Study links low vitamin D to dementia risk

The American Journal of Clinical Nutrition recently published a study that describes the impact of vitamin D status on brain health. The results of the study reveal that vitamin D deficiency increases the risk of dementia.

Study: Vitamin D and brain health: an observational and Mendelian randomization study. Image Credit: Lightspring / Shutterstock

Background

Vitamin D, a hormone precursor, is known to influence brain health by modulating neurotrophic growth factors, inflammation and thrombosis. Vitamin D status in the body is usually monitored by measuring blood levels of 25-hydroxyvitamin D, which is a form of vitamin D produced in the liver. The prevalence of vitamin D deficiency (

According to the available literature, neurodegenerative diseases and cognitive decline are associated with changes in the size and shape of the brain (cerebral morphometry). An association between vitamin D status and brain morphometry has also been established in the literature. In this context, a large systematic review concluded that vitamin D deficiency is associated with lower brain volume.

This study investigated the association between vitamin D status and various brain neuroimaging features. They also investigated whether severe vitamin D deficiency could increase the risk of dementia and stroke.

study design

Scientists collected prospective data from the UK Biobank to investigate the effect of 25-hydroxyvitamin D concentrations on neuroimaging findings and the risk of dementia and stroke.

They investigated the basic causative factors of neuroimaging outcomes and dementia and stroke using nonlinear Mendelian randomization analysis. In Mendelian randomization, measured variation in known genes is used to study the causal effect of modifiable risk factors on health outcomes in observational data.

Important observations

Analysis conducted after adjusting for socioeconomic factors revealed a strong association between 25-hydroxyvitamin D concentrations and neuroimaging characteristics.

A nonlinear association was observed between 25-hydroxyvitamin D concentrations and total brain volume, white and gray matter volume, and hippocampal volume. Low and high concentrations of 25-hydroxyvitamin D have been shown to be associated with lower total brain, white matter and gray matter volumes. This association was stronger in men than in women.

Additionally, an association was observed between lower 25-hydroxyvitamin D concentrations and white matter hyperintensity volume. White matter hyperintensities are indicators of structural brain alterations associated with a range of serious morbidities, including cognitive decline and stroke.

The impact of 25-hydroxyvitamin D concentrations on the risk of dementia and stroke was observed in the study. Participants with the lowest concentration of 25-hydroxyvitamin D had the highest risk of dementia and stroke.

Mendelian randomization

A nonlinear inverse correlation was observed between genetically determined vitamin D status and dementia risk. Participants with lower 25-hydroxyvitamin D levels had the highest risk of dementia. Specifically, participants with a hydroxyvitamin D concentration of 25 nmol/L had a 54% higher risk of dementia than those with 50 nmol/L of 25-hydroxyvitamin D.

In Mendelian randomization analysis, no association between 25-hydroxyvitamin D concentration was observed with neuroimaging characteristics and stroke risk. Further analysis revealed that 17% of dementia cases can be prevented by increasing the concentration of 25-hydroxyvitamin D to 50 nmol/L.

Significance of the study

The study results reveal that vitamin D deficiency can significantly affect brain health. Specifically, the study indicates that people with low vitamin D levels are at a higher risk of developing dementia.

As mentioned by the scientists, the results provide a vital opportunity to prevent dementia. They also highlighted the need for more extensive Mendelian randomization studies to confirm the proposed causal association between 25-hydroxyvitamin D concentrations and brain morphometry.[if–>