Individuals between 18 and 50 years old who have been using at least 2 joints per day for at least 3 years. They should have used cannabis during the last 24h but not during the 3h prior to participation to the study and they should test positive for cannabis in their urine. Individuals with another substance use or severe mental disorder will be excluded (except tobacco use)

Individuals between 18 and 50 years old diagnosed with alcohol use disorder according to DSM-V criteria and have been consuming alcohol for at least 3 years. Individuals who are diagnosed with another substance use or severe mental disorder will be excluded (except tobacco use).

Individuals matched in gender and age with the experimental groups and with no diagnosis of substance use or severe mental disorder (except tobacco use)

Cannabis Use

Alcohol Use Disorder

Healthy

We will measure performance of the subjects of each group on the visuomotor adaptation task, especially in the rotation condition, in which a perturbation will be induced between the anticipated location of the hand and the provided visual feedback, and in the washout condition, in which the rotation will be removed. We expect that subjects with cannabis use disorder will not show the expected implicit motor adaptation to the perturbation and consequently no deterioration of performance on the task, due to cannabis-induced cerebellar damage. In other words, we want to show that this visuomotor task is a cheap and quick biomarker of cerebellar dysfunction in chronic cannabis users.

Visuomotor adaptation task

VRT as a Biomarker of Cerebellar Dysfunction in Chronic Cannabis Use

A Visuomotor Rotation Task as a Biomarker of Cerebellar Dysfunction in Chronic Cannabis Use

Directional error of hand movement trajectories towards the target object on the rotation condition of the visuomotor rotation task.

Antoni Gual

MD, PhD, Head of Addiction Unit

Hospital Clinic of Barcelona

clozapine: clozapine--tablets, 12.5-100 mg, daily for 24 weeks

risperidone: risperidone--tablets, 0.5-5.0mg daily for 24 weeks

Clozapine

Risperidone

Total

Sex: Female, Male

Region of Enrollment

Based on the small sample size, it was not possible to test the differences between the two groups for statistical significance. Data on cannabis use were gathered weekly using the Timeline Follow-back (TLFB) method. At the end of the study, graphs were plotted showing days of cannabis use per week and rated as "Improved," "Unchanged," or "Worse" by a pair of expert judges. Raters were instructed to rate the graph "Improved" or "Worsened" if it appeared to be >20% better or worse and to rate it "Unchanged" if there was little or no change (less than ~20%).

Number of Participants Demonstrating Improvement in Substance Use

Based on the small sample size, it was not possible to test the differences between the two groups for statistical significance. Data on psychiatric symptoms were gathered using Brief Psychiatric Rating Scale (BPRS; weekly), Clinical Global Impressions Scale (CGIS; weekly) and Schedule for the Assessment of Negative Symptoms (SANS; bi-weekly). At the end of the study, graphs were plotted showing severity of symptoms and rated as "Improved," "Unchanged," or "Worse" by a pair of expert judges. Raters were instructed to rate the graph "Improved" or "Worsened" if it appeared to be >20% better or worse and to rate it "Unchanged" if there was little or no change (less than ~20%).

Number of Participants Demonstrating Improvement in Psychiatric Symptoms Using the BPRS, CGIS, and SANS at 24 Weeks

Overall Study

Alan I. Green, M.D.

Cannabis-Related Disorder

Substance-Related Disorders

Schizophrenia

Psychotic Disorders

clozapine--tabs, 450mg. max, daily, 24 weeks

clozapine

risperidone--tabs, 6mg max, daily, 24 weeks

cannabis/atrophy

VRT as a Biomarker of Cerebellar Dysfunction in Chronic Cannabis Use

First Episode Schizophrenia and Cannabis-Related Disorder Study

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