(CN) — As NASA prepares its Artemis program to send humans back to the surface of the moon, research revealed Tuesday finds that long-duration space travel may have more dangerous effects on the body than previously realized.
In a study published in the journal Radiology, doctors from the University of Texas Health Science Center at Houston performed brain MRI on 11 astronauts before they traveled to the International Space Station and again after they returned.
The researchers discovered that long-term exposure to the microgravity of space resulted in the swelling of the optic nerve, retinal hemorrhage and other structural changes to the eye.
"When you're in microgravity, fluid such as your venous blood no longer pools toward your lower extremities but redistributes headward," said study lead author Dr. Larry Kramer. "That movement of fluid toward your head may be one of the mechanisms causing changes we are observing in the eye and intracranial compartment."
Scientists have long known of vision problems occurring in astronauts who spend a lengthy amount of time in space. Tuesday's study shows other complications can arise, such as pituitary gland deformation and brain volume changes.
The results of the study provide evidence to the long-standing theory that increased pressure inside the head during spaceflight contributes to these effects on the body.
The MRI results found that long-term exposure to the microgravity of space expanded the astronauts' brain and cerebrospinal fluid volumes (CSF), with CSF being the fluid that flows through the hollow spaces of the spinal cord and brain.
"What we identified that no one has really identified before is that there is a significant increase of volume in the brain's white matter from preflight to postflight," Kramer said. "White matter expansion in fact is responsible for the largest increase in combined brain and cerebrospinal fluid volumes postflight."
The MRI also showed pituitary gland alterations, the gland located at the base of the skull, which helps other glands in the body function.
"We found that the pituitary gland loses height and is smaller postflight than it was preflight," Kramer said. "In addition, the dome of the pituitary gland is predominantly convex in astronauts without prior exposure to microgravity but showed evidence of flattening or concavity postflight."
The researchers are using the study to find ways to counteract potentially harmful effects of long-term spaceflight, including the use of a large centrifuge that can act as artificial gravity for astronauts either sitting or lying prone.
Kramer said the findings could also be used to help people on Earth who suffer from related health conditions.
"If we can better understand the mechanisms that cause ventricles to enlarge in astronauts and develop suitable countermeasures, then maybe some of these discoveries could benefit patients with normal pressure hydrocephalus and other related conditions," he said.
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