Changes in certain regions of the brain in female patients have been observed in a study that states these changes occur as a result of irritable bowel syndrome (IBS).
The findings show that IBS is associated with both decreases and increases in grey matter density in key areas of the brain involved in attention, emotion regulation, pain inhibition and the processing of visceral information.
These study findings show actual structural changes to the brain, which places IBS in the category of other pain disorders, such as lower back pain, temporomandibular joint disorder, migraines and hip pain - conditions in which some of the same anatomical brain changes have been observed, as well as other changes.
"Discovering 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," said Dr. Emeran Mayer of University of California, Los Angeles (UCLA).
"Also, 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," he said.
Researchers employed imaging techniques to examine and analyze brain anatomical differences between 55 female IBS patients and 48 female control subjects. Patients had moderate IBS severity, with disease duration from one to 34 years (average 11 years).
The average age of the participants was 31.
"The grey-matter changes in the posterior insula are particularly interesting since they may play a role in central pain amplification for IBS patients," said David A. Seminowicz, of McGill University.
"This 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," he said.
Decreases in grey matter in IBS patients occurred in several regions involved in attentional brain processes, which decide what the body should pay attention to.
The thalamus and midbrain also showed reductions, including a region - the periaqueductal grey - that plays a major role in suppressing pain.
"Reductions of grey matter in these key areas may demonstrate an inability of the brain to effectively inhibit pain responses," Seminowicz said.
The observed decreases in brain grey matter were consistent across IBS patient sub-groups, such as those experiencing more diarrhea-like symptoms than constipation.
"We noticed that the structural brain changes varied between patients who characterized their symptoms primarily as pain, rather than non-painful discomfort," said Mayer, director of the UCLA.
"In contrast, the length of time a patient has had IBS was not related to these structural brain changes," he added.
The study appeared in the journal Gastroenterology.