In adolescents, cannabis use precedes the appearance of psychotic symptoms, such as hallucinations, feelings of being watched, or the impression of having special power.
Cannabis use makes teens sensitive to psychosis according to a study published in the journal Journal of the American Medical Association (JAMA) in psychiatry.
Researchers at the University of Montreal in Canada followed for four years nearly 4000 adolescents, aged 13 at the beginning of the study. Each year, they completed an electronic questionnaire to assess their drug use and psychotic symptoms. These disorders could appear during consumption, but also afterwards.
Previous studies had also noted that psychotic symptoms were more common among cannabis users. With their research, scientists have been able to show that the drug was the cause.
“Many people believe that cannabis can only trigger psychotic symptoms in at-risk individuals, but this study challenges this belief,” said Patricia Conrod, a researcher at CHU Sainte-Justine and a professor in the Department of Psychiatry at the University of Montreal.
The study found that cannabis use predicts an increase in psychotic experiences 12 months after smoking and that the more marked the use of marijuana in an individual, the more psychotic experiences in turn increased the year next.
“Although our study only proved the appearance of psychotic symptoms and not severe psychiatric disorders, these symptoms may suggest risks,” concluded the researcher.