Actively Recruiting
Investigating the Neural Correlates of Cognitive Function Associated With Cannabis Abstinence in Psychosis Patients and Non-Psychiatric Controls With Cannabis Use
Led by Douglas Mental Health University Institute · Updated on 2026-05-22
134
Participants Needed
1
Research Sites
N/A
Total Duration
On this page
AI-Summary
What this Trial Is About
Researchers are investigating how 28 days of abstaining from cannabis affects brain function and cognitive abilities in people with psychosis who use cannabis, as well as in non-psychiatric controls who use cannabis. The study aims to better understand the brain changes linked to cannabis use and cognitive problems, and how these might recover after stopping cannabis. This research could help develop new treatments for problematic cannabis use. The study is interventional and involves brain imaging and cognitive testing in both patient and control groups. Participants will be assigned randomly to either a group encouraged to abstain from cannabis for 28 days using contingency management, or a control group that continues their usual cannabis use. The study includes psychosis patients who use cannabis, non-psychiatric cannabis users, and non-psychiatric controls who do not use cannabis. All participants will undergo magnetic resonance imaging (MRI) and complete a memory task both at the start and after 28 days. Urine samples will be collected twice weekly to confirm abstinence. During the study, participants will complete brain scans and cognitive tests at baseline and after 28 days to measure changes in brain activity and structure, including gray matter volume, cortical thickness, and diffusion. Researchers will also monitor behavior during memory tasks and verify cannabis abstinence biochemically. The total involvement spans the 28-day intervention period with follow-up assessments, helping to understand neural recovery and cognitive changes related to cannabis use.
CONDITIONS
Brief Title
Investigating the Neural Correlates of Cognitive Function in Psychosis Patients and Non-Psychiatric Controls With Cannabis Use
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Able to provide informed consent in English or French
- Heavy cannabis use defined as weekly use for at least six months and/or a diagnosis of cannabis use disorder
- Full-Scale IQ of 75 or higher
- For psychosis patients: meet DSM-5 criteria for a psychotic disorder
- For psychosis patients: be an outpatient on stable medication for at least two months
- For psychosis patients: clinically stable with PANSS-6 total score less than 30
You will not qualify if you...
- Current substance use disorder other than cannabis use disorder
- Contraindications for MRI scanning
- Positive urine screen for psychoactive substances other than cannabis, nicotine, or caffeine
- Current suicidal or homicidal thoughts
- History of head injury requiring hospitalization or loss of consciousness over 5 minutes
- Current medical conditions requiring hospitalization or regular monitoring
- Being pregnant
- For non-psychiatric controls: any DSM-5 Axis 1 diagnosis other than cannabis use disorder
- Currently taking psychotropic medication
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - 28 days
Participants undergo behavioral interventions including contingency management to encourage cannabis abstinence or continue cannabis use as usual. Participants provide urine samples twice weekly for abstinence verification.
Twice weekly visits for urine sample collection
Duration - At baseline and Day 28
Participants undergo structural and functional magnetic resonance imaging while completing a memory task at baseline (pre-abstinence) and after 28 days.
2 imaging visits
Trial Site Locations
Total: 1 location
1
Douglas Mental Health University Institute
Montreal, Quebec, Canada, H4H 1R3
Actively Recruiting
Research Team
C
Charlene Osei-Afrifa
How is the study designed?
Study Type
INTERVENTIONAL
Masking
SINGLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
BASIC_SCIENCE
Number of Arms
5
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