Irritable Bowel Syndrome (IBS) affects not only the intestines of its sufferers but may lead to measurable changes in their brains as well, according to new research. IBS is thought to affect up to 20% of the population – women suffer from it much more frequently than men – and is characterized by abdominal discomfort, pain, bloating, and constipation or diarrhea (or both).

The finding removes the idea once and for all that IBS symptoms are not real and are 'only psychological.'

Patients in the study filled out questionnaires about their IBS symptoms as well as their levels of depression and anxiety, which commonly accompany IBS. The participants – all women – suffered from IBS for an average of 11 years; healthy women served as controls. All participants also underwent brain scans (MRIs), so that the grey matter of various brain regions could be compared.

The researchers at UCLA and McGill University found that even after controlling for depression and anxiety, several key areas of the brain were different in IBS patients and controls. They found changes in the grey matter of the posterior insula, a part of the brain that receives sensory information from the intestines. Study author David A. Seminowicz says in a news release that "[t]his particular finding may point to a specific brain difference or abnormality that plays a role in heightening pain signals that reach the brain from the gut."

Another interesting result was that there were decreases in certain brain areas of the IBS patients, particularly in those that control attention and pain. This suggests that the brains of IBS patients may have trouble "deciding" what to pay attention to, and that their brains may not be able to "effectively inhibit pain responses," says Seminowicz.

The study's findings are noteworthy, since IBS had previously been considered a functional disorder, meaning that a patient's anatomy is normal, but the way it functions is not. Study author Emeran Mayer says that "[d]iscovering structural changes in the brain, whether they are primary or secondary to the gastrointestinal symptoms, demonstrates an 'organic' component to IBS and supports the concept of a brain-gut disorder." He also adds 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."

Next the team will work on trying to find genetic factors behind IBS, and will also include men in the study. As the authors also point out, it's still unclear whether these brain changes are the cause or the result of the problems with the gut – but hopefully more research will work to tease this apart.

The study was published in the July 2010 issue of Gastroenterology.