Increased Peroxidation and Reduced Antioxidant Enzyme Activity in Alzheimer's Disease

The overall peroxidation activity in brain tissue by region from patients with Alzheimer's disease (AD) and age-matched controls was determined employing the thiobarbituric acid-reactive substances (TBARS) assay, a measure of lipid peroxidation, followed by a determination the activities of the antioxidant enzymes Cu/Zn superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT), in the frontal, temporal, and cerebellar cortex of 10 AD and 9 control brains. The level of TBARS was elevated in all regions, with particular statistical significance in the temporal cortex when compared to age-matched controls. SOD activity was significantly decreased in AD frontal and AD temporal cortex, while catalase activity was significantly decreased in AD temporal cortex. There was no significant difference in GSH-Px activity found in any of the regions examined. This study supports the theory that in AD the brain is affected by increased oxidative stress which, when combined with a decrease in SOD activity, produces oxidative alterations, seen most significantly in temporal cortex in AD, where the pathophysiologic changes are most severe.