Evidence that abnormalities of central neurohormonal systems are key to understanding fibromyalgia and chronic fatigue syndrome.
Crofford, L J, Demitrack, M A · Rheumatic diseases clinics of North America · 1996 · DOI
Quick Summary
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.
Why It Matters
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.'
Observed Findings
- Abnormalities of the hypothalamic-pituitary-adrenal (HPA) axis are present in both FM and CFS
- Dysfunction of sympathetic stress-response systems occurs in both conditions
- Symptoms of FM and CFS frequently worsen during periods of physical or emotional stress
- Both conditions frequently begin after acute or chronic stressful events
Inferred Conclusions
- Central neurohormonal system abnormalities are key to understanding FM and CFS pathophysiology
- Both conditions represent 'stress-associated syndromes' characterized by impaired stress-response regulation
- Dysfunction of the HPA axis and sympathetic nervous system may increase vulnerability to these syndromes and perpetuate their symptoms
Remaining Questions
- What causes the initial HPA axis and sympathetic nervous system dysfunction in some individuals but not others?
- Are neurohormonal abnormalities primary drivers of symptom severity, or secondary consequences of the illness?
- How do specific types of stressors interact with these neurohormonal abnormalities to trigger or exacerbate symptoms?
What This Study Does Not Prove
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.