Scott, L V, Dinan, T G · Journal of affective disorders · 1998 · DOI
This study measured a stress hormone called cortisol in urine samples from people with ME/CFS, people with depression, and healthy individuals. The researchers found that people with ME/CFS had lower cortisol levels than healthy people, while people with depression had higher levels. This suggests that ME/CFS and depression affect the body's stress response system in opposite ways.
This study provides biological evidence that ME/CFS involves a different mechanism than depression, despite overlapping symptoms like fatigue and low mood. Understanding that ME/CFS involves HPA axis hypoactivity (low cortisol) rather than hyperactivity may help guide more targeted treatment approaches and validates ME/CFS as a distinct condition from depression.
This study does not prove that low cortisol causes ME/CFS symptoms, only that an association exists. It cannot explain why the HPA axis becomes underactive in ME/CFS or whether this is a primary cause or secondary consequence of the illness. The small sample size and cross-sectional design limit generalizability and cannot establish causality.
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 →
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