To assess associations between vitamin D status and trajectories of change in subdomains of cognitive function, researchers from Rutgers University and the University of California, Davis, monitored 382 people (average age of 75) for around five years. The participants were a diverse group, both in ethnicity and cognitive status at baseline.
Around 60% of all the study participants had low vitamin D levels in their blood, including 70% of the African-American and Hispanic participants. Those who were either vitamin D deficient (less than 12 ng/mL serum levels) or insufficient (12 to 20 ng/mL) had faster declines (around 2 to 3 times faster) in episodic memory and executive function than those with adequate vitamin D levels, independent of other potential risk factors, the authors reported. Vitamin D status was not significantly associated with declines in semantic memory or visuospatial ability, however. When removing those participants who had dementia at the start of the study, the correlation between vitamin D and cognitive decline was still present.
“Given that [vitamin D] insufficiency is medically correctable, well-designed clinical trials that emphasize enrollment of individuals of nonwhite race/ethnicity with hypovitaminosis D could be useful for testing the effect of [vitamin D] replacement on dementia prevention,” the study authors wrote.
While there have not been any clinical studies demonstrating that vitamin D supplementation can improve memory, the study authors suggested older patients should consult their physicians about taking vitamin D.
For related information, see the Journal of Neuropsychiatry and Clinical Neurosciences article “Delirium and Hypovitaminosis D: Neuroimaging Findings.”