Frequent lengthy space travel takes a toll on astronauts' brains, study shows

"We found that the more time people spent in space, the larger their ventricles became," said Rachael Seidler, a professor of applied physiology and kinesiology at the University of Florida and an author of the study. "Many astronauts travel to space more than one time, and our study shows it takes about three years between flights for the ventricles to fully recover."

Space has proven challenging for the human body. I know that prolonged habitation affected bone density and increased the risk of kidney stones, but are there any other well-documented health concerns?

[EDIT] I looked into it and found a few other concerns:

• Vision problems
• Muscle density loss
• Radiation sickness ( ! )
• Weakened immune system