More than a bad trip: Experts warn about the risk of cannabis-induced psychosis

When Kalpit Sharma started smoking cannabis, he thought it was just part of "living his life" as a university student. After all, he had been told that the drug was relatively harmless.

That all changed in the summer of 2021, when he started hearing voices in his head.

"I would bike around, and the chain of the bike, it came off. And I thought that I could speak to birds, and birds were telling me how to put the chain back on," said Sharma, who was studying at York University in Toronto at the time.

Those voices are known as auditory hallucinations — a hallmark of psychosis. When they became more frequent and insistent, he went to the Centre for Addiction and Mental Health for an assessment.

Sharma was shocked when he was told that he had been exhibiting signs of psychosis — and eventually he was diagnosed with schizophrenia.

"The ground slipped beneath my feet," he told White Coat, Black Art host Dr. Brian Goldman. "I'm going to be looked at differently. I'm going to be separated from society. I'm not going to be my parents' Kalpit ever again."

Sharma, who is now 23, said that after consulting with physicians, he believes his heavy smoking of high-THC cannabis contributed to his psychosis and schizophrenia. Now he urges consumers to educate themselves as increasingly potent cannabis products become commercially available in Canada.

Researchers are also sounding the alarm that, while casual cannabis use isn't harmful for most people, possible connections are being found between using cannabis products with high-potency THC (tetrahydrocannabinol, the main psychoactive ingredient in cannabis) and harmful health effects, particularly among young men.

"I think that people remain unaware of this connection between cannabis use and potential risk of chronic psychotic disorders," said Dr. Daniel Myran, a researcher with the Ottawa Hospital Research Institute and a family physician.

According to Health Canada's 2023 Cannabis Survey, 21 per cent of 16-to-19-year-olds who use cannabis use it daily or almost daily. In the 20-to-24-year-old group, that number goes up to 23 per cent.

In 2023, Myran co-authored two studies looking into the connection between cannabis and psychosis. They found a 220 per cent increase in emergency room visits in Ontario for cannabis-induced psychosis between 2014 and 2021 — with the number rising from about 400 people to about 1,400 over that seven-year period.

"For men aged 14 to 24, the risk of developing schizophrenia rises to over 40 per cent within three years" of showing up in an ER for cannabis-induced psychosis, he said.

Myran was also lead author of a separate study released in early February that found 27.5 per cent of people who visited an emergency room for cannabis use developed an anxiety disorder for the first time within three years.

Starting in 2020, Sharma's cannabis consumption "skyrocketed" — when he and everyone else were inside because of pandemic lockdowns. But it was also shortly after more, and stronger, products became available in Ontario's cannabis shops.