New Clues To Alzheimer's

For years, doctors have known that the brains of people with Alzheimer's disease gradually get clogged with something called "amyloids," proteins that literally litter the brain, blocking neurons and erasing memories. But no one ever knew what caused these proteins to form, CBS News Correspondent Elizabeth Kaledin reports.

On Friday, researchers at The Amgen labs in California said they have finally figured it out.

"We have discovered an enzyme that plays a critical role in the formation of amyloids," explains Amgen Inc. research scientist Martin Citron. "And these amyloids make the amyloid plaque that causes Alzheimer's disease."

Researchers believe the enzyme may be present in the brain long before any symptoms of Alzheimer's disease even show up. In full-blown Alzheimer's, the enzyme slices brain cell proteins into fragments (amyloids) which form a toxic plaque that kills nerve cells in the brain.

The result is that people like Zan White can't remember things, sometimes don't recognize family members, and gradually lose touch with reality. "And the greatest fear is that you won't die soon enough," White says. "That you will be a vegetable."

There is no cure for Alzheimer's disease, and even the best current treatments can only control symptoms for a short time. The hope is that the discovery of what kick-starts Alzheimer's disease will lead to promising new drugs that can turn it off.

According to Alzheimer's specialist Dr. Normal Relkin, "What we did before in developing such drugs was shooting in the dark. This sheds a major light on how we can approach Alzheimer's therapy in the future."

In the same way that drugs called protease inhibitors block the protease enzyme linked to the AIDS virus, scientists believe they can develop a similar class of drugs to block the enzyme that leads to Alzheimer's disease. But since it's taken more than a decade to find that elusive enzyme, it's expected to take another five or 10 years to turn the discovery into a marketable treatment.