New Areas of Research for Alzheimer's Disease
The National Institute on Aging (NIA), part of the National Institutes
of Health (NIH), is the lead Federal agency for Alzheimer's Disease research.
NIA-supported scientists are testing a number of drugs to see if they prevent
Alzheimer's Disease, slow the disease, or help reduce symptoms. Some ideas that
seem promising turn out to have little or no benefit when they are carefully
studied in a clinical trial. Researchers undertake clinical trials to learn
whether treatments that appear promising in observational and animal studies
actually are safe and effective in people.
Mild Cognitive Impairment. During the past several years,
scientists have focused on a type of memory change called mild cognitive
impairment (MCI), which is different from both Alzheimer's Disease and normal
age-related memory change. People with MCI have ongoing memory problems, but
they do not have other losses such as confusion, attention problems, and
difficulty with language. The NIA-funded Memory Impairment Study compared
donepezil (Aricept), vitamin E, or placebo in participants with MCI to see
whether the drugs might delay or prevent progression to Alzheimer's Disease. The
study found that the group with MCI taking the drug donepezil were at reduced
risk of progressing to Alzheimer's Disease for the first 18 months of a 3-year
study when compared with their counterparts on placebo. The reduced risk of
progressing from MCI to a diagnosis of Alzheimer's Disease among participants on
donepezil disappeared after 18 months, and by the end of the study, the
probability of progressing to Alzheimer's Disease was the same in the two
groups. Vitamin E had no effect at any time point in the study when compared
with placebo.
Neuroimaging. Scientists are finding that damage to parts of
the brain involved in memory, such as the hippocampus, can sometimes be seen on
brain scans before symptoms of the disease occur. An NIA public-private
partnership—the Alzheimer's Disease
Neuroimaging Initiative (ADNI)—is a large study that will determine whether
magnetic resonance imaging (MRI) and positron emission tomography (PET) scans,
or other imaging or biological markers, can see early Alzheimer's Disease
changes or measure disease progression. The project is designed to help speed
clinical trials and find new ways to determine the effectiveness of treatments.
For more information on ADNI, call the NIA’s Alzheimer’s Disease Education and
Referral (ADEAR) Center at 1-800-438-4380, or visit
www.alzheimers.org.
Alzheimer's Disease Genetics. The NIA is sponsoring the
Alzheimer's Disease Genetics Study to learn more about risk factor genes for
late onset Alzheimer's Disease. To participate in this study, families with two
or more living siblings diagnosed with Alzheimer's Disease should contact the
National Cell Repository for Alzheimer's Disease toll-free at 1-800-526-2839.
Information may also be requested through the study’s website:
http://ncrad.iu.edu.
Inflammation. There is evidence that inflammation in the
brain may contribute to Alzheimer's Disease damage. Some studies have suggested
that drugs such as nonsteroidal anti-inflammatory drugs (NSAIDs) might help slow
the progression of Alzheimer's Disease, but clinical trials thus far have not
demonstrated a benefit from these drugs. A clinical trial studying two of these
drugs, rofecoxib (Vioxx) and naproxen (Aleve) showed that they did not delay the
progression of Alzheimer's Disease in people who already have the disease.
Another trial, testing whether the NSAIDs celecoxib (Celebrex) and naproxen
could prevent Alzheimer's Disease in healthy older people at risk of the
disease, has been suspended. However, investigators are continuing to follow the
participants and are examining data regarding possible cardiovascular risk.
Researchers are continuing to look for ways to test how other anti-inflammatory
drugs might affect the development or progression of Alzheimer's Disease.
Antioxidants. Several years ago, a clinical trial showed
that vitamin E slowed the progress of some consequences of Alzheimer's Disease
by about 7 months. Additional studies are investigating whether
antioxidants—vitamins E and C—can slow Alzheimer's Disease. Another clinical
trial is examining whether vitamin E and/or selenium supplements can prevent
Alzheimer's Disease or cognitive decline, and additional studies on other
antioxidants are ongoing or being planned.
Ginkgo biloba. Early studies suggested that extracts from
the leaves of the ginkgo biloba tree may be of some help in treating Alzheimer's
Disease symptoms. There is no evidence yet that ginkgo biloba will cure
or prevent Alzheimer's Disease, but scientists now are trying to find out in a
clinical trial whether ginkgo biloba can delay cognitive decline or
prevent dementia in older people.
Estrogen. Some studies have suggested that estrogen used by
women to treat the symptoms of menopause also protects the brain. Experts also
wondered whether using estrogen could reduce the risk of Alzheimer's Disease or
slow the disease. Clinical trials to test estrogen, however, have not shown that
estrogen can slow the progression of already diagnosed Alzheimer's Disease. And
one study found that women over the age of 65 who used estrogen with a progestin
were at greater risk of dementia, including Alzheimer's Disease, and that older
women using only estrogen could also increase their chance of developing
dementia.
Scientists believe that more research is needed to find out if estrogen may
play some role in Alzheimer's Disease. They would like to know whether starting
estrogen therapy around the time of menopause, rather than at age 65 or older,
will protect memory or prevent Alzheimer's Disease.
Clinical Trials in Alzheimer's Disease research
People with Alzheimer's Disease, those with MCI, or those with a family
history of Alzheimer's Disease, who want to help scientists test possible
treatments may be able to take part in clinical trials. Healthy people also can
help scientists learn more about the brain and Alzheimer's Disease. The NIA
maintains the Alzheimer's Disease Clinical Trials Database, which lists
Alzheimer's Disease clinical trials sponsored by the Federal government and
private companies. To find out more about these studies, contact the NIA’s ADEAR
Center at 1-800-438-4380 or visit the ADEAR Center website at
www.alzheimers.org/trials/index.html. You also can sign up for
e-mail alerts on new
clinical trials as they are added to the database. Additional clinical trials
information is available at
www.clinicaltrials.gov.
Many of these studies are being done at NIA-supported
Alzheimer’s Disease Centers
located throughout the United States. These centers carry out a wide range of
research, including studies of the causes, diagnosis, treatment, and management
of Alzheimer's Disease. To get a list of these centers, contact the ADEAR
Center.
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