August M
Spending months in orbit does more than challenge muscles and bones.
New research suggests it also changes the position and shape of the brain itself.
Brain movement in space
According to The Independent, a study by a team of researchers found that astronauts’ brains shift upward and backward inside the skull during spaceflight.
The longer individuals remained in microgravity, the more pronounced the changes appeared to be.
Most of the alterations gradually reversed within six months of returning to Earth, although some backward movement showed less recovery.
Why gravity matters
On Earth, gravity constantly pulls fluids and tissues downward, helping maintain a stable balance between the brain, cerebrospinal fluid and surrounding structures.
In space, that force disappears. Fluids move toward the head, often giving astronauts a puffy facial appearance.
Without gravity’s pull, the brain effectively floats higher within the skull and is influenced by surrounding soft tissues and bone.
Inside the study
Researchers analyzed MRI scans from 26 astronauts who spent anywhere from a few weeks to more than a year in orbit.
To measure subtle changes, the team aligned preflight and postflight brain scans by matching skull position. They then divided the brain into more than 100 regions to track shifts in specific areas.
The findings showed a consistent upward and backward movement after space missions. In astronauts who spent about a year aboard the International Space Station, some regions near the top of the brain shifted upward by more than 2 millimeters.
Regional differences
Areas linked to movement and sensation showed the largest displacement. Structures on opposite sides of the brain shifted toward the midline, moving in opposite directions in each hemisphere.
Because these opposing movements can cancel each other out in whole-brain averages, earlier studies may have overlooked them.
While larger shifts in a sensory-processing region were associated with changes in balance after flight, astronauts did not report clear symptoms such as headaches or cognitive issues related to the positional changes.
Implications for future missions
The researchers emphasized that the findings do not point to immediate health risks.
However, understanding how microgravity alters brain position may help space agencies prepare for longer missions, including potential journeys beyond low Earth orbit.
As space travel expands and missions lengthen, the study’s insights could inform strategies to protect astronaut health.
Sources: Reporting by The Independent.
