Brown, Molly M, Jason, Leonard A · Dynamic medicine : DM · 2007 · DOI
This study looked at 114 people with ME/CFS to see how often they also had fibromyalgia or multiple chemical sensitivity, and whether having more than one condition made their symptoms worse. The researchers found that about 44% had ME/CFS alone, while others had it combined with one or both of the other conditions. People with all three conditions were the most disabled and had the hardest time with daily activities compared to those with ME/CFS alone.
This study provides evidence that ME/CFS patients with co-occurring fibromyalgia and chemical sensitivity experience substantially greater disability than those with ME/CFS alone, validating the clinical experience of many patients with multiple diagnoses. Understanding this additive effect of comorbidities is important for treatment planning and rehabilitation strategies tailored to patients' actual burden of illness.
This study does not prove that MCS and FM cause additional disability in ME/CFS, only that they are associated with worse outcomes. The cross-sectional design means we cannot determine whether having multiple conditions causes worse functioning, or whether more severe baseline illness predisposes people to additional diagnoses. The study also does not establish whether CFS, MCS, and FM are truly separate diseases or manifestations of one underlying condition.
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
Brown, Molly M & Jason, Leonard A (2007). Functioning in individuals with chronic fatigue syndrome: increased impairment with co-occurring multiple chemical sensitivity and fibromyalgia.. Dynamic medicine : DM. https://doi.org/10.1186/1476-5918-6-6
BibTeX
@article{mecfsatlas-brown-2007-functioning-individuals,
author = {Brown, Molly M and Jason, Leonard A},
title = {Functioning in individuals with chronic fatigue syndrome: increased impairment with co-occurring multiple chemical sensitivity and fibromyalgia.},
journal = {Dynamic medicine : DM},
year = {2007},
doi = {10.1186/1476-5918-6-6},
note = {PubMed: 17540028},
url = {https://www.mecfsatlas.com/evidence/brown-2007-functioning-individuals},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/brown-2007-functioning-individuals
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