Vitamin D deficiency has long been associated with a higher risk of dementia, though that link doesn’t necessarily prove causality.
A new study published in Neurology, however, followed 800 people over 16 years.
They found that people who had higher vitamin D levels in their 30s and 40s tended to have lower levels of tau protein in later life.
Tau “tangles” have been linked to dementia.
Vitamin D deficiency, which can only be confirmed for sure with a blood test, is believed to affect about one in six UK adults.
Why might that happen?
The scientists compared participants’ vitamin D levels at the start of the study with brain scans conducted 16 years later.
34% of participants had vitamin D deficiency in the beginning.
Speaking to the University of Galway, the study’s lead author, Dr Martin Mulligan, said: “We found that higher vitamin D levels were associated with lower tau deposition in regions of the brain that are known to be affected earliest in Alzheimer’s disease.
“These results suggest that higher vitamin D levels in midlife may offer protection against developing these tau deposits in the brain and that low vitamin D levels could potentially be a risk factor that could be modified and treated to reduce the risk of dementia”.
And its other lead author, Professor Emer McGrath, pointed out that this study is “among the first to look at younger adults at mid-life, around the average age of 39. Low vitamin D in mid-life may be an important target to reduce the risk of early signs of preclinical dementia in the brain.”
More research is needed to prove whether vitamin D definitely causes these changes
Though compelling, this didn’t definitely prove that vitamin D deficiency increased dementia risk, or that having enough vitamin D prevented it.
“While these findings are very interesting, they only demonstrate an association between vitamin D and early signs of dementia in the brain. Further studies, for example a clinical trial, will be required to determine if vitamin D supplements could prevent dementia,” Professor McGrath said.
But Dr Mulligan added, “These results are promising as they suggest an association between higher Vitamin D levels in early middle age and lower tau burden on average 16 years later. Mid-life is a time where risk factor modification can have a greater impact”.
