Continuing Marijuana Use After a First Episode of Psychosis Increases Risk of Relapse
A 2016 article in the journal JAMA Psychiatry reports that continuing to use cannabis after a first episode of psychosis increases risk of relapse. The study by Sagnik Bhattacharyya and colleagues employed longitudinal modeling to determine the role of cannabis use in psychotic relapse. The researchers followed 90 women and 130 men for two years after a first episode of psychosis, and found that the more marijuana they used, the more likely they were to have a relapse of psychosis.
Relapse rates were highest (59.1%) for participants who used pot continuously following their first episode of psychosis. Relapse rates were lower (36.0%) for those who used cannabis intermittently thereafter, and lowest (28.5%) among those who discontinued cannabis use after their first episode of psychosis.
A statistical test known as a cross-lagged analysis was used to establish that cannabis use affected later relapse, rather than relapse of psychosis leading to further cannabis use.
Another statistical strategy using fixed-effect models revealed that risk of psychotic relapse was 13% higher during times of cannabis use than during periods of no cannabis use.
These findings offer some hope that the likelihood of psychosis relapse can be reduced, since ongoing cannabis use is a risk factor that can be modified, unlike family history or genetics. Bhattacharyya and colleagues called for research into interventions that can help discourage cannabis use in people who have had a first episode of psychosis.
Editor’s Note: N-acetylcysteine, a nutritional supplement sold in health food stores, can reduce cannabis use compared to placebo in teen users.
