How Studying Astronauts Could Help Tackle Ageing On Earth

(MENAFN- The Conversation) Astronauts who undergo long-duration spaceflight aboard the International Space Station often return with health problems that resemble some age-related conditions in people on Earth.

Remarkably, some of this decline reverses within months of their return but others persist. This raises an intriguing question: what can be learned from these rapid changes and could they help prevent or reverse aspects of age-related decline on Earth?

That question has turned space into a laboratory for ageing research. Spaceflight reproduces many features of ageing. Astronauts also experience unusual conditions, including very low gravity, increased radiation and disrupted sleep. Even so, changes that usually develop over decades on Earth can appear within weeks or months in space, giving scientists an opportunity to observe some ageing-related processes in fast-forward.

A 2026 study, which tracked four astronauts during the nine-day Axiom-2 mission, examined chemical markers attached to DNA that can be used to estimate biological age. This is an estimate of how old the body appears to be based on molecular changes, rather than the number of years a person has lived.

The astronauts' estimated biological age increased during the mission and began to fall after they returned to Earth. This does not mean that they physically aged by years in a matter of days. With only four participants, the study cannot provide firm conclusions, but it shows how rapidly the body can respond to the conditions of spaceflight.

Why would leaving gravity behind affect the body in ways that resemble ageing? On Earth, muscles, bones, and the cardiovascular system and other organs are adapted to function under the constant pull of gravity. That continual mechanical load helps keep these systems healthy, although their function often declines later in life. In space, many of those demands disappear.

When muscles age in fast-forward

Skeletal muscle provides one of the clearest examples. Astronauts lose muscle mass and strength at a startling rate in very low gravity, even while exercising for around two hours a day to attempt to limit the effects.

Some of the biological processes involved may overlap with those associated with sarcopenia, the age-related loss of muscle strength and mass that increases the risk of frailty, falls and loss of independence.

Scientists are still working out how closely muscle loss in space resembles sarcopenia, because similar effects can arise through different biological processes. The crucial difference is timescale. That compression is exactly what drew our team to space.

Through our UK Space Agency-funded MicroAge mission, we sent lab-grown human muscle constructs to the International Space Station.

These miniature muscles, roughly the size of a grain of rice, were engineered from human muscle stem cells. Using lab-grown tissue, rather than relying solely on the limited number of astronauts available for study, allowed us to compare muscle adaptations in very low gravity with those seen during ageing on Earth. It also allowed us to carry out early tests of possible ways to protect muscle. If some of the same mechanisms are involved in both settings, space could provide a useful opportunity to study years of biological change over the course of months for a single mission.

Our follow-up mission, MicroAge II, will explore the biology of this decline in greater detail. It focuses on mitochondria, the structures inside cells that produce most of the energy those cells need. Problems with mitochondria are recognised as one process involved in muscle ageing on Earth.

MicroAge II will investigate whether similar changes to their structure and function also contribute to rapid muscle loss in space. Why does any of this have significance beyond the space station?

Loss of muscle mass and function is one of the most consequential aspects of growing older. It underlies frailty, falls and the loss of independence that many people fear, yet effective treatments remain limited. Testing potential interventions in populations that age over decades is inevitably slow. Space research will hopefully help scientists identify relevant biological processes and test early ideas more rapidly.

Experiments in space cannot replace final clinical studies involving older people, however. Any treatment suggested by this work would still require extensive testing on Earth to establish whether it is safe and effective but would identify potential drug candidates far more quickly.

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