Early studies of the comorbidity between substance use and psychiatric disorders were primarily clinical [1,2]. However, the US Epidemiologic Catchment Area (ECA) study [3] of psychiatric disorders conducted in the early 1980s brought widespread attention to the high degree of association between psychiatric and substance use disorders in the general population [4]. This comorbidity has generated much scientific interest and an extensive literature. Research on comorbidity offers avenues to better understand etiology, natural history, treatment utilization, and, ultimately, more effective treatment and prevention efforts for substance and psychiatric disorders.
