Association of pain intensity, pain-related disability, and depression with hypothalamus–pituitary–adrenal axis function in female patients with chronic temporomandibular disorders

Patients with temporomandibular disorders (TMD) commonly experience myofascial and joint pain, pain-related disability, and other pain conditions including depression. The present study was carried out to explore the function of the hypothalamus–pituitary–adrenal (HPA) axis in relation to variables of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis II and comorbid depression in female patients with TMD. Cortisol and dehydroepiandrosterone (DHEA) levels were determined in saliva samples that had been collected at various periods after waking (0, 30, and 60 min) and at nighttime (2100–2200 h) from 52 female patients with chronic TMD pain and age- and gender-matched controls (n = 54, 20–40 years old). There were no significant differences in the levels and diurnal patterns of cortisol and DHEA secretion between groups of patients with TMD and controls. In patients, the cortisol awakening response (CAR) or diurnal cortisol rhythm were not associated with any variables of the RDC/TMD Axis II or the Beck Depression Inventory (BDI)-II total scores. However, the ratio of overall cortisol secretion within the first hour after waking (CARauc) to overall DHEA secretion during the post-waking period (Daucawk), defined as CARauc/Daucawk, was significantly associated with pain-related RDC/TMD variables (pain intensity and pain-related disability) and BDI-II total scores. Pain intensity and pain-related disability scores were also significantly associated with BDI-II total scores. These results indicated that an increase in molar cortisol/DHEA ratio due to the dissociation between cortisol and DHEA secretion was associated with pain intensity, pain-related disability, and depression in female patients with TMD.