Patients with irritable bowel syndrome (IBS) process pain signals from the gut abnormally, according to new research. These disturbed brain responses to pain are especially severe in patients with more depression symptoms.
“Our study has shown that patients with IBS are less able to suppress pain signals in the brain coming from the bowel and that depression plays a role herein,” said Professor Sigrid Elsenbruch from the University of Duisburg-Essen in Germany.
“This study confirms the complex relationship between the gut and the brain and shows that affective disorders may contribute to the development or maintenance of disturbed pain processing in IBS.”
The research will be presented at the 22nd United European Gastroenterology Week in Vienna. The findings suggest that depression, but not anxiety, contributes to the abnormal pain processing observed in IBS.
Depression and anxiety are often reported in patients with IBS, with a recent study reporting that 38 percent of IBS patients had clinically-confirmed depression (compared with six percent of healthy controls) and 32 percent had anxiety (compared with 13 percent of healthy controls).
“The fact that so many people with IBS have anxiety and depression has led many to speculate that IBS is primarily a psychological, not a physical, disorder,” said Elsenbruch.
“However, the condition is complex and most likely results from an interplay between psychological and biological factors.
“In fact, we don’t really know whether anxiety and depression result from having IBS or whether they contribute to the development or maintenance of symptoms. In many patients, both possibilities may be true at the same time.”
There has been quite a bit of scientific interest in the role of central nervous system mechanisms along the “brain-gut” axis in IBS. Studies have found that neural processing of visceral stimuli (stimuli generated from internal organs such as the intestine) is altered in IBS, with many IBS patients showing lower pain thresholds.
For the study, rectal distensions were performed using a pressure-controlled barostat system on 17 IBS patients as well as on 17 sex- and age-matched healthy controls. Neural activation in pain-related brain areas was evaluated through functional MRI (fMRI).
Interestingly, higher depression (but not anxiety) scores on the Hospital Anxiety and Depression Scale (HADS) were associated with reduced central pain inhibition in this study.
“Our findings suggest that patients with IBS do not process visceral pain signals in the same way as healthy people and are unable to suppress pain signals in the brain and, as a result, experience more pain from the same stimuli,” said Elsenbruch.
“The fact that the presence of depression was associated with altered brain responses suggests that depression may contribute to these abnormal pain processes in IBS patients.”
Source: United European Gastroenterology