Milovanovic, Branislav, Markovic, Nikola, Petrovic, Masa et al. · Journal of clinical medicine · 2025 · DOI
This study examined how the autonomic nervous system (the part that controls heart rate, blood pressure, and other automatic functions) works differently in people with ME/CFS compared to healthy people. Researchers tested 440 people, including those with ME/CFS from unknown causes and those whose ME/CFS developed after COVID-19, using heart and blood pressure monitoring tests. They found that both ME/CFS groups had significant problems with autonomic function and experienced fainting or near-fainting episodes at high rates, though the post-COVID group showed somewhat different patterns.
This study provides objective physiological evidence that autonomic dysfunction is a core feature of ME/CFS regardless of cause, which validates patient experiences of fainting and orthostatic symptoms. The identification of distinct hemodynamic patterns in post-COVID ME/CFS may help explain why these patients sometimes present differently and could inform future targeted treatments. These findings strengthen the case for autonomic dysfunction testing as a diagnostic tool in ME/CFS evaluation.
This study does not prove that autonomic dysfunction causes ME/CFS—only that it is associated with the condition; the direction of causation remains unclear. It does not establish whether the observed autonomic abnormalities persist long-term or respond to treatment, as it is a single-timepoint cross-sectional design. The study cannot determine whether autonomic testing should replace or supplement existing ME/CFS diagnostic criteria.
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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