Enhanced preattentive central nervous system reactivity in irritable bowel syndrome

OBJECTIVE: Irritable bowel syndrome (IBS) is a common functional disorder characterized by enhanced perceptual sensitivity and hypervigilance toward afferent signals from the viscera. We hypothesize that the increased responsiveness of IBS patients is a generalized phenomenon applying to stimuli other than visceral and attempt to demonstrate increased responsiveness to sounds as measured by the P1 scalp potential. METHODS: Event-related potentials were recorded from IBS patients and control subjects in an auditory task requiring detection of rare pitch targets in a designated ear. Visual words served as targets in an additional block. RESULTS: Compared to control subjects, IBS patients displayed a robust increase in the amplitude of the P1 scalp potential elicited by both attended and unattended sounds. CONCLUSIONS: Enhanced P1 indicates preattentive central nervous system dishabituation in response to repeated sounds. A generalized preattentive increase in central nervous system reactivity may be a feature that IBS shares with several anxiety disorders that frequently co-occur in these patients.