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Potential
Treatment
for Alzheimer's Identified
Excerpt By Emma Hitt, PhD, Reuters
Health
ATLANTA
(Reuters Health) - Researchers may have identified a new approach
to treating Alzheimer's disease, which has been linked to high
cholesterol levels in its victims.
An estimated
4 million people in the United States suffer from Alzheimer's,
which causes an ongoing decline of memory and reasoning ability
and can result in personality changes; it is the most common cause
of dementia in older people.
Some studies
have shown a relationship between high cholesterol levels and
increased susceptibility to Alzheimer's disease. While scientists
are unclear on the cause of the disease, they do know that brain
cells affected by Alzheimer's often show an increase in levels
of a protein called amyloid beta-peptide (a-beta).
When a-beta
levels are increased in cells, they join together to form a chain.
These chains then form the plaques and tangles in the brain that
are the hallmark of advanced Alzheimer's disease.
Writing in
the October issue of Nature Cell Biology, researchers led by Dr.
Dora M. Kovacs of Harvard Medical School in Charlestown, Massachusetts,
showed that cholesterol levels are directly linked to the amount
of a-beta produced.
They also
report that an enzyme called ACAT, which participates in the body's
normal production of cholesterol, might regulate the production
of a-beta, and therefore may be a target for therapies directed
towards Alzheimer's.
Using cells
specially engineered to overproduce cholesterol, Kovacs' team
also showed that drugs that block the actions of ACAT strongly
reduce the production of a-beta, and therefore may be useful in
treating the disease.
``Our results
point to a novel target for the treatment of Alzheimer's disease,''
Kovacs told Reuters Health. Kovacs also noted that studies in
patients taking cholesterol-lowering statin drugs, which lower
cholesterol in a different way than ACAT inhibitors, reduced the
patients' risk of developing not only Alzheimer's, but other types
of dementia as well.
``A lot more
work has to be done before ACAT inhibitors can really be considered
for the treatment of Alzheimer's disease,'' Kovacs said. But she
pointed out that ACAT inhibitors--unlike many other medications--are
expected to be able to cross the blood-brain barrier, which can
hinder the delivery of drugs to brain cells.
Since the
current study used only individual cells, the next ``major obstacle,''
Kovacs explained, will be to test ACAT inhibitors in mice specially
bred to have Alzheimer's disease.
``A potential
use for ACAT inhibitors for the treatment of Alzheimer's disease
is timely,'' Kovacs said, ``since a potentially safe class of
ACAT inhibitors have just recently been developed for the treatment
of atherosclerosis,'' a disease that also can result from high
cholesterol levels.
SOURCE:
Nature Cell Biology 2001;3:905-912.
Reference
Source 89
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