May 22 (HealthDay News) -- High levels of vitamin D might help keep the brain healthy as people age, new research suggests.

For the study, which included more than 3,000 European men aged 40 to 79, the researchers assessed the men's memory and how quickly they processed information. They also examined other factors that affect mental agility, such as physical activity levels and mood. Blood samples were taken to measure the men's circulating levels of vitamin D, which the body produces through exposure to sunlight and obtains through dietary sources.

The study authors found that high circulating vitamin D levels were associated with high scores on memory and information-processing tests, while low vitamin D levels were associated with poor scores. The findings appear online in advance of publication in the print issue of the Journal of Neurology, Neurosurgery and Psychiatry.

The exact link between circulating vitamin D levels and mental agility isn't clear, but it's possible that vitamin D increases certain hormonal activity or protects neurons and chemical-signaling pathways, according to the researchers.

"Previous studies exploring the relationship between vitamin D and cognitive performance in adults have produced inconsistent findings, but we observed a significant, independent association between a slower information processing speed and lower levels of vitamin D," said study author David M. Lee, of the University of Manchester in the United Kingdom, in a news release from the university.

"The main strengths of our study are that it is based on a large population sample and took into account potential interfering factors, such as depression, season and levels of physical activity," Lee added. "Interestingly, the association between increased vitamin D and faster information processing was more significant in men aged over 60 years, although the biological reasons for this remain unclear."

If vitamin D supplements can help reduce the effects of aging on the brain, the health implications could be significant because many people, particularly the elderly, are vitamin D-deficient, the researchers pointed out.

SOURCE: University of Manchester, news release, May 20, 2009