Twenty-four Hour Plasma Cortisol and Adrenocorticotropic Hormone in Gulf War Veterans: Relationships to Posttraumatic Stress Disorder and Health Symptoms

Background We aim to characterize the baseline functioning of the hypothalamic-pituitary-adrenal (HPA) axis in Gulf War veterans (GWV) and examine the extent to which posttraumatic stress disorder (PTSD) and unexplained health symptoms—which commonly co-occur—have similar or different biological correlates. Methods Thirty-one GWV, 20 with current PTSD and 11 without current or lifetime PTSD, and 16 healthy nondeployed subjects not exposed to the Gulf War theater underwent medical and psychiatric examination followed by blood sampling every half-hour over 24 hours for the measurement of cortisol and adrenocorticotropic hormone (ACTH). Results Gulf War veterans without PTSD or another psychiatric disorder had significantly lower 24-hour plasma ACTH levels, a significantly higher cortisol:ACTH ratio, and no difference in cortisol levels compared to nondeployed subjects and to GWV with PTSD, controlling for body mass index (BMI). Among GWV, health symptoms (mood and cognitive symptoms) were positively associated with, and hyperarousal symptoms were negatively associated with, the cortisol:ACTH ratio. Additionally, the self-reported acute effects of pesticides and of pyridostigmine bromide during deployment were associated with lower ACTH levels, controlling for BMI and PTSD. Conclusions The data provide evidence of HPA axis dysregulation in Gulf War veterans, which may be related to Gulf War deployment exposures. Despite the overlap of chronic unexplained health symptoms and PTSD in GWV, these symptom constellations appear to be biologically distinct.