Periodontitis is associated with cognitive impairment among older adults: analysis of NHANES-III

Background: Periodontitis is ubiquitous and associated with serological evidence of exposure to periodontal organisms, systemic inflammation and vascular disease. Dementia is a major public health problem likely related to a complex interaction between genetics and diseases associated with systemic inflammation, including diabetes, smoking and stroke. Methods: To assess relationships between systemic exposure to periodontal pathogens and cognitive test outcomes, data were analysed from the Third National Health and Nutrition Examination Survey (NHANES-III), a nationally representative cross sectional observational study among older adults. We included 2355 participants > 60 years who completed measures of cognition and Poryphyromonas gingivalis IgG. Using SUDAAN, logistic regression models examined the association of P gingivalis IgG with cognitive test performance. Results: Poor immediate verbal memory (< 5/9 points) was prevalent in 5.7% of patients, and 6.5% overall had impaired delayed recall (< 4/9); 22.1% had difficulty with serial subtractions (< 5/5 trials correct). Individuals with the highest P gingivalis IgG (> 119 ELISA Units (EU)) were more likely to have poor delayed verbal recall (OR 2.89, 95% CI 1.14 to 7.29) and impaired subtraction (OR 1.95, 95% CI 1.22 to 3.11) than those with the lowest (<= 57 EU), with dose-response relationships for both (p trend, delayed memory = 0.045, subtraction = 0.04). After adjusting for socioeconomic and vascular variables, these relationships remained robust for the highest P gingivalis IgG group (delayed verbal memory OR 3.01 (95% CI 1.06 to 8.53); subtraction OR 2.00 (95% CI 1.19 to 3.36)). In contrast, immediate verbal memory was not significantly associated with P gingivalis. Conclusion: A serological marker of periodontitis is associated with impaired delayed memory and calculation. Further exploration of relationships between oral health and cognition is warranted.