Pesquisa sugere que altas quantidades de vitamina B podem retardar a demência

Comprimidos diários com altas doses de vitamina B podem parar o processo de encolhimento do cérebro em idosos com problemas de memória e, também, adiar a progressão da demência, segundo pesquisa [Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial] da Universidade Oxford, na Inglaterra.

O estudo acompanhou por dois anos 168 voluntários com transtorno cognitivo leve, que receberam pílulas com altas doses de ácido fólico, vitaminas B6 e B12 ou placebo. Essas vitaminas controlam os níveis de um aminoácio no sangue ligado a um maior risco de doença de Alzheimer.

Os resultados, publicados no periódico PLoS ONE, da Public Library of Science, mostram que o cérebro de quem tomou as vitaminas encolheu 0,76% ao ano, contra 1,08% entre os que tomavam placebo. O primeiro grupo também teve resultados melhores em testes cognitivos.

“Nossa esperança é que esse tratamento simples e seguro possa adiar o desenvolvimento de Alzheimer em pessoas com problemas leves de memória”, afirmou David Smith, coautor do estudo.

O artigo “Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial” publicado na PLoS ONE, está disponível para acesso integral, no formato HTML. Para acessar o artigo clique aqui.

Para maires informações publicamos, abaixo, o abstract:

Smith AD, Smith SM, de Jager CA, Whitbread P, Johnston C, et al. 2010 Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial. PLoS ONE 5(9): e12244. doi:10.1371/journal.pone.0012244

Abstract

Background
An increased rate of brain atrophy is often observed in older subjects, in particular those who suffer from cognitive decline. Homocysteine is a risk factor for brain atrophy, cognitive impairment and dementia. Plasma concentrations of homocysteine can be lowered by dietary administration of B vitamins.

Objective
To determine whether supplementation with B vitamins that lower levels of plasma total homocysteine can slow the rate of brain atrophy in subjects with mild cognitive impairment in a randomised controlled trial (VITACOG, ISRCTN 94410159).

Methods and Findings
Single-center, randomized, double-blind controlled trial of high-dose folic acid, vitamins B6 and B12 in 271 individuals (of 646 screened) over 70 y old with mild cognitive impairment. A subset (187) volunteered to have cranial MRI scans at the start and finish of the study. Participants were randomly assigned to two groups of equal size, one treated with folic acid (0.8 mg/d), vitamin B12 (0.5 mg/d) and vitamin B6 (20 mg/d), the other with placebo; treatment was for 24 months. The main outcome measure was the change in the rate of atrophy of the whole brain assessed by serial volumetric MRI scans.

Results
A total of 168 participants (85 in active treatment group; 83 receiving placebo) completed the MRI section of the trial. The mean rate of brain atrophy per year was 0.76% [95% CI, 0.63–0.90] in the active treatment group and 1.08% [0.94–1.22] in the placebo group (P = 0.001). The treatment response was related to baseline homocysteine levels: the rate of atrophy in participants with homocysteine >13 µmol/L was 53% lower in the active treatment group (P = 0.001). A greater rate of atrophy was associated with a lower final cognitive test scores. There was no difference in serious adverse events according to treatment category.

Conclusions and Significance
The accelerated rate of brain atrophy in elderly with mild cognitive impairment can be slowed by treatment with homocysteine-lowering B vitamins. Sixteen percent of those over 70 y old have mild cognitive impairment and half of these develop Alzheimer’s disease. Since accelerated brain atrophy is a characteristic of subjects with mild cognitive impairment who convert to Alzheimer’s disease, trials are needed to see if the same treatment will delay the development of Alzheimer’s disease.
Trial Registration

Controlled-Trials.com ISRCTN94410159

Citation: Smith AD, Smith SM, de Jager CA, Whitbread P, Johnston C, et al. (2010) Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial. PLoS ONE 5(9): e12244. doi:10.1371/journal.pone.0012244

Editor: Ashley I. Bush, Mental Health Research Institute of Victoria, Australia

Received: May 27, 2010; Accepted: July 22, 2010; Published: September 8, 2010

Copyright: © 2010 Smith et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: This work was supported by grants from the Charles Wolfson Charitable Trust, Medical Research Council, Alzheimer’s Research Trust, Henry Smith Charity, John Coates Charitable Trust, Thames Valley Dementias and Neurodegenerative Diseases Research Network of the National Institute for Health Research, UK, and the Sidney and Elizabeth Corob Charitable Trust, and Meda AB/Recip AB, Solna, Sweden. None of the funders or the sponsor (University of Oxford) played any role in the design and conduct of the study, collection, management, analysis, and interpretation of the data; nor in the preparation, review, or approval of the manuscript.

Competing interests: Dr. A. D. Smith is named as an inventor on two patents held by the University of Oxford on the use of folic acid to treat Alzheimer’s disease (US6008221; US6127370); under the University’s rules he could benefit financially if the patent is exploited. Drs. Refsum and A. D. Smith report having in the past received speaking honoraria from Recip AB, the company that donated the vitamin tablets, and from Axis-Shield, who make the equipment used to assay homocysteine. These competing interests do not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials. None of the other authors have any financial disclosures.

* E-mail: david.smith@pharm.ox.ac.uk

# These authors contributed equally to this work.

Reportagem da Agência Reuters, com informações complementares do EcoDebate.

EcoDebate, 10/09/2010
[T]
Tweet

[ O conteúdo do EcoDebate é “Copyleft”, podendo ser copiado, reproduzido e/ou distribuído, desde que seja dado crédito ao autor, ao Ecodebate e, se for o caso, à fonte primária da informação ]

Inclusão na lista de distribuição do Boletim Diário do Portal EcoDebate
Caso queira ser incluído(a) na lista de distribuição de nosso boletim diário, basta clicar no LINK e preencher o formulário de inscrição. O seu e-mail será incluído e você receberá uma mensagem solicitando que confirme a inscrição.

O EcoDebate não pratica SPAM e a exigência de confirmação do e-mail de origem visa evitar que seu e-mail seja incluído indevidamente por terceiros.