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Cannabinoid Use for Mental Health Disorders Questioned

October 29, 2019

There is very little evidence supporting the treatment of mental health disorders with cannabis, according to the results of a recent meta-analysis.

Although it has been suggested that cannabinoids and their synthetic derivatives could be used for the treatment of mental health disorders, their safety and effectiveness is still not fully understood.

To explore this further, researchers conducted a systematic review and meta-analysis including data from 83 studies (40 of which were randomized controlled trials) including 42 for depression, 31 for anxiety, 8 for Tourette syndrome, 3 for attention-deficit hyperactivity disorder (ADHD), 12 for post-traumatic stress disorder (PTSD), and 11 for psychosis. All studies examined the use of any type or formulation of a medicinal cannabinoid in adults aged 18 years or older.

Overall, pharmaceutical tetrahydrocannabinol (THC) was shown to improve symptoms of anxiety in individuals with other medical conditions, including non-cancer pain and multiple sclerosis, but the evidence was of low quality. It was also shown to worsen symptoms of psychosis in a single study and did not significantly affect any other primary outcome. However, it was associated with a greater number of individuals having adverse effects in 10 studies and the number of withdrawals due to adverse events in 11 studies.

“There is scarce evidence to suggest that cannabinoids improve depressive disorders and symptoms, anxiety disorders, attention-deficit hyperactivity disorder, Tourette syndrome, post-traumatic stress disorder, or psychosis,” the researchers concluded.

“There remains insufficient evidence to provide guidance on the use of cannabinoids for treating mental disorders within a regulatory framework. Further high-quality studies directly examining the effect of cannabinoids on treating mental disorders are needed.”

—Michael Potts


Black N, Stockings E, Campbell G, et al. Cannabinoids for the treatment of mental disorders and symptoms of mental disorders: a systematic review and meta-analysis [published online October 28, 2019]. Lancet Psychiatry.

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