Irritable bowel syndrome: classification and pathogenesis.

The irritable bowel syndrome (IBS), a chronic disorder of gut motility with a variable but continuous spectrum of clinical features, affects 15% of the population of developed countries. Its intestinal and extraintestinal symptoms arise principally from the global physiological changes that accompany emotional tension; but the advancing knowledge of neurohumoral control of gut motility has not yet revealed any features pathognomonic for IBS. Persons having IBS exhibit psychoneurotic traits in varying degree; and IBS patients (a minority of the whole) differ from nonpatients in having more severe life changes and in their learned illness behavior.