Smoking impairs cognitive function through the mediating effect of periodontitis in older adults.

OBJECTIVES: Evidence has shown that both smoking and periodontitis were linked to cognitive impairment. This study examines whether periodontitis mediates the effects of smoking status on cognitive function in older adults. METHODS: Using data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014, the study included 1728 older participants who have data on smoking, serum cotinine, periodontal examination, and cognitive function. Mediation analysis was performed to test whether extent of periodontitis mediated associations between smoking status and cognitive function, adjusted for sociodemographic and basic health factors. RESULTS: Compared to never-smokers, daily smokers exhibited significantly worse global cognitive function, with periodontitis mediating this effect (effect= -0.16; 95% CI= -0.29, -0.05). Similarly, periodontitis mediated the association between serum cotinine levels and cognitive function in the total sample (effect= -0.02; 95% CI= -0.03, -0.00). CONCLUSIONS: Periodontitis significantly mediates the impact of smoking on cognitive function. The findings highlight the potential roles of maintaining oral health and smoking cessation in mitigating cognitive decline.