ABSTRACT
Epidemiological studies in the U.S. general population show that mood disorders and substance use disorders are highly prevalent and that they frequently co-occur (1-3). Although the rate of co-occurrence, as reflected in odds ratios, generally exceeds 1.0, indicating that the association exceeds that due to chance, the prevalence rates vary substantially among the different mood disorders. For example, the Epidemiologic Catchment Area Study (ECA) showed that, among individuals with a lifetime diagnosis of bipolar disorder, 41% had a lifetime drug use disorder and 46% had a lifetime alcohol use disorder (1). This translates into an odds ratio of 5.6 for alcohol use disorders and 11.1 for drug use disorders. In contrast, although significantly elevated, the odds ratio for comorbid major depressive disorder (MDD) and alcohol use disorder was only 1.3 and for MDD and drug use disorder it was 3.8.
