Summary: Researchers found a link between low vitamin D levels and reduced brain volume. Lower vitamin D levels have also been linked to an increased risk of stroke and dementia. Up to 17% of dementia cases could be prevented by increasing vitamin D levels.
Source: University of South Australia
Dementia is a leading cause of disability and dependency among older people worldwide, affecting how they think and behave as they age. But what if you could stop this degenerative disease?
A world-first study from the University of South Australia could make this a reality, as new genetic research shows a direct link between dementia and vitamin D deficiency.
The study examined the association between vitamin D, neuroimaging characteristics and the risk of dementia and stroke and found:
- Low vitamin D levels have been associated with smaller brain volume and increased risk of dementia and stroke
- Genetic analysis supported a causal effect of vitamin D deficiency and dementia.
- in some populations, up to 17 percent of dementia cases could be prevented by getting everyone up to normal vitamin D levels (50 nmol/L).
Dementia is a chronic or progressive syndrome that leads to deterioration in cognitive function. Around 487,500 Australians are living with dementia and it is the second leading cause of death in the country. More than 55 million people worldwide suffer from dementia, with 10 million new cases diagnosed each year.
The genetic study, supported by the National Health and Medical Research Council, analyzed data from 294,514 UK Biobank participants and examined the effects of low levels of vitamin D (25 nmol/L) and the risk of dementia and stroke. Nonlinear Mendelian Randomization (MR) – a method to study the causal effect of modifiable exposure on a disease through measured variations in genes – was used to test the underlying causality for neuroimaging results, dementia and stroke.
Lead researcher and director of UniSA’s Australian Center for Precision Health, Professor Elina Hyppönen, says the findings are important for preventing dementia and recognizes the need to address vitamin D deficiency.
“Vitamin D is a precursor hormone that is increasingly recognized for wide-ranging effects, including on brain health, but until now it has been very difficult to study what would happen if we were able to reverse vitamin D deficiency prevent it,” says Prof. Hyppönen.
“Our study is the first to examine the effect of very low vitamin D levels on the risks of dementia and stroke using robust genetic analysis in a large population.
“In some contexts where vitamin D deficiency is relatively common, our results have important implications for the risk of dementia. In fact, we observed in this UK population that up to 17 per cent of dementia cases could have been avoided if vitamin D levels had been raised to a normal range.”
The results are incredibly significant given the high prevalence of dementia around the world.
“Dementia is a progressive and debilitating disease that can be devastating to individuals and families alike,” says Prof Hyppönen.
“If we are able to change that reality by ensuring none of us are severely vitamin D deficient, there would be other benefits as well and we could transform the health and well-being of thousands.”
“Most of us are probably fine, but for those who aren’t getting enough vitamin D from the sun for whatever reason, dietary changes may not be enough, and supplementation may well be necessary.”
About this news from vitamin D and dementia research
Author: Annabel Mansfeld
Source: University of South Australia
Contact: Annabel Mansfield – University of South Australia
Picture: The image is in the public domain
Original research: Open access.
“Vitamin D and brain health: an observational and Mendelian randomization study” by Elina Hyppönen et al. American Journal of Clinical Nutrition
Vitamin D and brain health: an observational and Mendelian randomization study
It has been suggested that higher vitamin D status has beneficial effects on the brain.
To establish the link between 25-hydroxyvitamin D [25(OH)D]Neuroimaging functions and the risk of dementia and stroke.
We used prospective data from the UK Biobank (37–73 years at baseline) to investigate the association between 25(OH)D concentrations and neuroimaging outcomes (N = 33,523) and the risk of dementia and stroke (N = 427,690; 3414 and 5339 incidents respectively). Observational analyzes were adjusted for age, sex, race, month, center, and socioeconomic factors, lifestyle, sun exposure, and disease-related factors. Nonlinear Mendelian randomization (MR) analysis was used to test the underlying causality for the neuroimaging results (N = 23,901) and dementia and stroke (N = 294,514; 2399 and 3760 cases respectively).
Associations between 25(OH)D and total, gray matter, white matter, and hippocampal volume were nonlinear, with lower volumes for both low and high concentrations (adjusted P-nonlinear ≤ 0.04). 25(OH)D had an inverse association with white matter hyperintensity volume [per 10 nmol/L 25(OH)D; adjusted β: –6.1; 95% CI: –11.5, –7.0]. Vitamin D deficiency was associated with an increased risk of dementia and stroke, with the strongest associations for those with 25(OH)D < 25 nmol/L (vs 50-75.9 nmol/L; adjusted HR: 1 .79, 95% CI: 1.57, 2.04 and HR: 1.40, 95% CI: 1.26, and 1.56, respectively).
Nonlinear MR analysis confirmed the threshold effect of 25(OH)D on dementia, with participants at 25 nmol/L compared to 50 nmol/L increasing the risk by 54% (95% CI: 1.21, 1.96). was predicted. 25(OH)D was not associated with neuroimaging results or stroke risk in MR analyses. The potential impact fraction suggests that 17% (95% CI: 7.22, 30.58) of dementia could be prevented by increasing 25(OH)D to 50 nmol/L.
Low vitamin D status was associated with neuroimaging outcomes and risks of dementia and stroke even after extensive adjustment for covariates. MR analyzes support a causal effect of vitamin D deficiency on dementia but not on stroke risk.