Brain Changes Found in Irritable Bowel Syndrome
Results of a new study strengthen the link between the brain and the bowels. Researchers found structural changes in certain brain regions in women who have irritable bowel syndrome.
Irritable bowel syndrome, a condition that affects as many as 20 percent of adults in the United States, is one of the most common disorders diagnosed by doctors, according to the National Institute of Diabetes and Digestive and Kidney Diseases. Women are affected more than men, and the syndrome typically first presents before the age of 35.
The abdominal pain, bloating, constipation, cramping, and diarrhea that characterize irritable bowel syndrome can be life-disrupting, making it difficult or even impossible for some people to work, travel, or attend social functions. Most people can control their symptoms with diet, medications, and stress management. The cause of the syndrome is unknown, although food allergy has been proposed as one possibility.
Irritable bowel syndrome has been considered to be a functional disorder rather than an organic one, as no one until now has found structural organ changes, specifically in the intestinal tract, associated with the syndrome. Researchers from the University of California, Los Angeles, and McGill University, however, discovered increases and decreases in gray matter density in certain areas of the brain of patients with irritable bowel syndrome that are associated with pain inhibition, emotion regulation, attention, and the processing of information on organ functioning.
The scientists made their discovery while using imaging techniques to evaluate brain structural differences between 55 females with irritable bowel syndrome and 48 healthy female controls. The patients had moderate disease and had had the syndrome for an average of 11 years.
After allowing for factors such as depression and anxiety, the researchers still found differences between the patients and controls in areas of the brain that are involved in cognitive and evaluative functions, including the area (viscerosensory cortex) that receives sensory information from the gastrointestinal tract.
Dr. Emeran Mayer, professor of medicine, physiology and psychiatry at the David Geffen School of Medicine at UCLA, and a study author, noted that their finding “supports the concept of a brain-gut disorder. He also pointed out that “the finding removes the idea once and for all that IBS symptoms are not real and are ‘only psychological.’ The findings will give us more insight into better understanding IBS.”
Researchers also uncovered changes in the brain that may have a role in intensifying pain in patients with irritable bowel syndrome, while also finding reductions in areas such as the thalamus and midbrain, which have a major role in suppressing pain. Study author David A. Seminowicz, PhD, of the Alan Edwards Centre for Research on Pain at McGill University said that “reductions in grey matter in these key areas may demonstrate an inability of the brain to effectively inhibit pain responses.”
Future studies will explore several areas of interest, including whether genes may be related to structural changes in the brain in patients with irritable bowel syndrome, and whether brain changes are a cause or consequence of having the syndrome.
National Institute of Diabetes and Digestive and Kidney Diseases
Seminowicz DA et al. Gastroenterology 2010 Jul; 139(1): 48-57