Research published in the November/December 2002 issue of Psychosomatic Medicine examined the relationship between chronic fatigue syndrome (CFS) and the body’s hormonal stress response system, known as the HPA axis. HPA stands for hypothalamus, pituitary, and adrenal glands, a system that plays a central role in maintaining physiological stability during stress.
The study included 40 subjects between the ages of 30 and 50. Half of the participants had been diagnosed with chronic fatigue syndrome, while the other half served as healthy controls. Researchers evaluated HPA axis function using an insulin tolerance test (ITT), which involved controlled insulin injections to provoke a stress response.
Blood and saliva samples were collected to measure hormonal responses before and after exposure to psychological stress, which consisted of a simulated job interview and a mental arithmetic task performed under the belief that the subjects were being videotaped. Hormonal responses were also measured before and after physical stress induced by exercise on a stationary bicycle.
Both the insulin tolerance test and the psychological and physical stress challenges were designed to assess HPA axis responsiveness. The researchers found that individuals with chronic fatigue syndrome had significantly lower levels of adrenocorticotropic hormone (ACTH), one of the key hormones of the HPA axis, compared to healthy controls. Notably, ACTH levels in the chronic fatigue group were already low before stress testing or the ITT was administered.
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