Cannabis may cause psychosis in Canadian youth, study says

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Youth aged 14 to 20 are more often diagnosed with psychotic disorders, including schizophrenia, compared to those born earlier, an Ontario study examining 30 years of data suggests, and cannabis use might be a major reason why. 

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The study, published in Monday’s issue of the Canadian Medical Association Journal (CMAJ), said that researchers looked at health data for more than 12 million Ontario residents born between 1960 and 2009 to look for cases of psychotic disorder.

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Young Ontarians diagnosed more

Residents had to be at least 14 years old to be eligible for the analysis. The researchers found more than 152,000 diagnoses of psychotic disorder (such as schizophrenia) over a 30-year period, with the annual rate increasing by 60% for those aged 14 to 20, but staying level or declining for those 21 to 50.

“Rather than just looking at what’s the overall rate of schizophrenia and psychotic disorders, we said, is it differing by birth cohorts?” Dr. Daniel Myran, a family physician and research chair at North York General Hospital, told CBC. “So did people born in the 1960s have a different rate of psychotic disorders than people born in the ’70s, ’80s or ’90s?” 

The researchers found that in the 14-20 age group, the rate in the ’90s was 62.5 per 100,000 people and rose to nearly 100 cases per 100,000 by the end of the study. 

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Drug use a leading possibility

Myran said there isn’t a single explanation for the rise, but he did say substance use including cannabis, stimulants, hallucinogens and synthetic drugs is a leading possibility contributing to the rising rates over 20 years.

Ottawa Hospital psychiatrist Sarah Brandigampola also suspects substance use as a possibility: “In males, we’re seeing a younger age of onset and a stronger correlation to cannabis use.”

Dazed and confused

Cannabis is more dangerous than you might think, say health experts. While short-term effects of using the drug include euphoria, relaxation and heightened sensory perception, in some people it can cause anxiety, panic, paranoia and confusion. It can also impair short-term memory, motor coordination and reaction time.

Long-term effects include memory loss and learning impairment addiction, chronic anxiety, and depression.

Cannabis use also has been linked to the development of psychotic disorders for those who are vulnerable, particularly for those who start in adolescence. It’s not great for the heart or lungs, either.

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“Everybody must get stoned”

And cannabis has been everywhere in Canada since former prime minister Justin Trudeau legalized recreational cannabis in 2018. A StatsCan report says that in 2023, more than one-third of adults aged 18 to 24 years (38.4%) and 25 to 44 years (34.5%) reported using cannabis in the previous 12 months, compared with 15.5% of adults aged 45 years and older. About 1 in 10 adults aged 18 to 24 years (8.7%) and 25 to 44 years (10.3%) reported using cannabis daily or almost daily in the previous 12 months, compared with 4.8% of adults aged 45 and older. Federal and provincial governments received $1.9 billion from the control and sale of recreational cannabis in 2022/2023, up by almost one-quarter (+24.2%) from a year earlier.

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