Potent cannabis linked to soaring schizophrenia cases as numbers triple

A new study has revealed that overuse of high-potency cannabis could be linked to a "concerning" rise in cases of schizophrenia in Canada after legalisation of the drug.

New schizophrenia cases in Ontario, Canada have nearly tripled since cannabis was legalised in 2015, according to a large-scale study. In just under two decades, the number of new cases rose from four per cent to over 10 per cent, the researchers said.

Researchers looked at the effects of cannabis legalisation in the country on the link between cannabis use disorder (CUD) and new schizophrenia diagnosis. The results have led the researchers to call for a review of the long-term effects of cannabis use.

Schizophrenia is a serious mental health condition that affects how people interpret reality, with patients often experiencing delusions, hallucinations and disordered thinking.

Previous studies have highlighted a link between cannabis use and psychosis in young adults, with high potencies of the drug increasing psychosis risk. The current study found rates of CUD and schizophrenia were higher in young men.

“Compared with individuals without CUD, individuals with CUD were more likely to be male, to be younger, to live in lower-income neighbourhoods, and less likely to be immigrants to Canada,” the authors wrote.

Dr Daniel Myran, study co-author and associate scientist at The Ottawa Hospital said: “We found that there have been concerning increases over time in the percentage of people with a new schizophrenia diagnosis who had received care for a cannabis use disorder before their diagnosis.

"Regular cannabis use is strongly associated with an increased risk of schizophrenia," he added.

The research team looked at data from hospital admissions between