Psychiatrist.comImpact of Cannabis Use on Time to Psychiatric Rehospitalization in Young Adults with Bipolar and Psychotic Disorders: A Survival Analysis

🧠 Mental Health / Behavioral Sensitivity

This retrospective cohort study examined 200 adults aged 18–29 years hospitalized for bipolar or psychotic disorders in 2017 and followed through May 2023. Investigators evaluated whether cannabis use documented at the index hospitalization was associated with psychiatric readmission during the following year. Cannabis was the most commonly reported drug, with 43% of patients reporting current use and 58% lifetime use. Cannabis use was associated with an elevated rehospitalization risk during the first month after discharge, with the effect diminishing by three months and becoming nonsignificant by six months. As an observational analysis, the findings demonstrate association rather than causation.

Clinical Considerations

• 58% of patients reported lifetime drug use and 44% reported current drug use at admission, excluding alcohol and tobacco.
• 37% of the cohort had a documented substance use disorder, highlighting the substantial comorbidity burden in this population.
• Cannabis was the most commonly used substance, reported by 58% of patients lifetime and 43% currently.
• Cannabis use at admission was associated with a 2.8-fold higher risk of psychiatric readmission during the first month after discharge (HR 2.8; 95% CI 1.3–5.9).
• The association persisted but weakened at three months (HR 1.9; 95% CI 1.1–3.3) and was no longer statistically significant by six months.
• The retrospective design and reliance on medical-record documentation mean the findings are observational association only evidence and residual confounding remains possible.

Practice Applications

• Recognize recent cannabis use as a potential marker for elevated short-term rehospitalization risk following psychiatric discharge.
• Monitor patients with bipolar or psychotic disorders closely during the first three months after hospitalization, when risk appears highest.
• Discuss cannabis use routinely during discharge planning and early outpatient follow-up visits.
• Integrate substance-use assessment with relapse-prevention and continuity-of-care planning for young adults with serious mental illness.
• Interpret these findings as hypothesis-generating observational evidence that did not establish causality.