Space.com reports that a recent study suggests that future astronauts on deep space missions, say to Mars or an Earth-approaching asteroid, will risk developing Alzheimer's due to a particular kind of cosmic radiation called high-mass, high-charged particles.
High-mass, high-charged particles
High-mass, high-charged particles, or HZE, are different from ordinary cosmic background radiation, according to Space.com. Cosmic rays, the result of solar flares, consist of hydrogen nuclei. However, HZE particles, caused by exploding stars or some other catastrophic event, have a much greater mass and speed.
Neurological effects examined
Space.com reports that the study, conducted by Kerry O'Banion, a neuroscientist at the University of Rochester Medical Center, bombarded the brains of mice with iron HZE particles generated by a particle accelerator at the NASA Space Radiation Laboratory at Brookhaven National Laboratory in New York in a dose comparable to what an astronaut would take during a round-trip to and from Mars. The mice thus treated showed a measurable degradation of mental function. Their brains show signs similar to brains with Alzheimer's, including abnormally high levels of beta amyloid, a protein that is a sign of the disease and helps to contribute to cognitive degeneration.
Shielding likely ineffective
A study conducted by NASA in 1983 concluded that shielding, at least as was understood at the time, would likely be ineffective in stopping HZE particles. Electromagnetic shields would have to be of a size and energy far out of proportion to the size of a Mars ship. Passive shields (i.e., made of material such as lead of concrete) would have to be too large and massive.
Low dose vs. high dose
One unanswered question concerns whether the same effect would happen with a low dose of HZE particles over a three-year Mars mission as happened to the mice with a high dose over a much shorter period of time, according to Space.com. One theory is that a human brain would be better able to tolerate a low dose over time than the mice demonstrated.
Thus far there is no effective treatment for Alzheimer's. The Alzheimer's Association reports that while there are some drugs approved by the FDA that temporarily alleviate some of the effects of the disease, nothing is yet available to treat the underlining causes. One particularly promising avenue consists of treatments that prevent beta amyloid from clumping together to form plaques and even flush the protein from the brain entirely. Prevention of Alzheimer's, with drug treatments still lacking, include diet and both physical and mental exercise.
Mark R. Whittington is the author of Children of Apollo and The Last Moonwalker. He has written on space subjects for a variety of periodicals, including The Houston Chronicle, The Washington Post, USA Today, the L.A. Times, and The Weekly Standard.