Introduction
Irritable Bowel Syndrome_Disease BackgroundIrritable bowel syndrome is a chronic, relapsing bowel disorder characterized by recurrent but not continuous abdominal pain or discomfort with altered bowel habits that may affect the patient’s quality of life. There are no identifiable physical, radiologic, or lab abnormalities indicative of organic disease. Irritable bowel syndrome is currently considered to be a disorder of gut-brain interaction that affects gastrointestinal (GI) motility, sensation, and secretion.
Epidemiology
The global prevalence of irritable bowel syndrome is between 4.1-12%. The occurrence of irritable bowel syndrome varies among different countries and demographic groups, with prevalence rates higher in Western Europe than in Asia. The Rome Foundation Global Epidemiological Study found that the prevalence rates in Europe and the United States were similar, whereas slightly lower rates were observed in Asia and Australia. Irritable bowel syndrome is most common in women and younger individuals (ie 18-39 years old). The prevalence is decreased with advancing age.
Pathophysiology
The pathogenesis of irritable
bowel syndrome is multifactorial, including genetic,
environmental, psychologic, and physiologic factors (eg altered gut
motility, visceral hypersensitivity, brain-gut interactions, gut microbiome,
intestinal barrier dysfunction, and mucosal immune dysregulation).
Disturbances in the
hypothalamic–pituitary–adrenal axis, altered serotonergic activity, bile acid
dysregulation, and compromised intestinal barrier function collectively promote
disordered gut motility, enhanced visceral pain perception, altered intestinal permeability, immune-activation,
altered gut microbiota, abnormal gut-brain signaling, and ongoing
inflammation. The gut microbiome plays a
central role in these pathways by shaping neurotransmitter balance, regulating
immune activity, and maintaining epithelial integrity, thereby acting both as a
contributor to disease manifestations and a potential focus for therapeutic
intervention.
Risk Factors
Risk factors for irritable bowel
syndrome may include a history of childhood sexual abuse, domestic abuse in
women, personality disorders, and anxiety or depression. Other risk factors
include chronic pain, sleep disorders, diabetes mellitus (DM), restless legs syndrome, gastroenteritis, dietary
factors, chronic stress, psychological factors, and surgeries.
The symptoms may be exacerbated by stress, alcohol, food, abdominal and/or pelvic surgery, a sequela of GI infection, and/or a difficult life-changing event in the patient’s life. It has no known association with the development of cancer, mortality, or inflammatory bowel disease (IBD).