Why dyspepsia can occur without organic disease: pathogenesis and management of functional dyspepsia

Hiroto Miwa

Functional dyspepsia (FD), one of the most common conditions in medicine, is a gastrointestinal disorder in which the patient suffers from chronic dyspeptic symptoms such as epigastralgia and a heavy feeling in the stomach despite the absence of organic disease. Elucidating the pathogenesis of FD means answering the question, "Why do symptoms occur?" The factors contributing to symptom manifestation in FD probably should be divided into 3 categories: (1) physiological abnormalities that directly induce symptoms, (2) factors that modify those physiological abnormalities, and (3) factors that govern abnormal responses to stress. The symptoms of FD are directly caused by two major physiological abnormalities-abnormal gastric motility and visceral hypersensitivity-occurring in patients who have acquired excessive responsiveness to stress as a result of the environment during early life, genetic abnormalities, residual inflammation after gastrointestinal infections, or other causes, with the process modified by factors including psychophysiological abnormalities, abnormal secretion of gastric acid, Helicobacter pylori infection, diet, and lifestyle. If the basis of this model of FD pathogenesis is excessive responsiveness of gastrointestinal function to stress and external stimuli, psychosomatic approaches to alter stress perception could be important treatment options. However, in the primary care setting, the treatment of FD has focused on local gastric factors, including abnormal gastric acid secretion, abnormal gastric motility, and H. pylori infection. Acid secretion inhibitors and prokinetics have been commonly used, and H. pylori eradication therapy has been carried out, but the effectiveness of drug therapy has been limited.