Milovanovic, Branislav, Markovic, Nikola, Petrovic, Masa et al. · Diagnostics (Basel, Switzerland) · 2025 · DOI
This study examined how the nervous system functions differently in people with POTS (a condition causing rapid heart rate when standing) who also have fainting episodes, ME/CFS, or post-COVID illness. Researchers used heart rate monitors, tilt tests, and breathing exercises to measure how well the autonomic nervous system—which controls heart rate and blood pressure—works in each group. They found that POTS appears differently depending on what condition causes it: in syncope patients it involves sympathetic overdrive, while in ME/CFS patients it involves parasympathetic weakness.
This study demonstrates that ME/CFS patients with POTS experience a distinct pattern of autonomic dysfunction—specifically parasympathetic impairment—that differs from syncope-related POTS, suggesting that treatment approaches should be tailored to the underlying cause. Understanding these autonomic profiles may help clinicians better recognize and manage dysautonomia in ME/CFS and post-COVID populations, potentially improving symptom management and diagnostic accuracy.
This study does not establish causation—it only describes associations between disease type and autonomic patterns observed during testing. The cross-sectional design cannot determine whether parasympathetic dysfunction causes or results from ME/CFS, nor can it explain the biological mechanisms driving these differences. Additionally, the small sample size and modest POTS prevalence limit generalizability to broader ME/CFS populations.
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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