Frequency of bipolar spectrum in 111 private practice depression outpatients

Background Mood disorders included into the bipolar spectrum are increasing, and overactivity (increased goal-directed activity) has reached the status of mood change for the diagnosis of hypomania in the recent studies by Angst (2003) and Akiskal (2001). Study aim was to find frequency of bipolar spectrum in remitted depressed outpatients by including sub-syndromal hypomania. Methods 111 depression-remitted outpatients were interviewed for history of hypomania and hypomanic symptoms with the Structured Clinical Interview for DSM-IV-Clinician Version (a partly semistructured interview), as modified by Benazzi and Akiskal (2003). Bipolar I patients were not included. All past hypomanic symptoms (especially overactivity) were systematically assessed.Wording of the questions could be changed to increase/check understanding.Subsyndromal hypomania was defined as an episode of overactivity (increased goal-directed activity) plus at least 2 hypomanic symptoms. Results Frequency of bipolar II (BPII) was 68/111 (61.2%, 95% confidence interval 52% to 69.8 %), frequency of major depressive disorder (MDD) was 43/111. The most common hypomanic symptom was overactivity. In the MDD sample, sub-syndromal hypomania was present in 39.5% (15.3% of the entire sample), and had 4 median symptoms. Bipolar spectrum frequency was 76.5% (95% confidence interval 67.9% to 83.5 %). Overactivity had higher sensitivity than elevated mood for predicting BPII diagnosis. Limitations Single interviewer. Conclusions By systematic probing more focused on past overactivity than mood change, and by inclusion of sub-syndromal hypomania, bipolar spectrum frequency was higher than the near 1 to 1 ratio versus MDD reported up to now (Angst et al. 2003). Given the wide confidence interval, the value in the depression population should be around 70%. Better probing skills by clinicians, and use of semi-structured interviews could much reduce the current high underdiagnosis of BPII and related disorders in usual clinical practice.