Alzheimer's Cure Elusive Despite Progress
Ronald Reagan's struggle shows how far we've come, how far we have to go.
Tomorrow's Plaque Fighters
Gandy says that scientists are in hot pursuit of three
First is the anti-plaque antibody approach. Using a vaccine and
allowing the body to make antibodies seems too dangerous. But what if you could
raise plaque-busting antibodies in the laboratory? Theoretically, you then
could find a dose that cuts plaque without killing the patient.
This isn't science fiction any more. Several companies are
racing to develop this strategy, known as passive immunization or passive
"It works in the mouse model," Gandy says. "It
should be effective."
The second idea is to keep plaque from forming clumps. Amyloid
gets particularly sticky when it combined with two substances: sugars and
metals (especially zinc). Drugs that block both of these combinations are in
the pipeline. And they work in mice, Gandy says.
The third idea -- and the one closest to reality -- involves
new uses for existing drugs. Amyloid doesn't just happen. It's the result of a
complex biochemical process. The process stops without a key set of
It's recently become clear that some of the
cholesterol-fighting drugs called statins block these enzymes. Data from trials
of one of these drugs -- Lipitor -- suggest that people taking the drug to
treat high cholesterol have a lower risk of Alzheimer's disease. The National
Institute on Aging (NIA) is conducting a large clinical trial to see whether
another of these drugs, Zocor, actually prevents Alzheimer's.
The NIA is also looking at another class of drugs capable of
blocking amyloid production. It's the NSAIDs or nonsteroidal anti-inflammatory
drugs -- the same class to which aspirin and ibuprofen belong. One of these
drugs, Ansaid, may be particularly effective against amyloid, Gandy says.
If these drugs already exist, why aren't they being used? The
reason is that amyloid plaques are notoriously hard to detect until Alzheimer's
disease is well under way.
That, too, is changing. Gandy says that new imaging techniques
called PET scans will allow doctors to see tiny spots of amyloid.
"This might be useful for very early diagnosis of people
getting Alzheimer's disease, decades before symptoms show up," Gandy says.
"And it will help with developing prevention drugs, because it will let you
see what is going on."
Many people who don't think plaque is the No. 1 bad guy have
another villain in mind. These are the tangled fibers in the brains of
Alzheimer's patients. It's been hard to work on anti-tangle drugs, because
there's no good animal model. But progress is being made, Gandy says.