van Staden, Werdie C W · Current opinion in psychiatry · 2006 · DOI
This paper examines why it can be difficult to distinguish between two conditions that both cause severe tiredness: undifferentiated somatoform disorder (a condition where physical symptoms occur without clear medical causes) and ME/CFS. The author argues that a key difference may be how patients experience their fatigue—some describe it as purely physical rather than mental—and that this distinction has not been properly studied or recognized in ME/CFS research.
Clarifying how ME/CFS differs from other fatigue-related conditions is essential for accurate diagnosis and appropriate treatment. This paper highlights an overlooked aspect of how patients experience their illness—specifically the claim of 'purely physical' fatigue—which may affect how clinicians understand and validate ME/CFS symptoms. Better conceptual clarity could improve diagnostic accuracy and reduce misdiagnosis between overlapping conditions.
This conceptual review does not provide empirical data distinguishing ME/CFS from undifferentiated somatoform disorder. It does not establish causation or prevalence rates, nor does it validate the 'mindless fatigue' concept through patient studies or neurobiological evidence. The paper's philosophical argument about the impossibility of non-mental fatigue is debatable and may not reflect how patients and clinicians actually use these descriptors.
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
van Staden, Werdie C W (2006). Conceptual issues in undifferentiated somatoform disorder and chronic fatigue syndrome.. Current opinion in psychiatry. https://doi.org/10.1097/01.yco.0000245753.83502.d9
BibTeX
@article{mecfsatlas-van-staden-2006-conceptual-issues,
author = {van Staden, Werdie C W},
title = {Conceptual issues in undifferentiated somatoform disorder and chronic fatigue syndrome.},
journal = {Current opinion in psychiatry},
year = {2006},
doi = {10.1097/01.yco.0000245753.83502.d9},
note = {PubMed: 17012941},
url = {https://www.mecfsatlas.com/evidence/van-staden-2006-conceptual-issues},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/van-staden-2006-conceptual-issues
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