Long-term space travel changes brain structure of astronauts

The effects of space travel on human anatomy are extensive, taking into account the harsh impacts of zero gravity and the rapid ascension into space. Yet, the amount of information detailing the effects spaceflight has on the configuration of astronauts' brains is limited, claimed in a recent study published by The New England Journal of Medicine and funded by the National Aeronautics and Space Administration (NASA).   

A team of researchers from the Medical School of South Carolina, University of Hospital Frankfurt in Germany and Shihezi University in Xinjang, China, analyzed the effects of microgravity on NASA astronauts' brain size, location and shape.  

Specifically observed was how astronauts' brains are affected by optic-disk edema and elevated pressure while in space after both long- and short-term missions. Astronauts having to sleep or be upside down while in space, researchers explained, is also one of the most important data components.  

"Maintaining this position for a long period of time has been associated with upward and posterior brain shift, increased density of brain tissue at the vertex, contraction of adjacent extraaxial cerebrospinal fluid (CSF) spaces and increased ventricular volume," said lead author Donna R. Robert, MD, from the Medical University of South Carolina. "Assessment for these changes after spaceflight could provide insights into the neurophysiological and anatomical changes in the brain caused by space flight."  

Robert and her team analyzed MRI brain scans taken before and after the spaceflights of 34 NASA astronauts—28 men and six women. Of the 34 astronauts, 18 participated in long-term missions to the International Space Station and 16 on short-term missions for the Space Shuttle Program.  

The before and after MRI brain scans were then interpreted by readers who were unaware of the length of each mission. They identified notable changes in three parts of the astrounauts' brain structure:  

• Volume of the central sulcus 
• Volume of CSF spaces at the vertex 
• Overall vertical displacement  

"We also generated paired preflight and post-flight MRI cine clips derived from high-resolution, 3D imaging of 12 astronauts after long-duration flights and from six astronauts after short-duration flights in order to assess the extent of narrowing of CSF spaces and the displacement of brain structures," Robert noted.  

Observations pointed to long-term mission having a more significant impact on the brain than short-term mission. The mean time in orbit for a long-term mission was roughly 165 days and roughly 14 days for the short-term mission, according to the study. Furthermore, Robert and her team concluded the following:  

• The narrowing of the central sulcus occurred in 17 of 18 astronauts after long-duration flights and in three of 16 astronauts after short-duration flights.  
• Cine clips from a subgroup of astronauts showed an upward shift of the brain after all long-duration flights (12 astronauts) but not after short-duration flights (six astronauts) and narrowing of CSF spaces at the vertex after all long-duration flights (12 astronauts) and in one of six astronauts after short-duration flights. 
• Three astronauts in the long-duration group had optic-disk edema, and all three had narrowing of the central sulcus. 
• A cine clip was available for one of these three astronauts, showing an upward shift of the brain.  

Robert concluded that researching neurophysiological and anatomical changes in the brain is important for NASA's future plans for longer duration space missions. 

"Our findings support the need for repeated longitudinal imaging over a longer period after space flight and the incorporation of advanced MRI techniques into NASA imaging protocols 15-17 to determine the persistence of these changes and their relationship to the VIIP syndrome," Robert said.