HPA Axis Dysfunction and Stress
The physiological stress response is a temporary phenomenon, which acts to prepare the neuroendocrine, musculoskeletal, and cardiovascular systems to respond appropriately to a stressful event Through activation of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoids (cortisol) are synthesized and secreted at a higher rate from the adrenal cortex. Simultaneously, sympathetic nervous system (SNS) activation results in increased secretion of catecholamines (epinephrine and norepinephrine) from the adrenal medulla. Under normal healthy circumstances, the stressful signal terminates, and through a negative feedback mechanism, glucocorticoid secretion drops, stimulation of the HPA axis decreases, while simultaneously, SNS activity and catecholamine secretion decreases, and homeostasis is restored (8)
Dysfunctions in the physiological stress response are seen when over time, the magnitude or duration of stress placed on the body exceeds its ability to cope. When this occurs, the adrenal glands (i.e.),glucocorticoid and catecholamine secretion from the adrenal cortex and medulla, respectively) are unable to respond appropriately in relation to the magnitude of stress. This is known as adrenal
exhaustion or adrenal insufficiency (9). In a military setting, a variety of factors can contribute to adrenal insufficiency, namely overtraining stemming from excessive endurance exercise without appropriate
recovery, operational demands, psychological stress, lack of sleep, and inadequate nutrition. Frequently, it is the cumulative stress that tips the balance and creates an adrenal exhaustion scenario, rather than one single stressor (9).
HPA axis dysfunction with adrenal exhaustion or fatigue is by far one of the biggest issues facing modern society, we just happen to have it much worse due the chronic stress activation noted above. HPA axis dysfunction needs to be tested for annually including job specific blood panels and series cortisol studies as traditional medical screens will not pick up the abnormalities in the blood. Plus all first responders should be screened for trace mineral levels along with other HPA axis hormones like testosterone and estrogen. This also opens the door for screening and counseling on metabolic syndromes, early cancer detection and fitness.
This topic and more are covered extensively in our on-line and live courses!