Association Between Oral Health Status and Cognitive Function Among Older Japanese

Objectives: Epidemiologic data examining the relationship between oral health status and cognitive status are sparse, especially in Asian populations. This study aimed to assess whether periodontal disease and tooth loss were related to cognitive impairment among older Japanese.
Methods: Study participants were 291 Japanese (101 men and 190 women, average age: 80.9 years), classified into three groups based on a clinical examination of oral health status: no periodontal disease, periodontal disease, and edentulous. Cognitive impairment was defined using the results of the Mini-Mental State Examination (MMSE) and Hasegawa Dementia Scale-Revised (HDS-R) scores. Multivariable logistic regression analyses assessed the relationship of the three-category oral health status variable (reference category = no periodontal disease) with low MMSE score (≤23) and low HDS-R score (≤20). Age, gender, years of education, body mass index, smoking status, drinking behavior and history of cardiovascular disease were tested as potential confounders.
Results: Among 291 study participants, 108 (37.1% [108/291]) had no teeth. There were 183 dentate participants, with 84 (45.9% [84/183]) defined as having periodontal disease. Of all study participants, 70 (24.1% [70/291]) had an MMSE score ≤23 and 32 (11.0 % [32/291]) had an HDS-R score ≤20. Periodontal disease and edentulous were significantly associated with a greater odds of low cognitive performance. The multivariable adjusted odds ratios (ORs) (95% confidence intervals [CIs]) for low MMSE score associated with periodontal disease and edentulous were 2.21 (1.01–4.84) and 2.28 (1.06–4.90), respectively. The multivariable adjusted ORs (95% CIs) for low HDS-R score associated with periodontal disease and edentulous were 4.85 (1.29–18.15) and 3.86 (1.05–14.20), respectively.
Conclusions: Poor oral health status was significantly associated with cognitive impairment among community-dwelling older Japanese. Additional longitudinal epidemiological studies with larger, more diverse populations and more complete information are needed to substantiate our findings.