Association of periodontitis and tooth loss with cognitive decline in the older adults - a systematic review

BACKGROUND: The increasing global burden of dementia highlights the importance of identifying factors that may contribute to cognitive decline in later life. Growing evidence suggests that chronic oral conditions, particularly periodontitis (PD) and tooth loss, may be associated with Alzheimer's disease (AD) and related dementias. This study synthesizes current observational evidence on the association between PD, tooth loss, and cognitive impairment (CI) among older adults. METHODS: A comprehensive literature search was conducted in PubMed, the Cochrane Library, Embase, Scopus, and Google Scholar for English-language studies published between 2010 and 2025. Cross-sectional and longitudinal cohort studies examining associations between PD, tooth loss, and CI were included. Study selection, data extraction, and quality assessment were performed in accordance with PRISMA 2020 guidelines. RESULTS: Thirteen studies met the inclusion criteria, with sample sizes ranging from 40 participants to over 500,000 individuals in large population-based cohorts. Most studies focused on adults aged ≥ 50 years, particularly those aged 60 years and above. Periodontal status, tooth loss, and cognitive outcomes were assessed using heterogeneous diagnostic methods. Most studies reported significant associations between PD or tooth loss and CI, dementia, or AD. Periodontal treatment appeared protective in several studies, although some associations weakened after adjustment for confounders. CONCLUSIONS: The findings support PD and tooth loss are consistently associated with adverse cognitive outcomes, although causal relationships cannot be established due to methodological heterogeneity and residual confounding. Integrating oral health care into geriatric and dementia-prevention strategies may help preserve cognitive function and improve quality of life among older adults.