How long growth hormones need to be restricted to produce the slowing of aging isn't known. "Do you have it during early development in the womb, in puberty, or can you have it at any stage that you wish?" Barzilai asked.
Barzilai noted that growth hormone is a very popular anti-aging therapy. Growth hormone changes the tone of the skin and fat distribution, and increases muscle mass.
"However, this study and other studies suggest that, for the purpose of aging and longevity, growth hormone might do exactly the opposite," he said. "In the short run, growth hormones are going to have positive effects, but certainly in elderly people I would suggest, and this study supports the notion, that we will kill them sooner rather than later."
One expert thinks the findings are intriguing but inconclusive.
"This is an interesting study, which has to be replicated by other researchers using a different dataset, because studies on exceptional longevity often cannot be replicated," said Leonid Gavrilov, a research associate at the Center on Aging at the University of Chicago.
The study found a sex-specific increase in IGF-1; it showed up only among the daughters of centenarians, while sons were not affected, Gavrilov noted. "The study does not suggest any explanation, or even a hypothesis, for this sex-specific effect. General conclusions suggested in this paper may be questionable if they are not applicable to men," he said.
"It may be interesting to put this study in a context of other findings, such as being born to a young mother helps to live to 100 years," Gavrilov said.
For more on aging, visit the National Institute on Aging.
SOURCES: Nir Barzilai, M.D., d
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