Dementia is one of the major causes of disability and dependency among older people worldwide, affecting thinking and behaviours as you age. But what if you could stop this degenerative disease in its tracks?
A world-first study from the University of South Australia has the potential to make this a reality as new genetic research shows a direct link between dementia and a lack of vitamin D, which can be created naturally in the body with exposure to sunlight, or supplemented with pills.
Investigating the association between vitamin D, neuroimaging features, and the risk of dementia and stroke, the study found low levels of vitamin D were associated with lower brain volumes and an increased risk of dementia and stroke.
Genetic analyses also supported a causal effect of vitamin D deficiency and dementia.
The research suggested that in some populations, as many as 17 per cent of dementia cases might be prevented by increasing everyone to normal levels of vitamin D (50 nmol/L).
How big is the problem?
Dementia is a chronic or progressive syndrome that leads to deterioration in cognitive function. About 487,500 Australians live with dementia and it is the country’s second leading cause of death.
Globally, more than 55 million people have dementia with ten million new cases diagnosed every year.
Supported by the National Health and Medical Research Council, the genetic study analysed data from 294,514 participants from the UK Biobank, examining the impact of low levels of vitamin D (25 nmol/L) and the risk of dementia and stroke.
Nonlinear Mendelian randomisation (MR) – a method of using measured variation in genes to examine the causal effect of a modifiable exposure on disease – were used to test for underlying causality for neuroimaging outcomes, dementia, and stroke.
What do the results mean?
Senior investigator and Director of UniSA’s Australian Centre for Precision Health, Professor Elina Hyppönen, says the findings are important for the prevention of dementia and appreciating the need to abolish vitamin D deficiency.
‘Vitamin D is a hormone precursor that is increasingly recognised for widespread effects, including on brain health, but until now it has been very difficult to examine what would happen if we were able to prevent vitamin D deficiency,’ said Professor Hyppönen.
‘Our study is the first to examine the effect of very low levels of vitamin D on the risks of dementia and stroke, using robust genetic analyses among a large population.
‘In some contexts, where vitamin D deficiency is relatively common, our findings have important implications for dementia risks,’ she said. ‘Indeed, in this UK population we observed that up to 17 per cent of dementia cases might have been avoided by boosting vitamin D levels to be within a normal range.
‘The findings are incredibly significant given the high prevalence of dementia around the world.
‘Dementia is a progressive and debilitating disease that can devastate individuals and families alike,’ said Professor Hyppönen.
‘If we’re able to change this reality through ensuring that none of us is severely vitamin D deficient, it would also have further benefits and we could change the health and wellbeing for thousands.
‘Most of us are likely to be ok, but for anyone who for whatever reason may not receive enough vitamin D from the sun, modifications to diet may not be enough, and supplementation may well be needed,’ she said.