This was one of the brain imaging studies.ClinicalCentral fear circuits less activated in IBS patientsSAN DIEGO, CA, May 22 (Reuters Health) - The threat of visceral discomfort appears to evokean emotional rather than fearful response in patients with irritable bowel syndrome (IBS),researchers report at the annual Digestive Disease Week meetings held here.Dr. Bruce D. Naliboff, of UCLA Medical Center, in Los Angeles, with colleagues there and atUC Irvine Medical Center, performed a PET study of 12 IBS patients and 12 controls to examinethe brain response associated with the fear of anticipated visceral discomfort.Brain scans were obtained on all subjects at baseline, during moderate rectal distension andduring expected but undelivered noxious distension. "Although we know that IBS is exacerbatedby stress, we conducted this study to learn more about the connection between the disease andbrain function," Dr. Naliboff said in an interview with Reuters Health.Brain scans showed that controls had "greater baseline activity in mid anterior cingulate cortex(ACC), and greater activation in the perigenual mid ACC, lateral prefrontal cortex, thalamus,periaqueductal grey and medullary regions" than did IBS patients.During visceral stimulation, "IBS patients showed greater activation in mid anterior cingulatecortex as well as posterior cingulate," compared with controls, the researchers note.They found that expected but undelivered rectal discomfort activated the central fear circuits inthe controls. IBS patients showed "less activation of the fear circuits but greater activity inposterior cingulate cortex.""Our findings indicate that the parts of the brain that respond in IBS patients are the same parts ofthe brain involved in processing emotionally charged information," Dr. Naliboff said. "Thesedata give us a better understanding of this stress-related disorder and may provide informationabout potential new medication targets," he explained."This brain imaging study is one of a series examining IBS, dyspepsia and fibromyalgia," Dr.Naliboff added.-Westport Newsroom 203 319 2700