Analysis of blood samples taken from Russian cosmonauts before and after their flight to the ISS showed that prolonged stay in space can provoke brain damage.
For years, scientists have investigated the adverse effects of space travel, including muscle wasting, bone changes, and visual impairment. Now German researchers from the Ludwig-Maximilian University of Munich, with the support of colleagues from the University of Gothenburg and the Institute of Biomedical Problems at the Russian Academy of Sciences, have announced signs of damage to brain cells present in blood tests of people who have been in orbit.
As described in an article published in the journal Jama Neurology, scientists from 2016 to 2020 observed five Russian cosmonauts who spent an average of no more than 169 days on the ISS. Blood samples were taken from the crew members of the station 20 days before the start of a long space flight, as well as a day, a week, and 21-25 days after returning to Earth. The goal was to measure five biomarkers: neurofilament thin polypeptide (NEFL), glial fibrillar acidic protein, tau protein, and two amyloid-beta.
As it turned out, after a long stay in space in men, whose average age was 49 years, the concentrations of neurofilament, glial fibrillar acidic protein and beta-amyloid Aβ40 were significantly increased. The first provides structural support for the long processes of neurons and regulates the diameter of the axon, which affects the speed of nerve conduction. The second is the main structural protein of astrocytes in the central nervous system and is considered a biomarker of astroglial pathology in neurological diseases.
The third is prone to the formation of toxic plaques in the brain, and such accumulations of β-amyloid peptide are a biological sign and a factor in the development of dementia and Alzheimer’s disease.
“This is the first time that concrete evidence of brain cell damage has been documented in blood tests in humans after space flights. Our findings need to be further explored and taken into account if space travel becomes more common in the future, ”said Professor Henrik Zetterberg, one of the study’s senior authors. Scientists admit that when the astronauts were in orbit, a fluid shift occurred in their brains, and this could affect the blood-brain barrier between the circulatory and central nervous systems.
The suggestion that the changes described above may be related to impaired brain function is supported by changes that were also detected in magnetic resonance imaging after space travel. But further research is needed to understand what causes the damage. “If we can figure out what causes the abnormalities, the biomarkers we have found will help us understand how best to solve the problem,” Zetterberg concluded.
Photo: Exit of a member of the ISS crew into open space / © NASA