Stress-Mediated Widespread Hypersensitivity in People with Irritable Bowel Syndrome: A Psychosomatic Approach

Abstract

Irritable bowel syndrome (IBS) is a functional disorder with no clear organic pathology. Psychosocial factors, particularly stress, have been implicated in the aetiology and presentation. The biopsychosocial model of IBS demonstrates how psychosomatic processes occur along the braingut axis. It also provides a foundation for understanding how alterations to the brain-gut axis can evoke psychosomatic processes that underpin IBS. Research has identified how stress-mediated changes along the brain-gut axis are associated with visceral hypersensitivity in IBS. Other research has also demonstrated the presence of hypersensitivity in somatic structures. The aim of this study was to demonstrate stress-mediated effects on widespread hypersensitivity in a somatic structure. Impaired conditioned pain modulation, which may also exhibit stress-mediated effects, was also explored. The study sample comprised the IBS group which included 16 females aged 19 to 50 (M = 29.47, SD = 8.55) and the control group which included 20 females aged 18 to 55 (M = 28.24, SD = 12.08). The first stage of the method was a series of electric shocks to the forearm, with the addition of a cold pack to the contralateral forearm to test for conditioned pain modulation. Participants then completed a version of the Trier Social Stress Test. The third stage was a repeat of Stage One. Participants intermittently provided ratings of pain unpleasantness, pain intensity and stress. Heart rate was monitored continually. A series of mixed ANOVAS were used for statistical analysis. For stress-mediated hypersensitivity, there were no significant group differences for significant for pain unpleasantness ratings, F(1, 31) = 1.35, p = .254. However, they were marginally significant for pain intensity ratings, F(1, 32) = 4.06, p = .052, where IBS participants rated the pain slightly higher. There were no group differences in conditioned pain modulation both before, F(1, 33) = 1.45, p = .237 and after, F(1,23) = 3.42, p = .074 the Trier Social Stress Test. This study demonstrates some rudimentary evidence for IBS sufferers experiencing stress-mediated widespread hypersensitivity. Further research with interdisciplinary study designs such as this one are encouraged to continue to elucidate the psychosomatic aetiology and presentation of IBS.