The drug rapamycin has potential to increase the lifespan of humans and other mammals - however, it has limited effect on aging process itself, according to new research.

Dr. Dan Ehninger, lead researcher and senior author of the new study, explained that as the body gets older, it runs a higher risk of developing deleterious conditions like Alzheimer's disease, diabetes, cancer and cardiovascular disorders.

"Current efforts to develop therapies against age-related diseases target these disorders one by one," he said. "Influencing the aging process itself may be an alternative approach with the potential to yield broadly effective therapeutics against age-related diseases."

Targeted therapy designed to halt the body's own decline could thus preempt age-related illnesses, circumventing an entire spectrum of costly and deadly diagnoses.

In 2009, the scientific community was galvanized by a study that linked rapamycin to longer lifespans in mice. "Rapamycin was the first drug shown to increase maximal lifespan in a mammalian species. This study has created quite a stir," Ehninger explained. "We wanted to address if rapamycin slows down aging in mice or, alternatively, if it has an isolated effect on lifespan - without broadly modulating aging."

Now, the team has determined that while the drug may indeed increase lifespan, its effects on the aging process are less impressive. Although rapamycin was shown to have some positive effects on aging traits like memory impairment and reduced red blood cell counts, similar results were recorded in young mice administered the drug, leading the researchers to conclude that its influence in those areas was unrelated to the aging process.

The increased lifespan observed in mouse subjects could instead be the result of rapamycin's capacity to inhibit tumor growth.

"This is a well-known rapamycin effect, which we were able to confirm. Cancer is the leading cause of death in the relevant mouse strains" he said. "Rapamycin, therefore, seems to have isolated effects on specific life-limiting pathology, but lacks broad effects on aging in mice."

However, Ehninger hinted that the obstacles separating mankind from a youth elixir is not limited to inadequate drugs. Aging is itself a tremendously complex process that is difficult to formalize and measure objectively. The biological decline, or "senescence," of the human body is really the accumulation of several degenerative processes that all manifest in different ways - and even their shared vanishing point, death, is an exceedingly intricate event.

That being said, rapamycin's ability to increase lifespan is still a significant observation.

"Such substances could open up new possibilities for medicine. However, this is still some way off," Ehninger said.


”Rapamycin extends murine lifespan but has limited effects on aging “, Frauke Neff, Diana Flores-Dominguez etc., Journal of Clinical Investigation (published online on July 25, 2013),