The role of psychological and biological factors in postinfective gut dysfunction

Background-Both psychological and physiological disturbances have been impl icated in the aetiopathogenesis of irritable bowel syndrome (IBS). Aims-To investigate how the psychological factors act, and the involvement of infective and physiological factors. Methods-Consecutive patients hospitalised for gastroenteritis reported life events for the previous 12 months, and past illness experiences on standar dised questionnaires. They also completed psychometric questionnaires for a nxiety, neuroticism, somatisation, and hypochondriasis. In some patients, r ectal biopsy specimens were obtained during the acute illness and at three months postinfection. Results-Ninety four patients completed all questionnaires: 22 patients were diagnosed with IBS after their gastroenteritis (IBS+), and 72 patients ret urned to normal bowel habits (IBS-). IBS+ patients reported more life event s and had higher hypochondriasis scores than IBS- patients. The predictive value of the life event and hypochondriasis measures was highly significant and independent of anxiety, neuroticism, and somatisation scores, which we re also elevated in IBS+ patients. Rectal biopsy specimens from 29 patients showed a chronic inflammatory response in both IBS+ and IBS- patients. Thr ee months later, specimens from IBS+ patients continued to show increased c hronic inflammatory cell counts but those from IBS- patients had returned t o normal levels, IBS+ and IBS- patients exhibited rectal hypersensitivity a nd hyper-reactivity and rapid colonic transit compared with normal controls , but there were no significant differences between IBS+ and IBS- patients for these physiological measurements. Conclusion-Psychological factors most clearly predict the development of IB S symptoms after gastroenteritis but biological mechanisms also contribute towards the expression of symptoms.