Chewing disability is associated with cognitive impairment among older adults: a population-based cohort study.

BACKGROUND: Chewing disability is associated with impaired quality of life, potentially leading to depression and cognitive impairment. While the chewing-ability-cognition relationship has been explored, examining whether depression mediates this relationship remains unclear. We investigated the association between chewing disability and cognitive impairment development and a potential mediation via depression among older persons.

METHODS: Older persons without cognitive impairment at baseline (n=973) from the three waves of the Panel on Health and Ageing of Singaporean Elderly (PHASE) were investigated. The outcome was incident cognitive impairment by the end of the study, while the exposure was chewing disability over the study period. Time-varying depression was the mediator. Time-fixed confounders included sex, ethnicity, education, marital status, living arrangement, and housing type, and time-varying confounders were age, smoking, cardiovascular diseases, diabetes, number of teeth, and denture wearing. We used marginal structural modeling to evaluate the effect of chewing disability on cognitive impairment development.

RESULTS: After six years, 11% developed cognitive impairment and chewing disability was reported by 33%. Chewing disability was associated with higher odds of developing cognitive impairment (OR 1.43, 95% CI 1.09, 1.87), of which 85.3% was explained by the controlled direct effect of chewing disability, whereas the remaining 14.7% could be eliminated if there was no depression.

CONCLUSIONS: Our findings indicate an association between chewing disability and cognitive impairment, while the role of depression could not be fully elucidated. Oral health should be incorporated as part of older persons' care for its potential to assess the risk for other systemic conditions.