Enhanced Suppression of Adrenocorticotropic Hormone and Cortisol Responses to Hypothalamic-Pituitary-Adrenal Function and Thyrotropin-Releasing Hormone Tests after Stressful Life Events in Patients with Major Depressive Disorder

Abstract

Background: It is commonly believed that there exists a relationship between the outcome of thyrotropin-releasing hormone (TRH) test, the combined dexamethasone/corticotropin-releasing hormone (DEX/CRH) test and stressful life events (SLEs) in major depressive disorder. Objective: SLEs influence the TRH and DEX/CRH tests in major depressive disorder when administered at the time of admission and improvement. Methods: The TRH and DEX/CRH tests were administered to patients hospitalized for major depressive disorders – on the 4th through the 7th hospital day and at the time of improvement. We measured ΔMAX TSH, ΔMAX ACTH, ACTH AUC, ΔMAX cortisol, cortisol AUC, ΔMAX ACTH/ΔMAX TSH and ΔMAX cortisol/ΔMAX TSH. Results: SLEs were significantly negatively associated with ΔMAX ACTH, ACTH AUC and cortisol AUC at the time of admission. However, these relationships lost significance at the time of improvement. The sample (41 patients at the time of admission, 18 patients at the time of improvement) was relatively small, which may have contributed to false-negative results. Conclusion: SLEs may be negatively associated with the outcome of the DEX/CRH tests in major depressive disorder. The hypothalamic-pituitary-adrenal axis in the DEX/CRH test was modulated by SLEs.