Frequent space travelers should wait three years after a longer mission to allow the physiological changes in their brains to reset, a new study suggests.
As we enter a new era in space travel, researchers were interested in how the human brain reacts to traveling outside Earth’s gravity.
They studied brain scans of 30 astronauts from before and after space travel. Their findings, published in Scientific Reports, reveal that the brain’s ventricles expand significantly in those who completed longer missions of at least six months, and that less than three years may not provide enough time for the ventricles to fully recover.
Ventricles are cavities in the brain filled with cerebrospinal fluid, which provides protection, nourishment, and waste removal to the brain. Mechanisms in the human body effectively distribute fluids throughout the body, but in the absence of gravity, the fluid shifts upward, pushing the brain higher within the skull and causing the ventricles to expand.
“We found that the more time people spent in space, the larger their ventricles became,” says Rachael Seidler, a professor of applied physiology and kinesiology at the University of Florida and an author of the study. “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.”
Based on studies so far, ventricular expansion is the most enduring change seen in the brain resulting from spaceflight, says Seidler, a member of the Norman Fixel Institute for Neurological Diseases.
“We don’t yet know for sure what the long-term consequences of this is on the health and behavioral health of space travelers,” she says, “so allowing the brain time to recover seems like a good idea.”
Of the 30 astronauts studied, eight traveled on two-week missions, 18 were on six-month missions, and four were in space for approximately one year. The ventricular enlargement tapered off after six months, the study’s authors report.
“The biggest jump comes when you go from two weeks to six months in space,” Seidler says. “There is no measurable change in the ventricles’ volume after only two weeks.”
With increased interest in space tourism in recent years, this is good news, as shorter space junkets appear to cause little physiological changes to the brain, she says.
While researchers cannot yet study astronauts who have been in space much longer than a year, Seidler says it’s also good news that the expansion of the brain’s ventricles levels off after about 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,” she says.
The results of the study, which was funded by NASA, could affect future decision-making regarding crew travel and mission planning, Seidler says.
Source: University of Florida
