Cosmonaut brains show space travel causes lasting changes
“We were designed for standing in gravity on Earth, and once that force is released, all the bodily fluids move upward,” says study author Peter zu Eulenburg of the Ludwig Maximilian University of Munich. The latest study suggests that the excess cerebrospinal fluid seems to compress the brain’s grey matter—the dark-colored neural tissue that contains nerve fibers and nerve-cell bodies. Though the brain largely bounced back after seven months on Earth, some effects seemed to linger.
The brain’s white matter, which is primarily made of nerve fibers, initially appeared unchanged. Yet in the months after the cosmonauts’ return to Earth, the volume seemed to shrink. The researchers speculate that the culprit is again cerebrospinal fluid. For the white matter, the increased pressure from the fluid may have forced some of the free water normally in the brain into the delicate white matter structure. Once the cosmonauts returned to Earth, the pressure lessened, water escaped, and white matter appeared to shrink.
Additional research is needed to determine what, if anything, these physical changes mean for cognition or psychological health. But the latest study adds to mounting evidence that life among the stars can have enduring consequences on Earth-born adventurers. Here are some of the other biological changes people headed to orbit—and maybe one day deeper into space—will need to prepare for.