Cannabis use linked to earlier onset of psychosis, study finds

A meta-analysis conducted by researchers at the University of New South Wales and published in the journal Biological Psychiatry has linked cannabis use to an earlier onset of psychosis. The study reviewed 149 international studies involving more than 71,000 participants, primarily from Europe, North America, and Australia.

On average, cannabis users developed psychosis approximately two and a half years earlier than non-users. The research highlights that this gap increases significantly with age. For individuals experiencing their first episode between the ages of 20 and 24, the onset was roughly 1.6 years earlier. This difference rose to 4.43 years for those developing the disorder between ages 25 and 29, and reached a maximum of 6.3 years for those developing psychosis after age 30.

Psychosis, which can involve hallucinations, delusions, and disorganized thinking, often manifests during late adolescence or early adulthood. While the study found a notable correlation in older age groups, researchers did not find a statistically significant difference in the timing of onset among adolescents compared to non-users, noting that psychosis is less frequent during mid-adolescence.