Irritable bowel syndrome (IBS) what has the brain to do with it?

Nitin K Sethi, MD

Assistant Professor of Neurology

New York-Presbyterian Hospital

Weill Cornell Medical Center

New York, NY 10065

The New York Times always has some good articles in its health section which I enjoy reading.  One such article which I read recently was titled ” Let the mind help tame an irritable bowel” by Jane E. Brody. I think everyone who suffers from IBS should read this well written piece. Ms. Brody discusses  the role played by the brain in IBS by highlighting the intimate connection between the gut and the brain. 

When we talk about the nervous system most people are only familiar with the central nervous system (CNS) (brain and spinal cord) and the peripheral nervous system (PNS) (peripheral nerves which control the movements of the limbs and help to transmit sensation like pain, temperature and touch from the periphery back to the brain). In addition to the CNS and the PNS, there is another nervous system which plays an equally important role. This is referred to as the autonomic nervous system (ANS). The ANS is the system which helps to maintain functions like sweating, blood pressure, erectile function and functioning of the smooth muscles of the gut among numerous other functions. This system is essentially involuntary meaning not under our voluntary control.

The brain and the gut are intimately connected and this has being referred to as the brain-gut axis. The small and large bowel are richly innervated with nerve fibres transmitting information to and from the brain. The secretory functions of the gut are controlled by the brain though neurotransmittors like serotonin and hormones such as gastrin, somatostatin, secretin, cholecystokinin and neuropeptides. Thus in essence the gut is under the control of the supercomputer aka ” BRAIN”.

People who have IBS have symptoms of bloating, flatulence, diarrhoea, abdominal pain and constipation. They usually fall into two broad categories: 1)in which diarrhoea symptoms predominate 2) in whom constipation symptoms predominate. When these people seek medical help a work up is initiated to determine the etiology. As doctors we want to rule other diseases which may mimic the presentation of IBS. It is specially important to rule out tumors of the gut (colon cancer etc ) hence in some patients a colonoscopy may be ordered. It is also important to rule out inflammatory bowel diseases (IBD) such as Ulcerative Colitis and Crohn’s disease.

If after work-up nothing “organic/ structural” is found, the diagnosis of IBS is entertained. No one yet knows what causes IBS, why some people have it and others don’t. One of the theories is that in people who have IBS either the nerves or the smooth muscles of the gut are extra-sensitive. They respond differently (as compared to people who do not have IBS). Another theory is that the nerves and smooth muscles perse are fine, it is the brain which processes the signals it gets from the gut differently.

As Ms. Brody rightly points out in her article (www.nytimes.com) this does not mean IBS is a psychosomatic condition. For a long time these patients were misunderstood and tagged as being too emotional, “it is all in your mind meaning psychological” and “there is nothing wrong with you”  labels. Now we know this is not true though we still do not know what the underlying problem is.  We do know that IBS symptomatology is exacerbated by emotional upsets meaning symptoms worsen at the times of stress.  Large meals, change in diet, eating a diet rich in wheat, barley or milk products, drinking too much coffee and tea or an overindulgence in alcohol can lead to a flare up of symptoms.

So if the brain plays such a big role in the symptomatology of IBS, can we harness the power of the brain/mind to control this disease? IBS should be the ideal disease to demonstrate the power of mind-body medicine. Well yes and no. To some extent therapies like hypnosis, meditation, yoga and massage help. Controlling your response to stress is also helpful (how you deal with stressful situations, knowing which triggers to avoid-stress at work, at home, in a relationship etc). A very important role is played by dietary modifications-knowing your triggers and knowing which foods to eat and how much and which to avoid.

Medicines are there, unfortunately they do not abate the underlying disease though they certainly help in controlling the symptoms. If you have diarrhoea predominant IBS, your doctor may prescribe an anti-diarrhoeal agent along with probiotics (once infective causes of diarrhoea have been ruled out by stool cultures). Constipation predominant IBS patients may be helped by increasing the fiber in their diet or by the judicious use of laxatives.

A combination of the above therapies (mind-body medicine and allopathic drugs) works best. After all that is what is referred to as holistic medicine.

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One thought on “Irritable bowel syndrome (IBS) what has the brain to do with it?

  1. I know someone who has a diagnosis of IBS. The interesting part about it is he seems to have a seizure either shortly before or shortly after defecation. Have you ever heard of this and if so, any recommendations? Test after test has been done to no avail.

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