Salivary cortisol response to awakening in chronic fatigue syndrome.
Roberts, Amanda D L, Wessely, Simon, Chalder, Trudie et al. · The British journal of psychiatry : the journal of mental science · 2004 · DOI
Quick Summary
This study tested how well the body's stress response system (controlled by the brain and hormones) works in ME/CFS patients. Researchers measured cortisol, a stress hormone, in saliva when people first woke up and for an hour afterward. They found that people with ME/CFS had a weaker cortisol response compared to healthy people, suggesting their stress-response system may not be working properly.
Why It Matters
This study provides objective biological evidence of a specific physiological abnormality in ME/CFS—HPA axis dysfunction—which could help validate the condition as a biological disorder rather than purely psychological. Understanding this mechanism may eventually inform treatment approaches targeting hormonal regulation and stress response.
Observed Findings
ME/CFS patients (n=56) showed significantly lower cortisol awakening response compared to healthy controls (n=35) when measured by area-under-the-curve.
The salivary cortisol response pattern over 60 minutes post-awakening differed between patient and control groups.
The cortisol awakening response measurements correlated well with results from more invasive HPA axis testing methods reported in prior literature.
The test was feasible to perform in a naturalistic home setting without requiring clinic visits.
Inferred Conclusions
HPA axis function is impaired in ME/CFS patients, demonstrated by attenuated cortisol response to awakening.
Salivary cortisol awakening response is a valid, non-invasive tool for assessing HPA axis capacity in ME/CFS.
The blunted cortisol response suggests reduced neuroendocrine reactivity to stress in this population.
Remaining Questions
Does the blunted cortisol response reflect a primary neurobiological abnormality in ME/CFS or a secondary adaptation to chronic illness?
How does HPA axis dysfunction at awakening relate to other times of day and to specific ME/CFS symptoms?
Does cortisol response improve or change over time, and does it predict clinical outcomes or treatment response?
What This Study Does Not Prove
This study does not prove that HPA axis dysfunction causes ME/CFS symptoms or that restoring cortisol levels will improve the condition. It demonstrates association, not causation, and does not explain whether this dysfunction is primary to the disease, secondary to chronic illness, or contributes meaningfully to patient disability.
Tags
Symptom:Fatigue
Biomarker:Blood Biomarker
Method Flag:Weak Case DefinitionSmall SampleExploratory Only
What is the mechanistic relationship between impaired HPA axis function and the fatigue, cognitive symptoms, and post-exertional malaise experienced by ME/CFS patients?