Overview
- MRI scans of 26 astronauts before and after spaceflight show the brain moves upward and backward, with the greatest displacement in sensory and motor regions linked to balance and orientation.
- Mission duration correlated with effect size, as yearlong stays produced the largest shifts, measured on the order of millimeters.
- An Earth-based head-down bed-rest study of 24 civilians reproduced similar brain position and shape changes, though astronauts experienced greater upward movement.
- Reported impacts included temporary disorientation, motion sickness in orbit, and postflight balance problems, with no serious headaches or cognitive impairment detected.
- Early evidence suggests the brain readjusts after return to Earth, with recovery reported around six months, yet small samples and demographic limits highlight the need for further study.