Long spaceflight changes astronauts’ brains forever, study shows. Here’s why
Astronauts come back to Earth with greater brain volume after soaring the zero-gravity Milky Way galaxy for long periods of time, and researchers say this change remains long after they step foot on land, a new study shows.
This previously unknown change can help NASA better prepare for longer missions and aid in finding remedies for earthlings who suffer from medical conditions similar to those astronauts deal with in space.
“[These changes] raise additional concerns for long-duration interplanetary travel, such as the future mission to Mars,” Larry Kramer, lead author of the study and professor of diagnostic and interventional imaging at the University of Texas McGovern Medical School in Houston, told the New Scientist.
More than half of all the crew members of the International Space Station (ISS) have reported vision problems after completing long-term space missions, according to a EurekaAlert press release about the study that was published Tuesday in the journal Radiology.
Previous studies have shown that astronauts receive extra cerebrospinal fluid (CSF) – fluid that surrounds the brain and helps it maintain normal function – that “squeezes the brain,” reducing empty space around the organ.
This squeezing contributes to vision issues like swelling in the nerves that sends visual information to the brain and bleeding in the retina – the light sensitive tissue – that can cause gradual to sudden sight loss.
This condition, known by NASA as “spaceflight-associated neuro-ocular syndrome,” can persist for years after returning to Earth, the study said.
But what scientists didn’t know was how long lasting these changes were. Now, researchers learned they may be permanent, according to the study.
Dr. Kramer and his team performed brain MRIs on 11 astronauts – 10 men and one woman – before they traveled to the ISS, the day after they returned from their mission and then several times throughout the year.
The average time in space for all the participants was 171 days, the study said.
The results showed a 2% increase in brain and CSF fluid volumes in all astronauts involved, the study said, and the fluids remained elevated after one year, which suggests permanent change.
This phenomenon can be explained by the lack of gravity in space, the study revealed. While traveling among the stars, the pressure of fluids in the body, like blood, pools toward your head instead of at your feet, because gravity isn’t there to maintain a pressure gradient like that on Earth.
“That movement of fluid toward your head may be one of the mechanisms causing changes we are observing in the eye and intracranial compartment,” Dr. Kramer said in the release.
The MRIs also revealed deformations in the astronauts’ pituitary gland, a pea-sized structure at the base of the skull that has many functions like secreting hormones into the bloodstream. Researchers say increased pressure in the brain from zero-gravity conditions causes this to happen.
“We found that the pituitary gland [flattens] and is smaller postflight than it was preflight,” Dr. Kramer said in the release.
Although the changes are small and still considered normal for healthy adults, researchers said they shed light on other non-astronaut medical conditions that currently have no remedies.
After returning from space, the astronauts’ brains showed a faster flow of CSF fluid in the channels that connect the cavities in the brain, the study said. This also occurs in people who suffer from “normal pressure hydrocephalus,” which causes difficulty walking, bladder control problems and dementia, according to the study.
Understanding solutions to these problems found in astronauts in space could lend itself to beneficial remedies for those on Earth, researchers said.
One option is to put astronauts in a centrifuge that can spin them quickly, creating artificial gravity that can counter the effects of microgravity, the study said.
This story was originally published April 16, 2020 at 11:04 AM with the headline "Long spaceflight changes astronauts’ brains forever, study shows. Here’s why."
