An interventional study of Contingency management in Psychotic Disorders, Cannabis Use Disorder and Cannabis Dependence, sponsored by Douglas Mental Health University Institute. Recruiting at 1 site in Canada. Open to participants aged 16 Years to 80 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-15.
Sponsored by Douglas Mental Health University Institute · Not applicable, Interventional, and Basic science
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.
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.
1,587 studies on the registry are indexed under Psychotic Disorders; 281 are open to participants now.
This study's planned enrollment of 134 is above the median of 65 across 1,320 interventional studies indexed under Psychotic Disorders.
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Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Psychosis patients with cannabis use will receive contingency management to encourage cannabis abstinence for 28 days
Behavioral: Contingency management
Psychosis Patients with cannabis use who will continue to use cannabis as usual
Non-Psychiatric controls with cannabis use will receive contingency management to encourage cannabis abstinence for 28 days
Behavioral: Contingency management
Non-Psychiatric Controls with cannabis use will continue to use cannabis as usual
Non-Psychiatric controls without cannabis use
Contingency management will be used to encourage abstinence
Change in fMRI brain activity pattern
fMRI will be used to measure differences between baseline (day 0) and day 28 in hemodynamic (BOLD) responses while participants complete a memory task
Time frame: Baseline, Day 28
Change in behavior during fMRI task
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.
Time frame: Baseline, Day 28
Change in brain morphology: gray matter volume
Using MRI, changes in gray matter volume will be analyzed from baseline (day 0) to day 28
Time frame: Baseline, Day 28
Change in brain morphology: cortical thickness
Using MRI, changes in cortical thickness will be analyzed from baseline (day 0) to day 28
Time frame: Baseline, Day 28
Change in brain morphology: diffusion
Using MRI, changes in diffusion based measures will be analyzed from baseline (day 0) to day 28
Time frame: Baseline, Day 28
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Douglas Mental Health University Institute