Hoping to reverse some of the burdens of growing older, Baltimore scientists will soon begin giving elderly volunteers supplements of human growth hormone to see if it makes them stronger and more vigorous.
The experiment, planned by the Francis Scott Key Medical Center and the National Institute on Aging, is the most ambitious of nine projects nationwide that will be using hormone supplements in an attempt to answer the ancient question: Is frailty a necessary part of aging?
Researchers emphasize that the project is not an attempt to push back the absolute limit of longevity, which many experts place at about 110 years. Rather, they hope to allow more people to approach that limit with stronger bones, more muscle and less fat, which could make them more independent and less inclined to end up in nursing homes.
"We don't think this is going to extend life but improve the quality of life," said Dr. Marc R. Blackman, director of endocrinology at the Francis Scott Key Medical Center. He and Dr. Mitchell Harman, chief of the endocrinology section at the National Institute on Aging, are directing the five-year, $1.4 million project in Baltimore.
If successful, the trials could mean benefits for society as well as the elderly themselves: The number of people dependent on caregivers is expected to reach 14 million -- twice today's number -- by 2030 unless disability rates are lowered.
Despite its hopeful billing, the research has its critics. Some scientists suggest that low hormone levels may be nature's way of protecting the elderly against such ills as cancer and heart disease. Artificially raising them, they warn, could promote rather than prevent illness.
"I have a healthy skepticism about reversing the normal process of aging," said Dr. Louis E. Underwood, chief of endocrinology at the University of North Carolina at Chapel Hill.
The experiments are based on evidence gathered over the last decade that the growth hormone not only makes children grow taller, but contributes to bone and muscle strength once people reach their maximum height. For many years, growth hormones have been given to abnormally short children to help them grow, but never routinely to old people.
The body's production of growth hormone tails off steadily as people age, which has led researchers to speculate that this may be partly responsible for the frailty that causes senior citizens to fall and break bones. Hip fractures, in particular, are a frequent hazard and lead to many deaths among the elderly.
Two years ago, scientists at the Veterans Affairs Medical Center in Milwaukee reported that growth hormone supplements increased "lean body mass" in a small group of healthy men ages 61 to 81. Lean body mass is the amount of one's body composed of bone, muscle and organs, rather than fat.
In Baltimore, 80 men and 80 women will be divided into groups receiving human growth hormone, sex hormone, combinations of the two or a placebo. Sex hormones are thought to reduce osteoporosis and prevent some heart disease in post-menopausal women.
Daily treatments will stretch over six months.
Small groups of patients will begin treatment on a staggered basis, with the first volunteers taking their first pills as early as next month.
The research team will be looking for any changes in fat content, muscle strength and bone density, and heart, kidney and immune function.
Scientists will also be looking for unintended side effects. For instance, growth hormone supplements are thought to cause some people to retain fluids, which could lead to congestive heart failure or carpal tunnel syndrome.
Also, researchers are concerned that growth hormones could stimulate the growth of pre-existing tumors that would have stayed small or grown very slowly if left alone.
In addition, there is the possibility that sex hormones could promote breast or uterine cancer in women and prostate cancer in men.