Examining the combined effects of social isolation and oral dysfunction on cognitive decline in community-dwelling older Japanese adults.

Aim: This research examines the relationship between cognitive decline and the combined factors of social isolation and oral dysfunction among community-dwelling older adults.

Methods: The participants of this cross-sectional study were community-dwelling older adults. Oral dysfunction (OD) was assessed using the Kihon checklist. Social isolation (SI) was assessed using two measures: reduced social contact and social disengagement. Mild cognitive impairment (MCI) was assessed using the National Center for Geriatrics and Gerontology-Functional Assessment Tool. The participants were classified into four groups according to OD and/or SI. Logistic regression analysis was conducted with MCI as the objective variable, and OD and/or SI as the independent variable.

Results: Of the 13 142 participants, the median age was 72 years (interquartile range 69-77 years), and 44.7% were men. Significantly higher odds ratios for MCI were found in the non-OD/SI (odds ratio1.16, 95% confidence interval 1.04-1.30) and OD/SI (odds ratio1.36, 95% confidence interval 1.15-1.61) groups than in the non-OD/non-SI group. There was no statistically significant association between OD/non-SI and MCI.

Conclusion: The combined factors of social isolation and oral dysfunction were associated with cognitive decline, and the single factors of social isolation were associated with cognitive decline. Geriatr Gerontol Int 2025; 25: 1108-1114.