The importance of subsyndromal symptoms in bipolar disorder.

Bipolar disorder continues to be characterized by poor clinical and functional outcomes in many patients. Poor outcomes may be related to subsyndromal symptoms, defined as symptoms that fail to meet the full diagnostic criteria for a mood episode. Several recent studies indicate that subsyndromal symptoms in bipolar disorder are strongly associated with deficits in both social and occupational functioning. Furthermore, subsyndromal symptoms appear to increase the risk of relapse. Combined, these factors emphasize the importance of aggressive treatment strategies at the onset of subsyndromal symptoms. In addition, the use of subsyndromal symptoms to broaden the diagnostic criteria for bipolar disorder is receiving increased attention. This article reviews and discusses these important issues.