Ageing of many tissues accelerates around age 50, according to an analysis of tissues in people ranging from teenagers to individuals in their sixties.Credit: Karen Haibara/AFP/Getty
It is a warning that middle-aged people have long offered the young: ageing is not a smooth process. Now, an exhaustive analysis of how proteins change over time in different organs backs up that idea, finding that people experience an inflection point at around 50 years old, after which ageing seems to accelerate.
The study, published 25 July in Cell1, also suggests that some tissues — especially blood vessels — age faster than others, and it identifies molecules that can hasten the march of time.
The findings add to mounting evidence that ageing is not linear, but is instead pockmarked by periods of rapid change. Even so, larger studies are needed before scientists can label the age of 50 as a crisis point, says Maja Olecka, who studies ageing at the Leibniz Institute on Aging — Fritz Lipmann Institute in Jena, Germany, and was not involved in the study.
“There are these waves of age-related changes,” she says. “But it is still difficult to make a general conclusion about the timing of the inflection points.”
Showing their age
Previous work has shown that different organs can age at different rates2. To further unpick this, Guanghui Liu, who studies regenerative medicine at the Chinese Academy of Sciences in Beijing, and his colleagues, collected tissue samples from 76 people of Chinese ancestry aged 14 to 68 who had died from accidental brain injury. The samples came from organs representing eight of the body’s systems, including the cardiovascular, immune and digestive systems.
The researchers then created a compendium of the proteins found in each of the samples. They found age-related increases in the expression of 48 disease-associated proteins, and saw early changes at around age 30 in the adrenal gland, which is responsible for producing various hormones.
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This tracks well with previous data, says Michael Snyder, a geneticist at the Stanford University School of Medicine in California. “It fits the idea that your hormonal and metabolic control are a big deal,” he says. “That is where some of the most profound shifts occur as people age.”
Between the ages of 45 and 55 came a turning point marked by large changes in protein levels. The most dramatic shift was found in the aorta, the body’s main artery, which carries oxygenated blood out of the heart. The team tracked down one protein produced in the aorta that, when administered to mice, triggers signs of accelerated ageing. Liu speculates that blood vessels act as a conduit, carrying molecules that promote ageing to remote destinations throughout the body.
