A new mechanism for diverticular diseases: aging-related vagal withdrawal

It is widely believed that diverticulosis, a common condition among the elderly, results from repeated colonic barotrauma related to low dietary fiber and low stool bulk. Recent evidence has challenged the dietary-barotrauma hypothesis. We propose an alternative hypothesis that diverticulosis may be attributable to colonic smooth muscle dysfunction that results from vagal attrition associated with aging. We previously proposed that broad aging-related attrition of autonomic nerves may unmask intrinsic sympathetic bias of end-organs, leading to the compendium of familiar conditions associated with senility. Unexplained cholinergic hypersensitivity and receptor over-expression in bowel affected by diverticulosis have recently been observed. These findings are highly suggestive of a compensatory response to loss of vagal innervation. The resulting autonomic dysregulation may induce bowel smooth muscle dysfunction, setting the stage for diverticula formation. Thus, diverticular bowel disease may be a manifestation of the aging-related systemic vagal withdrawal. The framework may extend to diverticula formation in other parts of the gastrointestinal and genitourinary tracts. For instance, aging-related vagal attrition may represent the common upstream mechanism that induces both sphincter of Oddi dysfunction and peri-ampullary duodenal diverticula, conditions that frequently occur together. Novel approaches to preventing and treating diverticular diseases by promoting vagal activity are proposed including the electrical or pharmacologic modulation of the autonomic system.