The number of birthdays you’ve had—better known as your chronological age—now appears to be less important in assessing your health than ever before. A new study shows that bodily organs get “older” at extraordinarily different rates, and each one’s biological age can be at odds with a person’s age on paper.
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The team sampled the blood of more than 5,500 people, all with no active disease or clinically abnormal biomarkers, to look for proteins that originated from specific organs. The scientists were able to determine where those proteins came from by measuring their gene activity: when genes for a protein were expressed four times more in one organ, that designated its origin. Next the team measured the concentrations of thousands of proteins in a drop of blood and found that almost 900 of them—about 18 percent of the proteins measured—tended to be specific to a single organ. When those proteins varied from the expected concentration for a particular chronological age, that indicated accelerated aging in the corresponding organ.
“We could say with reasonable certainty that [a particular protein] likely comes from the brain and somehow ends up in the blood,” explains Tony Wyss-Coray, a professor of neurology at Stanford University and co-author of the new study. If that protein concentration changes in the blood, “it must also likely change in the brain—and [that] tells us something about how the brain ages,” Wyss-Coray says.
By comparing study participants’ organ-specific proteins, the researchers were able to estimate an age gap—the difference between an organ’s biological age and its chronological age. Depending on the organ involved, participants found to have at least one with accelerated aging had an increased disease and mortality risk over the next 15 years. For example, those whose heart was “older” than usual had more than twice the risk of heart failure than people with a typically aging heart. Aging in the heart was also a strong predictor of heart attack. Similarly, those with a quickly aging brain were more likely to experience cognitive decline. Accelerated aging in the brain and vascular system predicted the progression of Alzheimer’s disease just as strongly as plasma pTau-181—the current clinical blood biomarker for the condition. Extreme aging in the kidneys was a strong predictor of hypertension and diabetes.
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Wyss-Coray anticipates this research could lead to a simple blood test that could guide prognostic work—in other words, a test that could help foretell future illness. “You could start to do interventions before that person develops disease,” he says, “and potentially reverse this accelerating aging or slow it down.”
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The momentum of commercial epigenetic testing is a “gold rush,” Shiels says. “There is a degree of oversell on what [the tests] can do.”
A single organ doesn’t tell the whole story of aging because deterioration processes are interconnected and affect an entire organism. “We understand a lot about the aging process on sort of a micro level,” Shiels says. “But a lot of the factors that drive age-related organ dysfunction are environmental. So it’s lifestyle, pollution, what you eat, microbes in your gut.”
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Source: Your Organs Might Be Aging at Different Rates | Scientific American
Robin Edgar
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