Exposure to cosmic radiation during missions to places like Mars can affect an astronaut's brain and accelerate the onset of Alzheimer's disease, suggests a new study by researchers from the University of Rochester Medical Center (URMC).

Earth's magnetic field protects the planet from cosmic radiation in space. When astronauts leave the Earth's orbit and are in deep space, they are constantly exposed to a shower of cosmic rays. Space travelers can be shielded from dangerous radiation associated with solar flares, but there are some forms of cosmic radiation that cannot be effectively blocked as the radiation exists in low levels in space.

Astronauts who are exposed to cosmic radiation for longer periods face the risk of their brain getting affected. This is a big concern for NASA as the space agency is planning to send astronauts to a distant asteroid in 2021 and a manned mission to Mars in 2035.

The space agency has been funding research work to determine the effects of cosmic radiation on astronauts. Earlier studies have already suggested that the exposure to radiation levels might cause health problems like cancer.

But this new study reveals another significant problem that astronauts could face during deep space missions. This is the first time researchers have suggested that exposure to cosmic rays could be harmful to the brain and produce cognitive problems.

For their study, the research team studied the impact of a particular form of radiation called high-mass, high-charged (HZE) particles. These particles travel at very high speeds by the force of exploding stars. They come in different forms; experts chose iron particles for this study.

Unlike hydrogen protons generated by solar flares, the mass and speed of the iron particles allowed them to penetrate through objects like a wall or a protective shielding of a spacecraft.

Scientists carried out their research at the NASA Space Radiation Laboratory at Brookhaven National Laboratory on Long Island. The team used the Lab's particle accelerators for colliding matter together at very high speeds and reproducing radioactive particles similar to the ones found in space.

They examined the effects of radiation on mice by exposing them to different doses of radiation. It also included levels of radiation that are comparable to what astronauts would be experiencing during a mission to Mars.

The mice were tested based on a series of experiments during which they had to recall objects or recognize locations. The researchers found that mice exposed to radiation were more likely to fail these tasks, suggesting neurological impairment.

The mice's brain also showed signs of vascular alterations and greater than normal accumulation of beta amyloid that mounts up in the brain and is one of the features of the Alzheimer's disease.

"These findings clearly suggest that exposure to radiation in space has the potential to accelerate the development of Alzheimer's disease," senior author of the study M. Kerry O'Banion, from the URMC, said in a statement.

"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."

The findings of the study appear online in the journal PLOS ONE.