Periodontal disease and risk of dementia: a systematic review and meta-analysis

Periodontal disease is a biofilm-associated, host-mediated inflammatory disease characterized by inflammation and destruction of the tooth-supporting tissues. An association between periodontal disease and adverse cognitive outcomes, including dementia, has been proposed; however, findings across studies remain inconsistent.

To systematically synthesize and examine the temporal association between periodontal disease and subsequent cognitive impairment and incident dementia.

Six large databases were searched for studies published from January 2000 to June 2025. Eligible studies employed longitudinal or prospective designs in which periodontal disease was assessed prior to cognitive outcomes. Data extraction and methodological quality assessment were performed independently by multiple reviewers. Adjusted hazard ratios (HRs) for incident all-cause dementia were pooled using random-effects meta-analysis where appropriate.

Thirteen studies met the inclusion criteria and were included in the synthesis. Most studies reported a positive association between periodontal disease and adverse cognitive outcomes. Four studies were included in the meta-analysis, which demonstrated a modest but statistically significant association between periodontal disease and incident all-cause dementia (pooled HR ≈ 1.12; 95% confidence interval, 1.01-1.24).

Longitudinal evidence suggests that periodontal disease is associated with an increased risk of incident dementia and cognitive decline. Although evidence across studies supports periodontal disease as a potentially relevant exposure associated with adverse cognitive outcomes, causality cannot be inferred.

Overall, the findings indicate an association between periodontal disease and adverse cognitive outcomes across longitudinal studies that is consistent with proposed biological mechanisms linking periodontal disease and cognitive impairment. However, heterogeneity in periodontal disease definitions, cognitive outcome measures, and variations in confounding adjustment across studies limited interpretation of the observed associations. Residual confounding and potential reverse causation cannot be fully excluded, underscoring the need for well-designed prospective and interventional studies.