Mind-Boggling Find: Astronauts’ Brains Are Being Reshaped By Space, Study Says

Last Updated:January 14, 2026, 18:34 IST

According to the report, prolonged exposure to microgravity causes the brain to shift upwards and backwards within the skull

This structural distortion is not merely a change in position; it is a physical deformation. (Representational image/AI-generated)

Long-duration space travel does more than just weaken an astronaut’s muscles and thin their bones; it fundamentally reshapes the human brain. According to a comprehensive study published in the journal Proceedings of the Academy of Sciences (PNAS), prolonged exposure to microgravity causes the brain to shift upwards and backwards within the skull. This physical displacement results in significant “crowding" at the top of the head, causing the stretching and compression of delicate neural tissue in ways never seen under Earth’s gravitational pull.

The research, led by Dr Rachel Seidler of the University of Florida, analysed MRI data from 26 astronauts before and after their missions aboard the Space Station (ISS). To ensure the findings were specific to spaceflight, the team compared these results against a control group of 24 volunteers who participated in a “head-down tilt" bed-rest study on Earth. While the earthbound volunteers experienced some fluid shifts, the changes in the astronauts were far more dramatic and cumulative. For those who spent a full year in orbit, the supplementary motor cortex—a region vital for physical movement—shifted upward by as much as 2.5 millimetres.

This structural distortion is not merely a change in position; it is a physical deformation. As the brain drifts upwards, it becomes compressed at the vertex (the top of the skull), while the lower regions are “tugged" upwards. The study found that these shifts are directly correlated with balance declines and sensory disorientation once the astronauts return to Earth. Dr Seidler noted that while the brain appears to be highly resilient—with much of the vertical displacement reversing within six months of returning to gravity—some structural changes and deformations in sensory regions persisted long after the mission ended.

The findings have profound implications for the future of space exploration, particularly for planned multi-year missions to Mars. Understanding how “brain crowding" affects cognitive performance and long-term neurological health is now a priority for space agencies. The study also highlighted a potential link between these structural shifts and Spaceflight-Associated Neuro-ocular Syndrome (SANS), a condition that affects the vision of roughly half of all long-duration astronauts.

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