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Extended spaceflight can affect the human brain

A large collaborative study conducted by scientists from the United States, Europe, and Russia has investigated the effects of long-duration spaceflight on the human brain. The researchers found that astronauts had increased levels of cerebrospinal fluid in the brain, along with reduced space between the brain and the surrounding membrane at the top of the head. Surprisingly, American astronauts had more enlargement in the perivascular spaces in the brain – the passages that serve as a cleaning system during sleep – in comparison to Russian cosmonauts. 

The study performed fMRI scans of the brains of 24 Americans, 13 Russians, and a few astronauts from the European Space Agency (ESA), both before and after they had spent six months on the International Space Station (a habitable artificial satellite located in the low Earth orbit). “I think it is one of the largest studies on space data, and for sure, one of the very few studies with NASA, ESA, and Roscosmos [the main Russian space corporation] data. It comprises data of almost 10 percent of all people who went into space,” said study senior author Floris Wuyts, a professor of Medical Physics at the University of Antwerp.

The scientists found an increased volume of fluid-filled channels in the brain after spaceflight, which was more prominent in the NASA than in the Roscosmos crew.

“An important implication of our findings is that the volume of fluid-filled channels in the brain of astronauts is linked to the development of the spaceflight-associated neuro-ocular syndrome, a syndrome characterized by vision changes and whose mechanisms are still not completely clear,” explained study co-author Donna Roberts, a neuroradiologist at the Medical University of South Carolina.

However, it is important not to speculate about pathology or brain health yet, according to Dr. Roberts. “The observed effects are very small, but there are significant changes when we compare the post-flight scans with the preflight scans,” she said.

The differences between the Americans and the Russians that the study results revealed are still a mystery and require further investigation. “We need to understand how specific microgravity-countermeasure usage, exercise regimes, diet and other factors may play a role in the differences we found between crews,” said co-author Elena Tomilovskaya, an expert in Gravitational Physiology and Space Medicine at the Russian Academy of Sciences.  

The study is published in the journal Proceedings of the National Academy of Sciences.

By Andrei Ionescu, Staff Writer

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