Rectal tone and brain information processing in irritable bowel syndrome.

We studied differences in rectal tone between healthy controls, nonpsychiatric irritable bowel syndrome (IBS) patients, and IBS patients with comorbid phobic anxiety disorders to assess the impact of psychiatric comorbidity on rectal tone. The groups were additionally compared with respect to brain information processing of everyday words with emotional content to see if we could identify an association between perception of emotional material in the brain and rectal tone. We found that both nonpsychiatric IBS patients and IBS patients with phobic anxiety disorder had increased baseline rectal tone compared with healthy controls (F = 9.81, P < 0.001). The phobic anxiety patients tended to have increased tone compared with nonpsychiatric IBS patients, but the difference did not reach statistical significance. Similar differences were found in the attentional elements of brain information processing activity assessed by event-related potentials. Rectal tone significantly predicted brain reactivity to emotional words, suggesting that changes in intestinal motor function may influence brain perception.