Poor evidence available on cannabinoids in mental health conditions

Researchers identified 83 studies reporting the effects of cannabinoids in several mental health conditions and found a lack of high-quality evidence supporting their use.

Cannabis flower

There is a lack of high-quality evidence supporting the use of cannabinoids in the treatment of mental disorders, the authors of a meta-analysis published in the Lancet Psychiatry have concluded (28 October 2019)[1]

The researchers identified 83 studies which reported the effects of cannabinoids — including pharmaceutical cannabinoids and their synthetic derivatives — in depression, anxiety, attention-deficit hyperactivity disorder, Tourette’s syndrome, post-traumatic stress disorder and psychosis.

Few randomised controlled trials examined the role of pharmaceutical cannabidiol or medicinal cannabis.

Overall, the researchers found there was no impact of cannabinoid treatment on any of the conditions. They also noted that most of the available data came from trials where mental disorders were not the primary condition being studied.

There was evidence that tetrahydrocannabinol improved anxiety symptoms in people with other conditions, including chronic pain and multiple sclerosis, but the quality of the evidence was low.

The team said that the findings were important given that several countries have now legalised the use of medical cannabinoids.

Louisa Degenhardt, lead author and researcher from the University of New South Wales, Australia, said: “Doctors and patients must be aware of the limitations of existing evidence and the risks of cannabinoids. These must be weighed when considering use to treat symptoms of common mental health disorders.” 


[1] Black N, Stockings E, Campbell G et al. Lancet Psych 2019;6(12):995–1010. doi: 10.1016/S2215-0366(19)30401-8

Last updated
The Pharmaceutical Journal, Poor evidence available on cannabinoids in mental health conditions;Online:DOI:10.1211/PJ.2019.20207406

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