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Oxidative stress and Alzheimer's disease

PERUGIA, ITALY. Oxidative stress occurs when the body's antioxidant defenses are unable to cope with the free radical attacks and oxidation reactions taking place in the body. There is a great deal of evidence that suggests that oxidative stress plays a crucial role in the initiation and progression of Alzheimer's disease (AD).

A team of medical researchers from Italy, Germany and the USA now reports that they have found further evidence of oxidative stress in Alzheimer's disease. They measured the level of 8-hydroxy-2'- deoxyguanosine (8-OHdG), a marker of oxidative damage to DNA, in white blood cells taken from 40 elderly Alzheimer's patients and from 39 age- and sex-matched controls. They also measured blood plasma levels of vitamin A, vitamin C, vitamin E, and carotenoids in all participants. The level of 8-OHdG was found to be 76 per cent higher in the AD patients than in the controls. Antioxidant levels were significantly lower in the AD patients with vitamin C levels being 43 per cent lower, vitamin E 20 per cent lower, lycopene 60 per cent lower, and beta-cryptoxanthin 90 per cent lower. The researchers also found a significant inverse relationship between 8-OHdG level and the plasma levels of lycopene, lutein, alpha-carotene and beta- carotene in Alzheimer's patients but not in the controls.

The researchers speculate that the low antioxidant levels may be caused by the fact that AD itself generates large amounts of free radicals. Other research has shown that supplementation with vitamins C and E reduces the risk of developing dementia and AD.
Mecocci, Patrizia, et al. Lymphocyte oxidative DNA damage and plasma antioxidants in Alzheimer disease. Archives of Neurology, Vol. 59, May 2002, pp. 794-98

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