Peripheral Body Temperature Rhythm As a Marker of the Severity of Depression Symptoms in Fibromyalgia

Background: Circadian rhythm alterations have been reported in fibromyalgia (FM) and depression. Peripheral body temperature (PBT) is a reliable measure of the circadian system, so we compared the PBT rhythm between persons with FM and controls. We evaluated PBT correlation with depression symptoms and pain severity in women with FM. Methods: We included 101 women aged 30-65 with FM diagnosis (FM group, n = 83) and controls (n = 18). Twenty-four-hour PBT was assessed by actigraphy. For the analysis, in the FM group, the PBT measurement was divided into four periods: morning (6 a.m.-noon), afternoon (noon-6 p.m.), evening (6 p.m.-midnight), and night (midnight-6 a.m.). According to their scores on the Hamilton Depression Rating Scale (HDRS), participants were classified as having mild or moderate to severe depression symptoms. Results: There was no difference in PBT between FM and controls. Subjects with FM and moderate to severe depression symptoms showed a higher PBT (p = .003) during the evening period (p = .004). The analysis of PBT rhythm revealed an interaction between time and group according to mild or moderate to severe depression symptoms (chi 2 (3) = 12.79, p < .005). The pain severity was positively correlated with PBT (ss=0.22, [CI 95%, 0.07-0.37], p = .003). Conclusions: PBT rhythm was not a sensitive measure for discriminating persons with FM from controls. In FM, PBT is related to the severity of depression symptoms and pain intensity.