The associations between basal salivary cortisol and illness symptomatology in chronic fatigue syndrome.
Torres-Harding, Susan, Sorenson, Matthew, Jason, Leonard et al. · Journal of applied biobehavioral research · 2008 · DOI
Quick Summary
This study looked at cortisol, a stress hormone, in 108 people with ME/CFS to see if abnormal cortisol levels were connected to symptoms like fatigue and pain. The researchers found that people with unusual cortisol patterns—especially those who didn't show the normal daily rise and fall—reported higher levels of fatigue. While abnormal cortisol appears linked to some ME/CFS symptoms, scientists still aren't sure whether this hormonal change causes the illness or results from it.
Why It Matters
Identifying abnormal cortisol patterns in ME/CFS patients could help explain some biological mechanisms underlying the condition and potentially guide future treatment approaches targeting neuroendocrine dysfunction. For patients, understanding hormonal factors may validate symptom reports and contribute to more personalized medical approaches.
Observed Findings
Fatigue severity was associated with alterations in salivary cortisol levels in the CFS cohort.
Pain symptoms showed significant association with cortisol levels.
Deviation from the expected normal cortisol diurnal pattern (normal rise and fall throughout the day) was particularly linked to increased fatigue.
The study measured both mean daily cortisol and temporal variation using regression slope analysis.
Findings suggest hypocortisolism or altered cortisol rhythm patterns may characterize a subgroup of CFS patients.
Inferred Conclusions
Abnormal cortisol patterns, particularly disrupted diurnal rhythm, may be a biological marker associated with fatigue in ME/CFS.
Cortisol dysregulation appears relevant to symptom severity, suggesting neuroendocrine involvement in the illness.
The relationship between cortisol abnormalities and ME/CFS symptomatology warrants further investigation to clarify pathophysiological mechanisms.
Remaining Questions
Does abnormal cortisol cause ME/CFS symptoms, or do chronic symptoms disrupt normal cortisol function?
Do cortisol abnormalities remain stable over time, or do they fluctuate with disease course?
What This Study Does Not Prove
This study does not prove that low or abnormal cortisol *causes* ME/CFS or its symptoms—only that they are associated. The cross-sectional design cannot determine whether cortisol abnormalities precede illness onset or develop as a consequence of it. The findings describe correlation, not causation, and may not apply to all ME/CFS patients.