Objectives: To test the hypothesis that the premorbid overactivity previously described in subjects with fibromyalgia is a core feature of the manic/hypomanic symptoms characterising bipolar spectrum disorders.
Methods: 110 consecutive patients with fibromyalgia were assessed for bipolar spectrum disorders using both categorical and dimensional approaches. The first was based on a version of the DSM-IV SCID-CV interview, modified to improve the detection of bipolar spectrum disorders, the second on the hypomania symptom checklist HCL-32, which adopts a dimensional perspective of the manic/hypomanic component of mood by including sub-syndromal hypomania.
Results: Both DSM-IV and Zurich criteria diagnosed high rates of bipolar spectrum disorder in patients with fibromyalgia (70% and 86.3%, respectively). Individuals with a major bipolar spectrum disorder (bipolar II disorder) and with a minor bipolar spectrum disorder (subthreshold depression and hypomania) did not differ in their demographic and clinical aspects. Hypomanic symptom counts on the HCL-32 confirmed high estimates of the bipolar spectrum, with 79% of subjects with fibromyalgia scoring 14 (threshold for hypomania) or above.
Conclusions: Overactivity reported in previous studies may be considered a core feature of hypomanic symptoms or syndromes comorbid with bipolar spectrum disorders. Major and minor bipolar spectrum disorders are not associated with differences in demographic or clinical characteristics, suggesting that fibromyalgia rather than being related specifically to depression is related to bipolar spectrum disorders and in particular to the hypomania/overactivity component.