The human body undergoes a lot of stress when in the microgravity environment of space that causes physiological changes to astronauts. One point of study for long-term space travel is how to determine what long-term impacts spaceflight will have on the body and how to mitigate them. A new study has been published that was investigating known vision problems in astronauts after extended periods in space. The study suggests that the impact of long-duration space travel is more far-reaching than previously believed.
According to the study, there is potential for brain volume changes and pituitary gland deformation. More than half the crew members on the ISS have reported changes to their vision following long-duration exposure to the microgravity of space. Evaluation of astronauts after staying aboard the space station have shown swelling of the optic nerve, retinal hemorrhage, and other structural changes to the eye.
MRIs used in the study identified an increase in white matter and a decrease in pituitary gland height. The researchers performed brain MRIs on 11 astronauts, including ten men and one woman who spent time on the ISS. The MRIs were performed a day after their return to Earth and then at intervals throughout the ensuing year. The study found that long-duration microgravity exposure caused expansions in the astronaut’s combined brain and cerebrospinal fluid volumes. The combined volumes remained elevated at one-year post-flight, suggesting the alterations were permanent.
The study found deformed pituitary gland with height loss was likely due to exposure to elevated intracranial pressures. The study also found an increase in volume on average in the astronaut’s lateral ventricles. However, the study notes that the ventricle changes were not outside of the normal range for healthy adults.
The team is studying ways to counter the effects of microgravity. One option that is being considered is the creation of artificial gravity using a large centrifuge they can spin people in a sitting or prone position. The team is also considering the use of negative pressure on the lower extremities to counteract the headward fluid shift due to microgravity. The research is ongoing.