By reducing the activity of one type of gene, scientists said they increased the average life span of mice by about 20 percent, a feat that in human terms is akin to extending life by about 15 years.

Moreover, the researchers at the National Institutes of Health found that memory, cognition and some other important traits were better preserved in the mice as they aged, compared with a control group of mice that had normal levels of a protein put out by the gene. The findings, published Thursday in the journal Cell Reports, strengthen the case that the gene, called mTOR, is a major regulator of the aging process.

The mice were bred to put out just 25 percent of the normal levels of mTOR protein, indicating that suppressing the activity of the gene "clearly makes mice live longer," said Toren Finkel, head of the laboratory of molecular biology in NIH's National Heart, Lung and Blood Institute and senior author of the new study.

Though mouse studies don't always translate to humans, Dr. Finkel and other researchers said the results raise the possibility that targeting the gene with drugs that inhibit its activity might one day be at least part of a strategy for prolonging longevity in people. Such a drug, an immunosuppressant called rapamycin, and some similar agents already are on the market and used to treat certain diseases, but researchers cautioned against taking such medicines, which have side effects, for anything but approved uses.

The results also build on a growing body of research challenging the belief that aging is an intractable biological process, prompting scientists to think of slowing aging as a possible way to prevent disease.

"What we need right now is for scientists and the public to wake up to the concept that you can slow aging," said Brian Kennedy, president of the Buck Institute for Aging Research in Novato, Calif., who wasn't involved in the new study. "If you do, you prevent many of the diseases that we're so scared of and that are associated with aging."

Click for more from The Wall Street Journal.