A new study shows that cosmic radiation — which would bombard astronauts on deep space missions — could accelerate the onset of Alzheimer’s disease.
“Galactic cosmic radiation poses a significant threat to future astronauts,” said M. Kerry O’Banion, M.D., Ph.D., a professor in the University of Rochester Medical Center (URMC) Department of Neurobiology and Anatomy and the senior author of the study.
“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.”
While space is full of radiation, the earth’s magnetic field generally protects people from these particles. However, once astronauts leave orbit, they are exposed to a constant shower of various radioactive particles, researchers explain.
With warnings, astronauts can be shielded from dangerous radiation associated with solar flares. But there are also other forms of cosmic radiation that cannot be effectively blocked, researchers note.
Because the radiation exists in low levels, the longer an astronaut is in deep space, the greater the exposure. That is why for the past 25 years NASA has been funding research into the potential health risks of space travel.
Several studies have demonstrated that galactic cosmic radiation could increase risks of cancer, cardiovascular, and musculoskeletal issues. This latest study examines the potential impact of space radiation on neurodegeneration, in particular, the biological processes in the brain that contribute to the development of Alzheimer’s disease.
O’Banion, whose research focuses on how radiation affects the central nervous system, and his team studied the impact of a particular form of radiation called high-mass, high-charged (HZE) particles. These particles, which are propelled through space at very high speeds by the force of exploding stars, come in many forms.
For this study the researcher chose iron particles. The mass of HZE particles like iron, combined with their speed, enable them to penetrate solid objects such as the wall and protective shielding of a spacecraft, the researchers said.
“Because iron particles pack a bigger wallop it is extremely difficult from an engineering perspective to effectively shield against them,” said O’Banion. “One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete.”
A portion of the research was conducted at the NASA Space Radiation Laboratory at Brookhaven National Laboratory on Long Island. The lab’s particle accelerators can collide matter together at very high speeds, which can reproduce the radioactive particles found in space.
For the latest study, the researchers exposed mice to various doses of radiation, including levels comparable to what astronauts would experience during a mission to Mars.
Back in Rochester, a team of researchers evaluated the cognitive and biological impact of the exposure. The mice underwent a series of experiments during which they had to recall objects or specific locations.
The researchers observed that mice exposed to radiation were far more likely to fail at these tasks — suggesting neurological impairment — earlier than these symptoms would typically appear.
The brains of the mice also showed signs of vascular alterations and a greater than normal accumulation of beta amyloid, the protein “plaque” that accumulates in the brain and is one of the hallmarks of the disease, researchers said.
“These findings clearly suggest that exposure to radiation in space has the potential to accelerate the development of Alzheimer’s disease,” said 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.”