Ciccone, Donald S, Natelson, Benjamin H · Psychosomatic medicine · 2003 · DOI
This study looked at 163 women with ME/CFS to see whether having other conditions like fibromyalgia or chemical sensitivities alongside ME/CFS made their illness different. About a third of the women had fibromyalgia, and another third had chemical sensitivities. The main finding was that women with multiple conditions were more likely to have depression than those with ME/CFS alone, but otherwise their symptoms and disability levels were fairly similar.
Understanding whether ME/CFS, fibromyalgia, and chemical sensitivities are variants of one condition or separate disorders affects how clinicians diagnose and treat patients. This study demonstrates that psychiatric comorbidity increases substantially with multiple unexplained syndromes, highlighting the need for comprehensive mental health screening in complex cases and informing whether unified or syndrome-specific treatment approaches may be more effective.
This cross-sectional study cannot establish causation—it does not prove whether depression causes comorbidity, comorbidity causes depression, or both share a common underlying biological mechanism. The study also uses retrospective diagnostic assignment and self-report questionnaires, which may introduce recall bias and cannot definitively rule out that the conditions are discrete disorders or that they represent a single process. These findings are specific to women and may not generalize to men with ME/CFS.
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
Ciccone, Donald S & Natelson, Benjamin H (2003). Comorbid illness in women with chronic fatigue syndrome: a test of the single syndrome hypothesis.. Psychosomatic medicine. https://doi.org/10.1097/01.psy.0000033125.08272.a9
BibTeX
@article{mecfsatlas-ciccone-2003-comorbid-illness,
author = {Ciccone, Donald S and Natelson, Benjamin H},
title = {Comorbid illness in women with chronic fatigue syndrome: a test of the single syndrome hypothesis.},
journal = {Psychosomatic medicine},
year = {2003},
doi = {10.1097/01.psy.0000033125.08272.a9},
note = {PubMed: 12651994},
url = {https://www.mecfsatlas.com/evidence/ciccone-2003-comorbid-illness},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/ciccone-2003-comorbid-illness
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