Poor Oral Health and Risk of Incident Dementia: A Prospective Cohort Study of 425,183 Participants

Background: The association between poor oral health and the risk of incident dementia remains unclear. Objective: To investigate the associations of poor oral health with incident dementia, cognitive decline, and brain structure in a large population-based cohort study. Methods: A total of 425,183 participants free of dementia at baseline were included from the UK Biobank study. The associations between oral health problems (mouth ulcers, painful gums, bleeding gums, loose teeth, toothaches, and dentures) and incident dementia were examined using Cox proportional hazards models. Mixed linear models were used to investigate whether oral health problems were associated with prospective cognitive decline. We examined the associations between oral health problems and regional cortical surface area using linear regression models. We further explored the potential mediating effects underlying the relationships between oral health problems and dementia. Results: Painful gums (HR = 1.47, 95% CI [1.317–1.647], p < 0.001), toothaches (HR = 1.38, 95% CI [1.244–1.538], p < 0.001), and dentures (HR = 1.28, 95% CI [1.223–1.349], p < 0.001) were associated with increased risk of incident dementia. Dentures were associated with a faster decline in cognitive functions, including longer reaction time, worse numeric memory, and worse prospective memory. Participants with dentures had smaller surface areas of the inferior temporal cortex, inferior parietal cortex, and middle temporal cortex. Brain structural changes, smoking, alcohol drinking, and diabetes may mediate the associations between oral health problems and incident dementia. Conclusion: Poor oral health is associated with a higher risk of incident dementia. Dentures may predict accelerated cognitive decline and are associated with regional cortical surface area changes. Improvement of oral health care could be beneficial for the prevention of dementia.