Alcohol and substance use differentially impact suicidal ideation in a longitudinal cohort of bipolar disorder

Background: Across bipolar disorders (BSDs), alcohol and substance use and suicidal ideation (SI) contribute to increased rates of morbidity and mortality. The goal of the present study was to investigate temporal relationships between the intensity/frequency (I/F) of use and impairment related to alcohol and substance use and SI in a longitudinal BSD cohort.

Methods: Participants with BDI (n=565), BDII (n=162), and BD NOS (n=61) were included (median enrollment=72 months). Alcohol and substance use were measured using a modified version of the AUDIT administered every 6 months. SI was measured every 2 months using item 9 from the PHQ-9. Linear mixed effects models tested concurrent associations and Dynamic Structural Equation Models tested prospective associations between alcohol and substance use I/F and impairment with SI.

Results: Cocaine I/F and alcohol and substance use impairment were concurrently associated with SI. When a person had more frequent and intense cannabis use compared to average, they had higher SI at the next timepoint. When individuals experienced more alcohol and substance use impairment than average, they had higher SI at the next timepoint.

Conclusions: I/F of cannabis use and alcohol and substance use impairment appear to lead to future increases in SI for those with BSDs.