Results on hypothalamicpituitary-adrenal (HPA) axis function in fibromyalgia are heterogeneous and studies that integrate psychological and biological mechanisms in the search for pathways to fibromyalgia are rare. The goal of the study was to evaluate cortisol release and HPA axis feedback regulation in fibromyalgia and its association with psychopathology and pain. Beneath assessment of pain thresholds and self-report of pain, salivary free cortisol release over the day before and after intake of 0.5 mg of dexamethasone was measured in 21 female patients with fibromyalgia and 26 control women. Depression was assessed by questionnaires and clinical interview. We found reduced feedback sensitivity and slightly enhanced cortisol release in patients with fibromyalgia compared with healthy control subjects. Post hoc analyses showed that these effects are exclusively found in those patients, who also had major depressive disorder. Patients with fibromyalgia had lower pain pressure threshold, whereas heat pain thresholds were comparable with control subjects. Pain pressure and heat pain thresholds were not associated with cortisol release. On the other hand measurements of affective pain experience and depression were positively correlated with salivary cortisol over the day. Our results support the hypotheses that HPA axis related alterations are associated with affective disturbances, for example, depression, in patients with fibromyalgia. PERSPECTIVE: The presented data suggest depression to be an important factor in HPA axis-related dysfunction in fibromyalgia. This might be one explanation for equivocal findings in the literature.
