2009 by Oxford University Press. All rights reserved. The hypothalamic-pituitary-adrenal (HPA) axis response to stress is well documented. However, less is established regarding the role of this neuroendocrine system in stress-related psychopathology. The current chapter reviews the scientific literature on HPA functioning in panic disorder, posttraumatic stress disorder (PTSD), social and specific phobia, and generalized anxiety disorder. More specifically, it examines studies that have characterized biological rhythms of HPA axis hormones at basal state, the endocrine response to laboratory and naturalistic challenges, the response to direct pituitary and adrenal stimulation, and the sensitivity of inhibitory feedback mechanisms. While the current literature does not directly support a link between symptoms and HPA dysfunction, several abnormalities have been identified and evidence suggests further study may prove fruitful in understanding the pathophysiology of specific disorders.
