Feb. 19 (HealthDay News) -- Women with irritable bowel syndrome (IBS) who've suffered physical and/or sexual abuse may have a heightened brain response that makes them more sensitive to abdominal discomfort, a new study says.

Symptoms of IBS, which affects 10 percent to 15 percent of people in the United States, include gastrointestinal discomfort, diarrhea and constipation.

In this study, researchers from the University of California, Los Angeles, and the University of North Carolina used brain imaging to study female IBS patients and found that those with a background of abuse weren't able to switch off a pain modulation mechanism in the brain as effectively as those with no history of abuse.

The study was published in February's online edition of Gastroenterology.

Previous research has found that more than 50 percent of people with IBS have been physically or sexually abused at some point in their lives. The findings of this new study may help explain why this subset of IBS patients tend to suffer more pain and poorer health outcomes than other IBS patients.

The researchers said their study improves understanding of how IBS develops, and may help lead to new treatments.

SOURCE: University of California, Los Angeles, news release, February 2008