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Travelling To Space May Alter Brain, Says Study

Upon return to Earth, this process is then gradually reversed, which then results in a relative reduction of white matter volume

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Keplar, NASA
According to co-author Andrew Casey, it was previously believed that the first stars that formed in the universe could not possibly still exist today. VOA

Spending long periods in space not only leads to muscle atrophy and reductions in bone density, it also has lasting effects on the brain, suggests a study.

The study, led by a team of neuroscientists from the University of Antwerp in Belgium and Ludwig-Maximilians-University (LMU) of Munich, showed that differential changes in the three main tissue volumes of the brain remain detectable for at least half a year after the end of their last mission.

“Our results point to prolonged changes in the pattern of cerebrospinal fluid circulation over a period of at least seven months following the return to Earth,” said professor Peter zu Eulenburg from the LMU.

“However, whether or not the extensive alterations shown in the grey and the white matter lead to any changes in cognition remains unclear at present,” he added.

The study, reported in the New England Journal of Medicine, was carried out on ten cosmonauts, each of whom had spent an average of 189 days on board the International Space Station (ISS).

The magnetic resonance tomography (MRT) scans performed in the days after the return to Earth revealed that the volume of the grey matter was reduced compared to before launch.

ISS Launched First satellite For Cleaning Space Junk
Space travel can alter brain: Study, Pixabay

Seven months later, this effect was partly reversed, but nevertheless still detectable.

In contrast, the volume of the cerebrospinal fluid, which fills the inner and outer cavities of the brain, increased within the cortex during long-term exposure to microgravity.

Further, the white matter tissue volume (those parts of the brain that are primarily made up of nerve fibres) appeared to be unchanged upon investigation immediately after landing.

But, the subsequent examination six months later showed a widespread reduction in volume relative to both earlier measurements.

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In this case, the team postulated that over the course of a longer stint in space, the volume of the white matter may slowly be replaced by an influx of cerebrospinal fluid.

Upon return to Earth, this process is then gradually reversed, which then results in a relative reduction of white matter volume.

According to the researchers, further studies using a wider range of diagnostic methods are deemed essential, to minimise the risks associated with long-term missions and to characterise any clinical significance of the findings. (IANS)

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Asteroids Are Falling On Earth’s Surface Twice As Often: Study

This enhanced impact rate poses a threat for the next mass extinction event.

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Asteroids
This Dec. 29, 1968, photo made available by NASA shows craters on the moon. For the past 290 million years, giant rocks from space have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study. VOA

Giant rocks from space are falling from the sky more than they used to, but don’t worry.

For the past 290 million years, large asteroids have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study in Thursday’s journal Science.

But no need to cast a wary glance up. Asteroids still only smack Earth on average every million or few million years, even with the increased crash rate. NASA’s list of potential big space rock crashes shows no pending major threats. The biggest known risk is a 4,200-foot (1.3-km) wide asteroid with a 99.988 percent chance that it will miss Earth when it whizzes very near here in 861 years.

Tell that to the dinosaurs. Most scientists think dinosaurs and a lot of other species went extinct after a huge space rock crashed into Central America about 65 million years ago.

Earth, Asteroids
Taurids meteor shower lights up the sky. The risk of asteroids hitting the Earth has grown over the years. Wikimedia

“It’s just a game of probabilities,” said study lead author Sara Mazrouei, a University of Toronto planetary scientist. “These events are still rare and far between that I’m not too worried about it.”

Mazrouei and colleagues in the United Kingdom and United States compiled a list of impact craters on Earth and the moon that were larger than 12 miles (20 km) wide and came up with the dates of them. It takes a space rock that’s half a mile (800 meters) wide to create holes that big.

The team counted 29 craters that were no older than 290 million years and nine between 291 million years and 650 million years old.

But we can see relatively few big craters on Earth because the planet is more than 70 percent ocean and past glaciers smoothed out some holes, said University of Toronto planetary scientist Rebecca Ghent, a study co-author.

Earth, Asteroids
These rocks were rare survivors from a very different time on Earth. Pixabay

Extrapolating for what can’t be seen brings the total to about 260 space crashes on Earth in the last 290 million years. Adding in other factors, the science team determined that the current space crash rate is 2.6 times more than the previous 700 million years.

Craters older than 650 million years are mostly wiped off on Earth by glacial forces so the scientists used impact craters on the nearby moon as a stand-in for holes between 650 million and 1 billion years old. The moon is a good guide for estimating Earth crashes, because it is close enough to be in the same bombardment path and its craters last longer.

Mixed reactions

So what happened nearly 300 million years ago?

“Perhaps an asteroid family was broken up in the asteroid belt,” Mazrouei speculated. The space rocks then headed toward the Earth and moon, and the planet got slightly more because it is a bigger target and it has higher gravity, Ghent said.

Oldest known asteroid family
An asteroid family. Wikimedia

Outside scientists are split about the research. Jay Melosh at Purdue said he found the number of craters too small to come to a reasonable conclusion, but Harvard’s Avi Loeb said the case was convincing.

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Humans might not have emerged without mass extinctions from space rocks about 250 million and 65 million years ago, Loeb said in an email, adding, “but this enhanced impact rate poses a threat for the next mass extinction event, which we should watch for and attempt to avoid with the aid of technology.”

“This demonstrates how arbitrary and fragile human life is,” Loeb wrote. (VOA)