Beyond the mouth: the impact of periodontal disease on dementia

Data sources The authors searched Medline via PubMed, Scopus, CINAHL, Web of Science, and PsycINFO for relevant studies published until April 2022. Study selection Longitudinal studies that assessed periodontal health as the exposure and cognitive decline and/or dementia as the outcome were included. Case reports, reviews, cross-sectional studies, and animal studies were excluded. Data extraction and synthesis Two authors independently reviewed studies for inclusion, extracted data, and assessed study quality. Meta-analysis was conducted to generate pooled odds ratios (ORs) for cognitive decline and hazard ratios (HRs) for dementia. Sources of heterogeneity were explored through subgroup analyses. Results A total of 24 studies were included for cognitive decline and 23 for dementia. Poor periodontal health was associated with increased odds of cognitive decline (OR = 1.23; 95% CI: 1.05–1.44) and dementia (HR = 1.21; 95% CI: 1.07–1.38). Tooth loss also appeared to increase the risk independently. However, significant heterogeneity existed between studies. Conclusions Poor periodontal health may increase the risk of cognitive decline and dementia, but the quality of evidence was low. Further high-quality, longitudinal studies with standardized assessments are needed to establish causality.