Vitamin supplements are widely used, and recent research suggests a possible connection between vitamin D and brain health, especially among older adults at risk of dementia. A study conducted by researchers at Emory University explored the impact of vitamin D on cognitive performance in adults with mild cognitive impairment (MCI) and sleep disturbances, conditions that heighten the risk of Alzheimer’s disease.
Mild cognitive impairment is considered an intermediary phase between typical age-related memory challenges and dementia. Sleep issues are prevalent in those with MCI, impacting nearly half of the patients, with potential implications for further cognitive decline.
Victoria Pak, an associate professor at Emory University’s Nell Hodgson Woodruff School of Nursing, highlighted the research findings to Newsweek, noting the possible connection between vitamin D supplementation and cognitive performance, particularly in individuals with MCI and sleep disturbances.
The study included 54 participants aged 50 and above, all experiencing sleep disturbances and either diagnosed or suspected MCI. The researchers evaluated the cognitive function of participants using the Montreal Cognitive Assessment (MoCA). This tool is commonly employed to assess memory and thinking skills.
Data on vitamin D supplement usage, including dosage and type, were collected from participants. After adjusting for variables like age, sex, body mass index, and educational level, the study revealed that those reporting a daily intake of 5,000 international units (IU) or more of vitamin D performed better on cognitive tests compared to those who did not supplement with vitamin D.
The study concluded that high-dose vitamin D was linked to better overall cognition in this participant group. However, the findings require cautious interpretation. The number of people taking 5,000 IU or more daily was relatively small, and the study was observational, not a clinical trial proving causation. Reverse causation is a possibility, meaning the link could stem from individuals with better cognitive function engaging in health-conscious behaviors, including taking supplements.
The study noted no substantial difference between the cognitive impact of vitamin D2 and vitamin D3, indicating the supplement dosage might be more crucial than the specific type of vitamin D. There are biological theories regarding the connection between vitamin D and cognition. Previous studies suggest vitamin D’s role in inflammation regulation. Inadequate sleep relates to increased inflammatory activity, potentially contributing to cognitive decline. Neuroinflammation might connect sleep issues and cognitive decline as well.
While the study found an association solely among participants with higher vitamin D intake, further exploration is needed. The next step involves a randomized clinical trial to directly test vitamin D supplementation’s effects. Such a trial could help confirm if vitamin D influences cognitive performance and whether it serves as a viable strategy for cognitive health support.
Despite the compelling results, larger studies are necessary. As Pak emphasized, “Since this was an observational study, we’re not yet at the point of recommending high-dose vitamin D. Whether supplementation is appropriate depends on the individual, so anyone considering it should talk with their healthcare provider about what’s right for them.”
Reference: Zhou S, Sudeshna P, Trotti LM, Bliwise D, Pak V. Vitamin D supplement intake is associated with better cognition in persons with sleep disturbance and mild cognitive impairment. Sleep Med. 2026 Oct;146:108960. doi: 10.1016/j.sleep.2026.108960.
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