While cannabis has become a mainstay in recreational dispensaries and medical clinics, scientists are still learning about its long-term psychological impacts. The drug’s increasing popularity—both recreationally and to treat conditions like chronic pain and anxiety—is making some researchers and consumers concerned over one of its most severe side effects: psychosis.
Cannabis is psychoactive, meaning it affects how a user’s brain works. For decades, researchers have been identifying how cannabis’ brain-affecting properties can cause symptoms of psychosis. Psychosis refers to any mental state where a person struggles to distinguish between what is real and what is not real. Psychosis is characterized by hallucinations, where people sense things that are not there, and delusions, where people hold inexplicable false beliefs. Some psychoses, like schizophrenia, are chronic, but psychosis can be drug-induced, with cannabis being considered one of the riskiest—if not the riskiest—drugs for chronic psychosis.
“Someone with cannabis-induced psychosis is at a higher risk of transitioning or being subsequently diagnosed with schizophrenia,” says Daniel Myran, a public health physician at the University of Ottawa, “than someone with methamphetamine-induced psychosis, or, you know, who’s having psychosis related to alcohol use or opioid use or cocaine use.”
Myran is the author of a February report published in JAMA Network Open that looked at rates of psychotic disorders in the Canadian province of Ontario among people who were flagged for cannabis use disorder—dependence on or abuse of cannabis, sometimes categorized as cannabis addiction. The study used data collected between 2006 and 2022 from over 13 million people in Ontario and found an association between cannabis use and psychosis onset.
