The interviewer also asked about past affective disorders, including depressive and manic episodes and the characteristics of the most severe episode. If subjects reported a lifetime diagnosis of both DSM IV major depression and mania or any lifetime diagnosis of a manic episode, they were affected by bipolar I disorder, while those persons who had at least one major depression and hypomanic episodes were diagnosed to have bipolar II disorder. Altogether, 201 subjects with bipolar I or II disorder were identified using these criteria of whom 152 (75.6%) had an additional diagnosis of DSM IV alcohol dependence (56 of 76, 74%, in bipolar I subjects and 96 of 125, 77%, in bipolar II subjects). Subjects with a bipolar II disorder without comorbid alcohol dependence were included into group 1 (n = 20) while a second group (group 2, n =56) encompassed those with a comorbid bipolar II and alcohol dependence diagnoses. Group 3 included subjects with a bipolar I diagnosis without alcoholism (n = 29) and group 4 consists of bipolar I subjects with a comorbid alcohol dependence (n = 96). Individuals with a history of mania (n = 27) without depression at baseline were excluded from the subsequent analyses.
