Vitamin D May Improve Cognition in People With Early Dementia

For anyone whose loved one is living with dementia or Alzheimer's, reports that potential drug treatments are failing or delivering mixed results can be worrying.

Yet there are also grounds for optimism. New evidence indicates that a widely available vitamin supplement could have a potentially beneficial effect in people showing early signs of dementia. It is also an inexpensive tablet that anyone can take each day.

Vitamin D and early dementia symptoms

A new study, published in Sleep Medicine, has linked daily vitamin D supplementation to a marked improvement in cognitive-test scores among people with two markers of early dementia: mild cognitive impairment (MCI) and sleep disturbances.

The researchers say this is the first study to examine the relationship between vitamin D supplements and cognition in patients with both of these important symptoms. However, it is a small observational study, so it cannot demonstrate that vitamin D improves cognitive performance.

Even so, the results contribute to increasing evidence that vitamin D could protect brain health and help prevent dementia. It also appears to offer benefits for ageing processes, heart health, and depression, as well as many other conditions.

As is often the case with neurodegenerative diseases, the scientists believe that intervening early could be essential.

"This may represent a critical window for intervention, when cognitive changes are emerging, but opportunities to support brain health may remain," says sleep scientist Victoria Pak of Emory University in Atlanta, Georgia.

How the vitamin D study assessed cognition and sleep

Pak and her colleagues evaluated 54 adults aged 50 or above. Every participant had either diagnosed or suspected MCI and displayed signs of sleep disturbance.

To assess cognitive function, the participants completed the Montreal Cognitive Assessment (MoCA). Their sleep quality was evaluated using two separate measures: the Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS).

They additionally reported how much vitamin D they took. When the researchers compared daily doses with cognitive and sleep measurements, they identified a notable pattern.

After adjusting for possible confounding variables, including age, sex, body mass index (BMI), vitamin D type, and educational level, the researchers found that those taking 5,000+ IU of vitamin D each day achieved MoCA cognitive-test scores ~13 percent higher (3.78 points higher) than those who did not take vitamin D supplements.

Those on lower daily vitamin D doses also recorded nominally higher scores than participants not taking vitamin D daily, although the findings for lower doses were not statistically significant.

Dose limits and the need for further research

The link at 5,000+ IU was present whether participants used vitamin D2 or vitamin D3. However, 5,000+ IU is slightly higher than the suggested maximum daily vitamin D intake of 4,000 IU, which is generally regarded as the safe upper limit for avoiding hypercalcaemia.

Therefore, the principal finding is not a revised recommendation on the amount of vitamin D people should take. This remains the case even though research is beginning to suggest that doses of 4,000 to 6,000 IU might provide better protection against certain adverse health outcomes.

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For now, the result is preliminary and comes from a small study. The researchers say it should be examined further in later studies involving larger participant groups.

Caution is necessary at this point, but the finding offers scientists a valuable avenue for future research, particularly because vitamin D is cheap and easily accessible.

Once the evidence is clearer, this could prove to be highly significant.

"Identifying accessible and modifiable factors, such as vitamin D supplement intake, during the earlier stages of cognitive decline may become increasingly important," Pak says, "particularly as rates of Alzheimer's disease continue to rise."

The findings appear in Sleep Medicine.

This article was fact-checked and edited by Fiona MacDonald. Although we take pride in our process, we are only human. If you notice an error, please let us know.