VRT as a Biomarker of Cerebellar Dysfunction in Chronic Cannabis Use
Keywords
Abstract
Description
The subjects have to realize movements towards a target, at a digitizing tablet, holding a digitizing pencil. Visual feedback is projected on a screen surface in front of the subject, which hides the sight of actual movements from the latter. In the experimental condition of rotation, the experimenter introduces a rotation of 45 grades between the movement realized by the subject and the visual feedback that is provided on the screen. Then, the subject is provided with a strategy in order to overcome this perturbation: that is, to make the movement aiming 45 grades to the opposite direction from the introduced rotation. This explicit strategy leads to immediate correction of the error, but as the time passes subjects tend to commit more and more errors due to implicit motor adaptation. This happens because the motor control system tends to correct the perceived perturbation between the anticipated and the actual location of the hand in an automatic and unconscious way. The conflict between the implicit and explicit strategies has the surprising consequence of a persistent and accumulative deterioration of performance that can only be resolved when the participants abandon the explicit strategy. Subjects with cerebellar damage show deficits in implicit motor learning and for this reason they do not show this progressive deterioration of performance. Given that chronic cannabis abuse can lead to cerebellar damage, the investigators hypothesize that subjects from the experimental group 1 (cannabis use) will have a significant smaller directional error on the rotation condition than controls. A second hypothesis is that this effect will be cannabis-specific, due to the high CB1R concentration on the cerebellum, so the alcohol dependence group is expected to perform similarly to control group
Dates
| Last Verified: | 08/31/2018 |
| First Submitted: | 09/02/2018 |
| Estimated Enrollment Submitted: | 09/05/2018 |
| First Posted: | 09/06/2018 |
| Last Update Submitted: | 09/05/2018 |
| Last Update Posted: | 09/06/2018 |
| Actual Study Start Date: | 08/31/2018 |
| Estimated Primary Completion Date: | 11/30/2019 |
| Estimated Study Completion Date: | 11/30/2020 |
Condition or disease
Intervention/treatment
Diagnostic Test: Visuomotor adaptation task
Phase
Arm Groups
| Arm | Intervention/treatment |
|---|---|
| Group 1 -Chronic cannabis use 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) | |
| Group 2 - Alcohol dependence 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). | |
| Control Group Individuals matched in gender and age with the experimental groups and with no diagnosis of substance use or severe mental disorder (except tobacco use) |
Eligibility Criteria
| Ages Eligible for Study | 18 Years To 18 Years |
| Sexes Eligible for Study | All |
| Sampling method | Non-Probability Sample |
| Accepts Healthy Volunteers | Yes |
| Criteria | Inclusion Criteria: - 18-50 years old - Right-handed - Daily consumption of cannabis for at least 2 years (cannabis group) or diagnosed Alcohol Use Disorder (alcohol group) Exclusion Criteria: - Non-corrected visual deficits - Regular consumption of other drugs except nicotine - Other Axis I or neurological diagnosis |
Outcome
Primary Outcome Measures
1. Change in directional error between baseline and after cessation of cannabis use [The visuomotor adaptation task duration will not exceed 20 minutes and subjects are expected to realize it at three different time points: baseline, 1 month, 3 months]
