Medical cannabinoids have been legalized in several parts across the globe due to the presence of tetrahydrocannabinol (THC) and cannabidiol (CBD), compounds that are known to have therapeutic effects for certain mental disorders. This study aims to analyze the safety and efficacy of medicinal cannabinoids in treating the symptoms of several mental disorders.

This systematic review and meta-analysis included a total of 83 eligible studies from the datasets of MEDLINE, Embase, Cochrane, and PsychINFO. Out of 83 included studies, 42 were of depression (n=2,551), 31 for anxiety (n=605), eight for Tourette syndrome (n=36), three for ADHD (n=30), 12 for PTSD (n=10), and 11 for psychosis (n=281). The safety and efficacy of medicinal cannabinoids were assessed in this study.

Medicinal THC was associated with improved anxiety symptoms among patients with other medical conditions. However, medicinal THC that did not contain CBD worsened the negative symptoms of psychosis and did not have any effect on the symptoms of other mental disorders. Pharmaceutical THC was further associated with an increased risk of adverse events and withdrawals. 

The research concluded that cannabinoids could improve the symptoms of mental disorders, like depression, anxiety, psychosis, and Tourette syndrome. However, THC without CBD was not associated with substantial benefits.