Cannabis use is changing—and so are its potential effects on mental health.
A new article in the Canadian Medical Association Journal highlights growing concerns about the connection between cannabis and psychosis, warning that today’s cannabis is far stronger than it used to be.
In Canada, the concentration of tetrahydrocannabinol (THC)—the compound in cannabis that causes the “high”—has risen dramatically over the last two decades. In the early 2000s, legal dried cannabis typically contained about 4% THC.
Today, most legal products contain around 20%, a fivefold increase.
Experts believe this surge in potency is a major factor in the rising number of cannabis-related mental health problems.
Studies show that using high-potency cannabis, especially products with more than 10% THC, can increase the risk of developing psychosis—a condition that can cause hallucinations, delusions, and disorganized thinking.
The risk is greater for people who use cannabis frequently, start at a young age, or are male. Having a history of mental health issues, such as depression or anxiety, also appears to make some individuals more vulnerable.
The link between cannabis use and long-term mental illness is becoming clearer. A large study in Ontario involving 9.8 million people found that those who visited the emergency department for cannabis use had a 14 times higher risk of developing a schizophrenia-spectrum disorder.
The risk skyrocketed for those treated for cannabis-induced psychosis—these individuals were more than 240 times more likely to later develop schizophrenia or a related condition.
Treatment for cannabis-induced psychosis usually begins with stopping cannabis use entirely. Continuing to use cannabis after a first psychotic episode increases the chance of symptoms returning. For people with severe or ongoing symptoms, antipsychotic medication can help manage the condition.
Quitting cannabis can be difficult, but behavioral approaches like motivational interviewing and cognitive behavioral therapy may help. These techniques, delivered by a doctor or psychologist, can give people the tools they need to resist cravings, change their habits, and stick with treatment plans.
Dr. Nicholas Fabiano, co-author of the article and a psychiatry researcher at the University of Ottawa, emphasizes how much cannabis has changed. “Cannabis from the 2000s is not the same as in 2025,” he said. “THC content has increased by five times. This is likely a significant driver in the increasing link between cannabis use and schizophrenia.”
As cannabis becomes more widely available, experts say it’s important for the public to understand the potential mental health risks—especially for young people and those already vulnerable to mental illness. Recognizing the signs early and seeking help could make a critical difference in long-term outcomes.
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Source: KSR.
