It took two years to determine how the dye works wonders in millimeter-long worms known as C. elegans, which are ideal for longevity studies because they live for only a few weeks.

By slowing the process of protein malformation, the dye extended the lifespan of healthy worms by more than 50 percent and curbed the disease in worms bred to mimic Alzheimer's, the study found.

"It takes you by surprise initially, then you realize that makes sense," said Gordon Lithgow, a Buck faculty member who credits Alavez with the "breakthrough concept."

The dye study also supports a broad-based effort to combat degenerative diseases, such as Alzheimer's and Parkinson's, that threaten millions of aging Americans, Lithgow said.

"We think the central focus should be on the aging process itself," he said.

The dye study cost about $250,000<NO1><NO>, Lithgow said, a reminder of the high stakes in scientific research. "You definitely take chances," he said, noting that some studies merely "run into the sand."

But the institute's expense pales compared with the $170 billion a year cost of Alzheimer's disease in the United States, a figure expected to hit $500 billion by 2050.

For Alavez and others involved in the dye study, getting a paper published in Nature can be a big career boost, Lithgow said.

Alavez said he hopes to return to Mexico City and establish an aging research lab there.

Research on the yellow dye and related compounds has already moved from worms to mice, and there are human trials underway using curcumin to treat conditions such as colon cancer, rheumatoid arthritis and depression.