A new study has demonstrated that astronauts have clinically significant brain changes after spaceflight. This is reported by JAMA Neurology.
Long-term stay in space has long lasting effects on the brain. A three-year study has proven this. But it is not known whether the structural changes to the brain are harmless or clinically significant.
This joint study was conducted by scientists from Germany, Sweden and Russia. They assessed the structural integrity of the human brain using blood markers in astronauts after they returned to Earth. It turned out that a long stay in space causes the brain to show noticeable signs of mild but lasting brain injury. It also ages faster than in normal humans.
Scientists examined longitudinal blood samples from five astronauts who had been aboard the ISS for an average of 169 days (5.5 months). All of the subjects donated blood right before the flight and immediately after returning to Earth. Two more samples were taken one and three weeks after landing.
In their blood, the researchers found significant increases in several brain-specific proteins, particularly during the first week after return compared to the original pre-mission values. These proteins indicate damage to long nerve fibers in the white matter of the human brain and glial cells.
The reason for the increase in specific brain proteins may be due to impaired venous outflow of the head in microgravity. This mechanism may over time lead to an increase in cerebrospinal fluid volume and pressure on the white and gray matter.
Scientists also noticed a decrease in tau protein (a marker of gray matter), which persisted even three weeks after the astronaut returned to Earth. Specialists believe that all this is evidence in favor of a complex response of the brain to stay in space, not just one type of tissue.
The researchers noted that further experiments and experiments are needed to figure out how to reduce the effects of microgravity on the human brain. This would minimize neurological risks on long missions. According to scientists, this should be done before planning a trip to Mars.