Abstract
Irritable bowel syndrome (IBS) is a common yet poorly understood functional bowel disorder. A multi-factorial aetiology has been proposed, and abnormalities in colonic motility, small bowel motility and visceral sensation have been observed experimentally. More recently, attention has turned to a quite distinct abnormality, namely psychological function. Studies have shown that for a significant proportion of the IBS population, co-morbid psychiatric disturbance may be aetiopathological, with the physical abnormalities described occurring in response to stress or anxiety induced experimentally. Others have suggested that psychological distress may occur as a result of severe gastrointestinal symptoms, and that psychosocial factors may be related to the presentation rather than genesis of the symptoms. Many of these studies contain methodological inadequacies which may adversely affect the results obtained. Comparison between studies, which may provide further insight, is often difficult due to inconsistencies in the experimental protocol and the non-standard ways in which data have been presented. It is likely, however, that differences between methodologies may, in part, explain the variations in results between studies.