Brain changes observed in astronauts engaged in lengthy space trips

Researchers at the University of Antwerp said they found “significant” microstructural changes in several white matter tracts.

The human brain can change and adapt in structure and function throughout a lifespan. As human exploration of space reaches new horizons, understanding the effects of spaceflight on human brains is crucial.

Previous research has shown that spaceflight has the potential to alter both the shape and function of an adult brain.

White matter refers to the parts of the brain that are responsible for communication between grey matter and the body, and between various grey matter regions.

To study brain structure and function after spaceflight, the researchers used a brain imaging technique called fibre tractography.

“Fibre tractography gives a sort of wiring scheme of the brain. Our study is the first to use this specific method to detect changes in brain structure after spaceflight,” explained team leader Dr Floris Wuyts.

The team acquired diffusion MRI (dMRI) scans of 12 male cosmonauts before and right after their spaceflights. They also collected eight follow-up scans, seven months after spaceflight. The cosmonauts all engaged in long-duration missions of an average length of 172 days.

The researchers found proof of the concept of ‘the learned brain’; in other words, the level of neuroplasticity the brain has to adapt to spaceflight.

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

“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.”

The follow-up scans revealed that seven months after returning to Earth, these changes were still visible.

“From previous studies, we know that these motor areas show signs of adaptation after spaceflight. Now, we have a first indication that it is also reflected at the level of connections between those regions,” Wuyts said.

The study illustrates a need for understanding how spaceflight affects our body, specifically via long-term research on the effects on the human brain. Current countermeasures exist for muscle and bone loss, such as exercising for a minimum of two hours a day. Future research may provide evidence that countermeasures are necessary for the brain.

The research was a collaborative project between the European Space Agency, Roscosmos, and a team of international researchers led by Wuyts.

Another study in 2020 showed that extended periods in space could could induce a reduction in overall brain matter and deformation of pituitary glands.

There have also been concerns over the impact that space travel has on astronauts’ sight as those that spend longer than a month in space typically develop neuro-ocular syndrome that affects their optic nerves.