Can Science Slow the Aging Process?
Dr. Steven Austad, professor of cellular and structural biology at UT Health Science Center - San Antonio, strongly believes science can substantially slow the aging process and nature holds the answer to longer, healthier, more productive lives. In fact, he bet a fellow researcher an estimated $500 million that the first 150-year-old person is already alive today. Each researcher invested $150 in a trust fund and the proceeds go to the winner in 2150. Austad hopes he's here to collect.
Looking to Nature for Answers
Once an aspiring zoologist, Austad became interested in the study of aging by accident. In the 1980s, while researching the mating behavior of a tropical wren at a small field station in Venezuela, he teamed up with a fellow scientist to study the reproductive behavior of opossums. To Austad's surprise, few lived longer than two years, far shorter than he expected. Something was accelerating their aging process.
Austad's research soon took him to Sapelo Island, five miles off the coast of Georgia, where a species of opossum had lived in isolation from predators and its mainland cousins for hundreds, if not thousands, of years. Nature provided what Austad couldn't duplicate — a laboratory for comparing the evolutionary biology and life spans of two, long-separated, genetically-related species living in the wild in vastly different environments. Two years later, his research revealed that the island opossums lived an astounding 25 to 50 percent longer, aged and reproduced more slowly, and had smaller litters. Even tissue samples from tendons of both species revealed genetic differences.
Two decades later, Dr. Steven Austad is still looking for answers in nature. Today, at the Sam and Ann Barshop Institute for Aging and Longevity Studies at UTHSC - San Antonio, he and fellow investigators are comparing the biology and cellular structures of long- and short-lived rats, mice, birds, bats, rodents and marmosets in hopes of gaining a better understanding of how humans age. Austad says humans are quite successful at aging, noting that 25 percent of human longevity is genetic and 75 percent is environmental. But with animals, aging is 100 percent genetic.
"Working on a dozen different species simultaneously is a new and unique approach to try to understand aging," says Austad. "More and more animal genomes are being sequenced all the time, so we're also getting more information." And with that genetic information come greater opportunities to visually identify molecular differences between similar long- and short-lived species and examine whether long-living species have common traits that can be applied to humans.
"The answer to this phenomenon," says Austad, "is in understanding the genome — the cell's DNA." They've discovered that the DNA of long-lived species repairs itself more quickly than that of short-lived species, and that their proteins are more stable and resistant to change. Healthy DNA helps organisms fight internal and external damage and disease, and keeps cells and organs functioning properly. Proteins, whose coding is contained within the DNA, form the cell's structure and run the body's chemical reactions. Stable proteins enable our cells and organs to operate longer, more efficiently. Both contribute to extended longevity.
Aging and age-related illnesses, like cancer and heart disease, are the result of damaged DNA. Malfunctioning proteins have been linked to Alzheimer's, Parkinson's and ALS disease. By studying the DNA of animal species that are especially successful at aging, like bats and birds, and comparing it to species that have shorter life spans, like laboratory mice, Austad hopes his research team will be able to identify mechanisms within the cell that govern aging and then design therapies that will enable humans to live longer, healthier lives.
The Possibility of Longer Life
Today, some laboratory animals in Dr. Austad's research projects are evidence that life can be extended through science. His team has successfully increased the life span of test animals six-fold by manipulating genes associated with how the body processes insulin — a protein involved in metabolizing glucose. In another experiment, researchers found that mice that ate considerably less lived 30 to 40 percent longer, which, according to Austad, would be 20 to 30 years in human terms. Studies involving insulin activity and production hold tremendous promise for slowing aging as well as managing diabetes. In fact, Austad envisions a day when medicine will be able to encourage the body to mimic the chemical reactions that occur when food consumption is reduced. "Basically, you'll flip a switch," he says, "without having to eat less. You will take your little caloric restriction pill every day that will make you age more slowly."
Although better nutrition, more exercise and less stress can add years to one's life, longevity researchers are looking for more immediate, biochemical ways to slow down aging. Today, 4 million people suffer from Alzheimer's disease and, in the next 20 years, an estimated 12 million people will be affected by this debilitating disease, which currently has no cure. Incidences of heart disease and cancer — the two most common age-related diseases — will also rise as baby boomers age, as will cases of diabetes, osteoarthritis and Parkinson's disease. With an estimated 40 million Americans to be aged 65 or older in 2010, our society must be prepared to meet the medical challenges of this large, aging demographic. Understanding which genes control which biological functions can help researchers develop therapies to prevent, treat or reduce the severity of these and other age-related diseases and disabilities.
"Aging affects all of us," says Dr. Austad. "People are going to continue to live longer because of medical advances. We want them to live healthier as well as live longer. The best way to achieve longer health is to figure out ways to medically slow aging. That's a different sort of approach than figuring out how to cure cancer or heart disease. If you can cure aging, or if you can slow it, then you can really delay or prevent a whole host of disabilities and diseases."