The efficacy of cannabinoids for the treatment of six major mental health disorders, including depression and anxiety, is not yet proven, researchers say today.
The new findings, published in The Lancet Psychiatry, is the most comprehensive analysis yet into medicinal cannabinoids, combining 83 studies that involve 3,000 people.
The Australian-led research concluded that using cannabinoids for mental health conditions cannot be justified based on current evidence.
However, the researchers concede there is very low-quality evidence that pharmaceutical tetrahydrocannabinol (THC) may lead to a small improvement in symptoms of anxiety in individuals with other medical conditions, such as chronic pain or multiple sclerosis.
Lead author Professor Louisa Degenhardt of the National Drug and Alcohol Research Centre (NDARC) at UNSW Sydney, Australia, said: “Our findings have important implications in countries where cannabis and cannabinoids are being made available for medical use.
“There is a notable absence of high-quality evidence to properly assess the effectiveness and safety of medicinal cannabinoids compared with placebo, and until evidence from randomised controlled trials is available, clinical guidelines cannot be drawn up around their use in mental health disorders.”
She added that countries where medicinal cannabinoids are already legal, doctors and patients must be aware of the limitations of existing evidence and the risks of cannabinoids.
The authors examined the available evidence for all types of medicinal cannabinoids and included all study designs to investigate the impact on remission from and symptoms of: depression, anxiety, attention-deficit hyperactivity disorder (ADHD), Tourette syndrome, post-traumatic stress disorder (PTSD), and psychosis.
They included published and unpublished studies between 1980 and 2018 and included 83 eligible studies, 40 of which were randomised controlled trials. Of the 83 studies, 42 focused on depression, 31 on anxiety, eight on Tourette syndrome, three on ADHD, 12 on PTSD, and 11 on psychosis.
The authors found seven studies, comprising 252 people, that pharmaceutical THC, with or without CBD, improved anxiety symptoms among individuals with other medical conditions, although they say this may have been due to improvements in the primary medical condition.
In one study of 24 people, pharmaceutical THC, with or without CBD, worsened negative symptoms of psychosis and did not significantly affect any other primary outcomes for the mental health disorders examined.
They also found that in 10 studies of 1495 people, it increased the number of people who had adverse events.
Prof Degenhardt said clinicians and patients must take into account the low quality and quantity of evidence for the effectiveness of medicinal cannabinoids in treating mental health disorders and the potential risk of adverse events.
“Given the likely interest but scant evidence to guide patient and clinician decisions around cannabinoids for mental health, there is an urgent need for randomised controlled trials to inform whether there are benefits of cannabinoids for these indications,” she added.
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. The Lancet Psychiatry 29 October 2019.
http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30401-8/fulltext
Leave a Reply