormal excitability of the corticomotoneuronal pathway and manipulation of novel objects with the hand. Three groups of adults aged 18-50 years were investigated: in iduals with a history of illicit hetamine use, in iduals with a history of ecstasy use but minimal use of other stimulants, and non-drug users. Transcranial magnetic stimulation was delivered to the motor cortex and the electromyographic response (motor evoked potential MEP) was recorded from a contralateral hand muscle. Participants also gripped and lifted a novel experimental object consisting of two strain gauges and an accelerometer. Resting MEP litude was larger in the hetamine group (6M, 6F) than the non-drug and ecstasy groups (p < 0.005) in males but not females. Overestimation of grip force during manipulation of a novel object was observed in the hetamine group (p = 0.020) but not the ecstasy group. History of illicit hetamine use, in particular meth hetamine, is associated with abnormal motor cortical and/or corticomotoneuronal excitability in males and abnormal manipulation of novel objects in both males and females. Abnormal excitability and hand function is evident months to years after cessation of illicit hetamine use.
No related grants have been discovered for Verity Pearson-Dennett.