Understanding and Treating Irritable Bowel Syndrome


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“We all know that the mind plays a role in disease, but it cannot be studied scientifically.”

From the beginning of my medical career, I was interested in understanding how the brain and the mind interact with the body, and how a dysregulation in these interactions can result in a range of medical problems, from heart attacks to unexplained abdominal pain, and from asthma attacks to non-cardiac chest pain. When I tried to find a thesis advisor for my dissertation in medical school in the early 70s, I typically got the answer from the leading professors that “we all know that the mind plays a role in disease, but it cannot be studied scientifically”. Luckily, after 5 failed attempts, I found the right mentor at the Institute of Physiology at the University of Munich, and embarked on a 4-year period of studying the influence of the brain and specifically the sympathetic nervous system on blood flow to the different layers of the heart. Even though I switched my focus from the heart to the gut during my subsequent clinical training in gastroenterology, I never lost my keen interest in studying brain gut interactions.

Around 10% of the US population suffer from chronically recurring symptoms of abdominal pain, discomfort and altered bowel habits, which are the hallmark symptoms of IBS. Even though IBS is the quintessential disorder of brain gut interactions, it has only been very recent that experts of the largest professional IBS organization, the ROME Foundation, came to agree on this definition.

“IBS is a disorder of neurotic housewives.”

What I experienced during these 50 years could fill a whole book with entertaining anecdotes, hard-to-believe statements by leading IBS authorities at the time, and often conflicting dietary and other treatment recommendations. For example, at an international meeting in the 80s, one prominent thought leader referred to IBS as “a disorder of neurotic housewives”, while another stated that it isn’t “a real disorder” in the first place. Then came the long-lasting period of attributing symptoms to disorders of gastrointestinal motility, e.g. altered contractile activity and intestinal transit, followed by a short period postulating an inflammatory process underlying IBS symptoms, and a period obsessed with “excessive intestinal gas production” to today’s theories about the role of an altered gut microbiome. While the new theories about IBS that appeared every few years – including the most recent focus on an altered gut microbiome – captured the imaginations of clinicians and investigators in the field, encouraged the pharmaceutical industry to come up with new medications, and the supplement industry with new microbiome-targeted treatments, my early conceptualization of IBS as a brain-gut disorder was rejected by the majority of IBS experts – until now.

“The Lumpers and Splitters”

While the ROME Foundation aimed to provide a systematic approach to the functional GI disorders by splitting them into some 40+ different separate entities, each of them with its own postulated mechanism and treatment recommendation, we suggested from early on that alterations in brain gut interactions, including increased perception of visceral signals (“visceral hypersensitivity”), and increased stress responsiveness, provided a unifying framework for all the different clinical manifestations affecting every part of the GI tract from the esophagus to the end of the intestine. Paralleling the different concepts about pathophysiology, treatment recommendations over the decades have ranged from drugs aimed at slowing or speeding up transit through the gut (so called motility drugs), and antibiotics (still in widespread use today). Dietary recommendations have ranged from high fiber diets to the today’s promotion of the “low FODMAP diet”, a diet devoid of many fiber-containing foods. Not surprisingly such a diet cannot be recommended for long term use due to its detrimental effects on metabolic health. Along the way have also been a wide range of supplements ranging from pro- and prebiotics to peppermint oil. While each of these treatment approaches has been shown occasionally to lead to a relieve of some IBS symptoms, none of them turned out to be the miracle treatment which had been expected.

“The majority of proposed treatments have not been much more successful than a placebo pill.”

It is ironic that while these various concepts promoted over the years have primarily fueled the careers of investigators, the output of modified classifications by the ROME Foundation and the profits of the pharmaceutical industry, they have not provided consistent and lasting relief for the millions of patients suffering from symptoms of chronic abdominal pain and discomfort. The majority of proposed treatments have not been much more successful than a placebo pill.

Patients who are interested to learn more about simple ways to self-manage their symptoms, may want to try my IBS class. I provide information and treatment recommendations which I have given to hundreds of IBS patients in my clinic over the years. This information is based on research performed at our center at UCLA, as well as by a few outstanding research groups around the world. For a recent summary of this research and a comprehensive concept of IBS pathophysiology, I refer to our recent review article The Neurobiology of IBS. While I have often been told by colleagues that this information is too complicated for patients to understand (!), I still have yet to meet a patient with IBS who didn’t embrace this information, was relieved by finally having a plausible explanation for their “unexplainable” symptoms, and who has not experienced significant symptom improvement from the recommended therapeutic approach.

Emeran Mayer, MD is a Distinguished Research Professor in the Departments of Medicine, Physiology and Psychiatry at the David Geffen School of Medicine at UCLA, the Executive Director of the G. Oppenheimer Center for Neurobiology of Stress and Resilience and the Founding Director of the Goodman-Luskin Microbiome Center at UCLA.