Prolonged spaceflight causes widespread changes in human brain, study finds

According to a new study, the human brain undergoes significant changes during spaceflight, with longer missions resulting in more pronounced effects.

NASA-funded research, which examined the brains of 30 astronauts before and after space travel, found that the duration of a mission, the time between missions, and the number of previous missions all influenced the nature and degree of these changes.

"Spaceflight induces widespread changes in human brain morphology," the study, published in Scientific Reports journal, found.

One key finding of the study was that space missions lasting at least six months led to a remarkable expansion of the cerebral ventricles — fluid-filled cavities at the brain's center — which cushion the brain and the spinal cord.

"Mission duration was associated with pre- to post-flight increases in left lateral ventricle volume, right lateral ventricle volume, and third ventricle volume," the researchers said.

Age-related enlargement of the ventricles could be associated with cognitive decline.

Interestingly, two-week-long missions resulted in smaller changes in ventricle volume compared to missions lasting six months or longer, meaning that short-term space tourists may not be affected.

The study said that most expansion occurred during the first six months in space and then appeared to taper off for longer missions.

Researchers also found that it took three years for the ventricles to fully recover after spaceflight, noting that shorter intervals may not be enough for the brain to regain its compensatory capacity.

The study also explored differences between novice and experienced astronauts but found no significant variation in post-flight brain changes between the two groups.

However, the extent of previous spaceflight experience did appear to impact the brain's response to future spaceflights. "Crewmembers who had completed multiple previous missions tended to show free water decreases within the brain," the study found.

The findings provide important insights into how current and previous spaceflight experience impacts the brain and may influence guidelines for future mission planning.

However, the scientists caution that they had a small sample of long-duration flyers and that further research is needed to understand these effects fully.

It could be crucial as humans continue to push the boundaries of space exploration with potential multi-year missions to Mars.

"Determining whether brain changes continue throughout prolonged microgravity exposure or plateau at some point during flight will help us to better understand the nature and mechanisms of these changes," the researchers said.