Vitamin B‐12 and Folate Status in Relation to Decline in Scores on the Mini‐Mental State Examination in the Framingham Heart Study

Abstract

To investigate the cognitive significance of low to low-normal plasma vitamin B-12 concentrations and to shed light on the role that folate status plays in the association between vitamin B-12 status and cognitive decline. Associations between plasma vitamin B-12 and folate and 8-year cognitive decline were evaluated, and the effects of interactions between vitamin B-12 status and folate status and supplemental folate use on cognitive decline were assessed. The Framingham Heart Study - a prospective epidemiological study. Five hundred forty-nine community-dwelling individuals aged 74.8 ± 4.6. Mini-Mental State Examination (MMSE), plasma folate, vitamin B-12, methylmalonic acid, homocysteine, demographic factors, and body mass index. MMSE scores declined by 0.24 points per year over the 8-year follow-up period. Decline was significantly faster in cohort members in the bottom two plasma vitamin B-12 quintile categories, and no apparent cognitive advantage was associated with plasma vitamin B-12 from 187 to 256.8 pmol/L over less than 186 pmol/L. In cohort members with plasma vitamin B-12 less than 258 pmol/L, having a plasma folate concentration greater than 20.2 nmol/L was associated with an approximate 1-point per year decline, as was use of supplemental folate. Plasma vitamin B-12 levels from 187 to 256.8 pmol/L predict cognitive decline. Furthermore, having plasma vitamin B-12 levels in this range or below in conjunction with high plasma folate or supplemental folate use predicts especially rapid cognitive decline.