Last year, researchers examined the brains of five Russian cosmonauts who spent five and a half months (around 169 days) on the International Space Station (ISS). Their findings confirm that long-term space travel can cause significant harm to the human mind and body.
Scientists already know that space travel has adverse effects on the body, such as worsened vision and weakened muscles and bones. However, the impact of being in space on the brain has not been extensively studied. The research, published in JAMA Neurology on October 11, 2021, finds solid evidence that spending time in orbit also damages brain cells.
The researchers had the five cosmonauts take blood tests once they returned to Earth. All five men had elevated levels of biomarkers indicating brain cell damage. “This is the first time that concrete proof of brain-cell damage has been documented in blood tests following space flights. This must be explored further and prevented if space travel is to become more common in the future,” highlighted Henrik Zetterberg, senior study coauthor and a neurochemist at the University of Gothenburg in Sweden.
The first blood samples were collected twenty days before each man traveled to the ISS and then three times when they returned to Earth: 1 day, one week, and 21 to 25 days after landing. The biomarkers the study analyzed included: total tau (T-tau), neurofilament light (NFL), two amyloid-beta proteins, and glial fibrillary acidic protein (GFAP).
The team found significantly elevated NFL, GFAP, and the amyloid-beta protein Aβ40 in the blood samples after the space sojourn. Unfortunately, the findings suggest that during the men’s time in space, a shift of fluid in the brain may have affected the blood-brain barrier.
While 169 days seems like a long time, other space travelers have stayed in space for twice as long! They include:
- Valeri Polyakov spent 437 consecutive days on the Mir space station from 1994 and 1995. To this day, Polyakov still holds the record for the longest time a person has stayed in space.
- Scott Kelly spent 340 days on the ISS from 2015 to 2016.
- Christina Koch spent 328 consecutive days in space while aboard the ISS in 2019.
According to the study, brain scans of astronauts from before and after space travel revealed changes associated with long-term developments such as aging, including deterioration in regions that control movement and the processing of sensory information. On the plus side, the results also suggest that an astronaut’s brain can potentially adapt to these changes over time.
Professor Rachel Seidler, from the University of Florida, explained:
We know that fluid shifts toward the head in space. When you see photos and videos of astronauts, their faces often look puffy because gravity isn’t pulling fluids down into the body.
What’s more, the researchers found that space travel causes fluid around the brain to puddle at the cerebrum’s base, making the brain float higher in the skull than it usually would. This likely plays a significant role in a condition known as Spaceflight Associated Neuro-Ocular Syndrome, which causes flattening in the back of the eye and visual changes. ‘It could be slower fluid turnover; it could be pressure on the optic nerve or that the brain is sort of tugging on the optic nerve because it’s floating higher in the skull,’ Seidler added.
Zetterberg envisions his research leading to new treatments to prevent or reverse any health issues caused by space travel. However, further research is certainly required to determine what, exactly, is causing the problem before that vision can come to fruition.
Zetterberg added:
To get there, we must help one another to find out why the damage arises. Is it being weightless, changes in brain fluid, or stressors associated with launch and landing, or is it caused by something else? Here, loads of exciting experimental studies on humans can be done on Earth.
While the study examined cosmonauts who stayed in space for an extended time, Zetterberg is confident that a shorter stay in space would also negatively impact the brain. As humans plan to spend more time in space, we must learn all that we possibly can about how it affects the human body. For example, NASA intends to land on Mars by 2030, but this would require astronauts to spend nearly two years in space!
