Crofford, L J, Demitrack, M A · Rheumatic diseases clinics of North America · 1996 · DOI
This study explores how stress-response systems in the brain and body may be broken in people with fibromyalgia and chronic fatigue syndrome (ME/CFS). Both conditions often start after stressful events and get worse during stressful times. The researchers found that the brain's main stress-management system—called the hypothalamic-pituitary-adrenal (HPA) axis—does not work normally in these patients, which could explain why their symptoms worsen with stress.
Understanding that ME/CFS involves fundamental abnormalities in how the brain manages stress responses—rather than representing purely psychological illness—helps legitimize the condition as neurobiological. This framework has guided decades of subsequent research into HPA axis dysfunction and autonomic nervous system dysregulation, providing a biological foundation for developing targeted treatments rather than dismissing symptoms as 'all in the head.'
This review does not prove that stress causes ME/CFS or fibromyalgia, only that stress-response system dysfunction is associated with these conditions. It does not establish whether HPA axis abnormalities are a cause, consequence, or contributing factor to symptom development. The study does not provide new experimental evidence and should be considered a theoretical framework rather than definitive proof of mechanism.
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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