The American quest for the fountain of youth is never ending, and thanks to a study in last week's New England Journal of Medicine, old folks and Eli Lilly & Co. have a hot new prospect: human growth hormone. By injecting a synthetic version of the hormone into a handful of healthy, aging men for six months, researchers managed to reverse the process by which lean body mass gives way to fat. Indeed, the six-month regimen seemed to undo 10 to 20 years of skin, bone and muscle deterioration, prompting speculation that prolonged youth would one day be an option for anyone who could afford the treatment (it would cost about $14,000 a year at current prices). But don't hold your breath. As one expert puts it, "To think this is going to be an anti-aging panacea is a mistake."
The new study, funded in part by Lilly, was the first to test the effects of growth hormone on healthy oldsters, but the results were no great surprise. Previous trials have shown that growth-hormone therapy can slow muscle loss and fat buildup in young patients with endocrine deficiencies. Since advanced age brings similar changes in body composition--often accompanied by a decline in growth-hormone production--it stood to reason that aging patients might benefit from the treatment. To find out, a team led by Dr. Daniel Rudman of the Medical College of Wisconsin and the Milwaukee VA Medical Center assembled 21 healthy men, 61 to 81, with low levels of growth hormone. For six months, 12 of the subjects received growth-hormone injections. The other nine didn't. The treated subjects enjoyed a 14 percent reduction in body fat and a 9 percent gain in lean body mass. They also showed slight gains in skin thickness and spinal density. By all these measures, they got younger.
So why not shout eureka? First, as Rudman and his colleagues duly note, the 12 men were by no means representative of the over-60 population. Though everyone slackens with age, only a third of the elderly experience the decline in growth hormone that this trial sought to counter. The treatment might do nothing for more typical aging males, or for women. A second reason for caution is that the observed effects don't necessarily represent improved health. The treatment may not enhance "muscle strength, mobility or the quality of life," Dr. Mary Lee Vance notes in an editorial accompanying the study. The treatment might even pose hazards. Potential side effects range from enlargement of the face and extremities to hypertension, arthritis and heart failure. There is also a possible cancer connection. People with acromegaly, a condition caused by excess growth hormone, are at increased risk of colon cancer. And one study of people taking human growth hormone for dwarfism found a rise in leukemia incidence.
As a medical field, hormone therapy holds rich possibilities. Last week alone, researchers reported in separate studies that the hormonal drug megestrol acetate could help emaciated cancer patients gain weight, and that treatment with a growth factor called TGF-beta might prevent some of the damage caused by heart attacks. Some statistical risks are justified when a treatment holds such promise. But until someone shows that the benefits of growth-hormone injections outweigh the risks to healthy adults, diet and exercise will be surer routes to good health.