Mars-bound astronauts face dementia risk from cosmic rays

Astronauts travelling to Mars could develop irreversible dementia because their brains will be bombarded with destructive space radiation, researchers, including those of Indian-origin, have warned.
Researchers found that exposure to highly energetic charged particles - much like those found in the galactic cosmic rays that bombard astronauts during extended spaceflights - cause significant damage to the central nervous system, resulting in cognitive impairments.
"This is not positive news for astronauts deployed on a two- to three-year round trip to Mars," said Charles Limoli, a professor at the University of California, Irvine (UCI).
"Performance decrements, memory deficits and loss of awareness and focus during spaceflight may affect mission-critical activities, and exposure to these particles may have long-term adverse consequences to cognition throughout life," said Limoli.

For the study, rodents were subjected to charged particle irradiation (fully ionised oxygen and titanium) at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory.
The researchers, including Vipan Kumar Parihar and Munjal Acharya of UCI, found that exposure to these particles resulted in brain inflammation, which disrupted the transmission of signals among neurons.

Imaging revealed how the brain's communication network was impaired through reductions in the structure of nerve cells called dendrites and spines.
Additional synaptic alterations in combination with the structural changes interfered with the capability of nerve cells to efficiently transmit electrochemical signals.
Furthermore, these differences were parallel to decreased performance on behavioural tasks designed to test learning and memory.

Similar types of more severe cognitive dysfunction are common in brain cancer patients who have received various photon-based radiation treatments at much higher doses.
While cognitive deficits in astronauts would take months to manifest, Limoli said, the time required for a mission to Mars is sufficient for such deficits to develop.
People working for extended periods on the International Space Station (ISS) do not face the same level of bombardment with galactic cosmic rays, as they are still within the protective magnetosphere of the Earth, researchers said.
The irradiated particles that compose these galactic cosmic rays are mainly remnants of past supernova events.

As a partial solution, Limoli said, spacecraft could be designed to include areas of increased shielding, such as those used for rest and sleep.
However, these highly energetic particles will traverse the ship nonetheless, he noted, "and there is really no escaping them."
The research appears in the journal Science Advances.