Link between vitamin D and dementia risk confirmed

Vitamin D deficiency is associated with a substantially increased risk of dementia and Alzheimer's disease in older people, according to the most robust study of its kind ever conducted.

An international team, led by Dr David Llewellyn at the University of Exeter Medical School, found that study participants who were severely Vitamin D deficient were more than twice as likely to develop dementia and Alzheimer's disease.

The team studied elderly Americans who took part in the Cardiovascular Health Study. They discovered that adults in the study who were moderately deficient in vitamin D had a 53 per cent of developing dementia of any kind, and the risk increased to 125 per cent in those who were severely deficient.

Similar results were recorded for Alzheimer's disease, with the moderately deficient group 69 per cent more likely to develop this type of dementia, jumping to a 122 per cent increased risk for those severely deficient.

The study was part-funded by the Alzheimer's Association, and is published in August 6 2014 online issue of Neurology, the medical journal of the American Academy of Neurology. It looked at 1,658 adults aged 65 and over, who were able to walk unaided and were free from dementia, cardiovascular disease and stroke at the start of the study. The participants were then followed for six years to investigate who went on to develop Alzheimer's disease and other forms of dementia.

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 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. 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."

Research collaborators included experts from Angers University Hospital, Florida International University, Columbia University, the University of Washington, the University of Pittsburg and the University of Michigan. The study was supported by the Alzheimer's Association, the Mary Kinross Charitable Trust, the James Tudor Foundation, the Halpin Trust, the Age Related Diseases and Health Trust, the Norman Family Charitable Trust, and the National Institute for Health Research Collaboration for Leadership in Applied Research and Care South West Peninsula (NIHR PenCLAHRC).

Dementia is one of the greatest challenges of our time, with 44 million cases worldwide – a number expected to triple by 2050 as a result of rapid population ageing. A billion people worldwide are thought to have low vitamin D levels and many older adults may experience poorer health as a result.

The research is the first large study to investigate the relationship between vitamin D and dementia risk where the diagnosis was made by an expert multidisciplinary team, using a wide range of information including neuroimaging. Previous research established that people with low vitamin D levels are more likely to go on to experience cognitive problems, but this study confirms that this translates into a substantial increase in the risk of Alzheimer's disease and dementia.

Vitamin D comes from three main sources – exposure of skin to sunlight, foods such as oily fish, and supplements. Older people's skin can be less efficient at converting sunlight into Vitamin D, making them more likely to be deficient and reliant on other sources. In many countries the amount of UVB radiation in winter is too low to allow vitamin D production.

The study also found evidence that there is a threshold level of Vitamin D circulating in the bloodstream below which the risk of developing dementia and Alzheimer's disease increases. The team had previously hypothesized that this might lie in the region of 25-50 nmol/L, and their new findings confirm that vitamin D levels above 50 nmol/L are most strongly associated with good brain health.

Commenting on the study, Dr Doug Brown, Director of Research and Development at Alzheimer's Society said: "Shedding light on risk factors for dementia is one of the most important tasks facing today's health researchers. While earlier studies have suggested that a lack of the sunshine vitamin is linked to an increased risk of Alzheimer's disease, this study found that people with very low vitamin D levels were more than twice as likely to develop any kind of dementia.

"During this hottest of summers, hitting the beach for just 15 minutes of sunshine is enough to boost your vitamin D levels. However, we're not quite ready to say that sunlight or vitamin D supplements will reduce your risk of dementia. Large scale clinical trials are needed to determine whether increasing vitamin D levels in those with deficiencies can help prevent the from developing."

add to favorites email to friend print save as pdf

Related Stories

'Sunshine vitamin' link to cognitive problems in older people

Jan 22, 2009

Researchers from the Peninsula Medical School, the University of Cambridge and the University of Michigan, have for the first time identified a relationship between Vitamin D, the "sunshine vitamin", and cognitive impairment ...

Vitamin D deficiency may compromise immune function

Feb 25, 2014

Older individuals who are vitamin D deficient also tend to have compromised immune function, according to new research accepted for publication in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM) ...

Recommended for you

Putting dementia carers in control

Sep 18, 2014

Experts will explore how improved support and powers for people caring for loved-ones with dementia can improve quality of life for both patients and carers around the UK.

Lilly, AstraZeneca team up on Alzheimer's drug

Sep 16, 2014

Eli Lilly and Co. plans to pay up to $500 million to fellow drugmaker AstraZeneca as part of a collaboration to develop and sell a potential Alzheimer's disease treatment that is in the early stages of clinical testing.

User comments

Adjust slider to filter visible comments by rank

Display comments: newest first

JVK
1 / 5 (4) Aug 06, 2014
Excerpt from another study: "This study shows unequivocally that manipulation of P-gp by the VDR to increase efflux of soluble Aβ, likely the monomeric form, is a promising mechanism for the prevention and treatment of AD and that maintenance of adequate vitamin D levels in the elderly may be crucial in preventing neurodegeneration."
http://www.jneuro...abstract

Biophysically-constrained nutrient-dependent ecological variation leads to ecological adaptations via synthesis of Vitamin D in my model. That fact links the hormone, Vitamin D to the pheromone-controlled physiology of human reproduction via conserved molecular mechanisms in species of mammals. The conserved molecular mechanisms explain the link between reduced olfactory acuity and specificity and age-related dementias associated with neurodegenerative diseases.
animah
5 / 5 (6) Aug 06, 2014
For you to pretend science supports your self-serving commercial scams is beyond the pale.

James V Kohl is a fraud, a fake scientist. The "scent of Eros" he markets is a scam.

An article about James V Kohl and his pheromone con game: http://freethough...s-place/
Mike_Massen
4.5 / 5 (2) Aug 07, 2014
From a food scientist who has studied food chemistry & microbiology during a post grad some 30 years after a Ba Sci, re alzheimers as my mother was going through it...

Unfortunately, the Vast majority of researchers are ignoring western diet low mineral contents in our diet - its scary that so many are ignoring metalloid enzymes yet so many are fundamental to our health & well being !

Eg. We ingest ~200ug copper daily yet our ancestors in Europe ingested 30+mg daily, thats a huge differential. Given Copper manages a ~200 Enzymes then what can we expect from a long lingering deficiency that affects all major functions of our biochemical organism.

Alzheimers researchers need to study the works of Paracelsus and determine realistically in that context what the appropriate level is for improved immune system signalling & brain function, just how we have adapted to high copper levels for ~6000 years and the effect on natural neuronal prions and their combinatorial effect upon AB...
JamesWebbsSpaceScope
not rated yet Aug 07, 2014
People should take at least 4000 IU per day, but you might need a lot more than that depending on bodyweight, and where you live.
JamesWebbsSpaceScope
not rated yet Aug 07, 2014
Try to get a brand that doesn't use some kind ( any kind ) of Stearate. Thorne is one. Also gels are probably better than tablets.

And D3 is better than D2.
indio007
1 / 5 (1) Aug 13, 2014
Just drink coffee and stop worrying.

Caffeine as a protective factor in dementia and Alzheimer's disease.
http://www.ncbi.n...20182054