Systemic oxidative stress in older patients with mild cognitive impairment or late onset Alzheimer's disease

A growing body of evidence from in vitro and animal models suggest that oxidative stress (OxS) might be involved in the pathogenesis of late onset Alzheimer's disease (LOAD). In contrast, data on human studies are scarce and controversial, mostly because of methodological limitations and low sample size. To address this issues, we evaluated the serum levels of products of lipid peroxidation, hydroperoxides, advanced oxidation protein products, homocysteine, total and residual antioxidant power, thiols, and uric acid in a sample of 395 older individuals: 101 LOAD patients, 173 patients with mild cognitive impairment (MCI), and 121 non-demented healthy controls. At univariate analysis, serum hydroperoxides were higher while residual antioxidant power was lower in MCI and LOAD compared with controls. By multivariate logistic regression analysis we found that, compared with controls, an increase of hydroperoxides levels were independently associated with a likehood to developed MCI or LOAD. Furthermore, residual antioxidant power levels decreases were associated with an increased risk of having MCI but not LOAD. Our study is among the first showing that a derangement of systemic redox balance might be an early event in LOAD development