Chapter 29 Towards an integrative model of irritable bowel syndrome

Abstract

It is being increasingly recognized that a significant amount of human suffering, medical costs, and general loss of productivity can be attributed to what traditionally has been labeled “functional” medical disorders or syndromes. Symptoms of functional disorders may appear in almost any organ system and take a variety of forms, but most common are symptoms of pain, discomfort, and loss of vitality. Functional disorders are characterized by the lack of a detectable organ lesion to account for these symptoms, which can vary from mild and infrequent to severe, continuous, and disabling. Biobehavioral models of chronic medical conditions have as their goal the integration of cognitive, behavioral, and neuroscience perspectives. While it is generally accepted that all chronic and uncomfortable conditions can in theory, be better understood if a multifactor approach is taken, it is much more difficult to describe specifically the mechanisms by which cognitive, affective and sensory processes produce symptoms and complex behaviors such as disability. This chapter discusses the application of such an integrative approach to one common functional disorder, irritable bowel syndrome. This chapter: (a) briefly reviews evidence that links psychological, colonic motor activity, and visceral sensory processes individually with the development and maintenance of IBS symptoms, (b) describes the use of evolving human experimental paradigms to study visceral psychophysiology in IBS, (c) based on recent findings, presents a preliminary biobehavioral model of IBS, which integrates neurophysiological, perceptual, and behavioral processes, and (d) describes how psychological and physiological treatment approaches can be integrated into this model.