A large team of researchers with members from Belgium, Russia, and Germany has found that people who spend a long time aboard the International Space Station experience an increase in the size of some of their brain ventricles. In their paper published in Proceedings of the National Academy of Sciences, the group describes their study of brain ventricles in cosmonauts that spent a significant amount of time in space, and what they found.
Source:
https://phys.org/news/2019-05-spaceflights-brain-ventricle-size.html