Adolescents who used cannabis reported a higher number of psychosis spectrum symptoms and increased distress prior to cannabis initiation, according to a recent cohort study.

The study assessed the association between adolescent cannabis initiation and psychosis spectrum symptoms by examining three hypotheses: shared vulnerability, self-medication, and contributing risk. Using data from 11,868 participants in the Adolescent Brain Cognitive Development (ABCD) Study, researchers found more psychosis spectrum symptoms and greater associated distress among adolescents who used cannabis compared to non-users, which supports the shared vulnerability hypothesis. This suggests that certain genetic and environmental factors may predispose adolescents to both cannabis use and psychosis spectrum symptoms.

Published in JAMA Psychiatry, the study also found increases in psychosis spectrum symptoms and distress before cannabis initiation, aligning with the self-medication hypothesis. Specifically, cannabis users exhibited a higher number of symptoms (B=0.86; 95% confidence interval [CI], 0.68-1.04) and greater distress (B=1.17; 95% CI, 0.96-1.39) compared to non-users. Pre-initiation increases in symptoms (B=0.16; 95% CI, 0.12-0.20) and distress (B=0.23; 95% CI, 0.21-0.26) were also statistically significant.

However, evidence for the contributing risk hypothesis was mixed. No significant increase in psychosis symptoms was observed following cannabis initiation, suggesting limited support for cannabis use as a direct cause of symptom escalation.

These findings highlight the importance of accounting for shared vulnerability and self-medication effects when modeling cannabis–psychosis risk associations. Adolescents with pre-existing susceptibilities to psychosis may be at greater risk of initiating cannabis use. Further longitudinal research may help clarify the association between adolescent cannabis use and psychosis risk over time.

Full disclosures can be found in the published study.