Relationships between cognitive function and frailty in older Korean adults: The moderating effect of the number of teeth.

Background: Cognitive function and physical frailty are known to be closely related. Among older adults with dementia, those who wear dentures have a higher mortality rate than those who do not wear them. This suggests the possibility that oral health may affect the cognitive-frailty relationship. This study aims to investigate whether the number of teeth present, acts as a moderating variable in the cognitive function-frailty relationship.

Methods: Data were obtained from the cross-sectional baseline study of the Korean Frailty Aging Cohort Study (2016-2017). Cognitive function was assessed using the Mini-Mental State Examination. Frailty score was based on the Cardiovascular Health Study Index. Oral condition was evaluated by the number of teeth present and analyzed using categories of 0-9 teeth, 10-19 teeth, and ≥20. The moderation effect was analyzed using the ordinary least squares (OLS) regression.

Results: Data on 2,310 older adults (1,110 men; mean age 75.9 ± 3.9 years) was analyzed. Adjusting for age, sex, income, education, alcohol drinking, body mass index, and number of comorbidities, cognitive function and frailty showed a negative association (B=-.030, p = .011). In the 10-19 teeth category, compared to the 0-9 teeth category, a negative association with frailty was found (B=-.152, p = .026). A significant interaction effect between the number of teeth and cognitive function was detected (p = .007).

Conclusion: The number of teeth may modify the degree of the association between cognitive function and frailty. For effective frailty management of older persons, cognitive function management and oral management should be considered and performed together.