Mark Borigini M.D.

Overcoming Pain


Marijuana and Psychosis

New research in adolescents and the effect of marijuana

Posted Jul 02, 2018

It’s becoming legal in so many places.  And why wouldn’t a curious youngster take a little for themselves?

After all, who can forget that PSA from the 1960s, with “Take Five” playing in the background, all the while showing that cute kid copying Dad performing all sorts of tasks from washing the car…to putting a tobacco cigarette in his mouth.

Fast forward to 2018, and today Junior is grappling with things a little less mundane:  from angst about what restroom to use, to trying to decide if he should take a toke of Acapulco Gold one of Dad’s Dead Head friends claims to have, or just go right to the Thai Stick. 

But don’t be surprised if that marijuana-using teen-aged son or daughter of yours stops making sense a little more frequently, or maybe even describes to you in real time, while in the same room with you, things that you just can’t seem to also see or hear.

The concern is certainly not new.  In a policy statement released in 2017 by the American Academy of Child & Adolescent Psychiatry: “Heavy use during adolescence is associated with increased incidence and worsened course of psychotic, mood, anxiety, and substance use disorders. Furthermore, marijuana’s deleterious effects on adolescent cognition, behavior, and brain development may have immediate and long-term implications, including increased risk of motor vehicle accidents, sexual victimization, academic failure, lasting decline in intelligence measures, psychopathology, addiction, and psychosocial and occupational impairment.”

There is now more robust data available, specifically addressing the psychosis effects of marijuana use in our youth:  A large prospective study published earlier this month in Journal of the American Medical Association: Psychiatry concluded that all young cannabis users face a risk of psychosis, and this risk was not limited to those users with a family history of schizophrenia or some other biological factor that increases their susceptibility to the effects of cannabis.

This Canadian study worked with 3720 adolescents from the Co-Venture cohort, which represents 76% of all grade 7 students attending 31 secondary schools in the greater Montreal area.

Over four years, students completed an annual Web-based survey in which they provided self-reports of cannabis use in the preceding year; and, of course, any psychosis symptoms.

Researchers found that 86.7% and 94.4% of participants had a minimum of two time points out of four on psychosis symptoms and cannabis use, respectively.  Cannabis use, in any given year, predicted an increase in psychosis symptoms a year later.

An obvious limitation of the study, as pointed out by the researchers, was that cannabis use and psychosis symptoms were self-reported and were not confirmed by clinicians. However, the researchers also point out that previous work has shown positive predictive values for such self-reports of up to 80%.

In addition, the study examined psychosis symptoms and not psychotic disorder, although having psychotic symptoms increases the risk for a psychotic disorder.

Marijuana use is here to stay.  For some users, psychotic symptoms will follow.  The reality that we all must face.

If the adolescent in your life needs something for pain, maybe suggest something besides pot?


Bourque J, Afzali MH, Conrod PJ. Association of Cannabis Use With Adolescent Psychotic Symptoms. JAMA Psychiatry. Published online June 06, 2018. doi:10.1001/jamapsychiatry.2018.1330