Image: MRI brain images taken before (A) and after (B) long-duration and short-duration (C and D) spaceflight (Photo courtesy of the NEJM).
A new study shows that long-duration space travel causes an upward shift of the astronaut’s brain and narrowing of cerebrospinal fluid (CSF) spaces, among other changes.
Researcher at the Medical University of South Carolina (MUSC; Charleston, USA), University Hospital Frankfurt (Germany), and other institutions used magnetic resonance imaging (MRI) scans to compare images from 18 astronauts’ brains before and after long stays on the International Space Station (ISS), and images of 16 astronauts’ brains before and after missions of short duration involving participation in the Space Shuttle program. All images were interpreted by readers who were unaware of the flight duration.
The researchers also generated paired pre-flight and post-flight MRI video clips derived from three-dimensional (3D) imaging in order to assess extent of narrowing of CSF spaces and displacement of brain structures, and also compared pre-flight and post-flight ventricular volumes by means of an automated analysis of T1-weighted MRIs. The main outcomes focused on the change in the volume of the central sulcus, the change in the volume of CSF spaces at the vertex, and vertical displacement of the brain.
The results showed that narrowing of the central sulcus occurred in 17 of 18 astronauts after long-duration flights (mean 164.8 days) and in 3 of 16 astronauts after short-duration flights (mean flight time 13.6 days). The video clips showed an upward shift of the brain after all long-duration flights, but not after short-duration flights, and narrowing of CSF spaces at the vertex after all long-duration flights. Three astronauts in the long-duration group suffered optic-disk edema, and all three had narrowing of the central sulcus and upward shift of the brain. The study was published on November 2, 2017, in the New England Journal of Medicine (NEJM).
“One of our theories is that because there is no longer the force of gravity pulling the brain down, the brain moves upward. This shift may also affect the fluid inside the skull which buffers the brain from shocks,” said lead author radiologist Donna Roberts, MD, of MUSC. “The implications would be whether or not there would be a requirement on a Mars mission to provide some type of artificial gravity.”
Space travel also affects other body organs; the heart, for example, changes shape and becomes more spherical. Another peril facing astronauts is exposure to cosmic radiation outside of the Earth's magnetic field, which can lead to accelerated development of atherosclerosis, rapid progression of advanced aortic root lesions, reduced lesional collagen, and intima media thickening of the carotid arteries.
Medical University of South Carolina
University Hospital Frankfurt