Here’s the findings and interpretations from the paper

Findings

54 trials were identified for inclusion (2477 participants; 1713 [69%] males, 764 [31%] females; median age 33·3 years [IQR 28·1–38·05; ethnicity data not available). 24 (44%) of these trials had a high risk of bias, and the certainty of evidence for most outcomes was low. Our meta-analysis revealed that a combination of cannabidiol and delta-9-tetrahydrocannabinol reduced cannabis withdrawal symptoms (SMD –0·29, 95% CI –0·57 to –0·02) and weekly grams of cannabis use (–1·00, –1·69 to –0·30) among those with cannabis use disorder, and a reduction in tic severity among those with tic or Tourette’s Syndrome (–0·68, –1·03 to –0·34) compared with placebo. Any cannabinoid type led to an increase in sleep time as recorded by an electronic device (0·54, 0·14 to 0·95) and sleep diary (0·55, 0·01 to 1·09) among those with insomnia. There was a reduction in autistic traits (–0·36, –0·66 to –0·07) among those with autism spectrum disorder. Cannabinoids led to an increase in cocaine craving among those with cocaine use disorder (0·69, 0·22 to 1·15) compared with placebo. There were no significant effects on outcomes associated with anxiety, anorexia nervosa, psychotic disorders, post-traumatic stress disorder, and opioid use disorder. There were insufficient data to meta-analyse studies of ADHD, bipolar disorder, obsessive-compulsive disorder, and tobacco use disorder. There was an absence of RCT evidence for the treatment of depression. Meta-analysis revealed higher odds of all-cause adverse events (OR 1·75, 95% CI 1·25 to 2·46) among those using cannabis versus control group (NNTH=7) but no higher odds of serious adverse events or study withdrawal.

Interpretation

There was some evidence that cannabinoids can reduce symptoms of cannabis use disorder, insomnia, tic or Tourette’s syndrome, and autism spectrum disorder, but the quality of this evidence was generally low. Cannabinoids were associated with a greater risk of any adverse events but not of serious adverse events. Overall, there is a crucial need for more high-quality research. Given the scarcity of evidence, the routine use of cannabinoids for the treatment of mental disorders and SUDs is currently rarely justified.