A FAMILY STUDY OF MANIC-DEPRESSIVE (BIPOLAR-I) DISEASE - IS IT A DISTINCT ILLNESS SEPARABLE FROM PRIMARY UNIPOLAR DEPRESSION

Objective: To determine whether bipolar I illness is autonomous or par t of a multifactorial continuum with unipolar depression. In this stud y, we compare familial bipolar I illness and depression among three gr oups: probands with bipolar I disorder; probands with primary unipolar disorder; and controls. We also examine a continuum of severity betwe en psychotic and nonpsychotic patients with bipolar I disorder. Consid erable data suggest that bipolar I illness is distinct from unipolar i llness as regards epidemiology, familial psychiatric illness, course, response to treatment, and biologic findings. Method: Probands were se parated into bipolar I and primary unipolar depressive groups. Persona lly interviewed family members of these patients were compared on vari ables of bipolar illness or schizoaffective mania and unipolar or schi zoaffective depression. A personally examined control group was compar ed with the relatives of the two proband groups. Similar analyses were performed using data obtained by a systematic family history method. For the same familial variables, psychotic and nonpsychotic manic prob ands were compared. Result: Familial mania is more frequent in familie s of patients with bipolar disease than in controls or in families of patients with primary unipolar disorder. The latter mio groups did not differ in amount of mania. Unipolar depressive illness or schizoaffec tive depression was higher in families of probands with bipolar and un ipolar disorder than in controls. Probands with bipolar disease separa ted into those who had psychotic symptoms (including schizoaffective m ania) and no psychotic symptoms did not differ from each other in risk for familial mania or depression. Conclusions: Bipolar I illness is a separate illness from primary unipolar illness because of an increase in familial mania. Patients with primary unipolar disease and control s show the same amount of familial mania. Lack of an increase in famil ial illness according to the severity of bipolar disease is against an affective continuum.