(PS3-D83) Impacts of Cannabis Use on Psychiatric Symptoms in Teens at High Risk for Mood Disorders

Epidemiological evidence suggests that cannabis use in the general population increases the risk for psychosis (Farris 2020), although its association with mood symptoms is less consistent. A greater understanding of the effects of cannabis on psychiatric symptoms among youth at high risk for developing mood disorders is needed. This study sought to elucidate the relationship between cannabis use (both impairment and frequency) and psychiatric symptoms (i.e., depressive, manic, psychotic, and suicidal symptoms) among youth at high risk for a mood disorder. Youth (ages 13-19) had at least one first-degree relative with a mood disorder (i.e., unipolar or bipolar disorder) and presented with significant mood instability. They were recruited to participate in a randomized clinical trial comparing a 12-session mobile-enhanced family-focused therapy to the same treatment with a scaled-down version of the mobile enhancement app. Youth were assessed by study clinicians at week 1 (pre-treatment), at a 9-week interval (mid-treatment), an 18-week interval (post-treatment) and finally at 27 weeks (follow-up). Cannabis use impairment and frequency were assessed using the Alcohol/Drug Use Scale. Psychiatric symptoms were assessed using the Adolescent Longitudinal Follow-Up Evaluation (A-LIFE). Cannabis use impairment and frequency correlated with hypomania and suicidal ideation cross-sectionally at the study’s baseline, respectively (r(68) = .31, p = .009; r(68) = .296, p = .04), but neither cannabis use impairment nor frequency were associated with depression or suicidal ideation at follow-up. Longitudinal analyses indicated that greater use of cannabis and more impairment from cannabis in one study interval predicted increases in hallucinations (F(1, 87.80) = 7.59, p = .007; F(1, 130.39) = 10.05, p = .002) and delusions (F(1, 159.85) = 5.32, p = .02; F(1, 154.22) = 3.47, p = .07) at subsequent study visits. These results replicate prior clinical trials that demonstrate a dose-dependent relationship between cannabis use and psychosis in youth at high risk for mood disorders. Future research should examine these relationships among youth at risk for psychotic disorders outside of the context of an active clinical treatment.