Supplementary Material for: Effects of childhood trauma and anxiety on the hypothalamic-pituitary-adrenal axis in chronic subjective tinnitus with distress

Introduction: There is some evidence for hypothalamic-pituitary-adrenal (HPA) axis hypofunction in chronic tinnitus, but findings are contradicting possibly due to clinical heterogeneity. This study aims to assess differential effects of childhood trauma and anxiety on HPA-axis functioning in adults suffering from chronic subjective tinnitus with distress. Methods: Salivary cortisol data were collected in 22 chronic subjective tinnitus sufferers (without major depression) and 29 healthy controls after awakening, at baseline and after a low-dose (0.5 mg) dexamethasone challenge. A factorial ANCOVA was conducted to compare the main effects of group (tinnitus versus controls), trauma and their interaction effect on the cortisol awakening response (CAR). Linear mixed models were fitted for baseline and post-dexamethasone cortisol levels with group, sampling time, trauma and their interactions as fixed factors and subject as the random effect. The Beck Anxiety Index, Anxiety Sensitivity Index and Panic Disorder Severity Scale were included to investigate effects of anxiety. Results: A significant interaction between group and trauma (F(1, 47) = 6.9755, p = 0.0112) was found, with the tinnitus group showing lower CARs (M = 5.1808, SD = 0.5821) than the comparison group (M = 5.9974; SD = 0.5251) in traumatised individuals only. No effects were found for baseline or post-dexamethasone cortisol. Anxiety scores had no effects on any of the outcome variables. Conclusion: A differential effect of childhood trauma, but not anxiety, on the HPA-axis function in chronic subjective tinnitus was partly confirmed by the finding of a blunted CAR in tinnitus sufferers reporting early-life adversity.