Intervention Review

Vitamin B12 for cognition

  1. Reem Malouf1,*,
  2. Almudena Areosa Sastre2

Editorial Group: Cochrane Dementia and Cognitive Improvement Group

Published Online: 21 JUL 2003

Assessed as up-to-date: 23 JAN 2006

DOI: 10.1002/14651858.CD004394


How to Cite

Malouf R, Areosa Sastre A. Vitamin B12 for cognition. Cochrane Database of Systematic Reviews 2003, Issue 3. Art. No.: CD004394. DOI: 10.1002/14651858.CD004394.

Author Information

  1. 1

    Cochrane Dementia and Cognitive Improvement Group, Oxford, UK

  2. 2

    Madrid, Spain

*Reem Malouf, Cochrane Dementia and Cognitive Improvement Group, John Radcliffe Hospital (4th Floor, Room 4401C), Headington, Oxford, OX3 9DU, UK. reemmalouf@yahoo.com.

Publication History

  1. Publication Status: Edited (no change to conclusions)
  2. Published Online: 21 JUL 2003

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Abstract

  1. Top of page
  2. Abstract
  3. Plain language summary
  4. 摘要

Background

An association between neuropsychiatric disorders and vitamin B12 deficiency has been recognized since 1849 when pernicious anaemia was first described. It has been suggested that deficiency of vitamin B12 might contribute to age-associated cognitive impairment. Low serum vitamin B12 concentrations are found in more than 10% of older people. A high prevalence of low serum vitamin B12 levels, and other indicators of vitamin B12 deficiency have been reported among people with Alzheimer's disease. A review is needed of trials assessing effects of vitamin B12 supplementation on cognitive function in later life.

Objectives

To examine the effect of B12 supplementation on cognitive function of demented and elderly healthy people in terms of preventing the onset or progression of cognitive impairment or dementia.

Search methods

The trials were identified from a search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 24 January 2006 using the terms B12, "B 12", B-12, B-complex, "B complex". In addition MEDLINE 1966 to 2006/01-week 3 and EMBASE 1980-2005/12 were searched to pick up studies with healthy volunteers.

Selection criteria

All randomized double-blind trials in which vitamin B12 at any dose was compared with placebo.

Data collection and analysis

Both reviewers applied the selection criteria to assess the quality of the studies. One reviewer (RM) collated and analysed the data. For each outcome measure data were sought on every patient randomized.

Main results

Three trials were included (De La Fourniere 1997; Hvas 2004; Seal 2002). One trial (Hvas 2004) reported follow-up results at 3 months after randomization, 2 months after treatment was completed; the data from this study were not combined with others. People with dementia and low serum vitamin B12 levels were recruited for the studies. The results showed no statistically significant evidence of a treatment effect of vitamin B12 supplementation compared with placebo, on cognitive function.

Authors' conclusions

Evidence of any efficacy of vitamin B12 in improving the cognitive function of people with dementia and low serum B12 levels is insufficient. The included trials (De La Fourniere 1997; Hvas 2004; Seal 2002) were restricted to a small number of patients with Alzheimer's disease and other types of cognitive impairment. No trials involving people without dementia or using other definitions of vitamin B12 deficiency were found.

 

Plain language summary

  1. Top of page
  2. Abstract
  3. Plain language summary
  4. 摘要

No evidence of the efficacy of vitamin B12 supplementation for cognitive function

Vitamin B12 is essential for maintaining normal function of the nervous system, but the relationship between vitamin B12 and cognitive function is not fully understood. From the three studies involving people with dementia or cognitive impairment and low blood levels of vitamin B12 eligible for inclusion in this review there was no statistically significant effect of vitamin B12 supplementation on cognition. The variety of measurement scales used to assess outcomes and uncertainty about diagnostic criteria for vitamin B12 deficiency create difficulties in pooling the results of trials.

 

摘要

  1. Top of page
  2. Abstract
  3. Plain language summary
  4. 摘要

背景

維他命B12對於認知的效用

在1849年開始出現關於惡性貧血描述時,即已經確認缺乏維他命B12與神精異常之間有關係。據信維他命B12缺乏可能導致與年齡有關的認知損傷。目前發現超過10%的老年人血清中維他命B12濃度較低。在阿茲海默症患者當中,普遍維他命B12濃度過低,並且有維他命B12缺乏的其他跡象。 因此有必要回顧試驗,評估補充維他命B12對於晚年認知功能的效益。

目標

評估失智患者以及健康的老年人補充維他命B12對於預防或是延緩認知損傷或是失智的功效。

搜尋策略

2006年1月24日使用關鍵字: "B 12", B12, Bcomplex, "B complex"搜尋Cochrane Dementia and Cognitive Improvement Group Specialized Register以找出試驗。此外也搜尋MEDLINE(1966年∼2006年1月第1周的)以及EMBASE(1980年∼2005年12月)以挑出健康的參與者。

選擇標準

所有進行維他命B12(任何劑量)與安慰劑的比較的隨機雙盲試驗。

資料收集與分析

兩位回顧作者應用選擇標準評估研究品質。一位評論者(RM)校對及分析了這資料。對每一隨機取得的病患之每一結果量表資料都予以檢視。

主要結論

三項試驗被納入De La Fourniere 1997; Hvas 2004; Seal 2002)。 1個試驗(Hvas 2004)報告了隨機分配後第3個月以及完成治療後2個月的後續追蹤結果;而這個研究的數據並無法與其他研究合併。 研究招募失智且低維他命B12濃度的人,證據顯示補充維他命B12與補充安慰劑對於認知功能影響的差異並不具統計上顯著。

作者結論

維他命B12對於改善失智症及低B12濃度患者認知功能的療效證據有限。 本回顧所納入的研究(De La Fourniere 1997; Hvas 2004; Seal 2002)由於招募的阿茲海默症患者數量以及認知損傷種類過少而受限。所有的試驗都是以阿茲海默症患者為對像,而且也沒有找到其他維他命B12缺乏的定義。

翻譯人

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

沒有關於補充維他命對於認知功能療效的證據,但維他命B12與認知功能間的關係未被完全了解。 3個合乎本回顧納入標準的研究,以失智症患者、認知損傷以及低維他命B12濃度過低者為對象的研究,發現補充維他命B12對於認知功能並沒有顯著效益。 由於衡量結果的方式眾多,而且診斷維他命B12缺法的標準不明,因此難以將試驗結果匯總。