Cosmic radiation during deep space travel could alter the cognitive function and behavior of astronauts on an extended mission — such as a trip to Mars. Cosmic rays are generated in the shockwaves of exploding stars outside our solar system and are composed primarily of ionized atomic nuclei moving at nearly the speed of light. Exposure to this radiation may be unavoidable for astronauts on any future mission to Mars.
Results of a study led by Jacob Raber, Ph.D., professor of behavioral neuroscience in the OHSU School of Medicine, recently published in the journal BMC Genomics suggest that long-term exposure to cosmic radiation, particularly to Iron-56 ions, could cause symptoms ranging from memory problems to impaired judgment. Moreover, these effects could be long-lasting and perhaps without resolve.
Researchers used mice to test both short- and long-term effects of radiation. They found that exposure to Iron-56 ions significantly affects the hippocampus, which is critical for memory function. The effects of space irradiation were dose- and time-dependent, with mice receiving the lowest and highest doses of radiation exhibiting the most apparent effects, including trouble recognizing new objects in their environments two weeks later.
The research findings suggest that mice receiving the intermediate dose did not suffer memory problems because the brain responded by healing itself via epigenetic changes. The lower dose was not strong enough to trigger a meaningful response but was still damaging enough to elicit the cognitive deficit. The low dose is likely similar to the level of radiation the astronauts would be exposed to on a mission to Mars.
Better understanding the underlying mechanisms could help scientists find ways to monitor and protect astronauts from cosmic radiation in future deep-space missions and lead to the development of potential treatment options.
Research published in the paper, “Short- and long-term effects of 56Fe irradiation on cognition and hippocampal DNA methylation and gene expression,” was supported by NASA grant NNJ12ZSA001N. Soren Impey assistant professor, Oregon Stem Cell Center, was the first author. Additional authors included Timothy Jopson, Carl Pelz, Amanuel Tafessu, Fatema Fareh, Damian Zuloaga, Tessa Marzulla, Lara-Kirstie Riparip, Blair Stewart, Susanna Rosi, and Mitchell S. Turker.
Read the full OHSU news release.