What is ageing? Even the field’s researchers can’t agree

Researchers studying ageing disagree on just about everything — including what ageing is, whether it is a disease and when it starts — according to a survey of about 100 scientists working in the field.

A key goal of ageing research is to help people live longer, healthier lives. But the exact causes of ageing, as well as effective approaches to slow or reverse it, remain elusive. For the field to tackle these challenges, researchers need to speak a common language, says Alan Cohen, who studies ageing at Columbia University in New York City. “There doesn’t have to be perfect consensus, but we need to sort things out quite a bit,” he says.

Vadim Gladyshev, another researcher in the field who is based at Harvard Medical School in Boston, Massachusetts, and his colleagues agree. They decided to survey participants at an international conference on ageing in Newry, Maine, in 2022, to better understand the views of those researching the topic. Respondents included early-career researchers, established scientists and industry professionals. The results are described in PNAS Nexus today¹.

Most researchers are clear in their own minds about what ageing is — but their perspectives don’t align with those of others, says Gladyshev. “People joke in the field that there are more theories than people.” Despite this, Gladyshev says he was surprised by the scale of the problem.

The latest results reflect those of a similar survey of 37 researchers conducted in 2019 by Cohen and his colleagues². Now “it’s unquestionably clear that there’s a huge disagreement”, says Cohen.

What is ageing?

When asked to describe ageing, one-third of respondents considered it to be a loss of function over time, from declines at the cellular level to a decrease in overall health and fitness. Others saw ageing as a gradual accumulation of deleterious changes. Not all respondents associated ageing with negative connotations, with some seeing it as a change in state — reversible or otherwise — or a continuation of development. And others approached the subject from a demographic standpoint, describing ageing simply as an increased chance of dying.