Having been in free fall for months, our bodies adapt in ways that create a long list of health problems for space travelers.
The latest evalution of the warping effects of microgravity on our biology focuses on the space around the blood vessels running through our brains, revealing changes associated with astronauts between missions.
Researchers from across the United States compared a series of magnetic resonance imaging (MRI) scans of 15 astronauts taken 6 months before their stay at the International Space Station and up to 6 months after their return.
Using algorithms to carefully assess the size of the perivascular voids (spaces in brain tissue thought to help with fluid balance), the team found that orbital time had a profound effect on brain plumbing. For first-timers, at least.
Between the group of veteran astronauts, there appeared to be little difference in the size of the perivascular spaces in the two scans taken before the mission and the four taken after.
“Experienced astronauts may have reached homeostasis,” said Juan Piantino, a neuroscientist at Oregon Health & Science University.
The results may not be too surprising given what we already know about how the brain distorts when constant tug of gravity is cancelled out.
Previous studies of brain tissues & their fluid volumes have shown that they are slow to recover from space, with some changes persisting for a year or more.
Currently, astronauts rarely make more than a few space trips in their lifetime, usually just hanging around once every six months. However, as the commercialization of the space industry accelerates, all that could change.
It would be helpful to know if repeat trips made the damage worse, or if the changes experienced during that first trip temporarily caused astronauts to adapt to a new normal.
“We have all adapted to use gravity to our advantage,” says Piantino.
“Nature didn’t put our brains in our feet – it put them on high. Once you take gravity out of the equation, what effect does that have on human physiology?”
Even in the context of enlarged perivascular spaces, it is not entirely clear whether if the changes comes with any appreciable health-risks.
We tend to make the most of this neural drainage system when we sleep. Draining the fluid around our gray matter seems to play an important role in getting rid of the waste products that builds up during our most active hours.
Without these channels to function effectively, disruption materials can build up accumulate, potentially contributing to an increased risk of neurodegenerative disorders such as Alzheimer’s disease.
It is too early to say whether microgravity affects cerebral spinal fluid circulation around our noggins, let alone if changes in shapes of network of channels is significant. This may not become clear until researchers have good-sized enough samples of veteran astronauts with substantial career under their belt.
Learn about these small adjustments that go beyond the potential-harms of working-off world in space industry.
“It also force you think about some basic, fundamental questions about science and how life evolved here on Earth,” says Piantino.
After all, the gravity ever present pull isn’t just something we all struggle with. It’s a force we’ve evolved to use, helping with blood circulation and waste shedding, and potentially a variety of other functions we’ve barely considered.
By studying the subtle changes in health & anatomy in conditions we have never experienced, we will almost certainly learn more about the diseases & disorders to which our bodies were forced to weather down here.
This research was published in Scientific Reports.