Ventricular cerebrospinal fluid lactate is increased in chronic fatigue syndrome compared with generalized anxiety disorder: an in vivo 3.0 T (1)H MRS imaging study. — ME/CFS Atlas
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Ventricular cerebrospinal fluid lactate is increased in chronic fatigue syndrome compared with generalized anxiety disorder: an in vivo 3.0 T (1)H MRS imaging study.
Mathew, Sanjay J, Mao, Xiangling, Keegan, Kathryn A et al. · NMR in biomedicine · 2009 · DOI
Quick Summary
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.
Why It Matters
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.
Observed Findings
Ventricular CSF lactate was increased 297% in CFS compared to GAD (p<0.001)
Ventricular CSF lactate was increased 348% in CFS compared to healthy controls (p<0.001)
Lateral ventricular volume did not differ significantly between groups
Diagnosis accounted for 43% of the variance in ventricular lactate concentrations
Elevated lactate in CFS remained significant even after controlling for ventricular volume
Inferred Conclusions
CFS is associated with significantly elevated ventricular lactate distinct from both anxiety disorders and normal physiology
The elevation may reflect decreased cerebral blood flow, mitochondrial dysfunction, and/or oxidative stress in CFS
Ventricular lactate could serve as a potential biomarker for differentiating CFS from neuropsychiatric conditions
Remaining Questions
Does ventricular lactate correlate with specific symptoms (fatigue severity, post-exertional malaise, cognitive dysfunction) or disease duration?
Does lactate normalize with effective treatment, or does it remain elevated independent of symptom improvement?
What This Study Does Not Prove
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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