The comorbidity of depression and substance use disorders

Depression and substance use disorders are highly prevalent in the general population and often co-occur within the same individual. This association is most commonly explained either by a causal relationship or a shared etio logic factor underlying both disorders. In light of these mechanisms of ass ociation, this article summarizes evidence from clinical, epidemiologic, an d genetic epidemiologic studies. Details of a large family study designed t o addresses key methodological and conceptual issues identified in the revi ew are also presented. The association of alcoholism with depression is lik ely to be attributable to casual factors rather than a shared etiology, but the scarcity of information for other classes of substance use disorders p recludes similar conclusions regarding their association with depression. T he lack of unidirectional and consistent patterns of association for depres sion and substance use disorders indicates that multiple mechanisms of como rbidity are likely to be simultaneously active in this population. (C) 2000 Elsevier Science Ltd.