Amid all the shocking and depressing news regarding the future of American healthcare and medicine, at least over the next four years, I thought I would tackle something a bit lighter today. What happens to the brains of astronauts aboard the ISS? Space medicine is a field of study, if fairly niche, and will likely have increasing implications as humanity increases its occupation of the solar system.
Space is an incredibly hostile environment for humans and all living things. However, we can build habitats, like the International Space Station (ISS), to provide a pressurized breathable atmosphere at a comfortable temperature. But there are two aspects of space that are challenging for us to handle with out current technology – microgravity and radiation. Astronauts aboard the ISS receive between 80 and 160 mSv of radiation in a 6 month mission, with a career limit of 600 mSv. Typical exposure on the surface of Earth is 2mSv per year.
We also evolved in 1G of gravity and our physiology has adapted to that. While in orbit astronauts experience what is called microgravity because they are in freefall. While there are theoretical ways to deal with this, through rotation, NASA has no plans to tackle this engineering feat anytime soon. There are private companies with plans for rotating modules as early as the 2030s, but that may be ambitious. Even when we manage a rotating space station, for deep space missions there will be no artificial gravity likely anytime this century.
So studying the effects of prolonged microgravity is essential for future space exploration and missions. We know already that prolonged microgravity causes bone and muscle loss and redistribution of body fluids, causing swelling, changes in the eyes, and other effects. There is also cardiovascular deconditioning. But what about the brain – how does that handle microgravity?
A recent study seeks to characterize the effects on cognitive function of being aboard the ISS. They studies 25 astronauts:
“Cognitive performance data were collected at five mission phases: pre-flight, early flight, late flight, early post-flight, and late post-flight. We calculated speed and accuracy scores, corrected for practice effects, and derived z-scores to represent deviations in cognitive performance across mission phases from the sample’s mean baseline (i.e., pre-flight) performance.”
And here is what they found:
“There was no evidence for a systematic decline in cognitive performance for astronauts on a 6-month missions to the ISS. Some differences were observed for specific subtests at specific mission phases, suggesting that processing speed, visual working memory, sustained attention, and risk-taking propensity may be the cognitive domains most susceptible to change in Low Earth Orbit for high performing, professional astronauts.”
That’s good news. There were some minimal effects early on, but nothing long term. Of course, longer durations would need to be studied to see if there are effects that take longer to appear. This study was not designed to determine the cause of any detected effect. Some early cognitive slowing could simply be due to the stress of launching into space and acclimating to a cramped and unfamiliar environment. Fluid shifts from microgravity or higher radiation levels may have an effect. They specifically looked at sleep and did not see any correlation, so that was likely not a strong effect.
It is good news that there was no significant effect, at least for a six month mission. Being an astronaut is a cognitively demanding job and we wouldn’t want them to be compromised just from being in space. It is also preferable that prolonged stays in low Earth orbit do not cause permanent harm to the health of astronauts.
This is a question that NASA and other space agencies will continue to explore. I had the opportunity to ask a NASA scientist what their overall plan was for dealing with the harsh environment of space. They don’t think there are many technological fixes, at least in the near future. Radiation and prolonged microgravity (or reduced gravity on the Moon or Mars) will continue to be a reality of space travel for the foreseeable future. NASA’s strategy, rather, is two things – get there fast, and study ways to mitigate any health effects.
This is why NASA continues to research the health of ISS astronauts. The ISS is essentially a test bed for all future crewed space missions. We need to understand as much as possible about the health effects of space and to figure out ways to limit or fix any negative effects.
Hopefully this study reflects an underlying reality that the brain does fine in microgravity, so at least we have one fewer things to worry about.
