In a study published in Scientific Reports, scientists evaluated changes in brain gray matter and ventricular volumes, extracellular free water distribution, and other parameters to understand changes in brain morphology induced by spaceflight.
Space travel is challenging for the human body as it exposes the body to various hazards such as microgravity and increased radiation, in addition to the psychological stress of social isolation in for a long time in a confined space.
In the present study, the researchers used magnetic resonance imaging (MRI) data from 30 astronauts, which varied significantly in space flight experience parameters. The researchers hypothesized that shifts in gray matter volume, ventricular expansion, and free water movement would be larger for longer missions, along with smaller changes in white matter microstructure. It has also been suggested that shorter intervals between missions and greater experience from previous flights cause smaller changes in brain structure.
According to the results of the study, longer space flights were associated with a higher degree of expansion of the third and right lateral ventricles of the brain. These changes also occurred in the first six months of being in space and subsequently stabilized for longer missions, as evidenced by a similar degree of expansion demonstrated by astronauts who were on six-month and one-year missions. It is important to note that these results are based on a small sample size, so further research is needed to understand the patterns of ventricular expansion.
The fractional volume of free water increased along the edges of the right lateral ventricle in novice astronauts after a space flight, and in those who had been on two or more missions, its decrease was observed in the same area. This suggests that astronauts who have experienced ventricular expansion during previous missions and slow recovery from spaceflight have significantly reduced ventricular expansion and CSF reabsorption after missions. Thus, multiple space flights and repeated adjustments and adaptation to changes in gravity cause significant changes in the fractional volume of free water.
For crew members who had intervals between missions of less than three years, no expansion was observed after the next mission ventricles, while those with a recovery period between missions of more than three years had ventricular expansion after the next mission. These results indicate that an interval of less than three years was insufficient for ventricular recovery.