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[ intro ]
We’ve been sending people into space since 1961,
but we still don’t entirely know what that does to their brains.
Now, we know how space travel
and weightlessness affect other parts of the body, like your muscles and bones.
So astronauts take plenty of precautions
like weight training to make sure that those parts of their bodies
don’t adapt too well to space life
and have a hard time re-acclimating to Earth.
But we’ve just started to learn how their brains change in space,
and whether they change back once they’re home, in the last six years.
Parts of your brain like the cerebellum
and motor cortex help you move around
and do things like telling your leg to step forward.
So it might not come as a surprise that weightlessness
might be affecting those areas and astronauts’ mobility.
One 2021 study found that being in space
starts to change the way astronauts coordinate movement like jumping, navigating obstacles,
and balancing after only two weeks.
And two weeks in space is a pretty short trip.
Astronauts who go on longer flights,
like a six-month trip to the International Space Station,
also have mobility and balance problems after coming home.
They even have more trouble coordinating precise movements, like putting a peg into a cylindrical
hole.
So researchers have started investigating how long these changes last.
They found that after short trips,
astronauts readapt back to Earth conditions in about two weeks,
while after longer trips, they seemed to regain their Earth legs in about a month.
So astronauts can readapt back to Earth conditions.
But the longer people spend in space,
the more long-lasting their behavioral effects can be.
And these behavioral changes aren’t just balance- and movement-related.
T
he way that astronauts think and solve problems also changes in space.
One study had astronauts perform a cognitive test for 3D abstract thinking,
similar to solving a puzzle on an iPad.
And they were able to complete the puzzle faster on Earth than in space.
But, plot twist, they could solve it faster in space
when their feet were supported to give them the feeling of standing on the ground.
So floating in space seems to have negative effects
on our problem-solving abilities.
Now, we’ve known anecdotally for years that many astronauts experience “space fog”
where they have trouble with cognition like attention and memory.
But the first brain imaging study to show that spaceflight really does change the brain
wasn’t published until 2016.
In that study, researchers analyzed MRI scans both before
and after two-week-long and six-month-long trips.
They found that the frontal pole,
a part of the brain that helps us with focused attention,
was smaller after the short space flight
and even smaller after the long space flight.
But space flight doesn’t shrink your entire brain.
The researchers found that some of the movement coordinating parts of the brain,
like the motor cortex, corpus callosum, and cerebellum, got bigger.
Taking the beuuhavioral and brain imaging studies together,
we can see that the movement coordination parts of the brain get bigger in space, and
astronauts have trouble moving around when they come back to Earth.
On the other hand,
the frontal pole of their brains gets smaller in space.
And last but not least, astronauts have trouble completing spatial puzzles.
And it’s possible these things could be related, but we just don’t know for sure
yet.
So in some ways, their brains change to suit their lives in space.
But that doesn’t help them when they return to Earth.
Another change that researchers found wasn’t in the astronauts’ brains,
but the holes in their brains.
Now before you freak out, everyone has holes in their brains,
on the order of millimeters wide,
that allow blood and cerebrospinal fluid to reach your brain cells.
After these astronauts went to space, those holes got 11.6% bigger,
and the space around the brain, which cushions it, got smaller.
Some researchers have suggested that this leads to a shift in where the brain sits
so that it takes up more space at the top of the head,
especially while sleeping.
They think this might explain why astronauts report feeling pressure in their head.
And these effects were seen in the follow-up scans seven months later,
meaning astronauts’ brains aren’t re-adapting to Earth…
at least not quickly.
Based on these findings,
we do not know if the astronauts’ brains would return to preflight conditions
after a full year or longer back on Earth
or how that might affect them in the long run.
We still need more research to find the answers.
But these returned astronauts are still able to move and think and do daily tasks,
so the fact that they left the Earth
and came back with so few changes is a good sign overall.
Now, the longest time any person has spent in space
so far is 438 consecutive days or 878 days total.
To put this all into perspective,
that’s five times longer than the long trips in these studies,
but still nothing compared to the trips to Mars that might be in our future.
So some researchers are hoping to study brain changes
in more detail on future flights.
But studies in the future might measure
how the brain responds in real time to these behavioral tests in space!
For now, we’re still just beginning
to understand the impacts of space travel on your brain.
So don’t try space travel at home.
But you can give your brain some extra strength training here on Earth
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[ outro ]