Dr. Emeran Mayer of the David Geffen School of Medicine at University of California, Dr. Douglas Drossman and Dr. Yehuda Ringel both at the University of North Carolina at Chapel Hill said that the women with the history of abuse may have a heightened brain response to pain that makes them more sensitive to abdominal discomfort.

The researchers used brain imaging to show that patients with IBS who also had a background of abuse weren't as able to turn off a pain modulation mechanism in the brain as effectively as were IBS patients who hadn't suffered abuse.

Previous studies showed more than 50 percent of patients with IBS have been physically or sexually abused at some time in their lives.

The findings, published online in the journal Gastroenterology, may help explain why those in this subset of IBS patients experience greater pain and poorer health outcomes than others with the disorder.