What Works for Reducing Cannabis Use in People With Psychosis or Depression? | Research

The takeaway

A systematic review of seven RCTs found preliminary evidence that treating the underlying mental health condition with standard medication and using longer psychological interventions may reduce cannabis use in people with psychotic or depressive disorders.

Read this if you treat patients with co-occurring psychosis/depression and cannabis use.

Only 7 RCTs existed for treating cannabis use in psychosis or depression

What the researchers found

From 1,713 initial articles, only 7 randomized controlled trials reported cannabis use outcomes from pharmacological or psychological interventions in mental health patients.

The limited evidence suggested two key findings:

1. Effectively treating the mental health disorder with standard pharmacotherapy was associated with reduced cannabis use.

2. Longer or more intensive psychological interventions appeared more effective than brief interventions, particularly for heavier cannabis users and those with more chronic mental disorders.

Motivational interviewing and cognitive-behavioral therapy appeared most promising, though specific recommendations about type and length of psychological treatment could not yet be made.

Why it matters

Cannabis use is common among people with psychosis and depression and worsens outcomes. Identifying effective treatments for concurrent cannabis use in these populations addresses a critical clinical gap.

The numbers in context

1,713 articles screened. 7 RCTs met inclusion criteria. Brief interventions appeared insufficient. Longer interventions and medication treatment of the primary disorder showed promise.

How the study worked

Systematic review of PubMed and PsychINFO databases from inception through December 2008. Searches combined cannabis use, mental disorders, and pharmacotherapy/treatment terms, limited to RCTs in humans.

What this study cannot tell us

Only 7 RCTs met criteria, severely limiting conclusions. Studies varied in design, populations, and outcomes. Most evidence was short-term. No specific treatment could be definitively recommended.

How to read the evidence

Systematic review methodology but limited by the very small number of qualifying RCTs (7 total) with heterogeneous designs.

When this study was published

Published in 2010. Research on dual diagnosis treatment has expanded since then, though evidence-based guidelines remain limited.

The bigger picture

Dual diagnosis (mental illness plus substance use) is the rule rather than the exception in many clinical settings. This review highlighted how little evidence existed for treating cannabis use specifically in people with serious mental illness.

Questions still open

Would integrated treatment (addressing both mental illness and cannabis use simultaneously) outperform sequential treatment? Are certain antipsychotics or antidepressants better at reducing concurrent cannabis use? What psychological intervention length is optimal?

Common questions

Does treating depression or psychosis reduce cannabis use?

The limited evidence suggested yes, effective pharmacological treatment of the primary mental health condition was associated with reduced cannabis use. This supports integrated treatment approaches rather than addressing each condition separately.

Are brief interventions enough?

The review found brief interventions appeared insufficient, particularly for heavier users and those with chronic mental disorders. Longer or more intensive approaches using motivational interviewing or CBT appeared more promising.

Read the original research

Treatment of cannabis use among people with psychotic or depressive disorders: a systematic review.

The Journal of clinical psychiatry, 71(3), 247-54

View on PubMed ↗Publisher’s paper ↗

Citation

Baker, Amanda L; Hides, Leanne; Lubman, Dan I. (2010). Treatment of cannabis use among people with psychotic or depressive disorders: a systematic review.. The Journal of clinical psychiatry, 71(3), 247-54. https://doi.org/10.4088/JCP.09r05119gry