Manic symptoms during depressive episodes in 1,380 patients with bipolar disorder: findings from the STEP-BD.

OBJECTIVE: Little is known about how often bipolar depressive episodes are accompanied by subsyndromal manic symptoms in bipolar I and II disorders. The authors sought to determine the frequency and clinical correlates of manic symptoms during episodes of bipolar depression.
METHOD: From among 4,107 enrollees in the National Institute of Mental Health's Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD), 1,380 individuals met criteria for bipolar I or II depressive syndromes at the time of enrollment and were assessed for concomitant manic symptoms. Illness characteristics were compared in patients with pure bipolar depressed episodes and those with mixed depressive presentations.
RESULTS: Two-thirds of the subjects with bipolar depressed episodes had concomitant manic symptoms, most often distractibility, flight of ideas or racing thoughts, and psychomotor agitation. Patients with any mixed features were significantly more likely than those with pure bipolar depressed episodes to have early age at illness onset, rapid cycling in the past year, bipolar I subtype, history of suicide attempts, and more days in the preceding year with irritability or mood elevation.
CONCLUSIONS: Manic symptoms often accompany bipolar depressive episodes but may easily be overlooked when they appear less prominent than depressive features. Subsyndromal manic symptoms during bipolar I or II depression demarcate a more common, severe, and psychopathologically complex clinical state than pure bipolar depression and merit recognition as a distinct nosologic entity.