• cortisol;
  • ACTH;
  • treatment resistance;
  • neuroendocrine challenge;
  • rapid cycling;
  • HPA system


The combined dexamethasone-suppression/human corticotropin releasing hormone challenge (DEX/hCRH) test was repeatedly applied in a rapid cycling patient (RC) with bipolar illness during different affective states. The results were compared to a matched control group (n = 8) of non-rapid cycling major depressive disorder patients in whom the DEX/hCRH test was applied at the beginning and end of a 6-week antidepressant treatment program. RC had normal DEX suppression tests but exhibited exaggerated cortisol and ACTH responses to hCRH. Furthermore, RC's hormone responses were unaffected by the current clinical state (depressive, hypomanic, euthymic), and significantly exceeded the hormone responses of the control group at the beginning (acute) and the end (remitted) of their treatment. These findings suggest that severe and irreversible hypothalamic-pituitary-adrenocortical (HPA) system dysregulation may characterize rapid cycling. Depression 3:204–208 (1995). © 1995 Wiley-Liss, Inc.