(ORDO NEWS) — Being in free fall for months on end, our body is rewired in such a way that space travelers have a long list of health problems.
The latest assessment of microgravity’s distorting impact on our biology focuses on the spaces surrounding the blood vessels that travel through our brains and has revealed the changes that remain with astronauts after spaceflight.
US researchers compared a series of magnetic resonance imaging (MRI) images of the brains of 15 astronauts taken before their six-month stay on the International Space Station and six months after their return.
Using algorithms to carefully measure the size of perivascular spaces (gaps in brain tissue thought to contribute to fluid balance), the team found that time spent in orbit had a profound effect on the brain’s plumbing. At least for the pioneers.
Among the veteran astronauts, there did not appear to be much difference in the size of the perivascular spaces in the two images taken before the flight and in the four images taken after.
“Experienced astronauts may have achieved some kind of homeostasis,” says Juan Piantino, a neuroscientist at the Oregon Health and Science University.
The results may not be all that surprising, given what we already know about how the brain warps when the constant pull of gravity wanes.
Previous studies of brain tissue and fluid volume have shown that they recover slowly after being in space, with some changes persisting for a year or more.
Nowadays, astronauts rarely make more than a few flights into space in their lifetime, usually spending about six months there. However, with the growth of the commercialization of the space industry, everything can change.
It will be useful to know whether repeated travel exacerbates the harm, or whether the changes that occurred during the first trip temporarily adapt the astronauts to a new kind of normal.
“We’ve all adapted to using gravity to our advantage,” says Piantino.
“Nature didn’t put our brains in our feet – she put them high up. If you take gravity out of the equation, how does that affect human physiology?”
Even in the context of the expansion of perivascular spaces, it is still not entirely clear whether this change carries a tangible health risk.
Generally, we use this neurological drainage system the most during sleep. Flushing fluids around our gray matter seems to play an important role in removing waste products that build up during more active times.
Without the effective functioning of these channels, damaging substances can accumulate, potentially contributing to an increased risk of neurodegenerative diseases such as Alzheimer’s disease.
It is still too early to tell if microgravity has any effect on the circulation of cerebrospinal fluid around our brain, let alone if there are significant changes in the shape of the channel network.
Perhaps this will become apparent only after the researchers collect a good sample of veteran astronauts with a long service record.
Knowing about these small changes goes beyond the potential harm of working after hours in the space industry.
“It also makes you think about some of the basic fundamental questions of science and how life evolved on Earth,” says Piantino.
The constant pull of gravity isn’t just something we struggle with, after all. It is a force that we have evolved to use to aid blood flow and waste removal, and potentially perform many other functions that we have not even thought about.
By studying the subtle changes in health and anatomy in conditions we have never endured, we will almost certainly learn more about the diseases and disorders that our bodies are forced to endure here below.
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