This finding helps explain why Alzheimer's is a disease of aging. More importantly, it suggests a new weapon: drugs that give nature's cleanup crew's a boost.

The discovery published in Thursday by the journal Science, was made in a tiny roundworm called C.elegans.

Worms can't get Alzheimer's. So Dillin's team used roundworms that produce human beta-amyloid in the muscle of the body wall. As the worms age, amyloid builds up until it eventually paralyzes them; they can wiggle only their heads.

Then the researchers altered the genes in a pathway called insulin/IGF-1, long known to be key in controlling lifespan. Making the worms live longer protected them from paralysis.

So, in slowing down the normal aging, something slowed the buildup of toxic amyloid. But what?

Why use worms to test for a human disease? They are commonly used in age-related diseases and genetically are similar. Scripps Research Institute and the Salk Institute in California are already on the trail to new drug candidates.

About 4.5 million Americans suffer with Alzheimer's and this number is expected to triple by 2050 as the baby boomers age. The brain disease gradually robs sufferers of their memories and ability to care for themselves. There is no known cure and only drugs used to temporarily retard the progress of Alzheimer's.

Scientists don't know what causes the disease but suspect it is a gooey-protein called beta-amyloid. All brains contain it, but healthy cells get rid of excess amounts. But with Alzheimer patients this gooey protein builds up inside the brain cells and form clumps that coat the cells - plaque that is the disease's hallmark.

"Every pathway we can discover that modifies amyloid provides us with new drug targets", said Dr Sam Gandy, a neuroscientist with the Thomas Jefferson University and an Alzheimer's Association spokesman. "This now opens a new pathway" for developing anti-Alzheimer's drugs.

The bottom line with this research is that the scientists are trying to confirm the belief that two proteins, HSF-1 and DAF16 help clear away these amyloid clumps and make them less toxic.

The hope is to create drugs that boost their effects, and amyloid might not build up in the first place. Dillon said initial drug attempts were showing promise in his worms.