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February 24, 2004
Early Vitamin E Supplements Stem Development of Hallmark
Alzheimer’s Symptoms in Mice
(Philadelphia, PA) - Vitamin E, a well-known antioxidant,
has been used to treat Alzheimer’s disease, but
with mixed results, especially in patients with advanced
symptoms. A risk factor for Alzheimer’s is oxidative
stress, a clinical condition characterized by an excessive
production of reactive chemicals in the brain, which
can damage important regions of this organ.
Domenico Praticò, M.D., assistant
professor of pharmacology at the University
of Pennsylvania School of Medicine, and colleagues
tested the idea that timing of vitamin E supplementation
for treating Alzheimer’s might be an important
factor in its effectiveness. They found that vitamin
E given to young transgenic mice before the formation
of telltale plaques reduces by up to half the levels
of amyloid deposited in the brain over time compared
to aged mice on the same regimen. This study appears
in the February edition of The FASEB Journal.
“Our findings indicate that an antioxidant is
important to cure or prevent disease only if given at
a very early stage,” says Praticò. “If
given when the disease is already established the chances
of a positive effect are very small.”
The researchers used a well-characterized transgenic
mouse that expresses a mutant gene present in humans
and forms Alzheimer’s plaques (similar to the
ones found in humans) in the brain starting at about
11 to 12 months. One group of mice received vitamin
E at five months, before plaques start to form. Another
group started at 14 months--a time when much plaque
had already been deposited--with the same amount of
vitamin E. They followed each group for eight months
and compared their outcome with controls that did not
receive vitamin E. The young group showed a 50 percent
reduction in the number of plaques deposited in brain
tissue as compared to the older mice. “This group
didn’t show any significant difference in plaque
reduction as compared to controls, suggesting that once
the plaque is deposited there’s very little that
an antioxidant can do,” says Praticò. This
finding also indicates that other mechanisms may play
a role in the disease once established.
The immediate implications of these findings are simple,
especially for patients diagnosed with mild cognitive
impairment (MCI), a possible precursor to Alzheimer’s:
Start taking vitamin E early. “They will benefit
the most,” says Praticò. “Considering
that up to 50 percent of patients with MCI will develop
Alzheimer’s within four years, and the fact that
recent epidemiological studies have clearly shown that
intake of antioxidants, in particular vitamin E, lowers
the risk of Alzheimer’s, MCI patients will be
the most appropriate target for this therapy.”
Penn scientists also contributing to this research
are Syuan Sung, Yuemang Yao, Kunihiro Uryu, Hengxuan
Yang, Virginia M-Y Lee, and John Q. Trojanowski. This
study was funded by the National Institutes of Health,
The Alzheimer Association, and the American Heart Association.
Dr. Pratico can be contacted at domenico@spirit.gcrc.upenn.edu
or 215-898-6446.
For
a printer friendly version of this release, click
here.
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