ビタミンＥの投与量(2000IU alpha tocopherol)は1日あたりの推奨摂取量よりもはるかに高く、一部で有害となる可能性があるレベルであるので、治療として推奨するには時期尚早であるという。
1 January 2014 Last updated at 00:46 GMT
Vitamin E 'beneficial' in dementia
A daily dose of vitamin E could help people with dementia, research suggests.
A study in the journal JAMA found people with mild to moderate Alzheimer's disease on high doses of vitamin E had a slower rate of decline than those given a dummy pill.
They were able to carry out everyday tasks for longer and needed less help from carers, say US researchers.
The Alzheimer's Society said the dosage was very high and might not be safe.
In the study, 613 people with mild to moderate Alzheimer's disease received either a daily dose of vitamin E, a dementia drug treatment known as memantine, a combination of vitamin E and memantine, or placebo.
Changes in their ability to carry out everyday tasks - such as washing or dressing - were measured over an average of two years.
The study found participants receiving vitamin E had slower functional decline than those receiving placebo, with the annual rate of decline reduced by 19%.
Those on vitamin E (also known as alpha tocopherol) also needed less help from carers.
"These findings suggest that alpha tocopherol is beneficial in mild to moderate Alzheimer's disease by slowing functional decline and decreasing caregiver burden," said a team led by Dr Maurice Dysken of Minneapolis VA Health Care System.
Commenting on the study, Dr Doug Brown, director of research and development at the Alzheimer's Society, said treatments which can help people with dementia carry out everyday tasks are key to enabling those with the condition to live well for as long as possible.
But he said more research was needed to see if vitamin E really does have benefits for people with dementia, and whether it would be safe to be taking such a high dose on a daily basis.
'Talk to GP'
"It is vitally important that people always seek advice from their doctor before considering taking supplements," he said.
"In this instance, the dosage of vitamin E taken by participants was much higher than the recommended daily allowance and was at a level that could be significantly harmful for some."
Dr Eric Karran, director of research at Alzheimer's Research UK, said the trial suggested vitamin E may modestly slow the decline in day-to-day functioning in people with mild to moderate Alzheimer's, but without having an effect on memory and thinking skills.
He said it was too early to recommend vitamin E as a treatment.
"Until the findings from this trial have been replicated, we would not encourage people to take high doses of vitamin E supplements to try to prevent or treat Alzheimer's," he added.
"If people are concerned about their vitamin intake or diet, they should talk to their GP."
Effect of Vitamin E and Memantine on Functional Decline in Alzheimer Disease
The TEAM-AD VA Cooperative Randomized Trial
Maurice W. Dysken, MD1; Mary Sano, PhD2; Sanjay Asthana, MD3
JAMA. 2014;311(1):33-44. doi:10.1001/jama.2013.282834.
Importance Although vitamin E and memantine have been shown to have beneficial effects in moderately severe Alzheimer disease (AD), evidence is limited in mild to moderate AD.
Objective To determine if vitamin E (alpha tocopherol), memantine, or both slow progression of mild to moderate AD in patients taking an acetylcholinesterase inhibitor.
Design, Setting, and Participants Double-blind, placebo-controlled, parallel-group, randomized clinical trial involving 613 patients with mild to moderate AD initiated in August 2007 and concluded in September 2012 at 14 Veterans Affairs medical centers.
Interventions Participants received either 2000 IU/d of alpha tocopherol (n?=?152), 20 mg/d of memantine (n?=?155), the combination (n?=?154), or placebo (n?=?152).
Main Outcomes and Measures Alzheimer’s Disease Cooperative Study/Activities of Daily Living (ADCS-ADL) Inventory score (range, 0-78). Secondary outcomes included cognitive, neuropsychiatric, functional, and caregiver measures.
Results Data from 561 participants were analyzed (alpha tocopherol?=?140, memantine?=?142, combination?=?139, placebo?=?140), with 52 excluded because of a lack of any follow-up data. Over the mean (SD) follow-up of 2.27 (1.22) years, ADCS-ADL Inventory scores declined by 3.15 units (95% CI, 0.92 to 5.39; adjusted P?=?.03) less in the alpha tocopherol group compared with the placebo group. In the memantine group, these scores declined 1.98 units less (95% CI, ?0.24 to 4.20; adjusted P?=?.40) than the placebo group’s decline. This change in the alpha tocopherol group translates into a delay in clinical progression of 19% per year compared with placebo or a delay of approximately 6.2 months over the follow-up period. Caregiver time increased least in the alpha tocopherol group. All-cause mortality and safety analyses showed a difference only on the serious adverse event of “infections or infestations,” with greater frequencies in the memantine (31 events in 23 participants) and combination groups (44 events in 31 participants) compared with placebo (13 events in 11 participants).
Conclusions and Relevance Among patients with mild to moderate AD, 2000 IU/d of alpha tocopherol compared with placebo resulted in slower functional decline. There were no significant differences in the groups receiving memantine alone or memantine plus alpha tocopherol. These findings suggest benefit of alpha tocopherol in mild to moderate AD by slowing functional decline and decreasing caregiver burden.
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