The Effect of an Internet-Based Intervention for Depression on Cortisol and Alpha-Amylase

Introduction: Psychotherapeutic interventions for major depressive disorder (MDD) have been suggested to beassociated with a normalization of biological stress system (i.e., the hypothalamic-pituitary-adrenal axis and theautonomic nervous system) dysregulation. Furthermore, pre-intervention cortisol parameters have been identifiedas prescriptive biological markers of treatment success. However, evidence of treatment effects on thebiological stress systems is still sparse, and results are heterogeneous. The current study examined the effect of aninternet-based intervention for MDD on salivary cortisol and alpha-amylase as well as hair cortisol concentrations.Moreover, the prescriptive capacity of pre-intervention cortisol and alpha-amylase concentrations ontreatment response was explored. Methods: Thirty-eight participants suffering from mild to moderate MDD collected saliva and hair samplesthroughout the intervention. Biological outcome parameters were salivary cortisol and alpha-amylase (awakeningresponse, total diurnal output, diurnal slope) and hair cortisol concentrations. Treatment response wasindicated by change in depression severity and perceived chronic stress. Results: Treatment response on depression scores or chronic stress was not associated with changes in any of thecortisol or alpha-amylase parameters. Exploratory analysis indicated that non-responders showed a steeperalpha-amylase slope pre-intervention. Discussion: The results indicate that changes in depressive symptoms did not correspond to changes of the biologicalstress systems, contradicting the suggested normalization of dysregulated hypothalamic-pituitary-adrenalaxis or autonomic nervous system activity through a psychotherapeutic intervention. However, the results pointto a potential role of pre-intervention alpha-amylase slope as a prescriptive marker of treatment response fordepression.