Lancet clinical review paper: why absence of evidence is not evidence of absence

After a review of historical clinical trials found limited evidence supporting medicinal cannabis for mental health conditions, care must be taken not to mistake gaps in RCT data for a lack of clinical benefit, writes Andrew Proudfoot.

A large Randomised Control Trial-focused review of cannabinoids for mental health and substance use disorders (SUD), covering 54 RCTs and 2,477 participants, was published in The Lancet Psychiatry this week by an austere, highly credible group of Australian researchers.