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 and Akiskal.
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. 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.). 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.