Vitamin B supplementation did not slow cognitive decline in patients with Alzheimer's disease

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Public release date: 14-Oct-2008

http://www.eurekalert.org/pub_releases/2008-10/jaaj-vbs100908.php

Contact: Debra Kain

JAMA and Archives Journals

Vitamin B supplementation did not slow cognitive decline in patients

with Alzheimer's disease

High-dose vitamin B supplementation for patients with mild to moderate

Alzheimer disease did not slow the rate of cognitive decline, according

to a study in the October 15 issue of JAMA.

Evidence of homocysteine (an amino acid produced by the body) elevation

in Alzheimer disease (AD) and the involvement of homocysteine in

neuropathological mechanisms suggest that reduction of homocysteine may

offer an approach to altering the disease. B vitamins that influence

homocysteine metabolism have been considered as a therapeutic option to

reduce risk of AD or slow its progression, according to background

information in the article. According to the authors, prior studies of B

vitamins to reduce homocysteine in AD have not had sufficient size or

duration to assess their effect on cognitive decline.

S. Aisen, M.D., of the University of California, San Diego, and

colleagues conducted a clinical trial to determine if reduction of

homocysteine levels with high-dose supplementation with folic acid and

vitamins B6 and B12 for 18 months would slow the rate of cognitive

decline in 409 individuals with mild to moderate AD. Participants were

randomly assigned to two groups of unequal size to increase enrollment

(60 percent treated with high-dose supplements [5 mg/d of folate, 25

mg/d of vitamin B6, 1 mg/d of vitamin B12] and 40 percent treated with

identical placebo). A total of 340 participants (202 in active treatment

group and 138 in placebo group) completed the trial while taking study

medication. Cognitive abilities were measured via testing with the

Alzheimer Disease Assessment Scale (ADAS-cog).

The researchers found that even though the vitamin supplement regimen

was effective in reducing homocysteine levels, it had no beneficial

effect on the primary cognitive measure: the rate of change in ADAS-cog

score did not differ significantly between treatment groups. The authors

did find that symptoms of depression were more common in the high-dose

supplement group.

" Many studies suggest that relative elevation of homocysteine is

characteristic of AD, and laboratory research implicates homocysteine in

neurodegenerative mechanisms. High-dose B vitamin supplementation in

individuals with normal levels of B vitamins was effective in reducing

homocysteine levels. However, our study does not support the treatment

of individuals with mild to moderate AD and normal vitamin levels with B

vitamin supplements, " the authors conclude.

(JAMA. 2008;300[15]:1774-1783. Available pre-embargo to the media at

www.jamamedia.org)

Editor's Note: Please see the article for additional information,

including other authors, author contributions and affiliations,

financial disclosures, funding and support, etc.

Editorial: B Vitamins for Prevention of Cognitive Decline - Insufficient

Evidence to Justify Treatment

In an accompanying editorial, J. e, M.D., F.R.C.P., and

Derrick A. , Ph.D., of the University of Oxford, England, comment

on the findings regarding B vitamin supplementation.

" The precise reasons the [study by Aisen and colleagues] failed to

detect any beneficial effect of B vitamins on the rate of cognitive

decline remain unclear, " they write. " However, until and unless new data

suggest otherwise, there is insufficient evidence to justify routine use

of homocysteine-lowering vitamin supplements for the prevention of

Alzheimer disease and cognitive decline among individuals with normal

vitamin status. "

(JAMA. 2008;300[15]:1819-1821. Available pre-embargo to the media at

www.jamamedia.org)

--

ne Holden, MS, RD

" Ask the Parkinson Dietitian " http://www.parkinson.org/

" Eat well, stay well with Parkinson's disease "

" Parkinson's disease: Guidelines for Medical Nutrition Therapy "

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