Changes in brain volume and deformation of the pituitary gland in astronauts may be the result of space travel, as a new study published in the journal Radiology suggests.
It has been hypothesized that chronic exposure to elevated intracranial pressure , or pressure within the head, during spaceflight is a contributing factor to these changes, optic nerve inflammation, retinal hemorrhage, and other ocular structural changes that affect the the vision.
Other brain changes
To find out, a brain magnetic resonance imaging (MRI) was carried out on 11 astronauts, including 10 men and one woman, before traveling to the International Space Station (ISS).
The MRI results showed that long-term microgravity exposure caused expansions in the combined volumes of the astronauts’ cerebrospinal fluid (CSF). The MRI also showed abnormalities in the pituitary gland, a pea-sized structure at the base of the skull: it loses height and is smaller after flight than before flight . This type of deformation is consistent with exposure to high intracranial pressures.
As noted by the study’s lead author, Larry A. Kramer of the University of Texas Health Sciences Center:
What we identified that no one has really identified before is that there is a significant increase in the volume of white matter in the brain from the pre-flight to the post-flight. In fact, the expansion of white matter is responsible for the largest increase in combined cerebrospinal fluid and brain volumes after the flight.
The researchers also observed a post-flight increase in volume, on average, in the astronauts’ lateral ventricles , spaces in the brain that contain CSF. The changes were similar to those that occur in people who have spent long periods of bed rest with their head tilted slightly downward.
Researchers are studying ways to counteract the effects of microgravity.
If we can better understand the mechanisms that cause the ventricles to enlarge in astronauts and develop suitable countermeasures, then perhaps some of these discoveries could benefit patients with normal-pressure hydrocephalus and other related conditions.