New scientific research has uncovered significant physical changes in the brains of astronauts following their missions in space. A study published on Monday, 13 January 2026, in the journal Proceedings of the National Academy of Sciences found that the brain's position and shape are altered by the microgravity environment of spaceflight.
Upward and Backward Brain Movement
The investigation, which analysed MRI scans from 26 astronauts before and after their space missions, discovered a distinct pattern of movement. The brain was found to shift "upward and backward within the skull". The regions responsible for sensory input and motor control exhibited the most pronounced displacement.
Professor Rachael Seidler from the University of Florida's department of applied physiology and kinesiology, a co-author of the study, explained the findings to Sky News' US partner NBC. "We need to understand these changes and their impacts to keep astronauts safe and healthy and protect their longevity," she stated.
Duration of Mission is a Key Factor
The research also established a clear link between the length of a space mission and the extent of the brain's physical transformation. "The people who went for a year showed the largest changes," Professor Seidler noted. While alterations were still detectable in astronauts who undertook two-week missions, she confirmed that "duration seems to be the driving factor."
To provide a comparative baseline, scientists also examined 24 civilian participants on Earth who underwent a "long-duration head-down tilt bed rest," a simulation of some spaceflight conditions. While similar brain shape and position changes were observed in this group, the astronauts exhibited a more significant upward shift.
Long-Term Implications for Space Exploration
The study highlights that while most of the brain's deformation recovered within six months after returning to Earth, some changes persisted. This raises important questions for the future of human space travel, particularly for ambitious long-duration missions to the Moon and Mars.
"The health and human performance implications of these spaceflight-associated brain displacements and deformations require further study to pave the way for safer human space exploration," the authors concluded in their paper. Understanding these neurological adaptations is now seen as a critical step in safeguarding astronauts on future voyages beyond Earth's orbit.
