Brain vitamin D forms, cognitive decline, and neuropathology in community-dwelling older adults

Abstract

Introduction: Vitamin D purportedly protects against cognitive decline and dementia based on observational data using circulating 25-hydroxyvitamin D (25(OH)D). Little is known about vitamin D in the human brain and the association with dementia or neuropathology.

Methods: Decedents of the Rush Memory and Aging Project (n = 290) had vitamin D concentrations measured in four brain regions. Associations with cognitive and neuropathological outcomes were estimated using linear and logistic regression.

Results: The main form of vitamin D in all brain regions measured was 25(OH)D₃ . Higher brain 25(OH)D₃ concentrations were associated with a 25% to 33% lower odds of dementia or mild cognitive impairment (MCI) at the last visit before death (all P ≤ .031). However, brain 25(OH)D concentrations were not associated with any post-mortem neuropathology outcome studied.

Discussion: Higher brain 25(OH)D₃ concentrations were associated with better cognitive function prior to death. Additional research is needed to clarify the specific mechanisms underlying this potentially protective relationship.

Keywords: Alzheimer's disease; aging; cognitive decline; dementia; neuropathology; nutrition; vitamin D.

Figure 1:

Boxplots of 25(OH)D₃ concentrations in 4 human brain regions (AWS anterior watershed, MF midfrontal cortex, MT midtemporal cortex, CR cerebellum) (n=290). Boxplot indicates the median (middle line of the box), first quartile (lower boundary of the box), and third quartile (upper boundary of the box) of 25(OH)D₃ concentrations in each brain region. Brackets indicate post-hoc pairwise comparison tests with Tukey adjustment that have significant p values.