The effect of prolonged spaceflight on cerebrospinal fluid and perivascular spaces of astronauts and cosmonauts

Long-duration spaceflight induces changes to the brain and cerebrospinal fluid compartments and visual acuity problems known as spaceflight-associated neuro-ocular syndrome (SANS). The clinical relevance of these changes and whether they equally affect crews of different space agencies remain unknown. We used MRI to analyze the alterations occurring in the perivascular spaces (PVS) in NASA and European Space Agency astronauts and Roscosmos cosmonauts after a 6-mo spaceflight on the International Space Station (ISS). We found increased volume of basal ganglia PVS and white matter PVS (WM-PVS) after spaceflight, which was more prominent in the NASA crew than the Roscosmos crew. Moreover, both crews demonstrated a similar degree of lateral ventricle enlargement and decreased subarachnoid space at the vertex, which was correlated with WM-PVS enlargement. As all crews experienced the same environment aboard the ISS, the differences in WM-PVS enlargement may have been due to, among other factors, differences in the use of countermeasures and high-resistive exercise regimes, which can influence brain fluid redistribution. Moreover, NASA astronauts who developed SANS had greater pre- and postflight WM-PVS volumes than those unaffected. These results provide evidence for a potential link between WM-PVS fluid and SANS.

Automated summary

Long-duration spaceflight causes changes in the brain and cerebrospinal fluid compartments, leading to spaceflight-associated neuro-ocular syndrome (SANS). MRI analysis showed increased volume of perivascular spaces (PVS) in basal ganglia and white matter after spaceflight, with more significant changes observed in NASA crew members than Roscosmos crew members. The differences in PVS enlargement may be attributed to various factors, including the use of countermeasures and exercise regimes. NASA astronauts with SANS had larger pre- and postflight PVS volumes compared to unaffected individuals, suggesting a potential link between PVS fluid and SANS.