Antioxidant defences and oxidative stress markers in erythrocytes and plasma from normally nourished elderly Alzheimer patients

Objectives: to investigate blood markers of oxidative stress, and enzymatic and non-enzymatic antioxidants in normally nourished elderly people with A lzheimer's disease. Design: case-control study. Subjects: twenty patients with Alzheimer's disease and 23 elderly control s ubjects, living at home, free from disease and not undergoing any treatment known to have a strong influence on blood oxidative stress markers or anti oxidant defence systems. Methods: we performed a nutritional evaluation, including anthropometric an d biological measures and a 3-day dietary record. We determined concentrati ons of antioxidant vitamins (alpha -tocopherol, retinol) and malondialdehyd e in plasma and erythrocytes. We also measured erythrocyte enzymatic activi ties of glutathione peroxidase and copper-zinc superoxide dismutase. Results: the two groups were similar in age, body, mass index, dietary reco rd and serum albumin concentration. After adjustment for age, sex and cardi ovascular co-morbidity, mean plasma concentration of alpha -tocopherol was lower in those with Alzheimer disease than in control subjects (15 +/- 3.5 mg/l compared with 18.2 +/- 3.5; P=0.002), as was the mean plasma concentra tion of retinol (0.54 +/-0.2 mg/l ts 0.7 +/-0.2; P=0.014). The mean concent ration of free plasma malondialdehyde was higher in those with Alzheimer's disease (0.70 +/-0.2 mmol/l is 0.5 +/-0.1; P=0.036). In Alzheimer disease p atients, free plasma malondialdehyde concentrations were inversely correlat ed with levels of alpha -tocopherol (P=0.002) and retinol (P=0.025). Erythr ocyte levels of vitamins and enzymatic activities were similar in the two g roups. Conclusion: lower plasma concentrations of alpha -tocopherol and retinol in normally nourished elderly patients with Alzheimer's disease than in contr ols could suggest that these antioxidant vitamins had been consumed as a re sult of excessive production of free radicals.