Gaab, Jens, Hüster, Dominik, Peisen, Renate et al. · Psychosomatic medicine · 2002 · DOI
This study looked at how the stress-response system (a hormone system in the brain called the HPA axis) works in ME/CFS patients compared to healthy people. Researchers exposed both groups to different types of stress—mental stress, exercise, and a hormone test—and measured how their bodies responded. ME/CFS patients showed lower levels of a stress hormone called ACTH at baseline and during stress tests, but their cortisol levels were mostly normal, suggesting their stress system works differently rather than being broken.
Understanding HPA axis dysfunction in ME/CFS is critical because stress—both physical and psychological—characteristically worsens symptoms in this population. This study provides mechanistic evidence that the problem may lie in how the brain signals the stress response rather than in the glands' inability to produce hormones, potentially pointing toward future therapeutic targets. These findings help explain why ME/CFS patients have paradoxical responses to standard stress and why their symptom patterns differ from other conditions.
This study does not establish whether HPA axis dysregulation causes ME/CFS symptoms, is a consequence of chronic illness, or is merely an associated finding. The findings are correlational and cannot determine the direction of causality. Additionally, the study does not explain why ACTH is blunted while cortisol remains relatively normal, or whether correcting this dysregulation would improve clinical outcomes.
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 →
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