quote: OBJECTIVE: Disease severity in the irritable bowel syndrome (IBS) is highly influenced by psychiatric comorbidity. The mechanism of this influence is generally unknown, even if the brain-gut axis seems to be involved. Recent research has indicated that IBS patients have aberrant perception of visceral stimuli in the CNS. We compared IBS patients with and without comorbid phobic anxiety to see if the comorbid disorder influenced brain information processing of auditory stimuli, and looked for possible consequences with respect to visceral sensitivity thresholds and disease severity. CONCLUSIONS: The study suggests an association between information processing in the frontal brain and visceral sensitivity characteristics in IBS patients, and indicates that subjective disease-related symptomatology is predicted by brain perceptual characteristics. The findings indicate that an interaction between IBS-related and anxiety-related hyperreactivity in the frontal brain may constitute a psychophysiological mechanism for the contribution of psychiatric comorbidity to severity and duration of the irritable bowel syndrome.