America
Astronauts at high risk of dementia-like condition
New York, May 3
What happens to an astronaut's
brain during a mission to Mars? Nothing good. It's besieged by
destructive particles that can forever impair cognition, reveals a new
study.
The 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 of radiation oncology at the University of California, Irvine.
"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," Limoli added.
For the study, rodents were
subjected to charged particle irradiation (fully ionized oxygen and
titanium) at the NASA Space Radiation Laboratory.
The researchers
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 behavioral tasks designed to test learning and memory.
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 do not face the same level of bombardment
with galactic cosmic rays, as they are still within the protective
magnetosphere of the Earth.
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 study was published in Science Advances.