It was found that most of the crew on board the International Space Station (ISS) experience optic nerve edema, as well as excess fluid that expands their actual brain volume.
“When you're in a microgravity state, a fluid like your venous blood no longer merges with your lower extremities but is redistributed,” says Larry Kramer, professor at the Center for Health Sciences at the University of Texas at Houston and lead author of the study, published in Radiology at this week.
“The movement of fluid towards your head may be one of the mechanisms causing the changes we see in the eyes and intracranial region.”
Comparing the results of MRI scans of the brains of 10 men and one female astronaut taken before and after the trip to the ISS, they found that prolonged exposure to microgravity causes their brains and cerebrospinal fluid, a clear fluid that acts as a buffer for the brain, to expand. According to the researchers, the brain remained in a new state for a whole year after the flight.
“What we have identified, which has not yet been identified, is a significant increase in white matter in the brain from pre-flight to post-flight state,” Kramer said in a statement. “White matter expansion actually accounts for the greatest increase in combined brain and cerebrospinal fluid volumes after flight.”
They also found that microgravity deforms and slightly compresses the pituitary gland in the brain, which plays a central role in the regulation of vital bodily functions.
The exact long-term effects of microgravity on overall brain health are still not fully understood. Symptoms of this phenomenon, called 'normal pressure hydrocephalus' – a condition in which fluids build up in the brain, causing its ventricles to enlarge, causing difficulty in walking, bladder problems, and dementia – have not been seen in astronauts.
But that doesn't mean we shouldn't look for ways to stop these changes in the brain. One solution would be to create artificial gravity using a massive centrifuge in space. Special costumes are also considered.
