Freeman, R, Komaroff, A L · The American journal of medicine · 1997 · DOI
This study tested whether ME/CFS patients have problems with their autonomic nervous system—the part of the nervous system that controls automatic functions like heart rate and blood pressure. Researchers found that ME/CFS patients had abnormal heart rate and blood pressure responses during standing and tilting tests, and their nervous system wasn't regulating these responses properly. The findings suggest that either deconditioning from reduced activity, a viral infection damaging the nervous system, or both could explain why many ME/CFS patients feel dizzy or faint when standing up.
This study provides objective physiological evidence that autonomic nervous system dysfunction is a real biological feature of ME/CFS, not a psychological artifact. Understanding these abnormalities helps explain debilitating symptoms like orthostatic intolerance and offers a potential window into disease mechanisms, which could guide future diagnostic testing and treatment development.
This study does not prove that autonomic dysfunction causes ME/CFS or that it is the primary disease mechanism. The cross-sectional design cannot establish whether autonomic abnormalities are primary pathology or secondary to deconditioning and inactivity. The study also does not establish whether autonomic dysfunction is present in all ME/CFS patients or if it is a subgroup feature.
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 →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Freeman, R & Komaroff, A L (1997). Does the chronic fatigue syndrome involve the autonomic nervous system?. The American journal of medicine. https://doi.org/10.1016/s0002-9343(97)00087-9
BibTeX
@article{mecfsatlas-freeman-1997-does-chronic,
author = {Freeman, R and Komaroff, A L},
title = {Does the chronic fatigue syndrome involve the autonomic nervous system?},
journal = {The American journal of medicine},
year = {1997},
doi = {10.1016/s0002-9343(97)00087-9},
note = {PubMed: 9217617},
url = {https://www.mecfsatlas.com/evidence/freeman-1997-does-chronic},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-27. https://www.mecfsatlas.com/evidence/freeman-1997-does-chronic
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