Affective disorders in first-degree relatives of adolescent onset bipolars, unipolars, and normal controls.

Two hundred and fifty-nine first-degree relatives of 23 adolescent bipolars (81 relatives); 26 unipolars (95 relatives); and 24 normal controls (83 relatives) were assessed for the presence of affective disorders, using the family history method. First-degree relatives of bipolar probands were significantly more likely to have a bipolar illness than those of unipolar probands (p = 0.03) and normal controls (p = 0.001). Rates of unipolar depression in first-degree relatives of bipolars and unipolars were not significantly different but differed significantly between bipolars and normals (p = 0.002) and unipolars and normals (p = 0.006). The implications of these findings for clinical work, diagnosis, and research in adolescents with affective disorders are discussed.