Retrospective Evaluation of the Dexamethasone Suppression Test as a Predictor of Response to Electroconvulsive Therapy in Patients With Comorbid Major Depressive Disorder and Posttraumatic Stress Disorder

Background: There is evidence that response to dexamethasone suppression test (DST) can be predictive of treatment outcomes in major depressive disorder (MDD). The purpose of this study was to explore if DST response, at both 1 and 0.5 mg of dexamethasone doses, is predictive of the effectiveness of electroconvulsive therapy (ECT) in depression symptom reduction in patients with comorbid posttraumatic stress disorder (PTSD) and MDD who are treated with ECT. Methods: We performed a chart review of all patients with both PTSD and MDD receiving ECT from January 2002 through December 2008, who had DST performed before starting ECT. A total of 32 patients meeting these criteria were identified. Those patients were divided into 3 groups based on their response to the DST: enhanced suppressors (n = 13), normal suppressors (n = 14), and nonsuppressors (n = 5). Posttraumatic stress disorder and MDD outcomes after completion of the primary ECT treatment series were measured. Results were stratified by pretreatment DST responses. Results: Nonsuppressors showed significantly more response to ECT, in both MDD and PTSD symptom scales, as compared with normal suppressors and enhanced suppressors. Normal suppressors showed significantly more response to ECT than enhanced suppressors. Electroconvulsive therapy did not appear to be effective in depression symptom reduction for enhanced suppressors. Conclusions: This study suggests that DST results may be predictive of depression symptom reduction in response to ECT in patients with comorbid PTSD and MDD, with patients suppressing morning cortisol production in response to 0.5 mg of dexamethasone showing little improvement. In addition, this study lends further evidence that ECT is an effective treatment for some patients with comorbid MDD and PTSD.