Molecular Fingerprint Of Biological Aging Revealed

"Age is more than just a number," said senior author Aditi Gurkar, Ph.D., assistant professor of geriatric medicine at Pitt's School of Medicine and member of the Aging Institute, a joint venture of Pitt and UPMC. "Imagine two people aged 65: One rides a bike to work and goes skiing on the weekends, and the other can't climb a flight of stairs. They have the same chronological age, but very different biological ages. Why do these two people age differently? This question drives my research."

The researchers compared 196 older adults who were classed as either healthy or rapid agers by how easily they completed walking challenges. The team found that among the participants the healthy agers were 75 years old or older and could ascend a flight of stairs or walk for 15 minutes without rest, and the rapid agers were between the ages of 65 to 75 years old and had to rest to complete these challenges. 

The team said this study was unique because the rapid agers were chronologically younger than the healthy agers which allowed them to home in on the markers of biological aging, unlike other studies that compared younger adults with older people. 

"Other studies have looked at genetics to measure biological aging, but genes are very static: the genes you're born with are the genes you die with," said Gurkar. "We chose to look at metabolites because they are dynamic: They change in real-time to reflect our current health and how we feel, and we have the power to influence them through our lifestyles, diet, and environment."

To define a molecular fingerprint of biological aging in blood samples from the participants a metabolomic analysis was conducted which revealed clear differences between the two groups, indicating that metabolites in the blood could reflect biological age.25 metabolites were identified that they termed the Healthy Aging Metabolic (HAM) Index. 

This index was found to be better than other commonly used aging metrics at distinguishing healthy and rapid agers. To validate the HAM Index a separate cohort of older adults was analyzed from another study, the new index was found to correctly predict whether the participants could walk outside without stopping for 10 minutes with 68% accuracy.

"We took a very different cohort of people from a different geographical region, and we saw the same metabolites were associated with biological aging," said Gurkar. "This gives us confidence that the HAM Index can truly predict who is a healthy ager versus a rapid ager."

"While it's great that we can predict biological aging in older adults, what would be even more exciting is a blood test that, for example, can tell someone who's 35 that they have a biological age more like a 45-year-old," Gurkar said. "That person could then think about changing aspects of their lifestyle early -- whether that's improving their sleep, diet or exercise regime -- to hopefully reverse their biological age."

"Today, in medicine, we tend to wait for a problem to occur before we treat it," she added. "But aging doesn't work that way -- it's about prevention. I think the future of medicine is going to be about knowing early on how someone is aging and developing personalized interventions to delay disease and extend healthspan."