Age-Related Changes in the Enteric Nervous System

As we enter the 21 century, the segment of the population that is the most rapidly expanding is that comprised of individuals 85 years of age and older. Dysfunctions of the gastrointestinal (GI) system, including dysphagia, constipation, diarrhea, and irritable bowel syndrome are more common complaints of the elderly, yet our knowledge of the aging GI tract is incomplete. Compared to the rapid advances in the neurobiology of aging in the CNS, the understanding of age-related changes in the enteric nervous system (ENS) is poor. In this brief review I recap experiments that reveal neurodegenerative changes, and their functional correlates, in the ENS of mice, rats and guinea pigs. Clinical literature seems indicative of similar structural and functional age-related changes in the human ENS. Current studies that address the mechanisms underlying agerelated changes in the ENS are introduced. The future directions for this field include physiological and pharmacological studies, especially at the cellular and molecular level. Research in the aging ENS is poised to make major advances, and this new knowledge will be useful for clinicians seeking to better understand and treat GI dysfunction in the elderly.