Recent research from Emory University suggests that a popular vitamin supplement could play an unexpected role in brain health for older adults at risk of dementia. The study observed that higher-dose vitamin D supplementation was linked to better cognitive performance among adults experiencing mild cognitive impairment (MCI) and sleep disturbances. These factors are associated with an increased risk of Alzheimer’s disease.
Understanding Mild Cognitive Impairment
Mild cognitive impairment is often seen as a transitional stage between regular age-related memory changes and dementia. Sleep problems are common among individuals with MCI, affecting nearly half of such patients. These issues might also heighten the risk of further cognitive decline.
Victoria Pak, an associate professor at Emory University’s Nell Hodgson Woodruff School of Nursing, stated, “Our findings give us an interesting lead on the relationship between vitamin D supplement intake and cognitive performance, particularly in people with mild cognitive impairment and sleep disturbances.” Pinpointing potentially changeable factors is crucial when cognitive symptoms begin to appear.
The Study Details
The research studied 54 adults aged 50 and older who reported both sleep disturbances and diagnosed or suspected MCI. Researchers assessed their cognitive function using the Montreal Cognitive Assessment (MoCA), a tool commonly used for evaluating memory and thinking skills. Participants provided information on their vitamin D supplement use, including dosage and type.
After considering factors like age, sex, body mass index, and education level, researchers found participants who took 5,000 international units (IU) or more of vitamin D daily performed better on cognitive tests than those who didn’t take supplements. Lower doses didn’t show a significant association with cognitive performance.
Considerations and Limitations
The researchers emphasized caution over the findings. Although high-dose vitamin D supplementation correlated with better overall cognition, the study’s observational nature means it can’t prove causation. Also, the number of participants taking 5,000 IU or more daily was relatively small.
Reverse causation could be possible. People with better cognitive function might tend to engage in health-conscious behaviors like supplement intake. The study did not find significant differences between vitamin D2 and D3, implying dosage might be more crucial than supplement type.
Potential biological explanations include vitamin D’s regulation of inflammation, related to sleep disruptions and cognitive decline through neuroinflammation.
Future Research and Recommendations
The Emory researchers suggested a randomized clinical trial as a next step to explore vitamin D’s direct impact. A larger study could help determine if vitamin D has a causal effect on cognitive performance, potentially outlining a strategy to support cognitive health.
Despite promising results, further, larger studies are required. “Since this was an observational study, we’re not yet at the point of recommending high-dose vitamin D,” Pak noted. Individuals should consult healthcare providers to decide the suitability of supplementation 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.
Contact for more insights on this story: Kara Dolman and Emma Lee-Sang.