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PARIS, FRANCE. It is now generally accepted that cumulative oxidative damage to cells and DNA is the
major cause of aging. There is substantial evidence that oxidative stress is intimately associated with
atherosclerosis and thrombosis (blood clot formation). Now researchers at the Hopital de la Salpetriere
report that oxidative stress is also involved in mental (cognitive) decline among older people. Their study
involved 684 women and 482 men born between 1922 and 1932. The participants had blood samples
drawn upon entry to the study and also underwent the Mini-Mental Status Examination (MMSE), a
recognized test of mental functioning. The blood samples were analyzed for carotenoids, vitamin E (in red
blood cells), selenium, and TBARS. TBARS (thiobarbituric acid reactive substances) level is a reliable
indicator of oxidative stress. After four years the participants underwent another MMSE and the results were
compared to those obtained at entry to the study. A clear association between TBARS levels and the extent
of cognitive decline as determined by MMSE scores was discovered. The participants with the highest
levels of TBARS were more than twice as likely to have experienced a significant mental decline over the
four-year test period than were the participants with lower levels.
The participants with low levels of selenium were found to have a 58 per cent higher risk of experiencing
mental decline than the participants with higher levels. The researchers also found a clear association
between high selenium levels and educational levels perhaps indicating that better educated people eat a
healthier diet or are more likely to take supplements. No association between mental decline and blood
levels of vitamin E or carotenoids was observed, but there was a significant inverse relation between vitamin
E levels and TBARS levels. The researchers conclude that poor antioxidant status is associated with a
greater risk of cognitive impairment and that this risk may be substantially reduced by supplementing with
antioxidants. NOTE: This study was partially funded by Merck, Sharp and Dohme, a major manufacturer of
pharmaceuticals.
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