Russian cosmonaut Mikhail Kornienko returning from a year-long mission in space

Russian cosmonaut Mikhail Kornienko returns from a 340-day stay in space. Some portions of the brain dwindle during long space flights. Credit: NASA/Bill Ingalls

Medical research

Space crews’ grey matter shrivels during long stays in orbit

Seven months after cosmonauts landed, some brain tissues had recovered but others had not.

Flying in space shrinks some regions of cosmonauts’ brains — an effect that persists long after crews come home.

Researchers know that spaceflight causes parts of the brain to swell and tilt, but Angelique Van Ombergen at the University of Antwerp in Belgium and her colleagues wondered precisely how time in orbit affects brain volume, especially well after the return to Earth. To investigate, the team studied brain scans from ten Russian cosmonauts before and after orbital stints of around six months.

About one week after the cosmonauts returned to Earth, some portions of their brains showed a larger volume of cerebrospinal fluid — which cushions and cleanses the brain — than before the flight. By contrast, certain regions of the brain’s grey matter, containing neurons that produce signals, shrank over the same time period. Most of the grey matter recovered in the following seven months, whereas the brain’s white matter, which transmits neural signals, withered in the months after landing.

The authors say that brain-volume changes might help to explain medical problems related to long-term space travel.