Differential Hypothalamic-Pituitary-Adrenal Axis Reactivity to Psychological and Physical Stress1

Healthy men exhibit a differential hypothalamic-pituitary-adrenal axis (HPA) response to exercise stress and fall into two groups: high responders (HR) and low responders (LR). The present study examined whether HR to physical stress also exhibit higher HPA reactivity to psychological stress than LR. We examined 14 HR and 13 LR classified based on their ACTH responses to high intensity exercise after pretreatment with dexamethasone. Both groups were of similar age, height, weight, and fitness level. Trait anxiety scores on the Spielberger Trait Anxiety Scale were not different. Subjects underwent a psychological stress test consisting of an interview and mental arithmetic. This test raised heart rate, blood pressure, and plasma ACTH and cortisol levels in both HR and LR. HR tended to have higher heart rates and blood pressures in anticipation of the psychological stress test than LR. ACTH responses of HR were higher, although not significantly, throughout the psychological stress test than LR. HR had a significantly (P < 0.05) greater net integrated cortisol response to the psychological stress than LR. This suggests that the adrenal cortexes of the HR are hypertropic and/or hypersensitive to ACTH. We conclude that men who are highly responsive to exercise stress are also highly responsive to psychological stress.