The role of hypocortisolism in chronic fatigue syndrome.
Nijhof, Sanne L, Rutten, Juliette M T M, Uiterwaal, Cuno S P M et al. · Psychoneuroendocrinology · 2014 · DOI
Quick Summary
This study looked at stress hormone levels (cortisol) in adolescents with ME/CFS by measuring saliva samples. Teenagers with ME/CFS had lower cortisol levels than healthy peers, and those who improved with treatment showed their cortisol levels normalize, while those who didn't recover showed little change. The findings suggest that restoration of normal cortisol production during treatment may be linked to better outcomes.
Why It Matters
This is the first study examining HPA axis dysfunction in adolescent ME/CFS, expanding understanding beyond adults. The finding that cortisol normalization—rather than baseline levels—predicts treatment success may help identify which adolescents are likely to benefit from specific interventions and could inform personalized treatment strategies.
Observed Findings
CFS patients had significantly lower pre-treatment salivary cortisol awakening response compared to healthy controls.
Recovered CFS patients showed significant rises in cortisol output that reached normal levels after 6 months of treatment.
Non-recovered CFS patients showed only slight, non-significant improvements in cortisol levels.
Each standard deviation increase in pre- to post-treatment cortisol change was associated with 93% higher odds of recovery.
Hypocortisolism was significantly correlated with reduced sleep quantity in CFS patients.
Inferred Conclusions
Hypocortisolism is a biological feature associated with adolescent ME/CFS.
Normalization of cortisol during treatment, not baseline cortisol levels, is associated with clinical recovery.
HPA axis restoration may be an important component of successful treatment outcomes in adolescent CFS.
These findings suggest future treatment strategies should monitor and potentially target HPA axis recovery.
Remaining Questions
Does HPA axis recovery actually *cause* clinical improvement, or is it simply a biomarker of broader recovery?
What This Study Does Not Prove
This study does not establish that low cortisol *causes* ME/CFS or that restoring cortisol is the mechanism of recovery; it only shows an association. The study also cannot determine whether cortisol changes are a primary driver of recovery or a marker of broader physiological normalization. Results are limited to adolescents and may not generalize to adults with ME/CFS.
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 →