Familial variation in episode frequency in bipolar affective disorder.

Objective: Bipolar affective disorder is a familial illness characterized by recurrent episodes of mania and depression, but little is known about the familial nature of episode recurrence or its associated clinical features. The authors analyzed the recurrence frequency of affective episodes (episode frequency), along with associated clinical and demographic variables, in families with at least three members with a major affective disorder.

Method: Members of 86 families ascertained through probands with bipolar affective disorder who had two or more first-degree relatives with a major affective disorder were interviewed by psychiatrists and assigned an all-sources diagnosis.