Abstract
Spaceflight induces widespread changes in human brain morphology. It is unclear if these brain changes differ with varying mission durations or one’s history of spaceflight experience (e.g., number of prior missions, time between missions). Here we addressed this issue by quantifying voxelwise post-flight changes in gray matter volume, white matter microstructure, extracellular free water (FW), and ventricular volume in a sample of 28 astronauts. We found that longer missions induced greater ventricular expansion and larger FW displacement at the top of the brain. A greater number of prior missions was associated with white matter microstructure declines in a tract supporting voluntary leg movement. Longer inter-mission intervals were associated with greater ventricle expansion, with compensatory ventricular expansion observed only in those crewmembers with inter-missions intervals of 3 years or longer. Longer missions therefore induce more extensive brain fluid shifts, and the ventricles may require at least 3 years to recover post-flight.
Competing Interest Statement
YED, NEB, APM are employed by KBR. The other authors declare no competing interest.
Footnotes
Funding National Aeronautics and Space Administration grant #NNX11AR02G (RDS, AM, SJW, JJB)
Natural Sciences & Engineering Research Council of Canada postdoctoral fellowship (HRM)
National Aeronautics and Space Administration Human Research Program augmentation grant (HRM)
National Institute on Aging fellowship 1F99AG068440 (KEH)