Irritable Bowel Syndrome in the Older Adult
The accredited CME learning activity based on this article is offered under the auspices of the CE department of the University of Toronto. Participating physicians are entitled to one (1) MAINPRO-M1 credit by completing this program, found online at www.geriatricsandaging.ca/cme.htm
Anil Minocha, MD, FACP, FACG, Division of Digestive Diseases, Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA.
Thomas Abell, MD, FACG, Division of Digestive Diseases, Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA.
Irritable bowel syndrome (IBS) in the older adult offers challenges for diagnosis and treatment; however, very little research has been done in this regard. IBS has significant impact on the quality of life, especially in frail individuals. The diagnostic criteria have not been validated in older subjects. Diagnostic strategy needs to be modified to account for the expanded list of differential diagnosis, including high prevalence of colorectal cancer. There is a lack of evidence related to the efficacy of the treatment regimens used. Therapy should focus on specific symptoms and be matched for the potential for side effects and drug interactions. The prognosis for IBS is excellent and in a majority of cases symptoms disappear within five years.
Key words: Irritable bowel syndrome, Functional bowel disorder, Rome II criteria, older adults, spastic colon
Introduction
Irritable bowel syndrome (IBS) is a prevalent yet poorly understood disorder. Older IBS patients have a high prevalence of numerous disabling rheumatological, neurological, and cardiovascular disorders that can impact on clinical presentation and management. Factors like dementia, polypharmacy, undernutrition, incontinence, and failure to thrive further complicate the overall picture. As a result, epidemiology and clinical presentations of IBS in older adults remain to be well established.
Epidemiology
IBS is the most common reason for referral to gastroenterologists in the US. While the overall prevalence of IBS is 10–20%, IBS in the older population is about 10%.1,2 The disorder accounts for 12% of primary care visits and 28% of all referrals to the gastroenterologist. Aging patients with fecal soiling are more likely to seek help.
A majority of the patients present in the third or fourth decade of life. IBS occurs predominantly in females, at least in Western society. Data from Eastern cultures like India suggest a male predominance; the reasons for the discrepancy remain controversial.
Etiopathogenesis
The pathophysiology of IBS remains uncertain. Abnormal gastrointestinal motility, visceral hypersensitivity, psychological dysfunction, infections, food sensitivities, and emotional stress have been documented in many patients.3–6 Despite a plethora of investigations, no single abnormality has been demonstrated to be specific to IBS.
Many patients demonstrate increased anxiety, depression, phobias, and somatization although they may not meet the criteria for a major psychiatric diagnosis. Psychological distress does not cause IBS but may influence how patients cope with symptoms.
Aging results in a decreased number of neurons in the myenteric plexus along with a concurrent increase in deposition of collagen in the colon. This results in impaired response of the senescent colonic muscle to excitatory factors. The uncoordinated colonic motility may lead to symptoms of IBS, suggesting impaired control of neuromuscular
function.3
No single marker of dysmotility has been established for IBS. However, the gut's performance in the frail older patient is significantly impaired. Visceral hyperalgesia is found in a subset of patients. It is not specific to the colon but can be demonstrated at different sites in the gut.
The increased prevalence of diverticulosis may contribute to IBS symptoms in the older population (Figure 1). Older females have a higher incidence of constipation due to the failure of the anorectal angle to open or excessive perineal descent.