Vitamin D at 5,000 IU linked to better cognition in 54 adults

A number on a dementia screening test separated two groups of older adults: participants reporting at least 5,000 IU of vitamin D daily scored more than 13% higher on the Montreal Cognitive Assessment, or MoCA, than those who did not report that intake. The result comes from an Emory University study of 54 adults with sleep disturbances and mild cognitive impairment (MCI), an intermediate stage between normal cognitive aging and dementia.

The MoCA measures memory and thinking skills and is widely used to screen for dementia risk. In the study, lower daily vitamin D doses were not associated with higher cognitive scores. Performance also did not differ according to the form of vitamin D: D2, typically derived from plants or fungi, or D3, produced after sun exposure or found in animal-based foods.

The timing is central to the researchers’ interpretation. Sleep problems and cognitive decline often appear together, and the study notes that 50% of people with moderate to severe Alzheimer’s disease report sleep disturbances. Victoria Pak, the study’s senior author and an associate professor at Emory University’s Nell Hodgson Woodruff School of Nursing, described MCI combined with sleep disturbance as a possible window when cognitive changes are emerging but opportunities to support brain health may remain.

So, concretely, the finding gives researchers an accessible factor to test earlier in the course of cognitive decline, particularly among people already experiencing both symptoms. It does not yet tell patients to take high-dose supplements: the participants reported their intake, the sample was small, and the preliminary study showed correlation rather than causation.

That distinction matters as Alzheimer’s dementia affects more than 7 million Americans, a number projected to reach nearly 13 million by 2050. The Emory team’s result, published in Sleep Medicine, points toward a specific question for larger studies: whether changing vitamin D intake can improve cognition, rather than merely appearing alongside better scores.