The structure of affective symptoms in a sample of young adults

Symptoms of bipolar disorders include depression and mania. The term "bipolar" implies states that are opposite to each other. Construing scales that define mania and depression as opposite ends of one dimension cannot account for the existence of mixed symptoms. One self-report instrument, the Internal State Scale (ISS), combines both dimensions in one measure. However, the ISS only assesses internal subjective states and does not tap other typical and more objective symptoms of (hypo-) mania. To explore the factorial structure of affective symptoms in a general population sample, we extended the Center for Epidemiologic Studies-Depression Scale (CES-D), adding items to assess manic symptoms as described in DSM-IV. The scale was completed by 2,059 young adults. The results for the original CES-D are comparable to prior studies. Factor-analysis for the extended CES-D revealed two factors in women and men: most manic symptoms loaded high on a factor "euphoria-activation," whereas the other factor included all typical dysphoric-depressive symptoms, but also included the "manic symptoms" of distractibility and irritability. Our results support a two-factor model of bipolar symptoms in the general population with irritability being more closely associated with dysphoria than euphoria. The implications and limitations of the present results are discussed.