Lookup NU author(s): Dr Nuno Mendonca,
Dr Antoneta Granic,
Professor John Mathers,
Dr Carmen Martin-Ruiz,
Emeritus Professor Chris Seal,
Professor Carol Jagger,
Dr Thomas Hill
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2017 AMDA - The Society for Post-Acute and Long-Term Care Medicine.Objectives: Although the biological rationale for the association between folate, vitamin B12, and homocysteine with cognitive function seems plausible, conflicting results have been reported. This study aimed to determine the associations between 1-carbon (1-C) metabolism biomarkers (folate, vitamin B12, and homocysteine), and cognitive impairment at baseline and the rate of cognitive decline over 5 years in the very old. Design: The Newcastle 85+ Study was a prospective longitudinal study of people 85 years old and followed over 5 years in Northeast England. Setting: Community-dwelling and institutionalized. Participants: The analytical sample included 765 very old participants with 1-C metabolism biomarkers and cognitive measures. Measurements: Global cognition was measured by the Standardized Mini-Mental State Examination (SMMSE) at baseline, and at 3 and 5 years of follow-up and, attention-specific cognition with the Cognitive Drug Research (CDR) System at baseline, and at 1.5 and 3.0 years of follow-up. Baseline red blood cell folate (RBC folate), plasma vitamin B12, and total homocysteine (tHcy) concentrations were determined by immunoassay. Linear mixed models were used to estimate the associations between quartiles of 1-C metabolism biomarkers and cognition over 3 (CDR) and 5 years (SMMSE). Results: Compared with participants in the lowest quartile of RBC folate concentrations (<612 nmol/L), those in the highest quartile of RBC folate concentrations (>1280 nmol/L) had 1 more point on the SMMSE at baseline (β = +1.02, SE = 0.43, P = .02). Those in quartile 4 of tHcy (>21.4 μmol/L) had 1 point less in the SMMSE at baseline than those in the lowest quartile (<13.5 μmol/L) (β = -1.05, SE = 0.46, P = .02). Plasma vitamin B12 was not predictive of global or attention-specific cognition at baseline and at follow-up. None of the 1-C metabolism biomarkers except tHcy was associated with the rate of decline in attention scores over 3 years. Conclusion: RBC folate and tHcy, but not plasma vitamin B12, were associated with better global cognition in the very old at baseline but were not predictive of rate of decline over 5 years.
Author(s): Mendonca N, Granic A, Mathers JC, Martin-Ruiz C, Wesnes KA, Seal CJ, Jagger C, Hill TR
Publication type: Article
Publication status: Published
Journal: Journal of the American Medical Directors Association
Print publication date: 01/09/2017
Online publication date: 21/06/2017
Acceptance date: 02/04/2016
ISSN (print): 1525-8610
ISSN (electronic): 1538-9375
Publisher: Elsevier Inc.
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