A 10-year program shows that vitamin D in midlife could impact early markers of dementia
There vitamin D it’s what we take in the summer while in the sun or in the winter, through a supplement, when the doctor tells us we have little of it. For a long time, research associated it with bone health, then with immune defenses. AND in recent years its name has appeared more and more often alongside that of Alzheimer’sbut almost always in studies of older people. A study published in Neurology Open Access he looked at a different age: 39 years old. And he found that vitamin D levels at that age could be linked to what happens in the brain sixteen years later.
Vitamin D and Tau
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The researchers worked on data from the Framingham Heart Studya program that follows the health of families in Massachusetts (USA). Between 2002 and 2005, 793 participants had blood drawn to measure vitamin D: the average in the group was 38 nanograms per milliliter, and about a third were below 30 ng/ml, which many consider the limit of insufficiency. Sixteen years later, part of them returned for brain scans capable of detect tau and amyloid, the two proteins that accumulate in the brain before Alzheimer’s becomes diagnosableoften decades before the first symptoms. None at the time of the scans had dementia or other known neurological conditions. But those with higher levels of vitamin D at age 39 showed, in subsequent scans, fewer tau deposits in areas related to memory and orientation than Alzheimer’s. The higher the vitamin D concentration, the lower the tau load, with the relationship following a continuous scale rather than a simple threshold. With amyloid, however, no correlation emerged: researchers explain this by the fact that tau accumulates first, and is the easiest to intercept in a group that is still relatively young. Neither sex nor the APOE e4 genetic variant, which increases the risk of Alzheimer’s, changed the outcome.
cognitive functions
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Biology perhaps offers an explanation: vitamin D receptors are present throughout the nervous system, including the hippocampus. And it regulates inflammatory processes and counteracts some forms of cellular damage related to aging, two mechanisms directly involved in the accumulation of tau. In animal studies, a few weeks of a vitamin D-deficient diet was enough to increase tau and amyloid in the brain and accelerate the death of neurons. In human clinical trials, outcomes are less uniform, but an analysis that pooled data from 24 controlled studies on more than 7,500 people found a modest but consistent positive effect on cognitive functionsmore marked in those who started from already low levels.
Neurology study records an association, does not prove a cause. Those with more vitamin D might also do more physical activity, spend more time outdoors or eat better, variables that would contribute to better brain health. But the framework and connection between low vitamin D values at age 39 and the presence of some indicators of Alzheimer’s 16 years later is certainly interesting for those who deal with neurodegenerative diseases.
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