These questions and many more like them are often asked by patients with GI disorders. They are also asked by physicians who are confronted with a confusing set of symptoms and few “objective” physiological markers for disease (like infections or blockage). As you might expect there are no simple answers, but new research has begun to point the way to a better picture of how stress and GI problems might be linked and even ways to address the role of stress in treatment.

The first thing to remember is that stress has a strong impact on the GI tract in everyone. It is well known that patients with IBS often report that stressful events precede the onset or exacerbation of IBS symptoms. In one survey study for example 73% of IBS patients reported that stress altered their stool pattern, and 84% reported that stress led to abdominal pain. Interestingly in the same study 54% of persons without IBS also reported stress altered stool patterns and 68% reported stress caused abdominal pain. While affecting everyone, stress does seem to more strongly impact GI function in persons with IBS or similar disorders, such as dyspepsia, or chronic heartburn.

In a recent study examining IBS patients over a several year period, up to 90% of the fluctuations in symptoms could be predicted by chronic stressors during the several preceding months. Another recent study examined patients who developed an acute GI infection (often after traveling in a foreign country). Most of the subjects recovered over a period of a few weeks with treatment but a significant percentage seemed to develop chronic symptoms similar to IBS. Level of stress during the three months prior to the infection was a strong predictor of who did and did not develop these chronic symptoms. Thus while stress is not the sole cause of IBS some stress clearly play a significant role in generating and prolonging symptoms in susceptible individuals, especially those with some GI symptoms.

What kinds of stress are most important? It is interesting that a variety of early studies did not find very strong relationships between daily ups and downs and symptom fluctuations. This is consistent with patients’ reports that even on relaxing days symptoms can be severe. Newer studies like those described above have taken a different point of view and this has led to a much better understanding of the kinds of stress which may be important in GI disorders. For example, the long-term study of IBS patients that successfully connected symptom fluctuations with stress used a ‘life stress’ approach. In this approach major events in ones life such as; changes in a job, family tension, moving to a new city, or loss of a friend are monitored and rated as to the amount of threat they pose to the individual. The chronic (over a month or more) and most threatening stressors were those associated with increases in IBS symptoms. Those with none of these stressors over a several month period had very few exacerbation of symptoms. Those with multiple chronic and threatening stressors had a very high probability of symptom exacerbation. To the extent possible the investigators demonstrated that it was the stress and not changes in diet, exercise or medications which led to symptom differences.

Similarly, in the post-infection study the life stress method was also used. Subjects who developed chronic symptoms reported having experienced a life event that most often involved some disruption of personal relationships in the three months prior to the infection. In addition, the post-infectious symptom group also experienced an excess of life events in the three months following the acute gastroenteritis. So the newest evidence points to significant and especially longer lasting, and threatening stressors as the most important in influencing GI symptoms. One or two good or bad days may not be that important, but one's response to major life events may be critical for managing IBS symptoms.

This new data is consistent with the developmental model of IBS which indicates that a history of major traumatic events (i.e. physical and/or sexual abuse) or major losses (i.e. the loss of a parent) during childhood are present more frequently in patients with IBS than healthy controls. In addition to daily stressors, a history of severe emotional trauma such as physical and sexual abuse especially when incurred during childhood also appears to be associated with an increased risk to become an IBS patient. In a study of women at the University of North Carolina, 53% of women with IBS had a history of abuse, while 37% of women with structural GI diagnoses gave such a history. Not surprisingly, patients who have experienced life threatening resulting in post-traumatic stress disorder (PTSD) also have a high incidence of IBS.

How might these kinds of stressors lead to increased symptoms in IBS or other GI disorders? It does not appear to be true that under stress patients just worry or complain more about symptoms (although in some cases this may be important). Instead we believe that stress may disrupt the function of nerve and even immune cells in the GI tract and in the brain. For example, in the study of the patients with gastroenteritis discussed earlier, the study found that stressful life events preceding the infection and 3 months after the infection appeared to have the greatest predictive value for the development of postinfectious IBS symptoms. In addition to the differences in psychological parameters however, patients with post-infectious IBS had persistence of chronic inflammatory changes in rectal mucosa (a layer of tissue inside the colon) while the mucosa in those patients without persistent symptoms returned to normal at 3 months post infection. These kinds of changes in the mucosa have been previously linked to certain types of bowel symptoms.

The findings suggest that, in predisposed individuals, enteric infections and presumably other causes of mucosal irritation can precipitate on-going IBS symptoms and mucosal changes which may persist long after the infection or inflammation has resolved. Stress can also increase GI symptoms by changing how the brain controls unwanted and painful sensation. Our own built in pain control system is constantly active, allowing painful information from any part of the body to be noticed (in fact it overrides almost all other information to gain our attention). The system also can suppress pain and other sensations when the information is old or unnecessary for action. Stress can disrupt this pain control system allowing more attention to certain physical sensations to predominate, especially those from areas we are concerned about or have had problems with. It is also well known that the same parts of the nervous system that respond to stress, the autonomic nervous system, is the primary control system for the GI tract, influencing muscle contractions, biochemical changes and digestion.

The focus of new research by the Neuroenteric Disease Program and other laboratories is on the biochemical and nervous system mechanisms that allow stress related changes that begin in the brain to impact different body areas such as the GI tract. In addition, much of the work on stress as it impacts GI symptoms has been done in IBS. It may very well be true that the same kinds of life events may impact susceptible individuals in other parts of the GI tract. At the UCLA Neuroenteric Disease Program we are beginning what is the first comprehensive study of how stressful life events may impact another chronic GI problem, that of heartburn. If you are interested in this study or know anyone who suffers from heartburn and might be interested please call (310) 312-9381.