NASA has just published the results of the ‘Twins Study ‘ or Twin Study that analyzes the health effects of long-duration space flights.
For nearly a year, American astronauts and identical twins Scott and Mark Kelly lived separate lives , one on Earth and one in space. Thus, while Mark was enjoying his retirement in Tucson, Arizona, his brother floated in microgravity aboard the International Space Station that orbits about 250 miles above the planet.
Ten scientific teams studied the twins’ physiology, memory and genes before, during and after that year, looking for any deviations that might suggest that Scott’s 340 days in space affected him physically. While researchers have hinted at tempting suggestions about what NASA’s Twins Study found, now a comprehensive study published in the journal Science confirms that prolonged space travel causes stressors that can manipulate genes, send to the immune system. an overload or impair the brain’s ability and memory of reasoning. It is not yet clear whether these stressors have long-term health implications.
This is “the most comprehensive view we’ve had of the human body’s response to space flight,” says Susan Bailey of Colorado State University in Fort Collins who led one of the research teams.
In the first days after Scott reached space in March 2015, he took blood samples that were sent to Earth. The tests revealed epigenetic tags in more than 1,000 of his genes that were not in his pre-flight samples or in his brother Mark’s samples. These chemical markers, which can turn a gene on or off when added or removed, can be caused by environmental factors and are reversible. Those most affected were genes that regulate DNA repair and the length of telomeres, the ends of chromosomes, Bailey’s team found.
Scott’s telomere measurements showed that they had grown an incredible 14.5% more. The researchers expected to find their telomeres shortened amid the low-gravity environment and radiation-bathed space. However, within 48 hours of returning to Earth in March 2016, his telomeres had shortened to their pre-flight length. And several months later, some telomeres were even shorter , the authors state.
The most frequently changed genes in those early spaceflight blood samples were those involved in regulating the immune system. This indicates that, while a body is in space, “the immune system is almost on high alert as a way of trying to understand this new environment,” says Christopher Mason, co-author of the study.
Scott’s chromosomes also went through many structural changes. The parts of the chromosomes were swapped, reversed, or even fused; changes that can lead to infertility or certain types of cancer.
Once he returned to Earth, most of the changes Scott underwent reverted to the previous state. But not all. For example, about 91% of the genes that had changed activity while in space returned to normal six months later , while the rest remained as when in space. Six months after his return, his immune system was still on high alert, his DNA repair genes were still very active, and some of his chromosomes were still upside down. Tests of Scott’s speed and accuracy on short-term memory and logic problems showed that his cognitive abilities had declined from pre-flight levels.
Whether these results are definitely due to spaceflight is not entirely clear, partly because the observations are from a single individual, making the sample too small.
While NASA’s Twins Study is impressive, the work underscores the fact that we are not yet ready for long-term space travel , experts clarify.
Referencia: F. Garrett-Bakelman et al. The NASA Twins Study: a multidimensional analysis analysis of a year-long human spaceflight. Science. Published online April 11, 2019. doi: 10.1126/science.aau8650.
