New research led by a team from the University of Antwerp has looked at the brains of cosmonauts before and after their six-month space missions and reported that prolonged periods in microgravity alter the structure of the brain. Some changes were still noticeable seven months after they came back to Earth.
The international team took MRI scans of 10 male cosmonauts before they went to space followed up with a second scan a few weeks after they returned to Earth. In seven cases, they also conducted a third scan after several months. As reported in the New England Journal of Medicine, the team noticed a reduction in the volume of gray matter throughout the brain, with particular effects in both the orbitofrontal cortex, which is involved in decision making, and the temporal cortex, which plays a role in the processing of sensory inputs and memory formation.
Reductions were also reported in the brain's white matter, the substance that connects different areas of gray matter to each other. The team also noticed changes in the distribution of the cerebrospinal fluid, which removes waste products and protects the brain. Without gravity, more fluid moves to the head and accumulates there.
“Changes occur in the gray and white matter and cerebrospinal fluid,” lead author Dr Angelique Van Ombergen said in a statement. “And some of those changes remain detectable even seven months after the mission has ended.”
While gray matter levels were similar to those measured pre-flight after seven months, the changes to the cerebrospinal fluid persisted. This could potentially explain why astronauts can experience problems with their clarity of vision. The study focused on changes to the structure of the brain but not how these changes might affect function. However, they are planning to investigate this in more detail and are interested in working out how long it takes for the brain to return to normal.
“This is definitely something we want to look into and something which we think is also necessary if we want to understand the exact dynamics over time,” Dr Van Ombergen told IFLScience. “In addition, broader prospective studies to fully uncover the potential clinical consequences for astronauts are also necessary. Combining e.g. brain scans with clinical tests or behavioral data is necessary if we want to fully comprehend what’s going on.”