Dementia: low levels of vitamin D linked to poor cognitive function

Dementia: low levels of vitamin D linked to poor cognitive function

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A new study has found that lower levels of vitamin D are associated with a higher risk of dementia in older people. Andriy Onufriyenko/Getty Images
  • For the first time, a new study has explored vitamin D levels in the human brain and the potential effect on cognitive outcomes.
  • Researchers have found that higher levels of vitamin D are associated with a lower risk of dementia in older adults.
  • Despite the findings, the exact role of vitamin D in cognitive function is still not fully understood.

An estimated 6 million people are living with Alzheimer’s disease (AD) in the United States.

This number is expected to reach 13 million by 2050 due to the country’s aging population. Alzheimer’s disease is also the sixth leading cause of death in the United States.

Every 65 seconds someone develops AD and 60-80% of people with dementia have it. Alzheimer’s disease affects memory, thinking, and therefore behavior as it progresses. Although it is most often a disease affecting people aged 65 and over, the early onset of AD can affect people in their 40s and 50s.

The possible causes of dementias, including AD, remain somewhat elusive and are the subject of ongoing research.

Recently, a new observational study investigates for the first time the presence of vitamin D in the brain and its potential effect on cognitive outcomes.

The study found that better cognitive function is associated with people who have higher concentrations of vitamin D in their brains. Before the study, it was unclear whether vitamin D was present in the brain.

Lead author Kyla Shea, Ph.D., a researcher at Tufts University in Massachusetts who specializes in the role of micronutrients in age-related disease and disability, said Medical News Today:

“A number of studies have reported that higher levels of vitamin D in the blood were associated with less cognitive decline or a lower risk of dementia. Even though these studies suggested associations, it was possible that blood levels were markers of something else because we didn’t know if vitamin D was even present in the human brain.

The study has just been published in Alzheimer’s & Dementia.

For the study, researchers analyzed data from 290 deceased people who had participated in the Rush Memory and Aging Project until their death.

None had dementia when first enrolled and all were elderly people living in the community. Participants’ cognitive health was measured throughout the study, and they agreed to donate their organs when they died.

The researchers found that higher concentrations of vitamin D in all four brain areas were associated with a 25-33% reduction in the risk of developing dementia or mild cognitive impairment at the time of individuals’ last visit before death.

Thomas HJ Burne, Ph.D., associate professor of developmental neurobiology at the University of Queensland, Australia, not involved in the study, said DTM:

“The study is certainly very new. I have never seen data on blood and brain levels of vitamin D in people who were monitored before the onset of the disease. This is a set of valuable data that can offer valuable insights.”

Dr. Burne noted that as an observational study, the results “at best [are] likely to reveal correlations and not underlying causal mechanisms. He also pointed out that since the participants were all within the range of normal vitamin D levels, the study did not examine associations between insufficient vitamin D levels and cognitive function.

Additionally, the study authors note another possible interpretation of their findings.

They wrote that it is possible that vitamin D concentrations in the brain may be an indicator of “cognitive resilience” and that people with high vitamin D levels may show “fewer signs of cognitive impairment despite neuropathological burden.” high”.

Another limitation of the study is that most of the participants were white. The researchers cite a need for future studies of more diverse populations.

Researchers tracked levels of a form of vitamin D, 25(OH)D3 in the brain.

They assessed vitamin D in the midtemporal cortex, mid-frontal cortex, cerebellumand anterior watershed white matter of the brain, all of which have been implicated in different types and stages of dementia, including AD and dementia with Lewy bodies.

Dr. Burne expressed concern about the difficulty of taking accurate measurements of 25(OH)D3 in “such a lipid-dense tissue”. He added that the study was unclear about whether participants received supplements, which he said could change the interpretation of the data.

Additionally, the study found no correlation between vitamin D levels and amyloid plaques, which were previously thought to be among the potential causes of Alzheimer’s disease. But researchers are still investigating any association between amyloid plaques and AD due to a continued lack of consensus on the theory.

“Amyloid accumulation does not appear to be the cause of dementia or cognitive impairment, which may explain the high failure rate of clinical trials aimed at treating amyloid,” Dr. Burne said. “Therefore, I am not surprised that there is no association between vitamin D and amyloid.”

Additionally, the researchers found no evidence of an association with Lewy bodies, suggesting that vitamin D is not linked to Lewy body dementia. They also didn’t find a link between vitamin D, white matter damage, or signs of mini-strokes.

“Our current research is moving towards vascular dementia, for which there is evidence of biological plausibility,” Dr. Shea said.

The role vitamin D plays in cognition is not fully understood. But this is the first study to examine vitamin D levels in the brain and the potential association with cognitive outcomes.

Dr. Shea noted that vitamin D appears to be involved in cell signaling pathways that may be part of neurodegeneration.

However, neurodegeneration is complex and poorly understood.

“No studies have shown a causal relationship between vitamin D deficiency and cognitive impairment, but many show a correlation,” Dr. Burne noted, citing a 2019 mouse study he conducted as an example.

Dr Burne added that vitamin D deficiency is linked to “reduced hippocampal volume and disrupted structural connectivity in patients with mild cognitive impairment”.

Most people in the United States have adequate levels of vitamin D, according to the National Institutes of Health.

Most children and adults between the ages of 1 and 70 need 15 micrograms or 600 individual units of vitamin D each day. Infants under one year of age need 10 mcg (400 IU) and adults over 70 need 20 mcg (800 IU).

But if you’re one of the 1 in 4 people with vitamin D deficiency, your doctor can tell you how much vitamin D supplementation you need.

If you are unsure whether you are getting enough vitamin D, you can ask your doctor to measure your vitamin D level with a blood test.

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