Factor structure of recalled DSM-IV hypomanic symptoms of bipolar II disorder

The DSM-IV-TR definition of hypomania in bipolar II disorder (BP-II) has yet to show its validity. The aim of the current study was to find the factor structure of hypomania by using DSM-IV-TR symptoms, and to assess the DSM-IV-TR definition of hypomania. One hundred ninety-seven consecutive BP-II remitted outpatients were interviewed by the Structured Clinical Interview for DSM-IV (SCID-CV) as modified by Benazzi and Akiskal (2003) and by Benazzi (2003), in a private practice, assessing the symptoms that were more common during past hypomanic episodes. The factor structure of hypomania was studied by principal component factor analysis. Almost all patients reported overactivity (increased goal-directed activity) during hypomania, and less commonly elevated mood. Overactivity plus three or more symptoms identified 89.3% of DSM-IV-TR BP-II. Factor analysis found three factors: factor 1, including racing thoughts ("mental activation"); factor 2, including elevated mood ("high mood"); and factor 3, including overactivity ("behavioral activation"). Elevated mood was correlated only with two of the nine DSM-IV-TR hypomanic symptoms. The three-domains structure of hypomania by Kraepelin (i.e., increased mood, thought, and activity) was found in the DSM-IV-TR definition of hypomania, partly supporting its list of symptoms. However, DSM-IV-TR priority given to mood change for the diagnosis of hypomania was not supported. An upgrading of overactivity to at least a priority level similar to mood change was supported by (1) its high frequency, (2) its utility to diagnose BP-II, and (3) by factor analysis showing that elevated mood (the "prototypical" symptom of hypomania in DSM-IV-TR) correlated with few symptoms, and that three factors (of which only one included elevated mood) were present.