Mars Astronauts May Develop Dementia-Like Impairment

Exposure to highly energetic charged particles resulted in cognitive impairment and dementia in rodents.

Results from a new study suggest that astronauts who have been to Mars may develop chronic dementia resulting from exposure to galactic cosmic rays.

Long-term brain damage was seen in rodents exposed to highly energetic charged particles similar to cosmic rays experienced by astronauts in extended spaceflights. The brain damage resulted in cognitive impairment and dementia, according to a study published by Nature’s Scientific Reports.

This team of researchers previously discovered short-term brain effects. These new findings may mean that astronauts are facing additional physical harm in the form of cognitive impairment.

“This is not positive news for astronauts deployed on a 2-to-3-year round trip to Mars,” said researcher Charles Limoli, PhD. “The space environment poses unique hazards to astronauts. Exposure to these particles can lead to a range of potential central nervous system complications that can occur during and persist long after actual space travel -- such as various performance decrements, memory deficits, anxiety, depression and impaired decision-making. Many of these adverse consequences to cognition may continue and progress throughout life.”

In the study, rodents were exposed to charged particle irradiation with fully ionized oxygen and titanium. Researchers discovered significant brain inflammation and neuron damage 6 months after the exposure.

Further analysis showed that the brain’s neuronal network was impaired from a reduction of dendrites and spines on the neurons, which disrupts signal transmission between brain cells, according to the study. Reduction of dendrites and spines on the neurons was associated with poor results from learning and memory tests.

They also discovered that exposure to the radiation impacted fear extinction, which is a process the brain uses to suppress unpleasant, stressful situations. For example, a child falls off their bike, but gets back on.

“Deficits in fear extinction could make you prone to anxiety, which could become problematic over the course of a 3-year trip to and from Mars,” Dr Limoli said.

The cognitive impairment seen in the study is similar to the deficits experienced in patients with brain cancer who received high-dose, photon-based radiation, according to the study.

These dementia-like deficits would take months to manifest, making it possible for those going to Mars to develop these conditions. However, astronauts working on the International Space Station would not experience that level of impairment since they are protected by the Earth’s magnetosphere.

This current study is part of a NASA program to determine how space radiation affects astronauts and find new prevention efforts.

Researchers said that potential solutions are being developed, including a spacecraft with additional protection against the highly energetic charged particles. However, these particles will likely travel through the spacecraft regardless of extra protection.

Preventative treatments are also in development. Researchers are currently working on creating pharmacological prevention strategies that include compounds that scavenge free radicals and protect neurotransmission, the study concluded.