Maes, Michael, Twisk, Frank N M, Johnson, Cort · Psychiatry research · 2012 · DOI
This study looked at whether ME, CFS, and chronic fatigue are truly different conditions or if they overlap too much to distinguish. Researchers tested 144 patients and found that post-exertional malaise (PEM)—where symptoms worsen after activity—is a key feature that separates ME from CFS. They also found that ME and CFS patients had higher levels of certain inflammatory markers in their blood compared to people with simple chronic fatigue.
This research addresses the longstanding diagnostic confusion between ME, CFS, and CF by providing evidence that PEM is a reliable biological and clinical marker distinguishing ME from CFS. If validated in larger studies, these findings could improve diagnostic accuracy and ensure appropriate patient classification for future research and treatment strategies.
This study does not prove that these inflammatory markers cause ME or CFS—only that they associate with these diagnoses. The cross-sectional design cannot establish causation or temporal relationships. Results need replication in larger, independent populations before changing diagnostic guidelines.
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
Maes, Michael, Twisk, Frank N M, & Johnson, Cort (2012). Myalgic Encephalomyelitis (ME), Chronic Fatigue Syndrome (CFS), and Chronic Fatigue (CF) are distinguished accurately: results of supervised learning techniques applied on clinical and inflammatory data.. Psychiatry research. https://doi.org/10.1016/j.psychres.2012.03.031
BibTeX
@article{mecfsatlas-maes-2012-myalgic-encephalomyelitis,
author = {Maes, Michael and Twisk, Frank N M and Johnson, Cort},
title = {Myalgic Encephalomyelitis (ME), Chronic Fatigue Syndrome (CFS), and Chronic Fatigue (CF) are distinguished accurately: results of supervised learning techniques applied on clinical and inflammatory data.},
journal = {Psychiatry research},
year = {2012},
doi = {10.1016/j.psychres.2012.03.031},
note = {PubMed: 22521895},
url = {https://www.mecfsatlas.com/evidence/maes-2012-myalgic-encephalomyelitis},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/maes-2012-myalgic-encephalomyelitis
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