We understand the drive and the passion to explore the new and unknown frontiers of space, but when it comes to the loss of cognitive function or serious IQ points, we know where to draw the line. While humans as a species, and space agencies now, have been speaking about traveling to other planets for as long as anyone can remembers, now knowing what awaits us in space may change a few of your minds-literally.
Though here on Earth we remain protected from many dangerous cosmic particles and rays, such as the carcinogenic UV rays of the Sun, when we venture outside of the protection of our home planet, we encounter a space filled entirely with new threats. And though these rays and particles may not be seen, they can pack a serious punch that may have you changing your mind about going to explore Mars. In a new study published this week in the journal Science Advances, professor of radiation oncology at UC Irvine, Charles Limoli says that even low doses of cosmic radiation can have drastic effects on the human brain. And with cosmic rays constantly bombarding the brain while outside of the protective layering of our Earth, serious brain damage causing cognitive and memory impairments could manifest in just a matter of months.
"As NASA prepares for the first manned spaceflight to Mars, questions have surfaced concerning the potential for increased risks associated with exposure to the spectrum of highly energetic nuclei that comprise galactic cosmic rays" Limoli says. "The exquisite susceptibility of neuronal architecture to the effects of charged particles reported here has important implications for human exploration into space and defines the need to further our understanding of radiation effects in the central nervous system as NASA prepares astronauts for one of the greatest adventures of humankind."
To study the effects that cosmic radiation could have on human brains, Limoli and his team of researchers exposed young mice to small doses of common particles encountered in space. Then they explored three possible outcomes-behavior, brain structure, and the changes to neural and glial cells. Six weeks after irradiation, the team sought out to find the "mind-numbing" effects of the cosmic particles and discovered that not only had the damage branched out significantly from where it started, but also that the changes to the anatomy and cellular function of the brain appeared to be permanent.
The change in the shape and function of the dendrites within the brain, which were the most concerning to the team, were directly related to loss of cognitive function and even seemed similar to defects in common neurodegenerative conditions like dementia. Not just cognition, but also memory and short-term recollection were also affected in the performance tests.
"Although similar types of changes have been shown to underly a host of neurodegenerative conditions that exhibit dementia, it remained uncertain how ionizing radiation exposure affected more mature neuronal subtypes to compromise neurotransmission" Limoli says. "Here, we show that very low doses of charged particles can compromise cognitive performance over extended times through mechanisms involving the reduction of dendritic complexity and alterations in synaptic integrity."
So Why Have We Not Seen These Changes In Our Astronauts to Date?
While astronauts have spent short stints in space, either traveling to the moon or orbiting it in the International Space Station, such changes have not been seen in any to date. So why have we not seen these changes before? Limoli believes that may still be thanks to the protection of the Earth, which may just extend a little bit farther out into space than researchers originally thought-saving our astronauts from devastating tolls on their brains.
"[The International Space Station] is protected by the Earth's magnetosphere, which deflects anything that has a charge" Limoli says. "Although space radiobiology research has uncovered a wealth of potentially problematic health risks associated with charged particle exposure, none may prove more difficult to manage than those related to the functional decrements found in the brain that may occur during a space mission, endangering its success."