Space twins show DNA effect
An extra-terrestrial twin study has given important insights into the health effects of living in space.
The year-long study compared astronaut Scott Kelly, who was in orbit, with his twin, Mark, back home on Earth.
The results gave insight into the potential health consequences for astronauts who remain in space longer than six months, though it is unknown if any of the changes that persisted in Scott Kelly upon return to Earth are related to spaceflight alone – or how long they will last.
Risks associated with spaceflight include exposure to radiation and microgravity, but the way these risks impact health during extended stays in space has been unclear.
Analyses identified several changes in Scott compared to his twin, some of which persisted after his time in orbit.
Changes included a small (less than five per cent) difference in DNA methylation. Also, expression of some of Scott’s genes, especially those related to the immune system, changed, though more than 90 per cent of these genes returned to normal expression levels six months after the flight.
Changes to the shape of Scott’s eyeball, including a thicker retinal nerve, were reported, as well as a decline in some of Scott’s cognitive abilities as measured by a series of tests.
The authors say these changes may not be attributed to space flight alone.