2. It’s not all in the gut
For years, IBS was called a functional disorder, meaning that while the body’s normal activities are impaired, medical tools don't pick up any structural abnormalities. This description made treatment challenging — how to treat something you can’t detect? — and was frustrating to some patients, said Kendra Kamp, an assistant professor of nursing at the University of Washington.
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“Some of them felt overlooked by the health care community,” explained Kamp, the author of numerous papers on IBS and other gut disorders. “It’s like, you have this label of IBS and that means we don’t know what to do with you.”
But science is getting closer to understanding the reasons why people feel gut pain and discomfort, absent traditional markers of disease, and it turns out the brain may play a role. Researchers have begun to examine how the central nervous system (the spinal cord and the brain) communicates with the enteric nervous system, which controls the digestive system. Their findings indicate that when the gut is irritated, the brain hears about it.
“We think in all [IBS] patients there’s some degree of disordered function in this gut-brain network,” said Greg Sayuk, M.D., a Washington University School of Medicine professor who studies IBS.
A few years ago IBS was renamed a disorder of brain-gut interaction, or DBGI — a reflection of a more nuanced understanding of this issue. Researchers, for example, now routinely look at how the brain and the digestive organs interact with all the fungi, bacteria and viruses living in the body, known as the microbiome.
"We are now relearning that they are integrated; that it’s not brain or gut, but it’s both, and that they are communicating," Kamp said.
The brain-gut connection is one reason why some IBS patients turn to behavioral medicine techniques to help manage their symptoms — but more on this later.
3. Women are more likely to suffer from IBS than men
IBS can plague people of any age, but symptoms typically appear for the first time before age 50, Shah said. And for women — who are up to two times more likely than men to develop IBS — rates start to tick up once puberty hits, begging the question of how IBS might be related to sex hormones, Kamp said.
One recent study found that IBS pain is more severe in postmenopausal females than in either men or menstruating women. Lin Chang, M.D., a gastroenterologist at University of California, Los Angeles and coauthor on the study, is now conducting federally funded research comparing the brain-gut-microbiome interactions in premenopausal versus postmenopausal women. The researchers’ hypothesis, she said, is that when estrogen levels dip (as they do in menopause, as well as during various points in the menstrual cycle), that leads to greater dysregulation of brain-gut interactions, affecting the microbiome. This in turn could lead to bloating, pain, changes in the stool or stool frequency — basically, an increase in IBS symptoms for those who already suffer from it.