What do astronauts those trim, elite space voyagers, exercised and trained to a level of physical fitness undreamed of by most of us have in common with elderly people back on Earth? Would it surprise you to learn that it's bone loss?
The zero gravity of space flight and the microgravity of living on a space station are really hard on bones. Studies conducted on astronauts between the ages of 36 and 53, evaluating their bones before their space missions, during the missions, and at six and 18 months after returning to Earth have shown that their bone mineral density drops up to 1.8% every month they spend in space. This is a rate of bone degeneration comparable to or exceeding the bone loss that senior citizens experience in a year.
Plus, even though astronauts exercise about 2.5 hours a day, 6 days a week while in orbit riding stationary bicycles, running on treadmills, and lifting weights they still lose muscle mass, tone, and strength on every journey into space. They have to spend months recovering from these space flights when they return to Earth, spending even more time in exercise programs, and following strict diets to recover to their previous levels of fitness.
A voyage into space is like getting old, only it happens so much faster
While this accelerated aging process is tough on astronauts, studying it may prove to be of benefit for those of us back on Earth. That's the hope of scientists from the Canadian Space Agency (CSA) and the Canadian Institutes of Health Research (CIHR), who are working in conjunction with NASA, the Japanese Space Agency, and other governments' space agencies.
First instituted by the CSA's chief scientist for life sciences Nicole Buckley, this program has compiled research on astronauts for several years now, and recently held their first national workshop on the effects on the human body of living in space. As Buckley puts it, "There's increasing interest in the whole process of aging pretty soon, were all going to be there and we have this great resource in space that can complement terrestrial research."
Because there have now been five decades in which to build up a body of research data of the aging effects of space travel, this provides a real wealth of information that can be applied to aging here on Earth. Just as the lack of gravity causes changes to bones, blood vessels, the heart, and other parts of the body in space, so too do gravity and the effects of aging cause those changes in the elderly here at home.
Astronauts experience hardening of the arteries, too
As one example of this accelerated aging process, it has been demonstrated that astronauts experience hardening of the arteries in space in remarkably similar ways to the way that the elderly experience it on Earth, and with similar effects. As the blood struggles to pass through the stiffened arteries, it must exert more pressure on the blood vessels, similar to what happens on Earth when plaque builds up in the arteries of elderly people. As Richard Hughson, a University of Waterloo scientist working on the CSA/CIHR study puts it, "We think we're still in the thinking stage what's happening is you damage the brain blood vessels to the extent that you have a reduction in total brain blood flow." He is comparing the astronaut data to data collected from 100 senior citizens on Earth over the last few years. "Our CIHR part of the funding has been looking at a fairly large group of elderly [people] to examine arterial stiffness and blood flow, and now to examine cognitive and motor function to see whether there is a relationship."
Although Hughson's research is still in its early stages, he is hopeful that the astronauts' time in space as debilitating as it may have been for them will pay off by improving the lives of senior citizens, and helping to identify the factors that cause bone loss, hardening of the arteries, and other conditions that affect them. Also, as the astronauts go through retraining and exercise programs on their returns from space to recover, information gained from their efforts may reveal ways that older people can utilize similar programs to recover some of their own bone mineral density and arterial health. If the astronauts can reverse the effects of zero gravity, maybe scientists can learn from their examples ways to help older people recover from the effects of aging. "If we can learn something from the astronauts that we can apply back to the population on Earth... that's really great."