We know that time in space affects our bodies, from our brains to our bones, but scientists are still not clear on the details. In a new study, researchers looked at how the length of space missions and the time between them may affect the fluid in the human brain.
This cerebrospinal fluid is stored in the brain in four so-called ‘pockets’ ventricles, helps protect and protect the brain. It is also associated with flushing out cellular waste and delivering nutrients from the bloodstream.
Researchers from the University of Florida, NASA Johnson Space Center and other US institutions have found that the way spaceflight increases ventricle size and cerebrospinal fluid volume depends on certain factors, including the time astronauts spend in space and the intervals between their space adventures. .
“These findings demonstrate that ventricular expansion continues with spaceflight with increasing mission duration,” to write University of Florida neuroscientist Heather McGregor and colleagues in their published paper.
In addition, “intervals of less than three years may not allow the ventricles enough time to fully recover their compensatory capacity.”
This increase in ventricle size and extra cerebrospinal fluid is something that has also been observed in previous studiesand it comes with an upward shift of the brain in the skull in microgravity, which in turn contributes to the redistribution of fluid.
Using MRI scans of 30 astronauts, the researchers built on those previous studies to find that the longer the spaceflight, the greater the increase in ventricle size — until about six months, where the rate of change appears to level off.
The swelling of the ventricles of the brain is thought to represent a compensatory mechanism during spaceflight, allowing the brain to accommodate for shifts in cerebrospinal fluid. Once back on Earth, the cerebrospinal fluid slowly drops back to its normal distribution.
“While it seems counterintuitive that there would be a greater change in this structure for shorter missions, this may reflect early, adaptive structural change in flight that gradually returns to baseline over time,” the researchers said. . to explain.
For the seven astronauts who had a gap of less than three years between missions, this ventricular expansion was not as prominent. The team suggests this means there isn’t enough time for the brain ventricles to shrink and reset themselves to handle the increase in cerebrospinal fluid.
The scans also showed that the more previous missions an astronaut had done, the less noticeable the increase in ventricle size was after a mission. It’s almost as if these astronauts’ brains were “less compliant” due to previous expansions, or had maxed out their ability to handle the stressors of spaceflight, the researchers argue.
“This finding suggests that the brain is affected by the cumulative effects over multiple flights and perhaps separate periods of adaptation to microgravity and the spaceflight environment,” to write the researchers.
Part of the challenge for scientists is that there aren’t really that many people going into space on a regular basis — 636 persons total at the time of writing. Analyzing the effects of spaceflight on larger groups of people becomes important to get a better idea of how different bodies and brains are affected.
This study did not address the subsequent health effects of changes in ventricle size and cerebrospinal fluid levels, but it is clear that brain shifts happen and are influenced by the duration and frequency of missions. Previously, this extra cerebrospinal fluid has been linked to vision problems for astronauts.
With longer missions planned to the Moon and Mars in the coming years, we need to understand as much as we can about what the astronauts will be doing to themselves — and nowhere is that more important than in the brain.
“These findings illustrate some potential plateaus in and limits of human brain changes with spaceflight,” to write the researchers.
The research has been published in Scientific Reports.
