Policy Implications of the Evidence on Cannabis Use and Psychosis

Abstract

There is consistent observational evidence and biological plausibility for the hypothesis that regular cannabis use is a contributory cause of psychosis. The evidence is at least as strong as that for causal relationships between heavy alcohol and amphetamine use and psychosis. On the grounds of prudence, the evidence warrants organized efforts to discourage regular cannabis use among adolescents and young adults. Clinical services should specifically identify young adults with psychoses who use cannabis and encourage them to desist. We need to develop preventive programmes that effectively inform young people about the mental health risks of early and frequent cannabis use. Jurisdictions that have legalized cannabis for medical or recreational use should regulate cannabis products in ways that reduce young people’s access to high potency products at an early age and prevent cannabis retailers from promoting more frequent and longer-term cannabis use among young adults.