Aging accelerates around the age of 50 - some organs are faster than others

The analysis of how different tissues age is the last one that suggests that aging does not move in a steady rhythm.

This is a warning that middle-aged people have long offered to young people: aging is not a smooth process. Now a comprehensive analysis of how proteins change over time in different organs supports this idea, finding that people experience an inflection point at about 50 years, after which aging seems to accelerate.

A study published on July 25 in Cell1 also suggests that some tissues, especially blood vessels, age faster than others and identify molecules that can accelerate time estres.

The results add to the growing evidence that aging is not linear, but is instead canceled by periods of rapid change. However, larger-scale research is needed before scientists can designate the age of 50 as a crisis point, says Maya Olecka, who studies aging at the Leibniz Institute on Aging - Fritz Lipman Institute in Jena, Germany, and did not participate 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 turning points."

Show your age

Previous work has shown that different organs can age at different rates2. To further figure it out, 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 origin aged 14 to 68 who died of accidental traumatic brain injury. Samples were taken from organs representing eight body systems, including the cardiovascular, immune and digestive systems.

Then the researchers created a collection of proteins found in each of the samples. They found an age-related increase in the expression of 48 proteins associated with the disease and saw early changes around the age of 30 in the adrenal glands, which are responsible for the production of various hormones.

This tracks previous data well, says Michael Snyder, a geneticist at Stanford University School of Medicine in California. "This is in line with the idea that your hormonal and metabolic control is a big deal," he says. "It is here that some of the deepest changes with the age of people are taking place."

At the age of 45 to 55, there was a turning point, marked by large changes in protein levels. The sharpest shift was found in the aorta, the main artery of the body, which removes oxygen from the heart. The team tracked down one protein produced in the aorta, which, when administered to mice, causes signs of accelerated aging. Liu suggests that blood vessels act as a duct, bringing molecules that contribute to aging to remote places throughout the body.

The study is an important addition to others that analyzed molecules circulating in the blood, rather than tissue samples taken from individual organs, as a way to monitor age-related changes, says Snyder. "We are like a car," he says. "Some parts wear out faster." Knowing which parts are prone to wear can help researchers develop methods of intervention to promote healthy aging, he says.

Halfway to 100

Last year, Snyder and his colleagues discovered the inflection points of aging at the ages of 44 and 603. Other studies have shown accelerated aging at different times, including around the age of 80, which went beyond the scope of the current study, says Oletska.

Discrepancies with other studies may arise due to their use of different types of samples, populations and analytical approaches, says Liu. As data accumulates over time, the key molecular pathways involved in aging are likely to be in line with research, he adds.

This data will accumulate quickly, says Oletska, because researchers are increasingly including detailed time series in their research, and not just comparing the "young" with the "old". And these results can help researchers interpret these periods of rapid change. "Currently, we do not understand what causes this transition point," she says. "This is a really intriguing developing area."