'Backward and upward and tilted': Spaceflight causes astronauts' brains to shift inside their skulls
The Astronaut Brain: How Spaceflight Shifts the Position of Our Most Important Organ
The effects of spaceflight on the human body have been well-documented, but exactly what microgravity does to the brain's anatomy remains an ongoing question. A new study published in January 2023 has shed light on this mystery, revealing that prolonged spaceflight causes the brain to shift backward and upward, and rotate upward, with some positional changes still detectable months after astronauts return to Earth.
The Study: A Collaboration Between MIT and NASA
Rachel Seidler and a team at the Massachusetts Institute of Technology (MIT) took MRI scans of the brains of 26 astronauts and 24 non-astronaut participants to determine the impacts of prolonged spaceflight on the brain. The study, which analyzed data from 15 astronauts who provided MRI scans before and after their missions to space, combined that with MRI data from another 11 astronauts and two dozen participants of a long-duration, head-down tilt bed rest "microgravity analog" experiment.
The Findings: A Widespread Repositioning of the Brain
Rather than track whole-brain movement, the researchers divided the brain into 130 separate regions and examined each one individually. The regional analysis showed many areas with significant displacement across two spatial axes, pointing to widespread repositioning rather than a localized effect. Across participants, the study found that brains tended to shift backward and upward, and rotated in pitch, indicating that microgravity is associated with a measurable change in how the brain sits inside the skull.
The Magnitude of the Shifts: Up to 2.52 Millimeters
The dataset included participants with a range of time-in-space histories, from short missions to long-duration stays, divided into groups of roughly two-week, six-month and one-year mission durations. It identified significant positional shifts across large portions of the brain, with some displacements measured as high as 2.52 millimeters (0.1 inches) in subjects with the most time in space.
The Comparison with Bed-Rest Participants: A Crucial Insight
When the researchers compared astronauts with the bed-rest participants, they found movement in broadly similar directions, but with key differences. Astronauts showed a stronger upward movement, while bed-rest participants showed a stronger backward component. Additionally, only a portion of the changes in brain shape observed after spaceflight were present in the bed rest group, and exactly how spaceflight affects individual brain regions remains unclear.
The Correlation with Balance Issues: A Critical Finding
The study also examined whether changes in certain brain regions correlated with differences in how astronauts performed after landing back on Earth. One thing that isn't immediately restored when someone returns from space is the inner ear's sense of direction, causing many astronauts to experience balance issues. The researchers found that displacement affecting sensory-related brain regions was correlated with larger declines in astronaut balance after spaceflight.
The Long-Lasting Effects of Spaceflight on Neuroanatomy
And, while astronauts normally find their footing within a week or so of their return, the physical shifts in their brains were found to persist for up to six months post spaceflight, underscoring, the study says, "the long-lasting effects of spaceflight on neuroanatomy."
The Implications: A Call for Future Research
The scientists note that their work faces constraints typical of spaceflight research, including limited sample sizes and tight imaging timelines, and recommend future studies with larger astronaut crews on a broad range of mission lengths to better understand how quickly brain shifts can begin, how they evolve and how that shapes recovery back on Earth.
The Future of Spaceflight and the Brain: A Complex Relationship
As space agencies and private companies continue to push the boundaries of space exploration, the effects of spaceflight on the human brain will remain a critical area of research. The study's findings highlight the complex relationship between microgravity and the brain, and the need for further investigation into the long-term effects of spaceflight on neuroanatomy. By understanding the changes that occur in the brain during spaceflight, scientists can develop strategies to mitigate these effects and ensure the health and well-being of astronauts on long-duration missions.
Conclusion: A New Era of Spaceflight Research
The study's findings mark a significant step forward in our understanding of the effects of spaceflight on the human brain. As we continue to explore the vastness of space, it is essential that we prioritize the health and well-being of astronauts, and that we invest in research that will help us better understand the complex relationship between microgravity and the brain. By doing so, we can ensure a safe and successful future for spaceflight, and unlock the secrets of the universe.
