What are Functional GI and Motility Disorders (FGIDs)?
Functional gastrointestinal disorders (FGIDs) are disorders of how the GI tract works and can affect any part of the gastrointestinal (GI) tract. FGIDs are not caused by structural or biochemical abnormalities. Because of this, x-rays, endoscopies, blood tests, and other GI tests can show essentially normal results. FGIDs are considered a "diagnosis of exclusion" where other GI diseases, such as Inflammatory Bowel Disease or Peptic Ulcer Disease are ruled out via the type of symptoms experienced and diagnostic testing. FGIDs are not psychiatric or psychological disorders, although stress and psychological difficulties often make FGID symptoms worse.
The most common FGIDs are Irritable Bowel Syndrome (IBS) and Functional Dyspepsia (FD). IBS typically presents as altered bowel consistency combined with abdominal pain that is usually relieved with a bowel movement. Functional Dyspepsia presents as ulcer-like symptoms with upper-GI pain and a feeling of indigestion. There may also be mild discomfort with fullness and possibly nausea soon after eating.
FGIDs are very common, affecting approximately 25 million Americans and accounting for 40% of a gastroenterologist's practice. Of those people with a functional GI disorder, 50 to 80% do not consult physicians. It is common for people with FGIDs who do not seek treatment to take over-the-counter medications and report significantly higher rates of job or school absenteeism and disability.
What are the important features of FGIDs?
Motility: involves the muscular activity, also known as peristalsis, of the GI tract. Normal motility is an orderly sequence of muscular contractions that extend the entire length of the GI tract. In FGIDs, motility is abnormal. You may experience fast motility, where there are rapid muscular spasms that can cause pain and diarrhea (IBS-D). Or you may experience very slow motility, where the contractions cause pain and constipation (IBS-C). You may also alternate between fast and slow motility.
Sensation: is how the nerves of the GI tract respond to stimuli, such as digesting a meal. In FGIDs, the nerves of your GI tract can be so sensitive that even normal contractions can lead to pain or discomfort.
Brain-gut dysfunction: occurs when there is a breakdown in the way the brain and GI system communicate. The GI tract has its own nervous system that controls its functions (the enteric nervous system). When you have a FGID, the regulatory system between the brain and the gut nervous system may be impaired. This can lead to increased pain and various bowel difficulties. Because brain-gut dysfunction involves the nervous system, symptoms caused by this impairment can be worsened by stress.
What is the cause of FGIDs?
To date there is no single identifiable cause for FGIDs. This ambiguity can cause significant frustration for both patients and clinicians treating these disorders. It can also lead patients to think that their symptoms are "all in their head." This is certainly not the case. The symptoms of FGIDs are real and can cause significant impairment and quality of life issues. Within the past 20 years there has been significant scientific attention given to FGIDs, including the underlying causes and mechanisms of each disorder. This research includes understanding the physiological, psychological, and social aspects of FGIDs. From this research, some general conclusions have been generated:
* Functional GI Disorders Impair Quality of Life
FGIDs are chronic illnesses, which may affect several aspects of a person's quality of life. This includes the ability to carry out daily activities, concerns about well being, an increase in health care utilization, and loss of social contact. Research studies conducted at the Northwestern Center for Functional GI & Motility Disorders often focus on measuring and improving quality of life for FGID patients.
* Psychological Stress Can Exacerbate GI Symptoms
There is increasing evidence that chronic GI symptoms can be exacerbated by psychological stressors. Intestinal, sensory and central nervous systems are involved in GI processes and motor function, and each is a component of the "brain-gut" axis. The brain-gut axis is a bi-directional pathway between the central and enteric nervous systems, and provides the linkage between sensation in the GI tract and intestinal motor function. External stressors, emotions, and thoughts have neural connections to the brain-gut axis, giving them the capability to affect GI functions. Because the brain-gut axis is bi-directional, GI activity and dysfunction can affect pain perception, mood, and behavior.
* Illness Experience and Health Status are Affected by Psychosocial Factors
Research has shown that patients with FGIDs can show greater psychological difficulties than healthy subjects or other medical patients. We have found in studies conducted at the Center that patients with FGIDs do not differ greatly from patients with Inflammatory Bowel Disease in how they cope with their illness, leading us to believe that GI symptoms in general are affected by psychosocial factors. These factors include coping skills, social support, and various personality traits. It is believed that IBS and other FGIDs are not psychiatric disorders, rather that psychosocial factors affect how each person interprets their illness and influences what their subsequent health outcomes are.