Space: the final frontier. Today, a manned mission to Mars is a more realistic possibility than ever. But to boldly go where no man has gone before can take its toll on our brains.
A recent study has looked at the possible effects of cosmic radiation on mammals' brains. Past research already pointed to possible dangers of increased cancer risk and other possible problems from the radiation in outer space.
But this new research is based upon a mice study, which means additional research will be needed.
The study, led by Jonathan D. Cherry, of the Department of Pathology and Laboratory Medicine at the University of Rochester School of Medicine and Dentistry, was conducted on mice because it would be unethical to conduct the study on human brains.
It is also not yet possible to test the effects of actual deep space on humans since they have only spent short time periods in outer space. All of space has radiation, but the earth's magnetic field blocks most of these particles from humans who remain within the planet's low orbit.
Leaving that protective layer of the earth exposes humans to radiation from solar flares and other sources in space. If a human spends a long period of time in space, even low levels of this radiation can build up over time.
The researchers used mice whose brains may develop cognitive problems and Alzheimer's disease at known rates. The mice were exposed to different amounts of radiation, including the amount likely to reach an astronaut on the long trip to and from Mars.
To understand how this radiation might affect humans, the researchers focused on the effects of one type of the radiation called high-mass, high-charged (HZE) particles on the mice.
After the radiation exposure, the mice were given a series of tasks, such as finding objects or certain locations.
The mice who were exposed to radiation performed more poorly in these tasks, which means they may appeared to have brain impairment earlier than they normally would have.
Dissection and close investigation of the mice's brains then revealed that those with radiation exposure had more build-up of the protein plaque that is found in patients with Alzheimer's disease.
"These findings clearly suggest that exposure to radiation in space has the potential to accelerate the development of Alzheimer's disease," said senior author M. Kerry O'Banion. "This is yet another factor that NASA, which is clearly concerned about the health risks to its astronauts, will need to take into account as it plans future missions."
There are different types of HZE particles, based on different elements. The researchers looked at iron HZE particles for this study because those types have enough mass to get through a spacecraft's shielding.
"Because iron particles pack a bigger wallop it is extremely difficult from an engineering perspective to effectively shield against them," O'Banion said. "One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete."
This study may not seem to affect most people right now. However, more and more astronauts may be heading into space in future years.
Space tourism has also already begun, and it may not be too far in the future when ordinary people can visit space.
Past research has shown possible risks for cancer, cardiovascular problems and musculoskeletal problems from cosmic radiation. This new information about possible risks to our brains is important to consider as we expand our horizons beyond Earth's horizon.
The study was published December 31 in the journal PLOS ONE. The research was funded by NASA, and the authors had no disclosures.