Mathew, Sanjay J, Mao, Xiangling, Keegan, Kathryn A et al. · NMR in biomedicine · 2009 · DOI
Researchers used a specialized brain scan to measure a substance called lactate in the fluid surrounding the brain in people with ME/CFS, people with anxiety disorder, and healthy people. They found that people with ME/CFS had about three times more lactate in their brain fluid than the other groups, suggesting their brain cells may not be using energy efficiently.
This study provides objective neurochemical evidence that ME/CFS involves measurable brain metabolic abnormalities distinct from psychiatric conditions like anxiety, potentially supporting recognition of ME/CFS as a biological disorder rather than primarily psychological. Elevated lactate suggests cellular energy dysfunction in the brain, which could explain fatigue and cognitive symptoms that define the illness.
This study does not prove that elevated lactate *causes* ME/CFS symptoms or establish the direction of the relationship. It is a single cross-sectional measurement that does not track whether lactate levels change with treatment or symptom severity. The findings do not establish the mechanism—whether the cause is reduced blood flow, mitochondrial defects, or other factors.
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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