Dexamethasone-suppressed cortisol awakening response predicts treatment outcome in posttraumatic stress disorder

Background: Posttraumatic stress disorder (PTSD) has been associated with several alterations in the neuroendocrine system, including enhanced cortisol suppression in response to the dexamethasone suppression test. The aim of this study was to examine whether specific biomarkers of PTSD predict treatment success in trauma-focused psychotherapy.

Methods: Data were collected in the context of a randomized controlled trial comparing two forms of trauma-focused psychotherapy. Basal cortisol and dehydroepiandrosterone sulfate levels, and the response to the dexamethasone suppression test were assessed pre-treatment in 24 PTSD patients. Treatment success was measured by pre- to post-treatment decrease in self-reported PTSD severity.

Results: A more suppressed cortisol curve after dexamethasone significantly predicted greater PTSD symptom decrease in trauma-focused psychotherapy, independent of the effects of gender, pre-treatment PTSD symptom severity, and trauma history. Basal early morning cortisol and dehydroepiandrosterone sulfate did not predict treatment response.

Limitations: The number of participants who completed the neuroendocrine measurements was small and a significant number of participants fulfilled criteria of co-morbid major depressive disorder.

Conclusions: This study suggests the use of the dexamethasone-suppression test for the cortisol awakening response as a biomarker for treatment response to trauma-focused psychotherapy. Measures of HPA-axis sensitivity appear to be an important predictor of positive clinical response in PTSD patients, and may lead to biomarker-based treatment matching in the future.