Irritable bowel syndrome

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Dr Mary Reid, Senior Lecturer
Institute of Health & Community Studies
Bournemouth University


The syndrome

Irritable bowel syndrome, or IBS is a condition believed to affect 10 – 15 per cent of adults.  It is the most commonly diagnosed functional digestive (or gastrointestinal) disorder, and it has received the biggest focus in research in this field to date (Thompson, Longstretch, Drossman, Eaton, Irvine & Muler-Lissner 1999).   The actual criteria used by different health care professionals for diagnosis varies slightly, but the Rome II classification for functional gastrointestinal illnesses was recently developed in order to aid research and clinical awareness.  Published in 1999, the Rome II system includes irritable bowel syndrome, functional dyspepsia, nonulcerative colitis,  functional abdominal pain, and a number of other conditions.   A functional gastrointestinal disorder is defined as a ‘variable combination of chronic or recurrent GI symptoms not explained by (known) structural or biochemical abnormalities’ (Drossman, Creed, Olden, Svedlund, Toner & Whitehead  1999), and is contrasted with a structural disorder, in which disease pathology or abnormal morphology can be demonstrated.   This does not mean that functional gastrointestinal disorders are less real or physical, compared to disease-based syndromes or conditions.  Rather, these disorders are all diagnosed on the basis of symptoms such as pain or other symptoms affecting the digestive tract (or other organs and pathways related to digestion), and are caused by more subtle levels of abnormal physiological functioning that are still as yet unknown.  Each disorder involves a somewhat different symptom cluster and location, as well as the kind of treatments used to manage them.

Patients experience IBS as chronic constipation, diarrhea, or abdominal pain, or some combination of these primary symptoms, although other forms of discomfort and distress may also be important.  A pattern of alternating constipation and diarrhea is also common.  IBS sufferers also experience the sensation of not being able to fully empty their bowels during a movement.  Abdominal pain or spasm and bloatedness are common symptoms and many patients feel significant relief after a bowel movement or passing of wind.  It is highly important to recognise that there are variants of this disorder, and that individual patients may suffer some but not all symptoms.

According to the Rome II system, IBS involves abdominal discomfort or pain lasting at least 12 weeks (which need not be consecutive in the preceding 12 months) as the primary symptom.  IBS is often sub-classified as diarrhea type, constipation type, or mixed symptom – type, depending on other major symptoms experienced by the patient.  Bloating is a common symptom and associated with significant discomfort.  In addition, at least two out of three other features are present:

(1) pain is relieved with defecation

(2) symptom onset is associated with a change in frequency of stool; and / or

(3) symptom onset is associated with a change in form (appearance) of stool

Abnormal stool frequency is usually defined as greater than three defecations a day or less than 3 times a week.     When pain is the primary symptom present and there is no relief from defecation or change in stool, the patient is usually diagnosed with one of the other categories of functional gastrointestinal disorder, such as functional abdominal pain.    In a recent survey involving over three hundred participants,  almost half reported receiving a clear diagnosis of IBS and two –thirds had lived with IBS for five or more years, with 70 per cent reporting episodes occurring at least once a week or more (IFFGD, 2002).

People with IBS are no more likely to develop serious gastrointestinal disease such as cancer than other individuals, and have no need for preventative check-ups.

Physiological and psychological factors involved in IBS


It is not yet possible to precisely diagnose individual causes of IBS, and the influences that maintain it, but much research aimed at getting a better picture of these factors has been conducted over the past few decades.  That several processes that are now generally believed to contribute to the development of this complex disorder has now been supported by research findings from a number of countries.  The fact that IBS symptoms are not attributable to ongoing disease or structural abnormality does not mean that this syndrome is not really ‘physical’ or less ‘real.’   IBS symptoms are undeniably physical, difficult to manage, and real.  Rather, the underlying causes appear to include the disruption of one or more aspects of the regulatory mechanisms underlying the body’s digestive functioning.

The digestive tract is a highly complex and sensitive system involving several different types of neurochemical messengers and nerve pathways that run between the brain to the digestive organs, and interact with a great number of other systems in the body, including higher order functions such as learning, memory, and emotional processing (see section below).  The bowel may become ‘irritable’ due to the occurrence irregular movements, too many or too little secretions in the stomach or  mucus cells situated along the intestinal wall, or from other messages that inadvertently disrupt normal functioning when the digestive tract is at rest or processing food and waste.   The bowel may become over-reactive to the passage of wind or fluid, for example, leading to over-active muscular contractions and delivering sensations like spasms, or the feeling of glass or other sharp and painful sensations along the length of the bowel.  In other cases, a bowel movement may be stopped, or result in efforts to expel materials from the bowel before they are ready.   Certain foodstuffs, such as dairy products (i.e. containing lactose) which may be very digestible for some people may not be digestible for others who lack the necessary biological enzymes for the processing of these dairy products.

The factors that can trigger these disruptions – occasionally or chronically – are many, and involve a person’s thinking, perceptions, feelings, and general arousal level, as well as other bodily functions that may have little to do with digestion in the first place.   Repeated injuries caused by inflammation may leave abdominal nerve receptors in a sensitised state.  For instance, if someone has had multiple abdominal operations or infections, later painful stimuli may be experienced as more painful than previously.

Various lifestyle and physical – environmental factors have been implicated in the development and maintenance of IBS.  These factors include diet and allergic response to some foods (e.g. lactose intolerance),  previous inflammation caused by gastrointestinal infection or prolonged use of antibiotic medication.   Genetic/familial factors and long-term use of certain kinds of pain relievers have also been implicated as contributors to the development of IBS.

The idea that emotional arousal or stress affects gut function is hardly new.   It has always been known that both psychological and physical dysfunctions affect the functioning of the digestive system (Drossman, 1999).  Stress has a strong impact on the gastrointestinal tract for anyone.  Symptoms such as pain, nausea, vomiting, bloating, diarrhoea, constipation, inconsistent passage of food or faeces are common in anxiety-based, and other kinds of disorders, including gastrointestinal disorders and diseases.   Various psychological factors have been linked to IBS and other functional abdominal syndromes.    For some people, these links have included a tendency to confuse emotional with sensory experiences (e.g. rapid contractions within the intestines caused by emotional upset is interpreted only as a physical irregularity and worrying symptom), co-existing depressive disorders, or a heightened and chronic sense of vulnerability, accompanied by a tendency to worry a lot (Slepoy, Pezzotto, Kraier, Burde, Wohlwent, Razzari & Poletto 1999; Chun, DeSautels, Slivka, Mitrani, Starz, DiLorenzo & Wald 1999).  For some people, this tendency may be a response to a history of major losses or trauma.

At least in a certain percentage of cases, these issues involving inner conflicts or responses to environmental events have been shown to precede the advent of gastrointestinal symptoms, although living with recurrent gastrointestinal symptoms is also likely to produce further symptoms of anxiety or depression, or both (Naliboff, Balice & Mayer 1998).   This does not necessarily mean that a person with a functional GI disorder such as IBS is psychologically unhealthy, or maladjusted.  Quite the contrary, experiencing conflicts and confusion over one’s feelings or responses to situations are part of normal adult development, and in some cases, when the conflict or confusion is not resolved easily, the body’s functioning may become somewhat disrupted or disordered.    Similarly for children, chronic abdominal discomfort or bowel movement irregularities have been shown to co-exist with experienced stress within home and school environments, in some cases (Woodbury, 1993).

A growing amount of research has pointed to the complex interactions between digestive symptoms and anxiety, stressful life events, and other issues involving adult development.   In addition,  fundamental ways of thinking and perceiving and coping may co-exist that may not always be adaptive, such as trying to avoid experiencing emotional pain or adopting a stoic attitude when symptoms do begin.  

Chronic stress, anxiety, emotional states and ANS functioning

Experiencing chronic anxiety or depressed feeling, even at mild levels, has been shown to have an impact on a person’s coping over time, and is implicated in the development of IBS in at least some cases (Tanum & Malt, 2001; Norton, Norton, Gasmundson, Thompson & Larsen 1999).   One consistent finding is that hyperactivity of the stomach (i.e. engorgement of the mucus linings of the stomach and intestines, increased muscular contractions of the intestinal wall, and accelerated secretion of certain neuroendocrines) accompanies aggressive feelings, anger and resentment, while fear has an inhibitory effect (Baldaro, Gattacchi, Codispoti & Tuozzi 1996).   While anxiety and worry are normal human emotions, and help us prepare for situations in which we need greater alertness and the capacity for faster responses, chronic anxiety can be disruptive to performance and a range of psychophysiological functions, including digestion. 

In some cases of emotional arousal, such as when one is angry or fearful,  the sympathetic branch of the autonomic nervous system  becomes activated.  This system has far-reaching and multiple impacts on the body, which include accelerating heart rate, ceasing digestive functions for the moment, and sending blood from the internal organs to the musculature of the body.  Sympathetic arousal has been commonly called the ‘fight or flight’ reaction.   These various responses have one aim, providing an advantage when a real and potent external danger occurs:  to resource the body to take fast action with increase muscular strength for running or fighting.    These responses also occur when a threat is only internal, such as when a frightening or unpleasant thought occurs.  When this arousal persists over time without a balancing response from the parasympathetic reaction (which has the opposite effect, and helps the body  to relax), other systems of the body may wear down or dysregulate, and not work properly as a consequence.  It may be experienced as a state of anxiety, or feeling keyed up or tense, but not everyone is aware of mild sympathetic arousal.   In addition to these direct effects of chronic sympathetic activation on the body, there may be indirect effects, as when a person consequently engages in certain self-soothing behaviours (such as smoking or compulsive eating of fatty foods) which also affects digestion.  

Although it is still not clear from available research, whether the experiencing of different emotions affects ANS functioning in different ways, other structural pathways in the brain have been shown to be involved in emotional experiencing as well as memory, and learning (Panskepp, 1998).   However, stressful situations have also been shown to impact on the body’s immune cells within the digestive tract as well, increasing the possibility for inflammatory responses.  

The ways patients cope with anxiety and stress

 There are many strategies or approaches to handling difficult situations that people use, and all of us tend to have characteristic or familiar ways of responding to them.  Difficult situations may include those in which we feel our ability to understand and know how to act, think, decide, or feel is somehow overtaxed or unclear; or that we have too much to do or decide about in a short space of time; or that our ability to handle a situation involving other people, work, or even our own reactions to events may not be sufficient.   Generally, we use the term coping or coping strategy to refer to responses in these situations.   Whether or not they are aimed at eventually resolving the conflicts or issues involved in the particular situation, they allow us to regulate our own inner responses to stress and difficult feelings and sensations.     

Some coping strategies tend to occur together, at least for some individuals, including using emotional discharge (e.g. verbalising experiences of anxiety or emotional pain, crying, expressing anger), seeking emotional support (e.g. seeking closeness to friends or helpful others for comfort and succour)  and attempting to avoid a painful situation, physically or in one’s mind.  These responses tend to correlate or link up with being somewhat anxious as a personality trait (Cohen & Lazarus, 1979).    

It also may be the case that certain personal styles of coping with illness might have positive or negative impacts on recovery.  For example, using denial (e.g. refusing the importance or negative value of certain events) or avoidance as a generalised coping strategy might be unhelpful in recovery where there was a need to  accept functional limitations that accompany an illness episode.   Some individuals tend to repress certain unpleasant experiences, including experiences of fear, humiliation, rage or grief.  Rather than consciously avoiding these experiences, these individuals do not recognise having these feelings, and may instead find they are suffering from a bodily-based symptom,  such as pain or other abdominal symptoms such as those found in IBS.   This kind of coping style would make it especially difficult for individuals to realise a link between illness symptoms and increased inner states of anxiety or arousal, potentially created by both the activation of certain emotional responses, and the individuals automatic tendency to repress them, or engage in another form of avoidant coping response (Burns, 2000; Guthrie, 1993). 

Although findings regarding the relationship between life stressors and symptom onset with FGID patients have been equivocal (e.g, Levy, Cain, Jarrett & Heitkemper 1997; Suls, Wam & Blanchard 1994), others have found a relationship reported by both patients and clinicians (Reid, in preparation; Pinto, Lele, Joglekar, Panwa & Dhavele 2000; Adler, Cohen & Felten, 1995). 

Emotional expression and inhibition
[click here to link to Emotional Expression in Overlaps Section]

A link has been found between the degree to which people actively attempt to express their emotions or inhibit them, and illness symptoms more generally.  Truae has shown that people who tend to inhibit or in some way minimize their emotional expression are more likely to also suffer from increased  tension, or other perceived pain symptoms (Truae & Michael, 1993).  A relationship between the inhibition of emotional expression and a variety of psychosomatic illnesses has been found in other correlational studies (Temoshok & Fox, 1984; Greer & Morris, 1975).  In at least one study, a group of patients suffering from functional gastrointestinal disorders was significantly more alexithymic (i.e. a syndrome involving difficulty in recognizing emotions or expressing them) than a similar group of patients suffering from inflammatory gastrointestinal disease, and both of these groups were more alexithymic than a relatively healthy group (Porcelli, Taylor, Bagby & DeCarne 1999).  Ali, Toner, Stuckless & Gallop (2000) also found a relationship between having a tendency to self-silence, or suppress emotional responses to situations and assume personal responsibility for negative events and IBS.   These findings fit with the hypothesis that there is some relationship between the cognitive and expressive deficits inherent in this construct and a tendency to somaticize (i.e, psychological distress will be diffuse), at least in the case of these disorders.     

Inhibition on a psychological level is thought to involve a burying of feelings as well as a relatively lack of expression, or emotion-generated action within a social environment.   This in turn is believed to influence physiological responses, leading to dysfunctional visceral, autonomic, and muscular activity (e.g, increasing muscular tension), consequently leading to other internal perceptions such as stress, pain or other psychosomatic symptoms.   Learning also plays an important role here.   

More recently, models of disorder have been developed by clinical researchers to describe how both neurophysiological and psychological factors may influence the development of IBS.   In neurogastroenterological research, concepts such as systems theory and dysegulation have been used to describe how chronic digestive symptoms may evolve and are maintained (Schwartz, 1989).   

The gut and the central nervous system (CNS), responsible for all communication within the brain as well as between brain and body, are connected through several pathways that involve the same neurotransmitters, endocrine and other neurochemical messengers, and nerve cells.   Together these two systems form multiple structural pathways called the brain-gut axis, feeding information from gut to brain, including the major centres involved in motivation, emotional processing, thinking and memory formation, and back down again to the gut.  Higher brain centers are connected to sensory cells and motor sites  involved in emotion, general arousal and alertness, and responses to threat.  In addition, there are different levels of activity that affect function during  active digestion of nutrients, and system maintenance at rest: secretion, chemical processing of food, contraction or motility, pain modulation, defense against disease, and transfer of information between the gut and several other organs within the enteric nervous system (ENS) as well as the CNS.   However, the gut has a ‘mini-brain’ and is capable of operating  somewhat independently as a complex and highly sensitive organ system.   This function has been demonstrated in relation to digestion, and speculation exists that it may also serve as an integral biological system for other functions that combine integrating, differentiating and more generally processing of experiences (Mayer, 2000). 

Mayer, Naliboff & Chang (2001) have proposed an model of IBS based on the concept of dysregulation.  The overall functioning of the enteric nervous system and its sub-systems can become disrupted or dysregulated anywhere along a chain of events, similar to a great clockwork that may begin to work somewhat erratically when there is some perturbation somewhere in the system, even a minor wheel.   Symptoms can be created by a number of different causes, including alterations in gastrointestinal motility and epithelial (secretory) functions,  or changes in how a person perceives bodily sensations (higher brain functions).   CNS alternations are believed to result from centrally-based messages related to the experience of stress or activation of certain emotion-related circuitry in this model, which may be caused by either internal or external stressors.    

In particular, Mayer and his colleagues have described an emotional motor system responsible for both the generation of emotional experience and gut dysfunction.  Circuits involving fear and anger responses have been mapped out.   Fear has its greatest impact on inhibiting upper GI motility and stimulating distal colonic function, while anger is associated with enhanced contractions of the upper and lower bowel and increasing both blood flow in the mucus-filled inner lining of the gut and gastric acid secretion (such as occurs routinely during the digestion of food).  In cases of IBS, risk factors associated with pathological or chronic stress in early life, along with genetic factors can add together  with other ‘trigger’ factors, such as current psychological stress, infections, or consumption of antibiotics and allergens contained in food.   In chronic cases involving IBS-type symptoms, a negative feedback system develops, as anxiety leading to gut symptoms are perceived as painful and worrisome, which in turn creates more anxiety, and so on. 

There are many component structures and functions in this model of an emotional motor system that forms an axis between brain and gut, including chemical mediators such as corticotrophin-releasing factor (CRF) as well as pathways outlined above in the CNS and ANS.  That different kinds of signals offered by varieties of emotional experiencing and their somewhat distinct but overlapping neurophysiological pathways invite the hypothesis that emotional experiencing is intimately involved in many aspects of information processing that have both psychological and physiological consequences. 

 A patient’s physiology can potentially become either cause or effect (or both) in relation to a combination of  psychological and physiological factors mediated by outputs of the emotional motor system and its network of autonomic, neuroendocrine, attention and pain modulatory sub-system responses.   If inflammation occurs for example, in conjunction with a period of more chronic anxiety also present, both factors will lend to the development of an alteration of CNS sensitivity in response to future feedback from the gut, with the result of pain, or changes in motility or secretory activity in the walls of the stomach or intestines.   Learning also plays an important role. 

Thus, these findings offer a good rationale to consider the role that emotional processing plays in the development and maintenance of psychosomatic disorder.   Emotional expression plays a critical role in maintaining health, although certain behaviours such as emotional expression may be controlled by a complex system of activating and inhibiting influences that are highly responsive to learning, and often initially resistant to re-programme once the system becomes regulated. 

Experiences of patients with IBS

Although published research typically focuses on groups of IBS patients, it is important to realise that people suffering with IBS symptoms experience individual disorders, and are therefore somewhat unique.   Not all IBS sufferers share exactly the same symptoms, nor are these necessarily caused by the same underlying processes.   In addition, patients may prefer different kinds of treatment, experience different needs associated with their illness and therefore choose different goals within their symptom management or recovery plan.     This is the most important thing for patients and health care professionals to remember, first and last. 

However, IBS can seriously compromise an individual’s quality of life, and therefore assessing those needs becomes paramount.  The discomfort caused may alter daily activities and performance. IBS is a high-ranking cause for absenteeism at work and sufferers have indicated that symptoms may frequently disrupt their ability to function well as home or socially as well. 

A number of patient-centred studies have shown more general problems that are common among most IBS patients, however, and these may need to be addressed in treatment at some point, if they become relevant to the individual case. 

1.  Patients may fear that other people (including health care professionals and family members) may disbelieve their claim that they are really ill, and their real need for treatment.  This often stems from actual encounters where diagnostic tests prove ‘negative;’ that is, a clear structural cause for a patient’s symptoms cannot be found, and physicians may fail to understand how their communications are being perceived by the patient (e.g. he or she may think the doctor is saying, your symptoms aren’t real).  A further lack of shared understanding or communication about the chronic nature of these symptoms (i.e. although they come and go, they persist and re-occur), they are unlike acute illnesses, and doctors in particular may not feel they are able to help patients develop realistic expectations about their condition or recovery, and these topics are not broached. 

2.  A related concern is that others do not appreciate the severity of their symptoms and the functional disability that results from them, since they just have IBS and not a ‘more serious’ disease like inflammatory bowel disease or cancer.    IBS pain can be extremely severe and consequently disabling.   Once a severe attack has occurred, a patient may begin to fear further attacks and restrict their interpersonal engagements as a consequence, which may do little to alleviate symptoms and in fact increase their emotional distress.   

3.  Some patients become concerned that their claim of symptoms will be perceived by others as a manipulation, or for secondary gain (e.g. to get others to do things for them, or to absent themselves from social or occupational obligations), or even that having symptoms in some way constitutes a personal ‘weakness’ of some kind.  Figuring out how to cope with symptoms and re-organise expectations of oneself and negotiate those held by others are not part of a routine agenda within medical care.   

In other cases, doctors may share their limitations in thinking about how to treat or monitor the effectiveness of medication-based treatments, or their ability to offer alternative forms of treatment, and so patients may feel left to get on with it, on their own with little guidance.   It is more likely that in these cases, health care professionals are exhibiting the limitations of their science rather than their personal reluctance to treat, or discharge their patient because he or she is not taken as seriously worthy of treatment.    Due to these limitations in doctors’ ability to treat, patients’ own concerns related to their illness may go unvoiced, and remain a source of anxiety.    

4.  Until recently, there has been lack of readily accessible information for patients and health care professionals alike, regarding treatment alternatives or ways to discover links between life stress and symptom occurrence.  Neither patient nor health care professional has known where to turn for further information or exploratory approaches to illness and recovery.


Useful organisations and links

International Foundation for Functional Gastrointestinal Disorders
P.O. Box 170864
Milwaukee, WI 53217
Phone: 1-888-964-2001 or (414) 964-1799
Fax: (414) 964-7176

CURE/ UCLA Neuroenteric Disease Program and
UCLA Center for Integrative Medicine
UCLA School of Medicine
11301 Wiltshire Boulevard
Los Angeles, California USA

Self-help Websites

IBS Self-help and Support Group

IBS Resource Center