Abstract
INTRODUCTION: Evidence is needed to evaluate whether low vitamin B(12) from mid- to late life, either alone or in the presence of elevated folate, is associated with cognitive decline. METHODS: Participants from the Framingham Heart Study without baseline dementia who had ≥ 2 measures of a three-component vitamin B(12) indicator (3cB(12)) and neuropsychological factor scores were included (n = 1994; mean age: 60 years). Adjusted linear mixed effects models estimated annual changes in each factor score between 3cB(12) quartiles. Interaction by folate status was also evaluated. RESULTS: Participants in the highest 3cB(12) quartile had slower declines in memory, executive function, and language compared to the lowest quartile (memory: β = 0.0071, 95% confidence interval [CI] = 0.003-0.01; executive function: β = 0.0056, 95% CI = 0.0009-0.01; and language: β = 0.0090, 95% CI = 0.004-0.01). Findings were largely robust by folate status (elevated: ≥ 20 ng/mL; non-elevated: 6-19 ng/mL). DISCUSSION: Improving B(12) status in dementia-free older adults may help mitigate cognitive decline into later life. HIGHLIGHTS: Higher vitamin B(12) status is associated with slower annual cognitive decline. Higher B(12) was linked with 0.05 to 0.09 standard deviation less cognitive decline over 10 years. B(12) and memory findings are robust for elevated, not non-elevated, folate status.