Michiels, V, Cluydts, R, Fischler, B et al. · Journal of clinical and experimental neuropsychology · 1996 · DOI
This study found that people with ME/CFS performed worse than healthy controls on thinking and memory tests. Patients showed slower processing speed, difficulty concentrating, and trouble learning and remembering new information. However, the researchers noted that cognitive problems varied widely between patients, so not everyone with ME/CFS experiences the same level of difficulty.
This research provides objective neuropsychological evidence of cognitive dysfunction in ME/CFS, validating patient reports of 'brain fog' and concentration problems. Understanding which specific cognitive domains are affected helps clinicians assess patients and supports efforts to recognize ME/CFS as a neurobiological condition rather than purely psychological.
This study cannot determine whether cognitive impairment is caused by ME/CFS pathology, is secondary to fatigue or other symptoms, or reflects pre-existing differences. The cross-sectional design prevents investigation of whether cognitive problems improve or worsen over time, or their relationship to disease progression.
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
Michiels, V, Cluydts, R, Fischler, B, Hoffmann, G, Le Bon, O, & De Meirleir, K (1996). Cognitive functioning in patients with chronic fatigue syndrome.. Journal of clinical and experimental neuropsychology. https://doi.org/10.1080/01688639608408290
BibTeX
@article{mecfsatlas-michiels-1996-cognitive-functioning,
author = {Michiels, V and Cluydts, R and Fischler, B and Hoffmann, G and Le Bon, O and De Meirleir, K},
title = {Cognitive functioning in patients with chronic fatigue syndrome.},
journal = {Journal of clinical and experimental neuropsychology},
year = {1996},
doi = {10.1080/01688639608408290},
note = {PubMed: 8941852},
url = {https://www.mecfsatlas.com/evidence/michiels-1996-cognitive-functioning},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/michiels-1996-cognitive-functioning
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