Advances
Against Alzheimer's Slow But Steady
November
Is National Alzheimer's Disease Awareness Month
The
fight against Alzheimer's disease has been marked by a recent series
of encouraging advances, experts report.
The
latest of these small steps came recently when a US Food and
Drug Administration (FDA) advisory committee recommended approval
of the medication memantine, which experts say seems to slow the progression
of moderate and severe Alzheimer's.
Some 4.5 million
US adults have Alzheimer's disease, which primarily affects older people
and is characterized by the progressive loss of memory and other cognitive
skills. An estimated 11.3 million to 16 million seniors are likely to
have the disease by 2050, the Alzheimer's Association
predicts.
According to these latest estimates of the current and
future prevalence of AD, reported by Dr. Denis A. Evans, and colleagues
of Rush-Presbyterian-St. Luke's Medical Center in Chicago, the most
notable increases will be among people age 85 and older, when by mid-century
8 million people in that age group may have the disease.
November is recognized
as National Alzheimer's Disease Awareness Month.
Currently, memantine is approved and being used to treat
patients in Europe under the name Axura®. If memantine is approved
in the US, it would be called the first medication in use for later-stage
Alzheimer's. A decision is expected by the end of the year.
There are few medications on the market geared specifically
for Alzheimer's and they have only limited effectiveness. Memantine
provides a ray of hope because it has a different mechanism of action:
it blocks the overproduction of a brain chemical called glutamate.
Alzheimer's
a Major Problem, and Growing
The current mainstays
of Alzheimer treatment, called cholinesterase inhibitors, work by boosting
levels of another brain chemical, acetylcholine. Cholinesterase inhibitors
are approved for use against mild and moderate forms of the disease.
"It's always
exciting when you find something that works in a different way because
it suggests that people for whom one drug doesn't work, another one
may," says William Thies, vice president of medical and scientific
affairs for the Alzheimer's Association.
"It also opens up the possibility that the medications
can be used together," Thies says.
Dr. Marshall Keilson, co-director of the Memory Disorders
Program at Maimonides Medical Center in New York City, says, "We're
excited because it [memantine] represents a new approach. It's the beginning
of a new category of treatments of Alzheimer's.
"It's not a miracle drug, and it's by no means
a cure," adds Dr. Keilson, "but it's a fresh view of treating
patients with Alzheimer's."
Medications
Geared Toward Symptoms
None of the available
or soon-to-be-available medications for Alzheimer's attack the underlying
cause of the disease, only the symptoms. That is because researchers
do not know the exact cause or causes of the disease.
The approved cholinesterase inhibitors elevate the levels
of acetylcholine. But, Dr. Keilson points out, "since the role
of this chemical in producing Alzheimer's is uncertain and may be late
in the course of the pathology, there's a certain limitation to what
the medications can do."
They have been shown to slow progression of the disease
in a certain percentage of patients. And some people were able to resume
watching television, reading a newspaper or carrying on a conversation,
he says.
Research currently is being conducted to see if medications
that have been approved for other conditions might be able to prevent
or treat Alzheimer's patients. They include nonsteroidal anti-inflammatory
drugs or cholesterol-lowering statins, but the jury is still out on
these medications.
On other fronts, certain drugs are being developed specifically
for Alzheimer's.
"If there's one thing that is different today about
Alzheimer's research than 20 years ago is that we've got this huge wealth
of basic information about how the disease develops and what the fundamental
biochemistry is," Thies says. "All of that information gives
us an opportunity to intervene."
Scientists do not yet know where to intervene but they
are hot on the trail. One of the main areas of research has been into
strategies to limit the production of amyloid, a protein that collects
in the brains of patients with Alzheimer's.
An experimental human vaccine apparently succeeded in
eliminating some of these protein clusters, but may also have caused
meningoencephalitis - or swelling of the brain. The trial was halted
last year but data is still being gathered and there is talk that the
vaccine has been modified and may be tried again.
Other studies are looking at compounds that would affect
different enzymes implicated in the protein buildup in the brains of
Alzheimer's patients.
Because many of the risk factors for Alzheimer's are
similar to those for heart disease, there has been speculation on the
role of diet in preventing Alzheimer's. Although diet and nutrition
is a notoriously difficult area to study, "it is perfectly reasonable
to say that there's a lot of good reason to adopt a lifestyle that leads
to healthy aging," Thies says.
Always consult your physician for more information.
Online
Resources
Alzheimer's
Association
Alzheimer's
Disease Education & Referral Center
Centers
for Disease Control and Prevention (CDC)
National
Institutes of Health (NIH)
National
Institute of Neurological Disorders and Stroke
US Department
of Heath and Human Services
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