Cosmic radiation could accelerate neurodegeneration like Alzheimer's
An eight-year long study on genetically engineered mice, published in open-access journal PLOS One, found that cosmic radiation accelerates the onset of Alzheimer's disease.
It is the first such study to explore effects of cosmic radiation, meaning high-mass, high-charged (HZE) particles like iron on the nervous system, leading to a phenomenon known as neurodegeneration, according to the authors.
The research by the University of Rochester Medical Center Department of Neurobiology and Anatomy used particle accelerators at Nasa's Space Radiation Laboratory on New York's Long Island to expose the animals to the highly radioactive particles.
The study team wanted to see if radiation had the potential to accelerate Alzheimer's in those who were genetically vulnerable. Mouse models have been widely used in this type of research and the rate at which they develop the disease is well known, so the team used mice that were genetically engineered to be predisposed to Alzheimer's disease.
The experiment had the expected result, leading to increases of "Aβ plaque pathology " in the mice - a symptom which can lead to Alzheimer's.
The potential risks of working and living in deep space, beyond low Earth orbit, are similar to the health risks of radioactive radiation exposure, including cancer, cardiovascular disease and cataracts.
"Galactic cosmic radiation poses a significant threat to future astronauts," said M. Kerry O'Banion, senior author of the study and a professor in the University of Rochester Medical Center Department of Neurobiology and Anatomy.
"The possibility that radiation exposure in space may give rise to health problems such as cancer has long been recognized. However, this study shows for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer's disease."
Earth's magnetic field, generated thanks to the massive iron core of our planet, normally deflects most harmful cosmic radiation, but once astronauts are outside of its protective shield they become constantly bombarded with these radioactive particles. The levels of radiation aren't high, but they would add up to cause significant damage over time.
These HZE particles can penetrate current spacecraft's thin protective shielding, which would have to be about 2 meters thick lead to block all particles. Other solutions may be more practical, like using water and fuel tanks around living quarters, or even magnetic shield generators.
"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," said O'Banion.
NASA currently foresees two prolonged manned missions into space: a trip to a faraway asteroid in 2021 and a trip to Mars in 2035. The round trip to Mars could take about three years.