Astronauts may have vision problems because of liquid in their brains

As astronaut's helmet reflecting a spaceship

A stint in space goes to your head


Going to space changes your brain. Astronauts who have spent months in microgravity have more liquid in their brains, which may affect their vision even after they get back home.

On Earth, gravity pulls all your bodily fluids down towards your feet. In space, that’s not the case. “As soon as you enter microgravity, bodily fluids flow to the upper part of the body,” says Angelique Van Ombergen at the University of Antwerp in Belgium. “That’s why when you see pictures of astronauts on the space station they look like they have a puffy head.”

Van Ombergen and her colleagues scanned the brains of 11 Russian cosmonauts before and after going to space to determine the effects of microgravity on the brain’s ventricles – chambers that hold cerebrospinal fluid.


They found that when the cosmonauts returned home, the volume of their ventricles had increased by an average of more than 11 per cent to accommodate the extra fluid flowing into their heads in microgravity. Even about seven months later, the ventricles were more than 6 per cent bigger than before the cosmonauts launched.

It is not yet clear what effects this might have on brain function. The team found a correlation between the volume of one of the four ventricles and loss of visual acuity, but it was not strong enough to be certain the inflated ventricle was actually causing the changes in vision that are a common complaint for astronauts.

The fact that there are changes in the brain should motivate additional study, Van Ombergen says. All the cosmonauts in this study were in space for about six months, so we don’t know if the effect gets more pronounced the longer they spend in microgravity – an important consideration for longer flights, such as a journey to Mars. They were also all men, and Ombergen says there’s a chance the effect could be different in women.

“We need to really check the brain, check the visual system, check cognition because we do not know if this has any effect on that, and check people who spent different durations in space to tell if the effect keeps increasing,” says Van Ombergen. “Currently, nobody knows.”

Journal reference: Proceedings of the National Academy of Sciences , DOI: 10.1073/pnas.1820354116

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