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 ( 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.

Fibromyalgia and other chronic pain syndromes

Hmm since fibromyalgia is in the news nowdays, maybe it is a good time to talk about it on the braindiseases weblog. I did my internal medicine residency before I did neurology and I remember reading about fibromyalgia in Harrison’s Principles and Practices of Internal Medicine (this book is called the bible of internal medicine, a book every good internal medicine doctor should know well). Fibromyalgia occupied half a page and was right at the end of the section a kind of neglected disease. Many doctors (and I include myself in that group) do not consider that the disease actually exists.

We all have patients in our practice who carry the diagnosis of fibromyalgia, they have constant complain of pain in different areas of the body. When they first present to a doctor a work-up is carried out to determine the etiology of this constant pain. However inspite of multiple tests including but not limited to blood tests, imaging studies and sometimes even invasive studies no cause can be found. All the inflammatory markers in the blood come back negative (these include tests like ESR). These patients frequently have other diagnosis which fall into the category of psychosomatic disorders like IBS (irritable bowel syndrome) and chronic fatigue syndrome. Some of them may carry psychiatric diagnosis like depression or somatisation disorder. Thus fibromyalgia has been in the past a kind of waste-basket diagnosis given to patients with unexplained complaint of chronic pain referrable to different parts of the body. Since we did not truly believe that the disease exists, we did not have any good treatments for it. Doctors either treated these patients with anti-depressants or pain killers. This caused some unintended problems with some patients becoming dependent on pain killers like vicodin.

So do we know anything more of fibromyalgia now than in the 90’s?

Do we understand its pathophysiology better today?

Does the disease actually exists?

Fibromyalgia is currently diagnosed as per the criteria laid out by the American College of Rheumatology (ACR).


A. Widespread pain must be present for at least 3 months. This pain must appear in all of the following locations:

  • Both sides of the body
  • Above and below the waist
  • Along the length of the spine

B. Pain in at least 11 of 18 specific areas called tender points on the body. The pain experienced when pressing on a tender point is very localized and intensely painful (not just tender). Tender points are located in the following areas:

  • The left or right side of the back of the neck, directly below the hairline
  • The left or right side of the front of the neck, above the collar bone (clavicle)
  • The left or right side of the chest, right below the collar bone
  • The left or right side of the upper back, near where the neck and shoulder join
  • The left or right side of the spine in the upper back between the shoulder blades (scapula)
  • The inside of either arm, where it bends at the elbow
  • The left or right side of the lower back, right below the waist
  • Either side of the buttocks below the hip bones
  • Either knee cap

Other long-term symptoms that may indicate fibromyalgia include:

  • Morning stiffness
  • Fatigue
  • Sleep disturbance
  • Numbness or tingling in the hands and feet
  • Headache

We nowdays think that these patients have an altered perception of pain and other visceral as well as somatic sensations. Let me explain this with a crude example. Suppose you have inflammation in your left shoulder joint, your brain shall get sensation from the sensory receptors located in the periphery of the joint.  The sensation shall travel to the sensory cortex of the brain (the part of the brain dealing with sensation) and you shall experience pain as a result. It is believed that fibromyalgia patients have altered pain perception in their brain, they either feel the pain too much or that it persists for longer than it is supposed to (crudely put maybe their brain is more pain sensitive). Some recent work involving functional MRI and other imaging studies does give some scientific evidence to suggest this.

Whatever the etiopathogenesis behind this disorder (if in fact the disorder does exist in the first place) now there are new drugs in the market been touted (and FDA approved) for the treatment of fibromyalgias. One of them is pregabalin marketed under the name of Lyrica. My personal experience using this drug in patients with fibromyalgia is very limited. If you or any of your loved ones is diagnosed with fibromyalgia, I would advise you to see a doctor with interest and experience in this disorder so that you can get benefits of newer treatment modalities.

Personal Regards,

Nitin Sethi, MD