Study: Marijuana Does Not Lead to an Increase in Psychotic Symptoms

NORML
 

PHILADELPHIA, PA — There exists “minimal evidence” in support of an association between cannabis use by itself and the onset of psychotic symptoms in young people, according to data published online ahead of print in the Journal of Adolescent Health.

Investigators from the University of Pennsylvania, Department of Psychiatry assessed the relationship between drug use and the onset of psychotic symptoms in a cohort of 4,171 young people ages 14 to 21. Authors reported that “neither frequent nor early cannabis use predicted increased odds of psychosis spectrum classification” after researchers adjusted for potential confounders (e.g., concurrent use of other substances, comorbid psychopathology, and trauma exposure).
They concluded:

“Overall, we found minimal evidence for associations between cannabis use by itself and psychosis spectrum symptoms.”

The findings are similar to those of a 2015 longitudinal study reporting that early-onset cannabis use is not positively associated with a greater risk of psychosis or other mental health disorders in mid-life.

A 2016 literature review published in the journal Current Psychiatry Reports concluded that cannabis use likely does not cause the psychosis, but rather, that subjects susceptible to the disorder may be more likely to engage in habitual use of the substance.

Full text of the study, “Cannabis use, polysubstance use, and psychosis spectrum symptoms in a community-based sample of U.S. youth,” appears in the Journal of Adolescent Health.