Mars-Bound Astronauts Face Chronic Dementia Risk From Galactic Cosmic Ray Exposure

A new study has warned that astronauts travelling to Mars on future extended mission may be at risk of chronic dementia due to exposure to galactic cosmic rays.

Charles Limoli from the University of California, Irvine, United States and his colleagues discovered that excessive exposure to highly energetic charged particles, like those found in the galactic cosmic rays which will bombard the astronauts during their extended space visits, causes serious long-term damage to the brain in test rodents, and it can result in cognitive impairment and chronic dementia.

This study is a follow up of a previous research which had shown the shorter-term effects of the galactic cosmic rays on the brain. Limoli indicates that the current findings raise a much greater alarm.

"This is not positive news for astronauts deployed on a two-to-three-year round trip to Mars," said Limoli, the professor of radiation oncology in UCI's School of Medicine.

For the research, rodents were exposed to an environment of charged particle irradiation, fully ionized oxygen and titanium, at the NASA Space Radiation Laboratory and the data gathered from the experiment was sent to Limoli's UCI lab.

Six months after the exposure, the team of researchers still found notable levels of brain inflammation and damage to neurons. Brain imaging was done and the results showed that the neural network of the brain was impaired due to reduction of spines and dendrites on these neurons. This reduction leads to the disruption of the transmission of signals among brain cells.

Researchers said these limitations were parallel to the poor performance in behavioral tasks that are designed to test memory and learning, according to Phys.org.

Further, Limoli's team discovered that the radiations affected "fear extinction". Fear extinction is an active process in which the brain's task is to suppress the previous stressful and unpleasant associations.

"Deficits in fear extinction could make you prone to anxiety," Limoli said, "which could become problematic over the course of a three-year trip to and from Mars."

Limoli explained that dementia-like deficiencies will take months to be evident in astronauts but the time required for the completion of a Mars mission is enough to develop such impairments. People working on the International Space Station for extended periods do not face such level of bombardment with galactic cosmic rays as they are still inside Earth's protective magnetosphere.

Preventive treatments provide some hope. Limoli's research team is working on pharmacological strategies involving compounds that scavenge free radicals and protect neurotransmission.