Scientific American reports:

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.

The new research, published on Wednesday in Nature, identified about one in five healthy adults older than 50 years old as an “extreme ager”—a person with at least one organ aging at a highly accelerated rate, compared with a cohort of their peers. One in 60 adults had two or more organs that were aging rapidly. The study team measured proteins related to organs, including the brain, heart, immune tissue and kidneys. The researchers hope their findings will lead to a future blood test that can pinpoint rapidly aging organs, letting doctors target them for treatment before disease symptoms begin.

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. [Continue reading…]