A comprehensive systematic review spanning 45 years of research has raised critical questions about the clinical utility of medicinal cannabis in mental health treatment. Published in The Lancet Psychiatry, the analysis of 54 randomized controlled trials involving 2,477 participants found no statistically significant benefit compared to placebo for anxiety, PTSD, psychosis, or opioid use disorder—conditions frequently cited as indications for cannabis prescription.
The findings are particularly striking given that depression, one of the most common reasons patients seek cannabis-based treatments, has never been evaluated in a rigorous randomized controlled trial. The review identified only three areas with meaningful evidence: cannabis use disorder itself, sleep duration in insomnia patients, and tic severity in Tourette’s syndrome. Notably, cannabis users experienced adverse events at rates 75% higher than placebo participants, raising safety considerations for clinical practice.
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