A number of previous studies suggest that Vitamin D deficiency associates with brain structural abnormalities and cognitive impairments. Joshua Miller, from the Rutgers School of Environmental and Biological Sciences (New Jersey, USA), and colleagues studied 382 men and women, in their 60s to 90s, residing in an outpatient clinic, assessing them for vitamin D levels and cognition once a year for an average of five years. The study included people with normal cognition, mild cognitive loss, and dementia. The group was racially and ethnically diverse, including whites, African Americans and Hispanics. Most (61%) had low vitamin D levels in their blood. While observing that 70% of the African-Americans and Hispanics in the study had low blood levels of vitamin D, the team found no difference in the rates of cognitive decline based solely on racial or ethnic lines, reporting that: “Low VitD status was associated with accelerated decline in cognitive function domains in ethnically diverse older adults, including African American and Hispanic individuals who exhibited a high prevalence of VitD insufficiency or deficiency.”
Miller JW, Harvey DJ, Beckett LA, Green R, Farias ST, Reed BR, Olichney JM, Mungas DM, DeCarli C. “Vitamin D Status and Rates of Cognitive Decline in a Multiethnic Cohort of Older Adults.” JAMA Neurol. 2015 Sep 14.