Examination of the intersection of bipolar I disorder status and cannabis use disorder severity in relation to health-related quality-of-life and lifetime suicide attempts.
Among people with bipolar I disorder (BD), cannabis use disorder (CUD) is highly comorbid and correlated with poorer clinical outcomes, including increased suicidal behaviors and decreased quality-of-life (QoL). However, research on different levels of CUD severity and their links to suicidal behaviors and QoL are underexplored. Using data from the National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III), this study examined the relationships between DSM-5 CUD severity and lifetime suicide attempts or health-related QoL in participants with and without lifetime bipolar I disorder (ns = 753 and 35,556, respectively). A logistic regression model, adjusted for sex, age, and race/ethnicity, indicated the rate of lifetime suicide attempts was 16.65% (95% CI [13.17, 20.83]) in people without BD and with severe CUD compared to 33.71% (95% CI [21.64, 48.36]) in people with BD and severe CUD. Additionally, an adjusted linear regression model showed that mental health QoL significantly declined in individuals without BD from those with no CUD symptoms (M = 51.49, 95% CI [51.33, 51.65]) to severe CUD (M = 45.28, 95% CI [44.35, 46.21]), whereas the mental health QoL for individuals with BD did not significantly vary across CUD severity. Physical health QoL was not significantly different across BD status nor CUD severity. Overall, these findings suggest that CUD severity is significantly associated with altered outcomes on lifetime suicide attempts and mental health QoL depending on lifetime BD status; however, BD may still play a more prominent role in mental health outcomes, regardless of CUD severity.