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Study: Low Vitamin D Levels Associated With Cognitive Decline

A new study concludes that older adults who are deficient in vitamin D are more likely to experience serious declines in their ability to think and plan.

Low levels of vitamin D have been associated with bone fractures, pain, and chronic diseases such as cancer, heart disease, diabetes and multiple sclerosis.

Researchers have found a link between deficiencies of the so-called "sunshine" vitamin and cognitive decline in older adults. One of the most common causes of vitamin D deficiency is a lack of exposure to sunlight, a particular concern for less physically-active seniors who are likely to spend fewer hours outdoors.

In tests conducted on more than 850 Italian adults ages 65 and older, scientists at Peninsula Medical School in England found that those with the lowest levels of vitamin D were 60 percent more likely to suffer a cognitive decline. "About a billion people worldwide do not have high enough levels of vitamin D. And obviously dementia itself is so common too that if there is any association between vitamin D levels and dementia it is something we should be concerned about," said Researcher David Llewellyn, a specialist in dementia, who led the study:

Llewellyn and colleagues followed the study participants for over six years, beginning in 1998, when investigators administered initial tests measuring the adults' attention span, ability to learn, to remember, and to plan and organize tasks.

While the researchers observed steep declines in most of these cognitive skills among adults with the lowest levels of vitamin D, attention span was the one exception, with test results showing no significant impact from the low vitamin levels.

Llewellyn says the discovery of a strong connection between dementia and inadequate levels of vitamin D is, in a way, good news. "Because we can treat vitamin D deficiency quite easily with supplements, which have already shown to be cheap but cost effective and safe. And we know they reduce the risk of falls and fractures and even early death. So, we are quite excited about it because it opens up the possibility that if we do clinical trials we may be able to reduce the incidence of new cases of dementia," he said.

Researchers think vitamin D may reduce mental decline by enhancing the formation of nerve tissue that is essential to a variety of brain functions, including enhanced cognitive ability.

Bill Thies is the chief medical and scientific officer at the Alzheimer's Association in Chicago, Illinois. The organization promotes research into the treatment and cure of the progressive neuro-degenerative disorder, which causes profound memory loss and eventual death.

While studies have shown that patients already suffering from Alzheimer's do not respond to vitamin D, Thies says it is possible dietary supplements of the micronutrient early in the disease process could prevent or slow the illness. "It may be very likely that vitamin D levels may be important as preventatives for Alzheimer's disease, but can not overcome the devastation of the disease once it is established," Thies said.

The study linking low levels of vitamin D and mental decline is published this week in the journal Archives of Internal Medicine.