Our organs appear to age at different rates, with our lungs and kidneys going through a burst of ageing in our 20s, decades before others, such as the uterus. Better understanding how organ ageing varies could help people adopt healthy habits that may be particularly beneficial at certain periods of life.
This isn’t the first time variation in organ ageing has been suggested. In 2022, researchers at the National University of Singapore made a similar finding based on protein molecules in blood.
But they focused on just nine organs and systems, such as the immune system, and didn’t look at markers of tissue health. “Our organs are organised in a way to perform certain functions, and changes in tissue structure are very relevant to ageing,” says at the University of Vienna in Austria.
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To move the research on, Rendeiro and his colleagues analysed nearly 26,000 images of tissue slices from 29 organs – including the brain, heart and lungs – donated after death by nearly 1000 people in the US.
The donors died when they were between 20 and 70 years old, mostly from physical accidents, suicide or after being taken off life support. Their tissue samples, which weren’t physically damaged, were collected soon after death.
Using data from 80 per cent of the donors, Rendeiro’s team trained artificial intelligence models to learn links between their age at death and the features of a particular organ’s tissue, such as its colour, texture and cell distribution. Separate models were created for each of the 29 organs.
The researchers then tested how well the models could predict the age at death of the remaining participants from images of their tissues. The predictions were accurate to within 4.9 years on average of the donor’s actual age, says Rendeiro.
In another analysis, the researchers used the models to explore how organs age across a person’s lifespan. They found that several organs, including the lungs and kidneys, age more than the rest of the body from 20 to 40 years old, says Rendeiro.
That could be because people may be more likely to smoke and drink alcohol during these decades, he says. Alternatively, that accelerated ageing may be occurring anyway and smoking or drinking exacerbates it, in which case, people may particularly benefit from abstaining or limiting these habits at these ages, he says.
The heart seems to age more rapidly than the rest of the body in people’s 30s, and again from age 45 to 55, while the brain, muscles and skin appear to age more quickly in our 30s and 60s. “Why is a mystery,” says Rendeiro.
The researchers also found that the uterus ages the most from age 45 to 55, which corresponds with the typical age of menopause in the US.
The results highlight how zooming out from the level of molecules to broader changes in tissue structure can deepen our understanding of ageing, says at Columbia University in New York. “Our ability to measure the ageing process, I think, is profoundly affected by the results.”
But larger studies that track people from a broader range of countries throughout their lives are needed, says Cohen.
The team hopes to one day dig into what drives distinct patterns of ageing for specific organs. “We have opened more questions than what we can address, and that’s a very exciting thing,” says Rendeiro.
bioRxiv
