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Intervention Review

Vitamin E for Alzheimer's disease and mild cognitive impairment

  1. Mokhtar Gad El Kareem Nasr Isaac1,*,
  2. Rebecca Quinn2,
  3. Naji Tabet3

Editorial Group: Cochrane Dementia and Cognitive Improvement Group

Published Online: 16 JUL 2008

Assessed as up-to-date: 15 JAN 2007

DOI: 10.1002/14651858.CD002854.pub2


How to Cite

Isaac MGEKN, Quinn R, Tabet N. Vitamin E for Alzheimer's disease and mild cognitive impairment. Cochrane Database of Systematic Reviews 2008, Issue 3. Art. No.: CD002854. DOI: 10.1002/14651858.CD002854.pub2.

Author Information

  1. 1

    Sussex Partnership NHS, Old Age Psychiatry, Eastbourne, East Sussex, UK

  2. 2

    Surrey & Borders NHS Trust, Ridgwood Centre, Surrey, UK

  3. 3

    University of Brighton, Postgraduate Medical School, Brighton, UK

*Mokhtar Gad El Kareem Nasr Isaac, Old Age Psychiatry, Sussex Partnership NHS, Milton Court Resourse Centre, Milton Road, Eastbourne, East Sussex, BN21 1SL, UK. mokhtarisa@hotmail.com.

Publication History

  1. Publication Status: Edited (no change to conclusions)
  2. Published Online: 16 JUL 2008

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Abstract

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

Background

Vitamin E is a dietary compound that functions as an antioxidant scavenging toxic free radicals. Evidence that free radicals may contribute to the pathological processes of cognitive impairment including Alzheimer's disease (AD) has led to interest in the use of Vitamin E in the treatment of Alzheimer's disease and Mild Cognitivie Impairment (MCI).

Objectives

To assess the efficacy of Vitamin E in the treatment of Alzheimer's disease and prevention of progression of Mild Cognitive Impairment to Alzheimer's disease.

Search methods

The Cochrane Dementia and Cognitive Improvement's Specialized Register was searched on 8 January 2007 using the following terms: "Vitamin E", vitamin-E, alpha-tocopherol. The CDCIG Registers contains records from major health care databases and ongoing trial databases and is updated regularly.

Selection criteria

All unconfounded, double blind, randomized trials in which treatment with Vitamin E at any dose was compared with placebo for patients with Alzheimer's disease or Mild Cognitive Impairment.

Data collection and analysis

Two reviewers independently applied the selection criteria and assessed study quality and extracted and analysed the data. For each outcome measure data were sought on every patient randomized. Where such data were not available an analysis of patients who completed treatment was conducted.

Main results

Only 2 studies met the inclusion criteria. The primary outcome used in the AD study was survival time to the first of 4 endpoints: death, institutionalisation, loss of 2 out of 3 basic activities of daily living and severe dementia (defined as a global Clinical Dementia Rating of 3). The investigators reported the total numbers in each group who reached the primary endpoint within two years for participants completing the study ("completers"). There appeared to be some benefit from Vitamin E with fewer participants reaching endpoint - 58% (45/77) of completers compared with 74% (58/78) - a Peto odds ratio of 0.49, 95% confidence interval 0.25 to 0.96.
However, more participants taking Vitamin E suffered a fall (12/77 compared with 4/78; odds ratio 3.07, 95% CI 1.09 to 8.62). It was not possible to interpret the reported results for specific endpoints or for secondary outcomes of cognition, dependence, behavioural disturbance and activities of daily living.

The primary outcome used in the MCI study which had 769 participants (257 in the Vitamin E group and 259 in the placebo group; a third Donepezil group of 253 was not included in this review) was the time to progression from MCI to possible or probable AD. A total of 214 of the 769 participants had progression to dementia, with 212 being classified as having possible or probable AD. There was no significant difference in the probability of progression from MCI to AD between the Vitamin E group and the placebo group. There was no significant difference between the placebo group and the Vitamin E group in adverse events. Five subjects died in each group and 72 discontinued treatment in the Vitamin E group and 66 in the placebo group.

Authors' conclusions

There is no evidence of efficacy of Vitamin E in the prevention or treatment of people with AD or MCI. More research is needed to identify the role of Vitamin E, if any, in the management of cognitive impairment.

 

Plain language summary

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

No evidence of the efficacy of vitamin E for people suffering from Alzheimer's disease (AD) and mild cognitive impairment (MCI)

Vitamin E is a dietary compound with antioxidant properties involved in scavenging free radicals. Laboratory and animal studies have pointed towards a possible role for Vitamin E in the prevention and management of cognitive impairment. To date only one randomized controlled trial has assessed the efficacy of Vitamin E in the treatment of AD patients and only one assessed the role of Vitamin E in patients with mild cognitive impairment (MCI). In the Vitamin E study for moderately severe AD patients a lower number of those taking Vitamin E declined to incapacity over a two year period compared with the placebo group. However, AD patients taking Vitamin E experienced a greater number of falls. In the MCI study, Vitamin E 2000 IU daily produced no significant difference in the rate of progression to AD compared to the placebo group.

 

摘要

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

背景

維他命E用於治療阿茲海默症及輕微認知損傷

維他命E是一種飲食化合物,它具有抗氧化的功能,並且可以清除有毒的自由基。 自由基導致認知損傷(包含阿茲海默症(AD)在內)的病理證據讓人們有興趣使用維他命E治療阿茲海默症及輕微認知損傷(MCI)。

目標

評估維他命E治療阿茲海默症,以及預防輕微認知損傷惡化為阿茲海默症的功效。

搜尋策略

2007年1月8日使用名詞: "Vitamin E", vitaminE, alphatocopherol搜尋Cochrane Dementia and Cognitive Improvement Group Specialized Register。該資料庫含有由主要健康照護資料庫的記錄及進行中臨床試驗資料庫的資料且規律地更新。

選擇標準

所有使用維他命E於任何劑量下所進行的無混淆的、雙盲、隨機的試驗與使用安慰劑的阿茲海默症或輕微認知損傷之病患做比較。

資料收集與分析

兩位回顧作者獨立地應用選擇標準及評估研究品質及摘錄和分析這些資料。針對每個結果衡量數據,隨機徵詢每位病人。如果有數據無法取得,則分析已完成治療的病人。

主要結論

僅2項研究達到納入標準。用於阿茲海默症組的主要評估結果為達到4個終結點中的第1個的存活時間(survival time):死亡、需要機構化照顧、喪失3個基本日常生活活動中的2個,以及嚴重的癡呆症(整體定義為臨床失智量表達到3)。 這些研究者報告了每個群組當中在兩年內達到主要結果(完成者)中的整體數目。較少數稱為完成者的參加者到達終結點且顯示由vitamin E處得到了一些效益58% (45/77)而與74% (58/78)相比較0.49的一Peto odds ratio(Peto勝算比),95% confidence interval 0.25到0.96。然而,更多使用維他命E的參加者受到一衰退(a fall)的痛苦(12/77 compared with 4/78; odds ratio 3.07, 95% CI 1.09 to 8.62)。對於特定終結點解釋其報告或對於其報告中之認知的次要結果、依賴性、行為的紊亂及日常生活活動。有769位參加者(維他命E群組中有257位且259位在安慰劑群組中;一第三由253位組成的Donepezil group未納入本評論中)形成用於該MCI研究的基本結果,該時刻是由MCI進展到可能或更為可能(possible or probable)之AD的時間。全部769位參加者中的214位惡化為癡呆症,同時212位被歸類為具有可能或更為可能之AD。 在維他命E群組及安慰劑群組間由MCI進行成為AD的可能性並無明顯的差異。在安慰劑與維他命E群組間的不良事件無明顯的差異。每一群組中有五位病患死亡且在維他命E群組中有72位間斷中止了治療,在安慰劑群組中有66位。

作者結論

無證據來證明有AD或MCI的病人使用維他命E進行預防或治療的效果。鑑別維他命E角色的研究,如果有這樣的研究的話,需要更多的、該種在管理認知損傷上的研究。

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

維他命E是一種飲食混合物,具有抗氧化劑的特性而涉及有毒自由基之清除。對維他命E的實驗室及動物研究對其角色已經指向可能是作為預防及控制認知損傷。 迄今僅一項隨機對照試驗已評估維他命E治療AD病患的功效且僅一項研究評估維他命E於具有輕微認知損傷(mild cognitive impairment (MCI))病患的角色。 以維他命E研究中等嚴重度AD時使用了維他命E病患經過兩年時間後與使用安慰劑的群組相比較,病情惡化到失去功能程度的數目較低。然而,使用維他命E的AD病患體會到較多衰退。 在MCI研究中,每日服用維他命E2000IU與使用安慰劑群組相較,在AD的惡化速率上並不會造成顯著的差異。