Abstract Body: Introduction: Studies have linked inferior oral health and limited dietary diversity with dementia independently, but their combined impact on cognition remains unprobed.
Methods: We included 14,918 participants aged 65 and over from seven waves (1998–2014) of the Chinese Longitudinal Healthy Longevity Survey, with follow-up to 2018. We assessed oral health using baseline data on natural teeth and denture use, and dietary diversity through a food frequency questionnaire. Cognitive impairment was defined as a Mini-Mental State Examination score below 24. We used Cox proportional hazards models to examine the independent and joint effects of oral health and dietary diversity on cognitive impairment risk, adjusting for demographics, lifestyles, and comorbidities.
Results: Among 14,918 participants (mean age 81.4 years, 48.4% female), 6,132 participants developed cognitive impairment during a median follow-up of 3.3 (IQR: 2.7–6.2) years. We found that either possessing 20 or more natural teeth coupled with denture use (Hazard Ratio = 0.58, 95% CI: 0.48–0.71), or maintaining a higher dietary diversity (HR = 0.73, 95% CI: 0.70–0.77), was associated with a reduced risk of cognitive impairment, respectively. In the joint effect analysis, compared to those with fewer teeth, no denture utilization, and low dietary diversity, individuals with 20 or more natural teeth and denture use, jointly with high dietary diversity, exhibited the lowest risk of cognitive impairment (HR = 0.43, 95% CI: 0.33–0.55, P-interaction = 0.047).
Conclusion: Retaining a good oral health status, through natural teeth maintenance and denture aids, along with a diverse diet, is associated with a lower cognitive impairment risk in Chinese older adults.