Functional somatic syndromes: 1 or many? Chronic Fatigue Syndrome research

We review the concept and importance of functional somatic
symptoms and syndromes such as irritable bowel syndrome and
chronic fatigue syndrome. On the basis of a literature review,
we conclude that a substantial overlap exists between the
individual syndromes and that the similarities between them
outweigh the differences. Similarities are apparent in case
definition, reported symptoms, and in non-symptom association
such as patients' sex, outlook, and response to treatment. We
conclude that the existing definitions of these syndromes in
terms of specific symptoms is of limited value; instead we
believe a dimensional classification is likely to be more
productive.

Wessely S, Nimnuan C, Sharpe M