NBC NEWS
Teenagers who used cannabis within the last year had a dramatically higher rate of developing a psychotic disorder, according to a study published Wednesday.
The study, led by researchers from the University of Toronto, found an 11 times higher risk of developing a psychotic disorder among teenagers who used cannabis compared with those who did not. When the analysis was limited to just emergency room visits and hospitalizations, there was a 27-fold increase in psychotic disorders in teenagers who had used the drug.
“When I see youths with psychotic symptoms, they’re almost always using lots of cannabis,” said Dr. Leslie Hulvershorn, a child psychiatrist and chair of the psychiatry department at Indiana University who was not involved with the study. “It would be unusual to see someone present with psychotic symptoms to a hospital and not have smoked cannabis.”
The paper adds to the growing body of research that links cannabis to an increased risk of psychotic disorders, particularly in adolescence. Use of marijuana, particularly higher-potency products, has been linked to a variety of mental health disorders, including schizophrenia, anxiety and depression.
“I think that there’s enough evidence out there for us to give recommendations that teens probably shouldn’t be using cannabis,” said the study’s lead author, Andre McDonald, a postdoctoral research fellow at McMaster University in Hamilton, Ontario. “If we can somehow ask teens to delay their use until their brain has developed a little further, I think that would be good for public health.”
While most teenagers who use cannabis will not develop psychotic disorders, McDonald said, the findings are concerning given how debilitating these conditions can be.
The new study, like previous research on marijuana and psychosis, does not directly prove that marijuana is causing psychotic disorders. While it’s possible that teens who were prone to develop psychotic disorders could have also been more likely to use cannabis, it’s unlikely because of how striking the association was, Hulvershorn said.
“The magnitude of the effect here is just hard to believe that it’s not related to cannabis,” Hulvershorn said.
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