A study published in The New England Journal of Medicine assessed changes in brain anatomy and structure of astronauts after short and long spaceflight.
During spaceflight, astronauts experience a phenomenon called microgravity, which is the feeling of weightlessness. It has been shown that microgravity can lead to the ‘visual impairment and intracranial pressure’ (VIIP) syndrome, characterized by optic-disk edema and pressure build-up in the skull. Additionally, studies comparing MRI scans of the brain before and after spaceflight have revealed significant changes in brain anatomy and structure. Further studies are required to better assess the anatomical and structural brain changes associated with spaceflight, and how these changes may affect overall brain function and contribute to VIIP syndrome.
A recent study by Roberts and colleagues, published in The New England Journal of Medicine, utilized MRI scans to assess brain displacement, brain ventricle volume, and changes in cerebrospinal fluid (CSF) spaces of astronauts that underwent long and short spaceflight missions. The brain’s ventricles are a network of four cavities that produce CSF, a fluid that surrounds and protects the brain. The study included a total of 34 astronauts, who underwent MRI scans before and after their space flight. Eighteen of the participants underwent long-duration (164 days in orbit on average) missions, while the remaining 16 underwent short-duration (13 days in orbit on average) missions.
Effects of Long-Duration Spaceflight
The study revealed that astronauts in the long-mission group had higher rates of CSF space narrowing, central sulcus narrowing, and upward shifts of the brain and brainstem. Closer analysis revealed that optic disk edema was observed in three participants, all of whom were part of the long-duration flights. All three participants had central sulcus narrowing, while an upward shift of the brain was observed in one of the three participants for whom appropriate data were available. Based on this data alone, the authors argue that narrowing of the central sulcus and upward brain shifts cannot exclusively be associated with optic disk edema. There was a subset of participants that did not develop optic disk edema, yet still presented with central sulcus narrowing and upward brain shifts.
Significant Differences in Brain Anatomy and Structure
Despite accounting for confounding factors, including previous flight experience, MRI scans revealed that astronauts before and after spaceflight had significant differences in brain anatomy and structure. Moreover, brain changes were far more common after long-duration flights, compared to short-duration ones. The authors observed an upward shift in the brain and narrowing of the CSP spaces and the central sulcus with longer spaceflights. Further studies are needed to better understand brain changes associated with spaceflights and the cause of VIIP syndrome so that proper preventative measures can be taken during long-duration spaceflights.
Written by Haisam Shah, BSc
Reference: Roberts, D. R., Albrecht, M. H., Collins, H. R., Asemani, D., Chatterjee, A. R., Spampinato, M. V., … & Antonucci, M. U. (2017). Effects of Spaceflight on Astronaut Brain Structure as Indicated on MRI. New England Journal of Medicine, 377(18), 1746-1753.
