Meta-analysis of 31 RCTs found limited evidence for cannabinoids treating psychiatric disorders

Of 31 RCTs (10 for cannabis use disorder, 6 for schizophrenia, 5 for opioid/tobacco use, 3 for anxiety, 2 each for Tourette's and anorexia, 1 each for ADHD, PTSD, and OCD), the review found limited evidence for acute symptom management in select conditions. No evidence supported mid- to long-term effectiveness. No study endorsed cannabis flower as treatment for any psychiatric disorder. Evidence quality was generally low to moderate.

Systematic review and meta-analysis searching 8 databases from inception to September 2020. Of 2,397 papers identified, 31 RCTs met inclusion criteria. Risk of bias was assessed using the revised Cochrane tool.

Despite widespread consumer belief in cannabis for mental health, the highest level of evidence (RCTs) provides only limited support for acute use in narrow applications and no support for ongoing treatment of any psychiatric disorder.

This meta-analysis creates an important reality check against the growing popular narrative that cannabis can treat psychiatric conditions. While some acute effects are supported, the gap between consumer expectations and clinical evidence remains wide.

Heterogeneity across RCTs in products, doses, and outcomes limits meta-analytic pooling. Many included trials were small. Rapid evolution of cannabis products means newer formulations are understudied. Publication bias possible.