Spaced out? The impact of spaceflight on the brain

Time in space ‘rewires’ the brains of astronauts, a new study has revealed. The research, published in Frontiers in Neural Circuits, is the first to analyse structural connectivity changes in the brain after long-duration spaceflight.

Led by Floris Wuyts of the University of Antwerp, Belgium, the researchers acquired diffusion MRI (dMRI) scans of 12 male astronauts before and just after their spaceflights. They also collected eight follow-up scans seven months after flight. Each of the astronauts had spent an average of 172 days in space.

The researchers used a brain-imaging technique called fibre tractography, which “gives a sort of wiring scheme of the brain,” explains Wuyts. Interestingly, they found that the brain underwent changes at the level of white-matter tracts. White matter is all the parts of the brain that are responsible for communication between grey matter and the body, and between various grey-matter regions. 

“We found changes in the neural connections between several motor areas of the brain,” says first author Andrei Doroshin, of Drexel University, Philadelphia, US. 

“Motor areas are brain centres where commands for movements are initiated. In weightlessness, an astronaut needs to adapt his or her movement strategies drastically, compared to Earth. Our study shows that their brain is rewired, so to speak.”

In other words, the brain must adapt to spaceflight, especially in the areas that control movement, and structural changes in white matter reveal that it does so.

The follow-up scans revealed that the astronauts still showed these changes in connectivity seven months on from their return to Earth.

The study is exploratory and the first of its kind, so the researchers note that they don’t yet know what these changes might mean for actual brain function.

“These findings give us additional pieces of the entire puzzle,” says Wuyts. “Since this research is so pioneering, we don’t know how the whole puzzle will look yet. 

“It is crucial to maintain this line of research, looking for spaceflight-induced brain changes from different perspectives and using different techniques.”

That’s important because if we know how spaceflight affects the brain, we might be able to find effective countermeasures. 

In fact, there are countermeasures already well established for the body. Astronauts, for instance, must take all kinds of actions while aboard space stations, such as exercising for two hours a day, to protect against the muscle and bone loss caused by zero-gravity. Similar measures for the brain could help protect against the as-yet-unknown impacts of these changes to the brain.

Long-duration spaceflight is so impactful on the brain and body because the conditions in which astronauts live are so different from those on Earth, namely the absence of gravity. 

Our bodies evolved to help us move and live under the gravitational conditions on Earth. When that very basic precedent is removed, the body – and now, evidently, the brain – is forced to adapt again.

These changes aren’t simply musculoskeletal. It’s thought zero-gravity affects us at a cellular level, and there’s ongoing to figure out the complexities of how our cells respond to these conditions.

Deepening research in this area is important, the researchers write, because future spaceflight may well be longer – a proposed mission to Mars, for example, would involve a minimum of nine months of spaceflight.