Effects of homocysteine lowering with B vitamins on cognitive aging: meta-analysis of 11 trials with cognitive data on 22,000 individuals.


Clarke, R; Bennett, D; Parish, S; Lewington, S; Skeaff, M; Eussen, SJ; Lewerin, C; Stott, DJ; Armitage, J; Hankey, GJ; Lonn, E; Spence, JD; Galan, P; de Groot, LC; Halsey, J; Dangour, AD; Collins, R; Grodstein, F; B-Vitamin Treatment Trialists’ Collaboration, ; (2014) Effects of homocysteine lowering with B vitamins on cognitive aging: meta-analysis of 11 trials with cognitive data on 22,000 individuals. The American journal of clinical nutrition, 100 (2). pp. 657-66. ISSN 0002-9165 DOI: https://doi.org/10.3945/ajcn.113.076349

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Abstract

BACKGROUND: Elevated plasma homocysteine is a risk factor for Alzheimer disease, but the relevance of homocysteine lowering to slow the rate of cognitive aging is uncertain.<br/> OBJECTIVE: The aim was to assess the effects of treatment with B vitamins compared with placebo, when administered for several years, on composite domains of cognitive function, global cognitive function, and cognitive aging.<br/> DESIGN: A meta-analysis was conducted by using data combined from 11 large trials in 22,000 participants. Domain-based z scores (for memory, speed, and executive function and a domain-composite score for global cognitive function) were available before and after treatment (mean duration: 2.3 y) in the 4 cognitive-domain trials (1340 individuals); Mini-Mental State Examination (MMSE)-type tests were available at the end of treatment (mean duration: 5 y) in the 7 global cognition trials (20,431 individuals).<br/> RESULTS: The domain-composite and MMSE-type global cognitive function z scores both decreased with age (mean ± SE: -0.054 ± 0.004 and -0.036 ± 0.001/y, respectively). Allocation to B vitamins lowered homocysteine concentrations by 28% in the cognitive-domain trials but had no significant effects on the z score differences from baseline for individual domains or for global cognitive function (z score difference: 0.00; 95% CI: -0.05, 0.06). Likewise, allocation to B vitamins lowered homocysteine by 26% in the global cognition trials but also had no significant effect on end-treatment MMSE-type global cognitive function (z score difference: -0.01; 95% CI: -0.03, 0.02). Overall, the effect of a 25% reduction in homocysteine equated to 0.02 y (95% CI: -0.10, 0.13 y) of cognitive aging per year and excluded reductions of >1 mo per year of treatment.<br/> CONCLUSION: Homocysteine lowering by using B vitamins had no significant effect on individual cognitive domains or global cognitive function or on cognitive aging.<br/>

Item Type: Article
Faculty and Department: Faculty of Epidemiology and Population Health > Dept of Population Health (2012- ) > Dept of Nutrition and Public Health Interventions Research (2003-2012)
Faculty of Epidemiology and Population Health > Dept of Population Health (2012- )
Faculty of Epidemiology and Population Health > Dept of Medical Statistics
PubMed ID: 24965307
Web of Science ID: 339599100018
URI: http://researchonline.lshtm.ac.uk/id/eprint/1805399

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