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The effect of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) severity on cellular bioenergetic function.
Tomas, Cara, Elson, Joanna L, Strassheim, Victoria et al. · PloS one · 2020 · DOI
Quick Summary
This study looked at how well the energy-producing parts of cells (mitochondria) work in people with ME/CFS compared to healthy people. Researchers found that both people with moderate and severe ME/CFS had problems with how their cells produce energy, but severely affected patients had additional problems with how their cells break down glucose for energy. This suggests that severe ME/CFS involves more widespread energy problems than moderate ME/CFS.
Why It Matters
This research provides cellular-level evidence that ME/CFS involves real, measurable abnormalities in how cells produce energy—findings that help validate patients' experiences of profound fatigue and suggest different disease mechanisms operate in moderate versus severe cases. Understanding these bioenergetic differences could eventually inform treatment strategies tailored to disease severity.
Observed Findings
Both moderate and severely affected ME/CFS patients showed reduced mitochondrial function compared to healthy controls, independent of disease severity.
Severely affected patients demonstrated higher rates of respiratory acidification than moderately affected patients and controls.
Severely affected patients had reduced glycolytic rates compared to moderately affected patients and healthy controls.
ATP-linked respiration rates were lower in both ME/CFS cohorts compared to healthy controls.
Disease severity correlated with glycolytic impairment but not with mitochondrial dysfunction alone.
Inferred Conclusions
Mitochondrial dysfunction is a consistent feature of ME/CFS regardless of disease severity, suggesting it is a fundamental cellular abnormality in the condition.
Severe ME/CFS involves compounded bioenergetic defects (both mitochondrial and glycolytic), whereas moderate ME/CFS primarily involves mitochondrial impairment.
The additional glycolytic dysfunction in severely affected patients may explain their more severe clinical phenotype.
Respiratory acidification must be accounted for in bioenergetic analyses to accurately assess glycolytic parameters in ME/CFS.
Remaining Questions
What This Study Does Not Prove
This study does not prove that mitochondrial dysfunction causes ME/CFS symptoms or that correcting these abnormalities will improve patient outcomes. It also does not establish whether the observed bioenergetic changes are primary disease drivers or secondary consequences, nor does it clarify how PBMC dysfunction relates to symptoms in other tissues.
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 →
Does the bioenergetic dysfunction observed in PBMCs reflect broader systemic energy metabolism abnormalities in other tissues affected by ME/CFS?
Are the observed mitochondrial and glycolytic impairments reversible, and could therapies targeting these pathways improve symptoms?
What mechanisms cause the transition from mitochondrial-only dysfunction in moderate disease to combined mitochondrial and glycolytic dysfunction in severe disease?
How do these cellular bioenergetic abnormalities relate causally to specific ME/CFS symptoms such as post-exertional malaise and cognitive dysfunction?