Recent studies suggest vitamin-D deficiency is associated with increased odds of cognitive impairment and dementia in later life, although previous findings from the United States have been mixed. Interest in vitamin D has intensified recently as research has suggested that it may play a role in a variety of age-associated diseases.

David Llewellyn, of the University of Exeter Peninsula Medical School ( UK ), and colleagues examined information from 3,325 adults aged 65 years and older from the Third National Health and Nutrition Examination Survey ( NHANES III ), a study that was carefully designed to accurately represent the U.S. non-institutionalized population.
Vitamin D levels were measured from blood samples and compared with performance on a measure of general cognitive function that incorporated tests of memory, orientation in time and space, and ability to maintain attention.

The researchers classified participants as being cognitively impaired if they scored in the worst 10 percent of older adults in the study. They found that the odds of cognitive impairment were about 42% higher in those people who were deficient in vitamin D, and 394% higher in people who were severely deficient.

According to Llewellyn, the majority of older adults have insufficient vitamin-D levels because skin becomes less efficient at producing vitamin D with age and sunlight ( UVB radiation ) levels are limited for much of the year.

Vitamin-D supplements have proven to be a safe, inexpensive and effective way to treat deficiency. However, few foods contain vitamin D and levels of supplementation are currently inadequate. More research is urgently needed to establish whether vitamin D supplementation has therapeutic potential for dementia.

Source: Alzheimer's Association, 2010

XagenaMedicine_2010