Cannabis commercialisation not decriminalisation drives up usage, study finds

Review reveals rise in users and rates of psychosis in countries where cannabis is sold commercially

Decriminalising the possession of cannabis or strictly regulating access to the drug do not appear to drive up usage, but when the drug is sold commercially the number of users increases and more mental health problems are seen, a review has found.

An international team analysed the dramatic shift in policies on cannabis between 2000 and 2025, including how the numbers of people taking the drug, its potency, and rates of psychosis changed after new rules came in.