Plasma levels of antioxidants are not associated with Alzheimer's disease or cognitive decline.

Antioxidants prevent oxidative stress that possibly causes neuronal loss in Alzheimer's disease (AD). We examined whether high plasma levels of the antioxidant vitamins A and E were associated with lower prevalence of AD or cognitive decline (CD). We performed a cross-sectional study within the Rotterdam Study. In an univariate model, higher levels of vitamins A and E were significantly associated with lower prevalence of AD. However, when additional adjustments were made for important confounders, such as age, gender and total cholesterol, the relation substantially weakened -- odds ratios per standard deviation increase were 0.87 (95% CI 0.64-1.19) for vitamin A and 0.94 (95% CI 0.60-1.48) for vitamin E. Antioxidants were not related to CD in non-demented subjects. Our findings suggest no association between plasma levels of vitamin A and E and AD or CD.