October 28, 2019

expert reaction to meta-analysis on medicinal cannabinoids for mental health conditions

A study, published in The Lancet Psychiatry, reports that there is currently insufficient good quality evidence to support the use of cannabinoids for the the treatment of some mental health conditions. 

Prof David Nutt, The Edmond J Safra Chair and Head of the Centre for Neuropsychopharmacology, Division of Brain Sciences,  Dept of Medicine, Imperial College London and Chair of DrugScience, said:

“The Lancet Psychiatry meta-analysis rather misses the point. Cannabis has been a medicine for millennia, with governments and regulators more recently expanding access through a variety of mechanisms, so subjecting it to the same requirements as modern synthetic medicines is not the most obvious nor necessary way to progress. Especially as when such trials have been done [e.g. with Epidiolex] HTAs are often not prepared to pay the full costs of the treatment. The authors should read the parallel paper in the BMJ [Freeman et al  https://www.bmj.com/content/365/bmj.l1141 ] that makes a clear case for n=1 trials with medical cannabis – just what patients are doing every day. Unfortunately in the UK this self-treatment is largely with black market cannabis of unknown strength and provenance, and is potentially associated with significant public health harms.  To overcome this, the UK charity DrugScience is setting up a new initiative TWENTY21 to allow access of medical cannabis to twenty thousand patients to collect effectiveness, safety, QALY and patient valued outcomes  in such real world data registries and personalised trials over the next two years.”

Dr Tom Freeman, Lead Director of the Addiction and Mental Health Group, University of Bath, said:

“This meta-analysis highlights the current low quality of evidence for the efficacy and safety of cannabinoids for the treatment of mental health disorders. The quality of evidence is also low for the use of cannabinoids in the treatment of other medical indications, as outlined in draft recommendations by the National Institute of Health and Care Excellence (NICE). Given the significant demand for access to these medications from patients, further research is urgently needed to strengthen the evidence. The only way for patients to access these medications at present is through private prescription which require vastly excessive costs, or via the illicit market which carries risk of prosecution as well as unknown product content, quality and safety. Last week, we published recommendations for strengthening the evidence for medicinal cannabinoids in the British Medical Journal [1]. The use of alternative trial designs such as N-of-1 trials (randomised controlled trials within individual patients) and observational patient registries could strengthen the evidence in a time- and cost- effective manner. These initiatives have the potential to increase access to these medicines in cases where they are effective and safe.”

[1] Freeman, T. P., Morgan, C., & Hindocha, C. (2019). Strengthening the evidence for medicinal cannabis and cannabinoids. BMJ 2019;367:l5871

‘Cannabinoids for the treatment of mental disorders and symptoms of mental disorders: a systematic review and meta-analysis’ by Nicola Black et al. was published in The Lancet Psychiatry at 22:30 UK time on Monday 28th October. 

Declared interests

Prof David Nutt: Prof David Nutt is Chair of DrugScience

Dr Tom Freeman: No conflicts of interest