Unstimulated cortisol secretory activity in everyday life and its relationship with fatigue and chronic fatigue syndrome: a systematic review and subset meta-analysis. — CFSMEATLAS
Unstimulated cortisol secretory activity in everyday life and its relationship with fatigue and chronic fatigue syndrome: a systematic review and subset meta-analysis.
Powell, Daniel J H, Liossi, Christina, Moss-Morris, Rona et al. · Psychoneuroendocrinology · 2013 · DOI
Quick Summary
This review looked at whether cortisol levels (a stress hormone) measured in saliva throughout the day are different in people with ME/CFS compared to healthy controls. Researchers found that people with ME/CFS showed a slightly smaller increase in cortisol when they first wake up, compared to healthy people. However, total cortisol levels during the day were not consistently related to how fatigued people felt.
Why It Matters
Understanding how the stress hormone system functions in ME/CFS could help explain why patients experience persistent fatigue and may guide development of targeted treatments. This review synthesizes evidence about a key biological system and identifies which cortisol measurements are most relevant to fatigue, directing future research priorities.
Observed Findings
Meta-analysis showed a small but statistically significant reduction in cortisol awakening response increase in CFS patients compared to healthy controls
Total cortisol output (combined measure across the day) was rarely associated with fatigue in any population studied
Cortisl awakening response increase and diurnal cortisol slope (rate of decline through the day) were the markers most frequently associated with fatigue across studies
There was considerable heterogeneity among included studies in methodology and outcome reporting
Inferred Conclusions
HPA axis dysfunction in CFS may be reflected more clearly in dynamic changes within the day rather than total hormone output
Future CFS research should prioritize measurement of within-day cortisol changes rather than total output
The relationship between cortisol patterns and fatigue warrants continued investigation with more standardized methodologies
Remaining Questions
Why is the cortisol awakening response attenuated in CFS, and what does this reveal about the underlying biological mechanism?
Does the modest correlation between cortisol dynamics and fatigue represent a causal relationship, or are both markers of a separate underlying process?
What This Study Does Not Prove
This study does not prove that abnormal cortisol patterns cause ME/CFS or fatigue—only that associations exist. The findings are correlational and modest in effect size; the small number of studies and heterogeneity in methods mean conclusions should be considered preliminary. This review cannot establish whether correcting cortisol patterns would improve fatigue.