Cannabis has changed dramatically over the past two decades, raising new concerns about its impact on mental health.
According to Dr. Nicholas Fabiano, MD, a psychiatry resident and researcher at the University of Ottawa, “Cannabis from the 2000s is not the same as in 2025. THC content has increased fivefold. This is likely a significant driver in the rising link between cannabis use and schizophrenia.”
In Canada, THC levels in legal dried cannabis have jumped from approximately 4% to 20% over the last 20 years. High-potency cannabis, particularly when used frequently, is associated with an increased risk of psychosis.
Younger males and individuals with a history of mental health disorders, such as depression or anxiety, appear especially vulnerable.
A large-scale study in Ontario involving 9.8 million people found a 14.3-fold higher risk of developing schizophrenia-spectrum disorders among those who sought emergency care for cannabis use. The risk skyrocketed to 241.6 times higher for those experiencing cannabis-induced psychosis.
Experts emphasize that treatment involves discontinuing cannabis use and, when necessary, using antipsychotic medication to manage severe or persistent symptoms. Behavioral interventions, including motivational interviewing or cognitive behavioral therapy, can also help individuals build strategies to resist cravings and adhere to treatment plans.
Dr. Fabiano reiterated, “The potency of today’s cannabis is unprecedented. This escalation is a critical factor in the growing association between cannabis use and schizophrenia.”
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