Meta Analysis of the Correlation between Periodontal Health and Cognitive Impairment in the Older Population

OBJECTIVE: To explore the correlation between periodontal health and cognitive impairment in the older population to provide the evidence for preventing cognitive impairment from the perspective of oral health care in older adults. METHODS: A comprehensive search was conducted in PubMed, Embase, the Cochrane Library, the Web of Science, the China National Knowledge Infrastructure, Wanfang Data, the China Science and Technology Journal Database, and the China Biomedical Literature Database, to include both cross-sectional and longitudinal cohort studies on the association between periodontal health and cognitive impairment in older adults. The search was completed in April 2023. Following quality assessment and data organization of the included studies, meta-analysis was performed using Review Manager 5.4. RESULTS: Twenty-two studies involving a total of 4,246,608 patients were included to comprehensively assess periodontal health from four dimensions (periodontitis, tooth loss, occlusal support, and masticatory ability), with the outcome variable of cognitive impairment (including mild cognitive impairment, Alzheimer's disease and all-cause dementia). Meta-analysis showed that, compared to those of periodontally healthy older adults, the risk of cognitive impairment in older adults with poor periodontal health, after adjusting for confounders, was significantly greater for those with periodontitis (OR=1.45, 95% CI: 1.20-1.76, P<0.001), tooth loss (OR=1.80, 95% CI: 1.50-2.15, P<0.001), compromised occlusal support (OR=1.87, 95% CI: 1.29-2.70, P=0.001), and reduced masticatory ability (OR=1.39, 95% CI: 1.11-1.75, P=0.005). The risk of cognitive impairment was higher in older adults with low-dentition than in those with high-dentition. Subgroup analysis revealed older individuals with fewer remaining teeth were at a higher risk of developing cognitive impairment compared to those with more remaining teeth, as shown by the comparison of number of teeth lost (7-17 teeth compared to 0-6 teeth) (OR=1.64, 95% CI: 1.13-2.39, P=0.01), (9-28 teeth compared to 0-8 teeth) (OR=1.13, 95% CI: 1.06-1.20, P<0.001), (19-28 teeth compared to 0-18 teeth) (OR=2.52, 95% CI: 1.32-4.80, P=0.005), and (28 teeth compared to 0-27 teeth) (OR=2.07, 95% CI: 1.54-2.77, P<0.001). In addition, tooth loss in older adults led to a significantly increased risk of mild cognitive impairment (OR=1.66, 95% CI: 1.43-1.91, P<0.001) and all-cause dementia (OR=1.35, 95% CI: 1.11-1.65, P=0.003), although the correlation between tooth loss and the risk of Alzheimer's disease was not significant (OR=3.89, 95% CI: 0.68-22.31, P=0.13). CONCLUSION: Poor periodontal health, assessed across four dimensions (periodontitis, tooth loss, occlusal support, and masticatory ability), represents a significant risk factor for cognitive impairment in older adults. The more missing teeth in older adults, the higher risk of developing cognitive impairment, with edentulous individuals particularly susceptible to cognitive impairment. While a certain degree of increased risk of Alzheimer's disease was observed, no significant association was found between tooth loss and the risk of developing Alzheimer's disease. Enhancing periodontal health management and delivering high-quality oral health care services to older adults can help prevent cognitive impairment.