[Aging-Associated Oral Microbiota Dysbiosis and Hypofunction: Their Role in Alzheimer's Disease Pathogenesis]

Alzheimer's disease (AD), a multifactorial neurodegenerative condition, imposes a major burden on societies with aging populations. Recent research indicates that oral cavity health is a critical factor influencing AD pathology, making proactive investigation of this modifiable risk factor essential. This review proposes that aging-related oral microecological dysbiosis and oral hypofunction may promote AD progression by inducing or exacerbating systemic inflammation and disrupting the homeostasis of the "oral-gut-brain" axis. Moreover, each factor may worsen damage through distinct biological pathways: oral microbiota dysbiosis allows direct invasion of the central nervous system by oral pathogens, promoting amyloid β-protein (Aβ) deposition and Tau hyperphosphorylation, while chronic sensory deprivation from oral dysfunction triggers neuronal degeneration and adverse remodeling in key cognitive brain regions. This review aims to systematically elucidate the roles of oral microbiota dysbiosis and oral hypofunction in AD pathogenesis in the context of aging, clarify their underlying biological mechanisms, and explore the potential value of integrating oral cavity health management into comprehensive AD prevention and treatment strategies.