Investigating the Neural Correlates of Cognitive Function in Psychosis Patients and Non-Psychiatric Controls With Cannabis Use

May 19, 2026 updated by: Rachel Rabin, Douglas Mental Health University Institute

Investigating the Neural Correlates of Cognitive Function Associated With Cannabis Abstinence in Psychosis Patients and Non-Psychiatric Controls With Cannabis Use

Cognitive impairment is well established in people with psychosis and is associated with cannabis use. The current study will investigate the neurobiological basis of cognitive change associated with 28-days of cannabis abstinence in people with psychosis and non-psychiatric controls with cannabis use. Participants will be randomized to a cannabis abstinent group or a non-abstinent control group and will undergo magnetic resonance imaging at baseline and following 28-days of abstinence. This study will help characterize the neuropathophysiological processes underlying cognitive dysfunction associated with cannabis use and its recovery which may guide the development of novel interventions for problematic cannabis use.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Background/Importance: Cognitive impairment is well established in people with psychosis and is associated with cannabis use. Despite high rates of cannabis use among people with psychosis and the general population, cannabis' effects on cognition and the brain and their recovery remain unclear. Therefore, this study will investigate the neurobiological basis of changes in cognitive processes associated with cannabis abstinence in people with psychosis and non-psychiatric controls.

Aims: To examine the effects of 28-days of cannabis abstinence in psychosis patients with cannabis use and non-psychiatric controls with cannabis use on (i) brain activity (paired with a memory task); (ii) brain morphology; (iii) to determine if changes in memory following 28-days of abstinence correlate with changes in brain activity and/or morphology and (iv) to determine if baseline brain function and morphology can predict successful abstinence.

Methods: Seventy-four psychosis patients with cannabis use and 60 non-psychiatric controls with cannabis use will be randomized to: (1) contingency reinforcement where biochemically verified abstinence at day 28 will be rewarded; or (2) a non-abstinent control group. The investigators will also recruit a group of healthy non-psychiatric controls (n=40) to determine if neural outcomes in cannabis-using participants do indeed normalize ("recover") following abstinence. Participants will undergo structural and functional magnetic resonance imaging while completing a memory task at baseline (pre-abstinence) and following 28-days of abstinence. Urine samples will be collected twice weekly for abstinence verification.

Relevance: This study will help to characterize the neuropathophysiological processes underlying cognitive dysfunction associated with cannabis use in people with psychosis and non-psychiatric controls which may help to guide the development of novel neurobiologically-informed interventions to treat problematic cannabis use.

Study Type

Interventional

Enrollment (Estimated)

134

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Canada
    • Quebec
      • Montreal, Quebec, Canada, H4H 1R3
        • Recruiting
        • Douglas Mental Health University Institute
        • Contact:
        • Principal Investigator:
          • Rachel Rabin, Ph. D.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

16 years to 80 years (Child, Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Able to provide informed consent in English or French
  • Heavy cannabis use (defined as weekly cannabis use for at six months) and/or DSM-5 diagnosis of CUD
  • Have a Full-Scale IQ ≥ 75
  • Meet DSM-5 criteria for a psychotic disorder (psychosis patient arm only)
  • Be an outpatient receiving a stable dose of medication(s) for at least two months (psychosis patient arm only)
  • Clinically stable (as measured by the PANSS-6, total score <30) (psychosis patient arm only)

Exclusion Criteria:

  • current SUD (other than CUD)
  • MRI contraindications
  • Positive urine screen for psychoactive substances other than cannabis, nicotine, or caffeine
  • Current suicidal or homicidal ideation
  • Head injury requiring hospitalization or loss of consciousness > 5 minutes
  • Current medical diseases that requires hospitalization or regular monitoring
  • Being pregnant
  • DSM-5 Axis 1 diagnosis (other than CUD) (non-psychiatric controls only)
  • Taking psychotropic medication

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Psychosis patients with cannabis use (Abstinent)
Psychosis patients with cannabis use will receive contingency management to encourage cannabis abstinence for 28 days
Behavioral: Contingency management
Contingency management will be used to encourage abstinence
No Intervention: Psychosis patients with cannabis use (Non-abstinent)
Psychosis Patients with cannabis use who will continue to use cannabis as usual
Experimental: Non-Psychiatric controls with cannabis use (Abstinent)
Non-Psychiatric controls with cannabis use will receive contingency management to encourage cannabis abstinence for 28 days
Behavioral: Contingency management
Contingency management will be used to encourage abstinence
No Intervention: Non-Psychiatric controls with cannabis use (Non-abstinent)
Non-Psychiatric Controls with cannabis use will continue to use cannabis as usual
No Intervention: Non-Psychiatric Controls without cannabis use
Non-Psychiatric controls without cannabis use

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in fMRI brain activity pattern
Time Frame: Baseline, Day 28
fMRI will be used to measure differences between baseline (day 0) and day 28 in hemodynamic (BOLD) responses while participants complete a memory task
Baseline, Day 28
Change in behavior during fMRI task
Time Frame: Baseline, Day 28
Behavioral responses (episodic memory performance) will be recorded by an external button box. These responses will be used to assess encoding accuracy during an episodic memory task.
Baseline, Day 28

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in brain morphology: gray matter volume
Time Frame: Baseline, Day 28
Using MRI, changes in gray matter volume will be analyzed from baseline (day 0) to day 28
Baseline, Day 28
Change in brain morphology: cortical thickness
Time Frame: Baseline, Day 28
Using MRI, changes in cortical thickness will be analyzed from baseline (day 0) to day 28
Baseline, Day 28
Change in brain morphology: diffusion
Time Frame: Baseline, Day 28
Using MRI, changes in diffusion based measures will be analyzed from baseline (day 0) to day 28
Baseline, Day 28

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Douglas Mental Health University Institute

Investigators

  • Principal Investigator: Rachel Rabin, Ph. D., Douglas Mental Health University Institute

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 21, 2022

Primary Completion (Estimated)

May 1, 2027

Study Completion (Estimated)

May 1, 2027

Study Registration Dates

First Submitted

May 18, 2022

First Submitted That Met QC Criteria

June 30, 2022

First Posted (Actual)

July 6, 2022

Study Record Updates

Last Update Posted (Actual)

May 22, 2026

Last Update Submitted That Met QC Criteria

May 19, 2026

Last Verified

August 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • IUSMD-21-11

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Contact the P.I.

IPD Sharing Access Criteria

Contact the P.I.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ANALYTIC_CODE

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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