Long space voyages may cause astronauts' brain cavities to expand

This study collected before and after brain scans from 30 astronauts who went to space.
Mrigakshi Dixit
Brain ventricles may expand during long space missions.
Brain ventricles may expand during long space missions.


Humanity is ushering in a new era of space exploration, where long spaceflights are bound to happen. This can pose major risks to the health of future explorers in several ways, ranging from decreasing bone density to causing alterations in brain function. 

A team of University of Florida researchers has now tried to demystify how the brain reacts to long spaceflight. 

Studying brain scans of 30 astronauts 

The study collected before and after brain scans from 30 astronauts who have been to space. Eight of those went to space for a two-week mission, 18 for six months, and four for a year. 

Changes in the ventricles of the brain were observed when the before and after images were compared. Ventricles are interconnected cavities that contain cerebrospinal fluid to cushion the brain. Additionally, ventricles also provide nourishment and remove waste from the brain.

By staying in a lower gravity environment for a longer period of time, this fluid tends to move upward, causing the ventricles to enlarge. While in the presence of gravity, this fluid is able to distribute evenly in the brain. 

The scans found that astronauts who went on longer missions of at least six months had larger ventricular expansion. Moreover, in seven astronauts who had fewer than three years between missions, the size of their ventricles did not return to normal.

The study indicates that after longer missions, astronauts should wait for at least three years to allow the ventricles to fully recover. 

“We found that the more time people spent in space, the larger their ventricles became,” said Rachael Seidler, a professor of applied physiology and kinesiology at the University of Florida and an author of the study, in a press release.

Seidler added: “Many astronauts travel to space more than one time, and our study shows it takes about three years between flights for the ventricles to fully recover.”

How the human brain adjusts to a gravity-free environment

The study also found that shorter trips to space may not lead to major brain changes. Thus, bringing some good news for the future of space tourism. 

Shorter missions of two-week trips left a minimal mark on the ventricles. “The biggest jump comes when you go from two weeks to six months in space. There is no measurable change in the ventricles’ volume after only two weeks,” Seidler said. 

Those that stayed in space continuously for a longer period of time, on the other hand, saw the ventricular enlargement diminish after six months. “We were happy to see that the changes don’t increase exponentially, considering we will eventually have people in space for longer periods,” added Seidler.

As a result, astronauts flying to Mars, which would take around 800 to 1,000 days, may be able to acclimate to the lengthy duration of journeys. 

The team claims that the long-term effects of ventricular expansion are still unclear. Shedding light on brain alterations and their possible consequences might be critical to the success of future deep-space human missions.

Nevertheless, the research is critical in understanding how the human brain adjusts and reacts to a gravity-free environment.  In the long term, the creation of artificial gravity-based spacecraft might be one approach to keeping astronauts healthy throughout these extended journeys.

The findings have been published in the journal Scientific Reports

Study Abstract:

Spaceflight induces widespread changes in human brain morphology. It is unclear if these brain changes differ with varying mission duration or spaceflight experience history (i.e., novice or experienced, number of prior missions, time between missions). Here we addressed this issue by quantifying regional voxelwise changes in brain gray matter volume, white matter microstructure, extracellular free water (FW) distribution, and ventricular volume from pre- to post-flight in a sample of 30 astronauts. We found that longer missions were associated with greater expansion of the right lateral and third ventricles, with the majority of expansion occurring during the first 6 months in space then appearing to taper off for longer missions. Longer inter-mission intervals were associated with greater expansion of the ventricles following flight; crew with less than 3 years of time to recover between successive flights showed little to no enlargement of the lateral and third ventricles. These findings demonstrate that ventricle expansion continues with spaceflight with increasing mission duration, and inter-mission intervals less than 3 years may not allow sufficient time for the ventricles to fully recover their compensatory capacity. These findings illustrate some potential plateaus in and boundaries of human brain changes with spaceflight

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