Changes in oral and cognitive functions among older Japanese dental outpatients: A 2-year follow-up study.

Background: The relationship between oral and cognitive functions among older people is highly debated.

Objective: To examine whether oral functions are related to changes in the levels of mild cognitive impairment (MCI) biomarkers in older Japanese outpatients.

Methods: This observational study included 52 outpatients aged ≥65 years who underwent dental examinations at the Fukuoka Dental College Hospital. The Mini-Mental State Examination (MMSE) was performed, and MCI blood biomarker levels were assessed at baseline and after 2 years. The present dental and periodontal conditions and the oral functions (tongue pressure and masticatory performance) were evaluated. Changes in parameters from baseline to follow-up were compared using the Wilcoxon signed-rank test, McNemar test or chi-squared test. Associations among changes in the parameters were analysed using Spearman's rank correlation coefficient.

Results: The follow-up rate in this study was 67%. The masticatory performance was improved (p < 0.001), whereas gingival inflammation was decreased (p < 0.001) over the 2-year period. A significant increase in the MMSE score (p < 0.001) and a decrease in MCI risk (p < 0.001) were noted. The decrease in MCI risk was correlated with the increase in both masticatory performance (ρ = -0.34; p < 0.05) and MMSE score (ρ = -0.56; p < 0.01).

Conclusion: A decrease in MCI risk, as demonstrated by the levels of the blood biomarkers, was correlated with an increase in the masticatory performance in Japanese outpatients.