Wessely, S, Nimnuan, C, Sharpe, M · Lancet (London, England) · 1999 · DOI
This study looked at several long-term illnesses that cause many physical symptoms but don't show obvious damage on standard medical tests, including ME/CFS and irritable bowel syndrome. The researchers found that these conditions have much more in common with each other than previously thought—they affect similar types of patients, cause overlapping symptoms, and respond to treatment in similar ways. Rather than treating each condition as completely separate, the authors suggest doctors and researchers should think of them as related conditions on a spectrum.
This study challenges the conventional approach of treating ME/CFS as an isolated condition and suggests it shares fundamental features with other functional somatic syndromes. Understanding these connections may help researchers identify common underlying mechanisms and could improve treatment strategies by learning from research across related conditions.
This review does not establish the cause of ME/CFS or related syndromes, nor does it prove that a dimensional model would be clinically superior to current diagnostic criteria. It also does not demonstrate that all patients with different functional syndromes are phenotypically identical or interchangeable in treatment response. The overlaps described do not establish whether they share common biological pathways.
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 →
Spotted an error in this entry? Report it →