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Decreases in plasma selenium linked to cognitive decline in elderly
  NEW YORK (Reuters Health) - Results of a longitudinal cohort study suggest that selenium status decreases with age and may contribute to declines in neuropsychological functions among the elderly.
"Because brain oxidative stress is a cause of cognitive impairment, selenium, which is an antioxidant, may protect against cognitive decline," Dr. N. Tasnime Akbaraly, of Universite Montpellier, France, and colleagues write in the January issue of Epidemiology.
The researchers recruited 1389 community-dwelling French subjects during 1991 to 1993 for a 9-year longitudinal study with 6 waves of follow-up. The participants ranged in age from 60 to 71 years at baseline when they provided information on sociodemographic factors and were tested to assess cognitive function.
Serum selenium levels were determined using electrothermal atomic absorption spectrometry. The baseline mean plasma selenium level was 1.09 μmol/L, and a decrease was observed over the entire follow-up period. Mean levels of selenium declined -0.055 μmol/L at 2 years and -0.096 μmol/L at 9 years.
The investigators report that cognitive decline was associated with decreases of plasma selenium over time after controlling for potential confounders.
Among subjects whose plasma selenium levels decreased, there was a higher probability of cognitive decline with greater decreases of plasma selenium. For those who had an increase in their levels of plasma selenium, greater cognitive decline was observed in those with the smallest selenium increases. No association was found between short-term selenium change and cognitive changes.
"Our results, together with information on involvement of selenoproteins in brain functions, support possible relationships between selenium status and neuropsychologic functions in aging people," Dr. Akbaraly's team concludes.
"In this context, the preventive effect of selenium supplementation at a nutritional level needs to be evaluated with large-scale studies," they suggest. "This dynamic approach could shed new lights on the potential benefits of supplementation."
Epidemiology 2007;18:52-58.
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