Neuroendocrinology of PTSD

Initial studies on the neuroendocrine basis of post-traumatic stress disorder (PTSD) showed a biological dysregulation of stress response systems that appeared to be incompatible with the stress response theories that had prevailed when PTSD was first established as a diagnosis. Cortisol levels were found to be lower and catecholamine higher in patients with PTSD than in those with major depression and other psychiatric disorders. There was no explanation for why levels of two stress hormones that are generally correlated—cortisol and norepinephrine—would be different, and it was also not clear why cortisol levels would be on the low end of the normal spectrum, when the classic stress response paradigms suggested stress results in elevated cortisol. The study of neuroendocrinology and hypothalamic–pituitary–adrenal (HPA) axis alterations in PTSD provides an object lesson in how paradoxical observations might be pursued toward a better understanding of the pathophysiology of a disorder. This chapter reviews HPA findings in PTSD in cross-sectional and prospective longitudinal studies.