Education and dementia - What lies behind the association?

Background: Low education seems to be associated with an increased risk of dementia and Alzheimer disease ( AD). People with low education have unhealthier lifestyles and more cardiovascular risk factors, but it is unclear how this affects the association between education and dementia. Methods: Participants of the Cardiovascular Risk Factors, Aging and Dementia ( CAIDE) study were derived from random, population- based samples previously studied in a survey in 1972, 1977, 1982, or 1987. After an average follow- up of 21 years, 1,449 individuals ( 72%) aged 65 to 79 participated in a re- examination in 1998. Results: Compared to individuals with formal education of 5 years or less, those with 6 to 8 years of education had OR of 0.57 ( 95% CI 0.29 to 1.13), and those with 9 years of education or more had OR of 0.16 ( 95% CI 0.06 to 0.41) for dementia. The corresponding ORs for AD were 0.49 ( 0.24 to 1.00) and 0.15 ( 0.05 to 0.40). The associations remained unchanged after adjustments for several demographic, socioeconomic, vascular, and lifestyle characteristics. The results were similar among both men and women. ApoE4 did not modify the association, but the risk of dementia and AD was very low among ApoE4 noncarriers with high education. Conclusions: The association between low education and dementia is probably not explained by the unhealthy lifestyles of the less educated compared with higher educated persons. Higher educated persons may have a greater cognitive reserve that can postpone the clinical manifestation of dementia. Unhealthy lifestyles may independently contribute to the depletion of this reserve or directly influence the underlying pathologic processes.