Systemic Oxidative Stress and Cognitive Performance in the Population-Based EVA Study

The aim of this study was to examine the relationships between cognitive functioning and blood levels of antioxidants and lipoperoxidation products in an elderly population. In 1991–1992, 1389 volunteers (574 men and 815 women aged 59 to 71 years) were recruited from the general population. Levels of selenium, carotenoids, and thiobarbituric-reactive substances in plasma and of vitamin E, glutathione peroxidase, and Cu-Zn superoxide dismutase in red blood cells were measured. Cognitive functioning was assessed with various psychometric tests. We used logistic regression to estimate the risk of poor cognitive functioning (<25th percentile of the score distribution) associated with low values of each antioxidants (<25th percentile) including potential confounding factors. A low level of total carotenoids (<1.86 μmol/l) was associated with poor cognitive performance in two tests assessing visual attention and logical reasoning: the Trail-Making Test part B [OR = 1.34 IC95% (0.99–1.81), p = .055] and the Digit Symbol Substitution from the WAIS-R [OR = 1.38 IC95% (1.02–1.89), p = .04]. Low levels of other antioxidants and high levels of thiobarbituric-reactive substances were not related to poor cognitive functioning. Results observed with plasma carotenoids are in accordance with previous data obtained mostly from dietary records.