Vitamin E for Alzheimer's disease (Cochrane Review)

A substantive amendment to this systematic review was last made on 21 August 2000. Cochrane reviews are regularly checked and updated if necessary.

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 in Alzheimer's disease has led to interest in the use of vitamin E in the treatment of this disorder.

Objectives: To examine the effects of vitamin E treatment for people with Alzheimer's disease.

Search strategy: The CDCIG Specialized Register was searched on 19 June 2002 using the following terms: "Vitamin E", vitamin-E, alpha-tocopherol.

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.

Data collection and analysis: Two reviewers independently applied the selection criteria an assessed study quality. One reviewer 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 one study was identified which met the inclusion criteria (Sano 1997). The primary outcome used in this study of 341 participants was survival time to the first of 4 endpoints, death, institutionalisation, loss of 2 out of 3 basic activities of daily living, or 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.

Reviewers' conclusions: There is insufficient evidence of efficacy of vitamin E in the treatment of people with Alzheimer's disease. The one published trial of acceptable methodology (Sano 1997) was restricted to patients with moderate disease, and the published results are difficult to interpret. There is sufficient evidence of possible benefit to justify further studies. There was an excess of falls in the vitamin E group compared with placebo which requires further evaluation.

Citation: Tabet N, Birks J, Grimley Evans J, Orrel M, Spector A. Vitamin E for Alzheimer's disease (Cochrane Review). In: The Cochrane Library, Issue 3, 2003. Oxford: Update Software.

---

This is an abstract of a regularly updated, systematic review prepared and maintained by the Cochrane Collaboration. The full text of the review is available in The Cochrane Library (ISSN 1464-780X).

The Cochrane Library is designed and produced by Update Software Ltd.

Update Software Ltd, Summertown Pavilion, Middle Way, Oxford OX2 7LG, UK
(Tel:+44 1865 513902; Fax:+44 1865 516918)

File Reference: AB002854.htm