Canada’s legalization of cannabis has been linked to a concerning increase in schizophrenia cases, according to new research. A 16-year study found that nearly tripled the number of new cases associated with cannabis use disorder (CUD) in Ontario.
The study evaluated over 13.5 million residents and found that after legalization, hospital care for CUD jumped by 270%. The proportion of new schizophrenia cases associated with CUD also increased from 3.7% to 10.3%, with young men aged 19-24 years most likely to be affected.
The researchers attributed this increase to the high potency of cannabis and rising regular use, as well as changing social norms. Dr. Daniel Myran, lead investigator, emphasized that heavy cannabis use can cause schizophrenia in vulnerable individuals earlier in life and worsen symptoms.
This study adds to mounting evidence on the association between cannabis use and increased risk for psychosis. The researchers note that further epidemiologic studies should consider long time intervals, sufficient numbers, and information on potency and quantity of cannabis used to accurately assess the impact of cannabis policy on mental health outcomes.
Source: https://www.medscape.com/viewarticle/has-legalized-cannabis-led-surge-schizophrenia-cases-2025a10002ti