Growth hormone: no elixir for old age?

Human growth hormone may be losing its allure as an antiaging drug.

In 1990, a team of researchers reported that a synthetic version of the hormone reversed some age-associated changes in body composition (SN: 7/14/90, p. 23). As part of the normal aging process, fat replaces lean body mass, including muscle. The researchers theorized that as people age, their secretion of growth hormone plummets, leaving them flabby and frail. In their study, elderly men who received treatment suddenly appeared more youthful and leaner.

But could growth hormone therapy actually boost the strength of an elderly person?

Maxine A. Papadakis of the Department of Veteran Affairs Medical Center in San Francisco, Calif., and her colleagues decided to find out. They recruited 52 healthy men age 70 to 85. The researchers assigned each man to a group that received either growth hormone or a dummy injection.

After 6 months, the team measured the effect of human growth hormone on body composition. It found that, compared to the placebo group, the growth hormone group's lean tissue mass increased by 4 percent and its fat mass dropped by 12 percent.

So far so good. But then the California scientists put the men through a series of tests designed to measure strength and cognitive function. Despite the changes in their body composition, the men demonstrated no significant improvement in muscle strength or endurance. They also found no change in mental acuity. The team reports its disappointing findings in the April 15 Annals of Internal Medicine.

For now, the researchers advise against using growth hormone to preserve functional ability in older adults. "There are no data to support its use in the elderly," Papadakis told Science News, noting that a year's worth of the synthetic drug costs $12,000.