Is overactivity the core feature of hypomania in bipolar II disorder?

Recent studies found that overactivity (increased goal-directed activities) may be as important as mood change (elevated and/or irritable mood) for the diagnosis of mania/hypomania (on family history and psychometric grounds), questioning DSM-IV-TR criteria always requiring mood change and listing overactivity among the other symptoms. The aim of the study was to find out if overactivity was at least as important as mood change for the diagnosis of hypomania.

A consecutive sample of 137 bipolar II disorder (BP-II) and 76 major depressive disorder remitted outpatients were interviewed with the Structured Clinical Interview for DSM-IV by a senior clinical and research psychiatrist in a private practice. Patients were asked if they had had hypomanic symptoms and episodes, and which were the most common hypomanic symptoms during the various episodes. The study aim had not been planned when variables were collected for different study goals.

Overactivity was the most common hypomanic symptom in BP-II, more common than elevated mood, and had the strongest association with BP-II among all the hypomanic symptoms (overactivity odds ratio = 15.4, elevated mood odds ratio = 12.6). Three factors were found: an 'elevated mood' factor including elevated mood and increased self-esteem; a 'mental activation' factor including racing/crowded thoughts, and a 'behavioral activation' factor including overactivity. There was no relationship between overactivity and mood change. Irritable mood was not associated with overactivity and elevated mood. BP-II was present in 21.6%of patients without a history of overactivity, and in 81.0% of patients with a history of overactivity. BP-II was present in 25.0% of patients without elevated mood, and in 63.3% of patients with elevated mood. As a predictor of BP-II, overactivity had a sensitivity of 90.5%, a specificity of 61.8%, and a positive predictive value of 81.0% (elevated mood: 72.2, 82.8, and 88.3%, respectively). Five or more hypomanic symptoms had the most balanced combination of sensitivity (82.4%) and specificity (85.5%) for BP-II, and a positive predictive value of 91.1%. Overactivity was present in 89.5% of patients with a history of > or = 5 hypomanic symptoms, while elevated mood was present in 76.6%.

Theresults seem to support the view that overactivity may be a core feature of hypomania, suggesting the upgrading of overactivity to a stem criterion for hypomania.