International space station space travel

Image by NASA

As humans spend longer amounts of time in space, researchers are eager to learn more about how the experience impacts our bodies. Recently, scientists have focused on the ways that space travel affects the human brain and conducted a study on the topic. The results were just published in a journal called JAMA Neurology and guess what? They’re not good.

About the study

For the study, researchers took specialized dMRI scans of 15 astronauts brains before leaving for space and again after they returned. Eight of the participants were in space for about 200 days, considered a long-duration mission. The remainder were in space for less than 30 days.

The results of the study showed a number of significant brain changes. Additionally, they helped explain some of the disorientation, mobility issues, and other unusual symptoms astronauts show after returning to earth.

The study’s focus

It was already known that the human brain shifts upward in an astronaut’s skull during space flight. Scientists were also aware that the area of the brain that processes sensory information increases in gray matter volume. The fact that space flight affects gray matter makes sense when placed in the context of the deficits astronauts experience once they’re back on earth. The brain’s gray matter that has a lot to do with a person’s muscle control and sensory perception.

What researchers weren’t yet sure of was how these effects relate to one another and how spaceflight affects areas of white matter in the brain. The study identified some possible answers to those questions.


Overall, the changes the study identified ran along the lines of changes that naturally occur in human brains due to aging. However, these changes occurred faster during space travel. Also, changes grew more pronounced the longer a person was in space and mirrored brain changes in rodents that were sent into zero gravity environments on earlier missions.

The study also showed that spaceflight decreased intracranial fluid at the top of the brain and increased fluid at the base of the brain. This movement is expected, given the brain’s physical upward movement. However, the study showed that if an astronaut had gone on more missions (regardless of length) these fluid shifts lessened.

Additionally, researchers looked at how the spaceflight affected white matter in the brain. White matter largely consists of fat covered nerve fibers and relays messages to different parts of the brain and nervous system. Researchers found that there were changes in white matter and the more changes an astronaut showed, the more their ability to balance, process spatial information, and maintain movement control was compromised.

This last piece of the study may have an implication for how astronauts are selected in the future. Gray matter development in human brains slows in a person’s third decade, but white matter development continues for years after that. As a result, astronauts may be vulnerable to permanent negative changes in their brains resulting from impacts in developing white matter.

Space and your body

The findings that show how space isn’t great for your brain shouldn’t be that surprising since we’re already aware of how space negatively impacts other parts of your body. Astronauts in zero gravity environments are exposed to radiation, experience eyeball distortions and changes in eye function, and show a loss of bone density and muscle mass.

Studies on ways space travel can affect the human body took a leap forward when astronaut Scott Kelly was sent into space for a year while his identical twin brother Scott stayed on earth. Adaptations that Scott was shown to experience went so far as to include shifts to his body on the molecular level and changes in gene expression. Some of these changes were consistent with how bodies typically change in a range of other stressful situations such as when mountain climbing or SCUBA diving. Doctors and researchers will be continuing to work with the Kelly brothers through the rest of their lives to better understand the effects of space travel over the long term.

More data is needed

While this study is a start to understanding space travel’s effect on the brain, more data is needed. For example, scientists want to understand why the changes are less dramatic the longer a person stays in space. They also want to understand how changes intersect with a person’s age or other biological factors, and if the changes are actually the body’s way of adapting to a zero-gravity environment.

Until more data is found, scientists will have to concede that we don’t really understand the full effects of space travel on human brains. In the meantime, they’ll take every precaution to make travel safe for astronauts to the best of our current ability.

Good news: The human body is resilient

Luckily, the findings aren’t all bad news. In as much as scientists have seen that the body reacts negatively to space travel, the body has also been shown to exhibit resilience. Scientists are very interested in what this recovery looks like. They’d like to better understand the timelines for astronauts to regain lost skills. They’d also like to learn more about how the recovery process is impacted by aging and a person’s biology.

Right now, we’re currently increasing the frequency and duration of space travel. Plans are even underway to try to reach Mars. The good health of our astronauts is of primary importance in this process and giving them the best shot at maintaining healthy bodies and brains is beyond important. It is a key part of developing successful missions and ongoing space travel.