Diagnosis and treatment of co-occurring affective disorders and substance use disorders

There is increasing interest in the comorbidity of affective disorders and substance use disorders. These disorders commonly co-occur, and the relationship is often complex and bidirectional. Two epidemiological surveys have emphasized the prevalence of comorbid mood and substance use disorders in community samples: the National Institute of Mental Health Epidemiologic Catchment Area (ECA) study [1] and the National Comorbidity Study (NCS) [2]. In the ECA study, an estimated 45% of individuals with alcohol use disorders and 72% of individuals with drug use disorders had at least one co-occurring psychiatric disorder. In the NCS, approximately 78% of alcohol-dependent men and 86% of alcohol-dependent women met lifetime criteria for another psychiatric disorder, including drug dependence. Interest in the co-occurrence of psychiatric and substance use disorders is clinically important as comorbidity has been found to have a negative impact on the course, treatment outcome, and prognosis of both syndromes. In this article, the relationship between substance use disorders and specific affective disorders is explored. The article begins with an overview of some of the general principles of diagnosis and treatment of co-occurring disorders; then the relationship between individual affective disorders and substance use disorders will be explored. Specifically, for major depression and bipolar disorder, the prevalence of co-occurrence with substance use, clinical characteristics, and treatment of individuals with co-occurring disorders will be reviewed.