Scientists Eye Future Treatments for Alzheimer’s
July 20, 2006 (Fisher Center for Alzheimer’s Disease) – Scientists meeting at the 10th International Conference on Alzheimer’s Disease and Related Disorders in Madrid, Spain, discussed several new therapies that may one day help ease the burden of Alzheimer’s disease.
They
include a drug for prostate cancer, a drug that targets a toxic brain
protein, a skin patch, and an experimental vaccine. All require further
testing to determine which, if any, are truly safe and effective for
the mind-ravaging illness.
Prostate Drug
In one study
involving 227 patients, the drug leuprolide acetate (brand name Lupron
Depot), a medication prescribed for men with advanced prostate cancer,
showed some benefit in slowing mental decline in men and women with
Alzheimer’s disease. Those who took the medication showed less decline
on mental state tests designed to measure memory loss and other
symptoms, although the benefits were slight.
The medication
came to the attention of researchers about 10 years ago, after an
observant wife noticed that her husband’s Alzheimer’s symptoms began to
improve when he started taking the drug for prostate cancer. Since that
time, the drug has undergone various small trials to test for
effectiveness and safety in people with Alzheimer’s disease. Next up
will be a larger study to test for effectiveness in combating the
symptoms of Alzheimer’s disease.
The drug acts as a hormone,
and is delivered through an implant under the skin. Side effects
include hot flashes. Scientists are not sure why and how leuprolide may
benefit the brain and slow the progression of Alzheimer’s symptoms,
though it seems to act differently than Alzheimer’s drugs currently on
the market, such as Aricept and Exelon. Likely years more research may
be needed before this medication can be fully tested.
Beta-Amyloid Drug
Another
small study of an investigational drug called Flurizan showed that
people with mild Alzheimer’s given high doses (800 mg twice a day)
declined more slowly on tests of memory and thinking. Those who stayed
on the medication for two years saw greater benefits than those who
were on the drug for only a year. Additionally, those on the drug had
fewer psychiatric incidents (even during the first year) than those
taking a placebo.
The
drug is designed to lower a toxic protein called beta-amyloid that
builds up in the brains of those with Alzheimer’s disease. Beta-amyloid
build-up can harm or kill healthy brain cells, including those
essential for memory and cognition. A larger trial involving 1,600
patients is currently under way, with results expected to be announced
late next year. The company that makes the drug, Myriad Genetics, has
also begun to enroll patients in a second large trial of the medication
at various medical centers throughout the U.S. and world.
Skin Patch
A
new skin patch that contains the Alzheimer’s drug Exelon (rivastigmine)
may be just as effective as pills, say researchers from the Karolinska
Institute in Stockholm, Sweden. The skin patch, however, may be
gentler. It appears to produce fewer side affects, such as nausea and
vomiting, the causes some patients on the pills to stop taking them.
Among
1,195 people with Alzheimer’s who were given either standard Exelon
capsules or a skin patch that delivers the drug through the skin (much
like the nicotine patch to stop smoking), both groups did similar on
memory tests. Like all currently approved Alzheimer’s drugs, however,
Exelon may produce some benefits or delay symptoms but does not stop
the underlying disease and relentless downward progression. The patch may be available next year if further testing proves it a safe and effective alternative.
New Vaccines
An
additional treatment that has shown some initial promise is a mixture
of immune system proteins, called antibodies, which may help to “mop
up” the excess beta-amyloid proteins that may lead to plaque
build-up and brain cell death. The treatment consists of intravenous
immunoglobulins (another name for antibodies) that seem to target and
remove beta-amyloid.
In a study of 19 people with Alzheimer’s
who were given injections of the antibodies, beta-amyloid levels
increased in the blood. This finding suggests that the vaccine may be
removing the toxic protein from the brain, and shifting it to the
blood. However, patients in the current study did not show any cognitive
improvement but did not deteriorate either. Earlier research has
suggested that ongoing treatments with this vaccine treatment may help
to slow the mental decline of Alzheimer’s disease.
Vaccines and
other immune-system treatments are very tricky, however, and some can
be dangerous. Several years ago, testing of another promising
Alzheimer’s vaccine led to severe brain inflammation
and death in one patient given the treatment. Many more years of
testing is likely required before this or other vaccines are
recommended for people with Alzheimer’s disease.
The Fisher Center
Many
new therapies are currently under development for Alzheimer’s disease.
They require years of testing to see if they are safe and effective.
The Fisher Center for Alzheimer’s Research Foundation continues to fund
basic research into the underlying causes of Alzheimer’s disease and
the search for a cure. For more information, visit www.alzinfo.org, The
Alzheimer’s Information Site.
By alzinfo.org, The
Alzheimer's Information Site. Reviewed by William J. Netzer, Ph.D.,
Fisher Center for Alzheimer's Research Foundation at The Rockefeller
University
Source: 10th International Conference on Alzheimer’s Disease and Related Disorders, Madrid, Spain, July 2006.
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