Oxidative stress and dementia in oldest-old subjects

The possible involvement of oxidative damage and antioxidant protection has been suggested in the pathogenesis of dementia, a cognitive disorder whose prevalence increase with aging. In this study we investigated the relationship between dementia and plasma status of antioxidants and oxidative products in oldest-old subjects. Plasma levels of thiobarbituric acid-reactive substances (TBARS), vitamin A, vitamin E, coenzyme Q10 (CoQ10), and serum levels of selenium (Se) and zinc (Zn) were determined in 30 demented patients aged 90 to 107 years in comparison with 32 normal individuals aged 90 to 103 years. Dementia was diagnosed according to DSM-IV criteria. TBARS, vitamin A, vitamin E and CoQ10 were measured by HPLC method. Zn and Se were measured by absorption spectrometry. Vitamins were expressed as lipid-adjusted concentrations. Demented men had higher plasma TBARS (p = 0.037) and lower plasma lipid-adjusted vitamin E (p = 0.043) than normal men, whereas no difference was found for the remaining variables. No difference was found between demented and normal women for the variables of interest. In oldest-old men, but not in women, dementia seems to be associated with an enhanced lipid peroxidation and a reduced vitamin E reserve. It remains to be resolved, however, as to whether this enhanced oxidative stress is a cause or a result of lowered antioxidants.