Humans are naturally wired to live on Earth, the planet made ideal for us. Still, our ambitious nature has propelled us beyond the ground beneath our feet to what lies above us – space and what it contains. Exploring space has been made possible with the construction of spacecrafts, a giant step taken by humankind away from his natural habitat. One might, then, wonder as to the consequences thereof. Science has, indeed, revealed some of the dire repercussions faced by humans living in space for long amounts of time. The new study provides an unprecedented take on the issue: the risk of developing conditions like dementia and cognitive disorders in astronauts because of a phenomenon being referred to as “space brain”. This research is part of NASA’s Human Research Program.
A team from the University of California, Irvine (UCI), led by researcher Charles Limoli, has found that highly energetic charged particles characteristic of galactic cosmic rays could yield adverse effects on astronauts engaged in long-duration spaceflights. It is to be noted that these findings are not based on experiments conducted on humans themselves. Rather, rodents were used as test subjects. The shocking results reveal that the highly-charged particles can trigger brain damage that, in turn, leads to dementia, “performance decrements, memory deficits, anxiety, depression, and impaired decision-making“, says Limoli. According to the latter, these effects might linger long after the space travel, persisting for the rest of the person’s life.
The authors of the new paper are now concerned about astronauts leaving the Earth for 2 to 3 years to explore Mars because the latter would be out there for long enough for the impairments to start developing.
“This is not positive news for astronauts deployed on a two-to-three-year round trip to Mars,” says Limoli, who is a professor of radiation oncology at UCI’s School of Medicine.
Six months after the test rodents were exposed to charged particle irradiation (fully ionized oxygen and titanium), their brains still displayed brain inflammation, and neurone damage entailing reduction in dendrites and spines which would then lead to disruption in the transmission of nerve impulses. These impairments are known to result in poor learning abilities and memory. Anxiety is yet another potential effect generated by the damage. Limoli and his team explain that the radiation causes deficits in fear extinction, a process involving the suppression of unpleasant and stressful associations in the brain.
“Deficits in fear extinction could make you prone to anxiety,” Limoli said, “which could become problematic over the course of a three-year trip to and from Mars.”
These findings support previous results obtained by Limoli himself, published in Science Advances last year. Furthermore, brain cancer patients having been subjected to high levels of similar radiation during their treatment also show cognitive dysfunction, according to other studies.
Thankfully, though, these effects would not be as severe to astronauts on the International Space Station (ISS), as they would be on Mars astronauts because of a decreased level of exposure to galactic cosmic rays; those working on the ISS are shielded by our planet’s magnetosphere.
No problem comes without solution, though. Limoli explains that they are actually looking into ways that could avoid the potential problems for future NASA projects that would take astronauts closer to Mars. For instance, spacecrafts could be made to include areas with increased shielding, and pharmacological strategies might also constitute prospective solutions.