Human beings are living longer than ever. Life expectancy in the United States has hit an all time high of nearly 79 years for people born in 2012. By the middle of the century, the number of people over 80 years old is predicted to triple, with exponential increases in age-related diseases expected to follow. Scientists are studying aging in the hopes that an understanding of the process will provide clues to extending not just the human lifespan, but the human health span—the number of years lived without disease or disability.
Previous research on aging has focused mostly on older adults, but diseases don’t emerge all at once; generally, age-related changes gradually accumulate in the body over time. “Thus,” the authors of a new study published this week in PNAS write, “intervention to reverse or delay the march toward age-related diseases must be scheduled while people are still young.”
This higher-Pace of Aging group performed poorer on tests of physical functions, such as balance, motor, and grip strength tests, than their biologically younger peers.
The researchers tracked aging in 954 adult participants using the Dunedin Study—a cohort of over 1,000 individuals followed from birth in 1972-73 in Dunedin, New Zealand. When the participants were 38 years old (and still free of the diseases that plague the elderly) the team evaluated each participant based on a suite of physiological markers of health to reveal each participant’s “biological age.” Despite all the participants being the same chronological age, the authors found that the study members’ biological ages ranged from 28 to 61. To find out if those who appeared to be older really were aging faster than their peers, the team looked back at the study participants’ health data from age 26. The researchers quantified change in measures such as heart, liver, kidney, and lung health, metabolic and immune system function, DNA integrity, and dental health to see how much each had deteriorated in the intervening 12 years. In other words, the researchers were looking at the participants’ “Pace of Aging.”
They found that study participants who appeared older at 38 had a higher Pace of Aging than their peers. This higher-Pace of Aging group performed poorer on tests of physical functions, such as balance, motor, and grip strength tests, than their biologically younger peers. The faster aging cohort members also showed steeper declines in cognitive functioning over the years. Further, the seemingly older individuals both felt and appeared older than their similarly aged peers; when Duke University undergraduates evaluated photographs of the study participants, the students scored those individuals as looking older.
The study is just a step toward a more complete understanding of aging, but the fact that the process can be studied in young humans could one day lead to better strategies for disease prevention and more effective anti-aging therapies.
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