Risk of schizophrenia six times higher among teens smoking cannabis

Teenagers who smoke cannabis are six times more likely to develop schizophrenia than their non-cannabis smoking peers, a study has found.

Significantly, the research published in the peer-reviewed Journal of Clinical Psychology also found no difference in results when comparing low or high cannabis usage.

Cannabis accounted for nearly half of all drug offences last year, and is the drug most commonly used by young people.

‘Significantly increased risk’

The study was conducted by analysing 591 previous research papers and by tracking children aged 12-18.

Researchers Shea-Lee Gordin and Sherif Shehata defined low cannabis use as twice a week or less, and high cannabis use as daily or near-daily use.

Concluding their findings, the researchers said: “Both high and low-frequency marijuana usage were associated with a significantly increased risk of schizophrenia”.


The study comes as figures showed that the number of admissions to psychiatric hospitals in Scotland jumped by 74 per cent since cannabis was effectively decriminalised six years prior.

Between 2015-16, 1,191 people were admitted, but last year the figure totalled 2,067.

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