Psychological stress increases visceral sensitivity in patients with irritable bowel syndrome (IBS) but not controls

Abstract

BACKGROUND: Psychological stress has been shown to increase IBS symptoms. During laboratory stress, 18S patients show greater emotional and rectosigmoid motor responses than healthy controls. AIM: To characterize the effect of experimentally induced psychological stress on perceptual sensitivity and emotional responses to rectal balloon distention in patients with IBS and controls. METHOOS: 12 healthy controls (TM, mean age 34.5+_9.5, range 2150) and 12 diarrhea predominant .IBS patients (4M, mean 39.2+_0.7, range 24-52) were studied during two laboratory sessions, 1 week apart. Subjects were randomized to receive either the stress or the control condition on Session 1 and crossed over to the other condition on Session 2 of the study. The stress condition entailed dichotomous listening to 2 conflicting types of music delivered simultaneously via separate headphone channels. Relaxation entailed listening to natural sounds. The stress and relaxation auditory stimuli were delivered over a 10 rain listening period preceding the rectal distention period, and during the rectal distentions but not during the distention rating periods. Validated verbal descriptor anchored visual analog scales were used to assess the severity of the sensations of unpleasantness and intensity. Stress Symptom Rating scales (SSR) were used to assess the emotional response to distention. Controlled visceral distention was performed using a rectal balloon catheter connected to an electronic distention device. Results: The IBS group scored significantly higher on SSR scales of stress, anxiety and anger during stress compared to relaxation (p< 0.05). Overall, IBS patients but not controls showed increased unpleasantness ratings of the rectal stimuli during the stress compared to control condition. These were significant for the highest stimulus level (45mmHg, p=0.035). There was a significant correlation between anxiety (p=O.02), anger (p = 0.02) and stress (p = 0.03) and sensory ratings of the 45mmHg distention during psychological stress for the IBS group but not for controls. CONCLUSION: IBS subjects had a stronger emotional response to acute psychological stress combined with visceral stimulation when compared to controls. As predicted the stressor led to increased visceral sensitivity in IBS. The results support an important role for central stress responses in the modulation of visceral sensation in 18S. Supported by NIH grants NR04881 (BDN), DK48351 (EAM), and funds from AstraZeneca R&D