Long Stays in Space can Cause Brain Injury

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A study of five Russian cosmonauts who had stayed on the International Space Station (ISS) reveals that extended time in space causes signs of brain injury. The study is published in the scientific journal JAMA Neurology

Scientists followed five male Russian cosmonauts working on the permanently manned International Space Station (ISS), in an orbit 400km above the surface of the Earth.

Early on in spaceflight history, extended time in zero gravity was found to result in muscle atrophy and bone loss. More recently, changes in vision were discovered during long flights, a potentially serious hazard. The vision changes were ascribed to increased cerebral pressure caused by the lack of gravity no longer pulling fluid into the lower extremities. On Earth this is similar to lying with a head-down tilt, causing fluids to pool in the upper body and head.

Blood samples were taken from the cosmonauts, whose mean age was 49, 20 days before their departure to the ISS, where they had an average stay of 169 days.

After landing on Earth, follow-up blood samples were taken one day, one week, and about three weeks after landing. Concentrations of three of the biomarkers analysed – NFL, GFAP and the amyloid beta protein Aβ40 – were increased after their stay in space. The peak readings did not occur simultaneously after the men’s return to Earth, but their biomarker trends nonetheless broadly tallied over time.

“This is the first time that concrete proof of brain-cell damage has been documented in blood tests following space flights. This must be explored further and prevented if space travel is to become more common in the future,” said Henrik Zetterberg, professor of neuroscience and one of the study’s two senior coauthors.

”To get there, we must help one another to find out why the damage arises. Is it being weightless, changes in brain fluid, or stressors associated with launch and landing, or is it caused by something else? Here, loads of exciting experimental studies on humans can be done on Earth,” he continued.

Changes also seen in magnetic resonance imaging (MRI) of the brain after space travel add evidence to the notion of spaceflight causing brain injurt. Clinical tests of the men’s brain function that show deviations linked to their assignments in space further support this, but the present study was too small to investigate these associations in detail.

Prof Zetterberg and his coauthors are currently discussing follow-up studies.

“If we can sort out what causes the damage, the biomarkers we’ve developed may help us find out how best to remedy the problem,” Prof Zetterberg said.

Source: University of Gothenburg

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