Long-term space stays can not only cause muscle atrophy and reduced bone density, but also have long-lasting effects on the brain, warns the first long-term study of Russian cosmonauts. Little is known about the different tissues of humans brain responds to exposure to microgravity, said researchers from the Ludwig Maximilian University of Munich (LMU) in Germany. It remains unclear whether and to what extent the previously observed neuroanatomical changes persist after returning to normal gravity.
The study, which appears in the New England Journal of Medicine, notes the varying changes in the three major tissue volumes of the brain for at least half a year after the end of their last mission detectable. The study was conducted on ten cosmonauts, each of whom spent an average of 1
In addition, seven members of the cohort were re-examined seven months after their return from outer space. "This is indeed the first study in which it was possible to objectively quantify changes in brain structures after a space mission, which also includes a prolonged follow-up," said Peter zu Eulenburg, a professor at the LMU. The MRI scans performed in the days after the return to Earth showed that the volume of gray matter (the part of the cerebral cortex that consists mainly of the cell bodies of the neurons) was reduced compared to the baseline measurement before starting The follow-up 7 months later, this effect was partly reversed, but still detectable. In contrast, the volume of cerebrospinal fluid filling the inner and outer cavities of the brain increased during long-term exposure to microgravity in the cortex.
In addition, this process was also observed in the outdoor spaces that cover the brain brain after returning to Earth, while the cerebrospinal fluid spaces inside returned to almost normal size. The tissue volume of the white matter (those parts of the brain that consist mainly of nerve fibers) appeared to be unchanged on examination immediately after landing. Subsequent examination at 6 months, however, showed a substantial volume reduction over both earlier measurements. In this case, the researchers postulate that during a prolonged stay in space, the volume of white matter can be slowly replaced by an influx of cerebrospinal fluid.
After returning to Earth, this process is then reversed gradually, which then leads to a relative decrease in the volume of white matter. "Taken together, our results point to persistent changes in the pattern of cerebrospinal fluid circulation over a period of at least seven months after returning to Earth," says Eulenburg. Gray and white matter, leading to changes in cognition, are currently unclear He said: "To minimize the risks associated with long-term missions and to characterize the clinical significance of their structural outcomes, further studies with a wider range of diagnostic methods are considered essential.