Study Confirm Link Between Deficiency of Vitamin D and Dementia

A team of international researchers found that deficiency of vitamin D is linked with elevated risk of dementia and Alzheimer's disease in older adults.

Researchers at the University of Exeter Medical School, based their finding on the evaluation of elderly Americans who were a part of the Cardiovascular Health Study. The study included 1,658 participants - aged between 65 years and above. They were able to walk unaided and did not suffer from dementia or cardiovascular disease and stroke at the start of the study.  They were followed for six years.

They noticed that those with severe deficiency of vitamin D had a two-fold increased risk of developing dementia and Alzheimer's disease. Those with moderate deficiency of vitamin D had 53 percent increased risk of developing dementia; and those with severe deficiency had a 125 percent increased risk of the disease.

Vitamin D - essential for strong bones, muscles and overall health - comes from three main sources. These include fish, vitamin D supplements and exposure of skin to sunlight. Older people are more likely to have vitamin D deficiency and be reliant on other sources as their skin is less efficient at converting sunlight into vitamin D. In most countries, UVB radiation in winter is too low to allow vitamin D production.

Surprisingly, similar results were seen for Alzheimer's disease.  People with moderate deficiency of vitamin D were 60 percent more likely to develop Alzheimer's disease. The risk increased to a 122 percent in those with severe deficiency.

Dr Llewellyn said: "We expected to find an association between low Vitamin D levels and the risk of dementia and Alzheimer's disease, but the results were surprising -- we actually found that the association was twice as strong as we anticipated. Clinical trials are now needed to establish whether eating foods such as oily fish or taking vitamin D supplements can delay or even prevent the onset of Alzheimer's disease and dementia. We need to be cautious at this early stage and our latest results do not demonstrate that low vitamin D levels cause dementia."

Dementia is listed as one of the largest challenges of present times - with 44 million cases worldwide. The experts predict that the number will increase three-fold by 2050 due to rapid population aging. This is the first study to investigate the association between vitamin D and dementia risk.

The finding is documented in the journal Neurology.