Australian meta-analysis finds cannabis users develop psychosis years earlier, especially after age 30

A large-scale meta-analysis conducted by Australian scholars reviewed 149 studies involving more than 71,000 individuals and found that cannabis users develop psychosis on average 2.5 years earlier than non-users. The age gap is small for users in their early 20s (about 1.6 years) but expands dramatically for people in their late 20s and 30s, with a six-year earlier onset reported for those in their 30s. Senior author Matthew Large said the analysis allowed fine-grained age subgroup assessment for the first time, confirming earlier suggestions of a link between cannabis and earlier psychosis.

Co-author Carly Stevens highlighted the likely cumulative nature of the risk, challenging the belief that only adolescent brains are vulnerable. Independent researcher Jack Wilson noted the growing availability of potent THC products and urged stricter regulation and public health messaging, including tighter controls on medicinal cannabis marketed without full Therapeutic Goods Administration approval.