WEEDS IN THE WIRING –
Feb. 4, 2025 – Experts say the new study, which looked at more than 13.5 million medical records of all individuals aged 14 to 65 between 2006 and 2022, adds to growing evidence that heavy cannabis use could lead to schizophrenia and psychosis. “If you look at the study, that increases considerably over time,” said Myran, who was first author of the study.
While the incidence of schizophrenia “was stable over time” without a population-wide increase, the incidence of psychosis that was not otherwise specified increased compared to before marijuana was legalised.
In certain age groups, particularly among young men, the incidence of schizophrenia did appear to be rising in Ontario.
Nearly 19 per cent of new schizophrenia cases in young men aged 19 to 24 were linked to cannabis use disorder at the end of the study, researchers said.
“I think the study is a reminder that, no, this is not necessarily safe or fine for everyone and that in particularly young people whose brains continue to develop, there is a very strong association between cannabis use and psychosis and schizophrenia,” Myran said.
