Vitamin D-dementia link confirmed

A link between vitamin D and dementia risk has been confirmed by an international team of researchers. Led by Dr David Llewellyn from the University of Exeter Medical School, the study found participants severely Vitamin D deficient were more than twice as likely to develop dementia and Alzheimer’s disease. “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,” said Llewellyn. The international team studied elderly participants in the Cardiovascular Health Study, an American study funded by the National Heart, Lung and Blood Institute. The 1,658 participants were aged 65 or over and free from dementia at the start of the study. They were followed for six years to see who went on to developed Alzheimer’s or dementia. Those moderately deficient in vitamin D had a 53% increased risk of developing dementia of any kind, with the risk increasing to 125% for those severely deficient. Similar results were recorded for Alzheimer’s disease; the moderately deficient group were 69% more likely to develop the disease, jumping to 122% for those severely deficient in vitamin D. The study also found evidence of a threshold level of vitamin D circulating in the bloodstream, below which the risk of developing Alzheimer’s or dementia increases. The team had hypothesised this might be 25-50 nmol/L and results confirm vitamin D levels above 50 nmol/L are most strongly associated with good brain health. “Clinical trials are now needed to establish whether eating food such as oily fish or taking vitamin D supplements can delay or even prevent the onset of Alzheimer’s disease and dementia,” said Llewellyn. “We need to be cautious at this early stage and our latest results do not demonstrate that low vitamin D levels cause dementia. “That said, our findings are very encouraging, and even if a small number of people could benefit, this would have enormous public health implications given the devastating and costly nature of dementia.” The study, published in Neurology, is the first to investigate a link between vitamin and dementia risk where the diagnosis was made by an expert disciplinary team using a wide range of information including neuroimaging. Vitamin D and the risk of dementia and Alzheimer disease