What happens to your brain in space? - BBC

Space messes with astronauts' brains – and that might be a big challenge for missions beyond the Moon.

With four billion or so years of evolution behind us, humans are well suited to life at normal gravity. Imagine then, the fears at the dawn of the space age over what would happen when we first left the Earth and experienced weightlessness. Would our blood congeal? Our bones crumble? Our brains explode in microgravity?

By the late 1950s, a series of flights with mice, spiders and eventually, dogs proved that animals could indeed survive in space. And when it later came to humans, we have shown that we can not only survive, but thrive.

"There is an adaptation that, in many ways, feels like a transformation," European Space Agency (Esa) astronaut Luca Parmitano told me in 2019, during training for his second long-duration mission to the International Space Station (ISS). "After a few weeks your body is different to what it was on the ground – you see and you feel your body change, your legs get skinnier and your face gets round."

A former Italian Airforce test pilot, Parmitano has recently been selected for his third space mission as one of the four crew members of Artemis III. Due to launch in 2027, this challenging flight in Earth orbit will test out lunar landers and spacesuits for a return to the Moon. It's little surprise Parmitano was chosen – when you talk to him, you get the impression that he's found that spaceflight comes naturally.

"One of the reasons the human race is so successful on Earth is our capability to adapt," he said. "But to see in the arc of a few weeks [in space] physical changes happening, it really blew me away how different I felt and how much more comfortable my new body just fit the environment that I was in."

The rigours of spaceflight on the human body – from muscles to bones to blocked sinuses – are well-documented in the 70-odd years since humanity first blasted into orbit. Less well-known is the effects zero-gravity has on our brains.

In space, our bodies no longer need to overcome the force of gravity with every action or movement. As a result, the bones that support our weight and the muscles that we use to lift, carry, walk and run begin to waste away. After just a few days in space, bones lose calcium and muscles start to deteriorate, which includes changes to the heart. The reason astronauts also tend to have puffy faces is a result of liquids no longer being constrained by gravity and pooling in the upper body.

This would all be fine if astronauts spent the rest of their lives in space, but if they ever want to return to Earth in good physical shape, they need to follow a rigorous exercise regime. Typically, this includes two hours a day in the ISS gym and, even then, after just six months in space they are carried out of their returning spacecraft and placed on stretchers. It can take up to four years for their bones to return to normal.

Much less understood, however, is what has been going on in astronauts' brains. And that could be a problem.

"The brain is probably the most important of our organs," says Esa flight surgeon Alessandro Alcibiade. "If you don't bring an effective brain to space and a working brain to space that will be all worthless."

Research on the effects of spaceflight on the brain has been limited to experiments on just a few astronauts during long-duration missions. Scott Kelly, for instance, spent a year on the ISS while his astronaut twin brother, Mark, remained on Earth. In the resulting study, researchers found Scott's cognitive abilities were largely unchanged during the mission compared to Mark, but decreased for about six months after he landed.

Now, new research published in the journal Frontiers in Psychology by scientists at Birkbeck, University of London in the UK – and shared exclusively with the BBC – has pulled together results from 15 brain imaging studies involving some 377 participants. These included astronauts as well as volunteers in spaceflight simulations on Earth, such as bedrest studies.

By combining all these sets of data, the Birkbeck team believes they have identified changes that take place in the brain when its exposed to microgravity.

"It's a beautiful neuroplasticity – we found that there are both structural and functional alterations in the brain," says lead author Elisa Raffaella Ferrè, a professor of cognitive neuroscience at Birkbeck, Univeristy of London. "We have identified a cluster of brain areas that undergo changes when gravity isn't there."