Identifying hypomanic features in major depressive disorder using the hypomania checklist (HCL-32)

Recent studies have challenged the traditional unipolar/bipolar divide with increasing support for a more dimensional view of affective disorders. We here examine the occurrence of hypomanic symptoms in individuals with a history of major depression selected to exclude indicators of underlying bipolarity.

The presence of hypomanic symptoms was assessed by the Hypomania Checklist (HCL-32) self-report questionnaire in a sample of almost 600 patients meeting DSM-IV criteria for Bipolar I disorder (BPI N=260) or Major Recurrent Depressive disorder (MDDR N=322). Subjects were recruited and assessed using consistent, robust methodology.

We found that a score of 20 or more on the HCL-32 yielded the best combination of sensitivity (68%) and specificity (83%) to distinguish between BPI and MDDR. Within our highly selected and well defined MDDR sample (for which exclusion criteria included personal or family histories of bipolar or psychotic illness), 17% of MDDR subjects scored over the threshold of 20 on the HCL-32.

The HCL-32 identified a substantial number of patients meeting DSM-IV criteria for recurrent major depression (even when selected to exclude personal and family histories of bipolar illness) who reported bipolar symptoms at a level similar to that reported by patients meeting diagnostic criteria for bipolar disorder. This demonstrates the limitations of using DSM-IV criteria to distinguish those with and without bipolar features of illness.