Family history in delusional depression.

Family psychiatric history was compared in the 472 first-degree relatives of 31 delusional and 35 nondelusional inpatients who met DSM III criteria for major depression with melancholia. Morbid risks for psychiatric illness or for psychiatric treatment variables did not differ between the two groups. Specifically, rates of affective and psychotic illnesses in families did not distinguish delusional from nondelusional probands. The findings do not support the hypothesis of a genetic relationship of nonaffective psychosis to delusional depression.