Depression precipitated by alcohol use in patients with co-occurring bipolar and substance use disorders.

OBJECTIVE: Bipolar disorder and substance use disorder frequently co-occur. However, little is known about the near-term effects of substance use on bipolar disorder. Thus, the present study tests whether alcohol use precipitates depression among patients with co-occurring bipolar disorder and substance use disorder. METHOD: This study uses data collected as part of 2 clinical trials (the first study was conducted from March 1999 through March 2004 and the second study was conducted from August 2003 through May 2007) of a manualized group therapy for patients with co-occurring bipolar disorder and substance dependence. One hundred fifteen participants were assessed at baseline and each month through month 8. Baseline diagnoses were made using the Structured Clinical Interview for DSM-IV, and monthly substance use and mood data were collected using the Longitudinal Interval Follow-Up Evaluation and the Addiction Severity Index. Generalized estimating equation methodology was used to analyze these longitudinal data. RESULTS: Our primary hypotheses were supported: days of alcohol use and an increase in days of alcohol use each significantly predicted the presence of a depressive episode in the subsequent month when controlling for current depression and current drug use. CONCLUSION: These data suggest that alcohol use in patients with bipolar disorder and substance dependence increases the risk of a depressive episode in the near term. TRIAL REGISTRATION: This study draws on data generated during 2 clinical trials. One was exempt from trial registration; clinicaltrials.gov Identifier for other trial: NCT00227838.