Teenagers who use cannabis face an 11 times higher risk of developing a psychological disorder, according to a recent study published in Psychological Medicine. The study analyzed medical records and survey responses from more than 11,000 young people in Ontario, Canada.

"We found a very strong association between cannabis use and risk of psychotic disorder in adolescence. Surprisingly, we didn’t find evidence of association in young adulthood," said researcher André McDonald in a statement collected by the Center for Addiction and Mental Health (CAMH), one of the organizations behind the study.

McDonald explained that "surprisingly," they found no evidence of this link between cannabis and psychological disorders in those between 20 and 33 years old. "These findings are consistent with the neurodevelopmental theory that teens are especially vulnerable to the effects of cannabis," he added. As explained in the study, "the brain is still developing" at that age.

The study also found that approximately 5 in 6 teenagers hospitalized or treated in the emergency room for psychotic disorders had previously used cannabis.

Although the CAMH, ICES and University of Toronto study does not directly prove that marijuana causes psychological disorders, it does establish a robust correlation that researchers say should continue to be examined. In addition, this relationship should serve as a warning when it comes to deregulate or decriminalize drugs :