Altemus, E et al. Abnormalities in response to vasopressin infusion in chronic fatigue syndrome. Psychoneuroendocrinology, 2001, 26, 175-188.
Several neuroendocrine studies have suggested hypoactivation of the hypothalamic-pituitary-adrenal axis in CFS. One possible determinant of this neuroendocrine abnormality, as well as the primary symptom of fatigue, is reduced hypothalamic secretion of corticotrophin-releasing hormone (CRH).
Because CRH and vasopressin secreted from the hypothalamus act synergistically at the pituitary to activate ACTH secretion, the ACTH response to peripheral infusion of vasopressin can provide an indirect measure of hypothalamic CRH secretion.
The researchers measured the ACTH and cortisol response to a one-hour infusion of arginine vasopressin in 19 patients with CFS (CDC criteria ’88 and ’94) and 19 age and sex matched healthy volunteers. The patients with CFS had been ill on average 3.7 years and nine were still working.
The results showed that the people with CFS had a reduced ACTH response to the vasopressin infusion and a more rapid cortisol response to the infusion.
"These results provide further evidence of reduced hypothalamic CRH secretion in patients with chronic fatigue syndrome."
The authors provided no indication of the current or past levels of stress in these individuals. This is unfortunate since the type of findings reported here are similar to those documented in relation to psychological stress (cf. Heim et al. Psychoneuroendocrinology 2000, 25, 1-35, for a review).
The use of strict criteria and the inclusion of a significant number of patients who were still working (suggesting modest levels of disability) could explain why these individuals did not have the abnormally low levels of cortisol found in some broadly-defined samples (and people suffering from burn-out). On the other hand, the changes noted here are consistent with some degree of ongoing stress, possibly as a consequence of being ill.
Theoretically, the changes could also be due to infection. However, none of the studies which focused on patients with ME and post-viral CFS have found low levels of cortisol, so my money remains on chronic stress as being a major cause of the reduced secretion of CRH.