Alcoholism and primary major depression: a family study approach to co-existing disorders.

Alcoholism and major depression appear together at much higher than chance rates, but reasons for this are obscure. We used the direct diagnostic assessment of 177 probands with primary, unipolar depression and 619 of their first degree relatives to explore the significance of concomitant alcoholism. The male relatives of alcoholic probands of both sexes had substantially higher rates of alcoholism than did the male relatives of non-alcoholic probands. Among female probands, but not among male probands, alcoholism was associated with markedly higher familial rates of primary depression, particularly among female relatives. These data contained no evidence that comorbidity itself was familial. The appearance of alcoholism in depressed women may indicate depression spectrum disease, a disorder which manifests as depression in women and alcoholism in men. In contrast, men with both primary depression and alcoholism may be exhibiting two distinct illnesses.