New Thinking About Alzheimer's Treatment
Current therapies are the triumph of hope over experience.
New Approaches Needed
There are only five drugs approved by the FDA specifically for
treatment of AD, and only four are widely used (the fifth, Cognex, has serious
side effects and has largely fallen out of use). But because they work on the
symptoms of Alzheimer's -- memory loss, confusion, agitation -- rather than on
the actual pathology that causes the symptoms, these drugs may be a case of too
little, too late.
"Everybody feels like we have to do something about this
disease fast. The numbers of people who are going to be affected by it is so
great, we know what a difference it could make if we could delay onset even by
five years. And we also know that the disease takes a long time to evolve in
the brain, so the sooner we intervene, the better," says Marilyn Albert,
PhD, director of the division of cognitive neuroscience in the department of
neurology at Johns Hopkins University School of Medicine in Baltimore.
The first brain changes of Alzheimer's disease may occur as
early as 10 to 20 years before the first symptoms of the disease appear, Bengt
Winbald, MD, PhD, professor of geriatric medicine and chief physician at the
Karolinska University Hospital and Karolinska Institute in Stockholm, Sweden,
Until recently, those changes have been too small or too subtle
to easily detect, making it extremely difficult to identify people who could
benefit from early intervention.
But that appears to be changing. A key theme at this year's
Alzheimer's conference is advances in brain imaging that may make it possible
to detect and diagnose early AD, leading to the development of drugs and other
treatment strategies that could halt or at least slow the progression of
Plaque Attacks and Tangled Webs
One of the most intriguing strategies discussed at this year's
conference involves drugs or vaccines aimed at clearing deposits of an abnormal
form of a protein that accumulates in the brains of people who suffer from
Alzheimer's. The protein, known as beta amyloid, forms clumps or
"plaques" and is a hallmark of Alzheimer's disease.
One experimental drug, called Alzhemed, has been shown in
animal and human studies to clear significant amounts of beta amyloid deposits
from the brain. A similar drug, known only as LY450139, has shown similar
effects in humans.
Several companies are also working on vaccines that can
stimulate the body to make antibodies that attack and dissolve beta-amyloid
deposits. Other experimental drugs and vaccines are aimed at treating another
suspected cause of AD, a different protein known as tau, which normally serves
as a building block of nerves. In the brains of people with advanced AD,
strands of twisted tau proteins, called fibrillary tangles, can be found inside