Combined dexamethasone/corticotropin-releasing factor test in chronic fatigue syndrome.
Van Den Eede, F, Moorkens, G, Hulstijn, W et al. · Psychological medicine · 2008 · DOI
Quick Summary
This study tested how well the stress-response system (HPA axis) works in ME/CFS patients compared to healthy people. Researchers gave patients a special test involving two hormones and measured cortisol levels in saliva. They found that ME/CFS patients had lower cortisol responses than healthy controls, suggesting their stress-response system may not be working properly—but this was especially true for patients without a history of childhood trauma.
Why It Matters
Understanding HPA axis dysfunction in ME/CFS could explain fatigue, immune dysregulation, and stress intolerance. This study adds objective biological evidence of abnormal stress hormone regulation and shows that early-life trauma history must be considered when interpreting HPA axis findings—important for both patient stratification and mechanistic research.
Observed Findings
CFS patients showed lower salivary cortisol responses after 0.5 mg dexamethasone compared to healthy controls (p=0.038 before CRF challenge; p=0.015 after CRF challenge).
When patients taking oral oestrogen were excluded, CFS patients without early-life stress history showed the most pronounced cortisol suppression (p=0.005 before CRF; p=0.008 after CRF).
Early-life stress history and oral oestrogen intake were identified as significant variables influencing cortisol responses.
The pattern suggests enhanced negative feedback sensitivity to glucocorticoids and/or reduced central HPA axis drive in CFS.
Inferred Conclusions
ME/CFS is associated with reduced cortisol responses in the combined low-dose Dex/CRF test, indicating HPA axis hypofunction.
This hypofunction is most clearly present in CFS patients without a history of early-life stress, suggesting ELS may mask or modify the HPA axis abnormality.
Enhanced glucocorticoid negative feedback and/or reduced hypothalamic-pituitary drive appear to be mechanisms underlying HPA axis dysfunction in CFS.
Early-life stress is an important confounding variable that must be considered in future CFS research on HPA axis function.
Remaining Questions
Why does early-life stress history appear to normalize or mask HPA axis dysfunction in ME/CFS patients?
What This Study Does Not Prove
This study does not prove that low cortisol causes ME/CFS or that correcting it will cure the disease; it shows an association. The findings are limited to female patients and cannot be generalized to men. It also does not establish whether the HPA axis abnormality is primary or secondary to other disease mechanisms.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →