Vitamin D status and cognitive performance in community-dwelling adults: A dose-response meta-analysis of observational studies

Low vitamin D status is linked with poorer cognition in adults while findings in relation to high levels are mixed. We performed a systematic review and meta-analyses to examine dose–response associations between 25-hydroxyvitamin D (25OHD) levels and cognitive performance in community-dwelling adults. Thirty-eight observational studies were included in dose–response meta-analyses. Positive, nonlinear associations were identified between baseline 25OHD levels and global cognition in cross-sectional and longitudinal analyses, and for performance in memory and executive function in longitudinal analyses. When restricted to studies involving older adults, the pattern emerged for specific domains in cross-sectional analyses. Poorer performance was associated with low 25OHD levels, while a sharp improvement was associated with levels up to 60–70 nM/L. Further improvement was observed only for longitudinal global cognition. Our findings support the association between low vitamin D and poorer cognition and suggest levels of at least 60 nM/L are associated with better cognition during ageing.