Bipolar II disorder family history using the family history screen: findings and clinical implications.

Psychiatric family history of bipolar II disorder is understudied. The aims of the current study were to find the psychiatric family history of bipolar II patients using a new structured interview, the Family History Screen by Weissman et al (2000), and to find bipolar disorders family history predicting power for the diagnosis of bipolar II. One hundred sixty-four consecutive unipolar major depressive disorder (MDD) and 241 consecutive bipolar II major depressive episode (MDE) outpatients were interviewed with the Structured Clinical Interview for DSM-IV (SCID). The Family History Screen was used. Sensitivity and specificity of predictors of the diagnosis of bipolar II (bipolar [type I and II] family history, bipolar II family history, atypical depression, depressive mixed state, many MDE recurrences, early onset) were studied. Bipolar II subjects had significantly more bipolar I, more bipolar II (50.7%), more MDE, and more social phobia in first-degree relatives than did unipolar subjects. Bipolar II subjects had many more first-degree relatives with bipolar II than with bipolar I. Among the predictors of the diagnosis of bipolar II, bipolar II family history had the highest specificity (82.8%), while early onset had the highest sensitivity. Discriminant analysis of predictor variables found that bipolar II family history and early onset were highly significant predictors. In conclusion, bipolar II family history was common in bipolar II patients, and it had high specificity for predicting bipolar II. If detected, it could reduce bipolar II misdiagnosis by inducing careful probing for a history of hypomania.