It should be kept in mind that although we found that self-medication drinking of mood symptoms is associated with an increased risk of subsequent alcohol dependence, there are other possible explanations for the comorbid associations between affective conditions and alcohol use disorders not explored here. In prior assessments of bidirectional comorbidity, most instances of comorbidity appears to result from mood disorders occurring subsequent to the alcohol use disorder.25 There may be several physiologic mechanisms that explain the comorbidity.36;50–52 Thus, it is likely that both causal pathways may operate.53;54 Furthermore, there may be common underlying genetic as well as social or environmental factors which predispose to an increased risk for both disorders.55–60
