Here’s What Space Travel Does to the Brains of Astronauts

If space travel is on your bucket list, prepare for your brain to change.

Researchers with the University of Michigan found that astronauts’ brains shrink and expand while traveling through space. Researchers looked at data from 27 astronauts in the first study believed to evaluate the effects of space travel on the human brain.

The study found that the brain’s gray matter decreased or increased across the brain, based on how long the astronauts were in space. Rachel Seidler, a professor of Kinesiology and Psychology at UM, said there could be a reason why gray matter changes while in space.

“We found large regions of gray matter volume decreases, which could be related to redistribution of cerebrospinal fluid in space,” Seidler said in a press release. “Gravity is not available to pull fluids down in the body, resulting in so-called puffy face in space. This may result in a shift of brain position or compression.”

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Gray matter increases were restricted to areas of the brain that control the lower limbs. Lower limb muscles experience the largest changes during spaceflight, and the gray matter increases suggest that the brain adapts to its environment during space travel, the study said.

The study focused on astronauts who completed space shuttle missions as well as those who completed a mission to the International Space Station. Twelve astronauts were shuttle crew members, while 14 spent a six-month period on the ISS.

The astronauts’ ages ranged from about 40 to 60 years old. Those who spent a longer duration in space experienced more gray matter changes, as their brains were adapting at all times.

“In space, it’s an extreme example of neuroplasticity in the brain because you’re in a microgravity environment 24 hours a day,” Seidler said.

Seidler is also leading a study in which volunteers spent up to three months on bed rest in a downward tilted position with their brains shifted upwards. The study’s findings were compared to the bed rest data, and it is believed that bed rest and spaceflight have similar effects on the brain.

“There are extensive similarities between the two [studies], with the pattern of increases and decreases shifted somewhat posteriorly in the bed rest subjects relative to flight,” the authors wrote.

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The gray matter changes found in study could also be related to cerebrospinal fluid redistribution, the authors said. The study’s findings were similar to patients suffering from idiopathic normal pressure hydrocephalus, a condition in which cerebrospinal fluid collects in the brain and causes pressure.

The patients had increases in cerebrospinal fluid and decreases in gray matter in regions similar to the astronauts. Seidler said changes within the brain could suggest new neuron connections, and that even after the brain returns to its regular state, the way the brain operates could still change.

“The behavior may return to normal, but the way the brain controls the behavior may change,” she said.

The study was published in Nature Microgravity and was supported by a grant from NASA.