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Time spent in space changes the structure of astronauts’ brains

Researchers have found changes in the brains of astronauts who visited the International Space Station, with parts of the brain called perivascular spaces expanding in volume.

This new study looks at how the space around blood vessels in the brain, which is filled with fluid, changed in 15 astronauts. The researchers looked at their brains before they went to space using magnetic resonance imaging (MRI), then after the astronauts had stayed on the International Space Station for periods of months, the researchers looked at their brains again at intervals of one month, two months, and six months after they came back to Earth.

The researchers found that these fluid-filled spaces in the brain, called perivascular spaces, got bigger in astronauts who went to the space station for the first time. However, astronauts who had already been to space and had been to the station for another mission didn’t show any change. That suggests that astronauts may adapt to space, according to the lead author Juan Piantino: “Experienced astronauts may have reached some kind of homeostasis,” Piantino said in a statement.

Though changes to brains might sound dramatic or alarming, the astronauts didn’t show any problems with balance or visual memories, so there isn’t a reason to think that they are suffering from problems due to these changes. The changes likely arise from the lack of gravity, which means that fluids tend to pool in the upper part of the body during extended stays in space. This is what gives astronauts a “puffy face” look and what may be responsible for the worsening vision that many astronauts experience.

“We all adapted to use gravity in our favor,” Piantino said. “Nature didn’t put our brains in our feet — it put them high up. Once you remove gravity from the equation, what does that do to human physiology?”

Previous research has found that astronauts’ brains tend to get larger when they spend time in space, which is also likely due to fluid redistribution, and that brains seem to adapt to the microgravity conditions by relying more on visual and touch information for balance than the body’s vestibular system.

Understanding how the human body changes during spaceflight is a major concern for space agencies, but studying this topic can also be beneficial to the people on Earth. With this study, according to Piantino: “These findings not only help to understand fundamental changes that happen during space flight but also for people on Earth who suffer from diseases that affect circulation of cerebrospinal fluid.”

The research is published in the journal Scientific Reports.

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