Selenium loss linked to cognitive decline in aged

NEW YORK (Reuters Health) - The results of a new study conducted by researchers in France suggest that selenium levels decrease with age, which may contribute to a loss of neurological abilities in the elderly.

Because "oxidative stress" is one cause of brain impairment, "selenium, which is an antioxidant, may protect against cognitive decline," Dr. N. Tasnime Akbaraly, of Universite Montpellier, and colleagues report in the journal Epidemiology.

Cognitive function refers to how the brain processes information, and includes functions such as comprehension, decision-making, memory and learning, abilities that may be lost in dementia.

The researchers recruited 1,389 French subjects between 1991 and 1993 for a 9-year study with 6 follow-up periods. At study entry, the participants ranged in age from 60 to 71 years and provided information on social factors, demographic factors and underwent tests to assess cognitive function. Overall, 703 subjects completed the study.

At study entry, the average selenium levels in the blood were 1.09 micromoles per liter -- and the average levels decreased by the end of the study. However, declines were not seen in all subjects.

The investigators report that cognitive decline was associated with decreases of selenium over time, after accounting for other risk factors. Subjects with the highest levels of selenium loss had a higher probability of cognitive decline.

For subjects with increases in selenium levels, those with the smallest increases had a higher rates of cognitive decline compared with those with the largest selenium increases. No association was found between short-term selenium changes and cognitive changes.

These findings, along with information on the relationship between brain functions and selenoproteins, proteins containing selenium, support a relationship between selenium levels and cognitive function in the elderly, Akbaraly's team concludes.

The ability of selenium supplements to protect against the loss of cognitive function in the elderly needs to be evaluated in a large clinical trial, the researchers suggest. "This dynamic approach could shed new light on the potential benefits of supplementation."

SOURCE: Epidemiology, January 2007.