Astronaut scans reveal rapid white matter changes and brains that float higher
With hopes for manned missions to Mars and space tourism in the offing, how the space environment impacts the human body is the source of much intrigue for scientists at NASA and beyond. A fascinating new study from the University of Florida (UF) has sought to provide answers, uncovering some thought-provoking changes in the brains of astronauts before and after missions into space.
The study was carried out by scientists at the UF's Department of Applied Physiology and Kinesiology, who worked with NASA's Johnson Space Center to analyze brain scans of 15 different NASA astronauts both before lift-off and following their missions.
These evaluations revealed changes in the brain's white matter in regions related to movement and sensory information. These are described as deteriorations, and according to the scientists, are similar to that which naturally occurs as the human body ages, although they occurred at a very accelerated rate.
But perhaps the most interesting tidbit to arise from the study was evidence of pools of fluid gathering at the base of the cerebrum after spaceflight. This is the large part of the brain that houses the cerebral cortex, and the pools of fluid gathered beneath meant that the brains of the astronauts were basically floating higher in the skulls following their missions in microgravity.
"We know that fluid shifts toward the head in space," says Rachael Seidler, a professor with UF's College of Health and Human Performance. "When you see photos and video of astronauts, their faces often look puffy, because gravity isn't pulling fluids down into the body."
By the same token, the scientists believe this effect, where a lack of gravity causes extra fluid to gather in the skull, may be a driver of what is known as Spaceflight Associated Neuro-Ocular Syndrome. This refers to physiological effects on the human body brought on by long-duration spaceflight after returning to Earth, which can impact the optic nerve causing visual changes and flattening of parts of the eye.
"It could be slower fluid turnover, it could be pressure on the optic nerve or that the brain is sort of tugging on the optic nerve because it's floating higher in the skull," Seidler says.
Promisingly, the scientists believe that the deterioration of the white matter is able to begin reversing itself after only a few weeks on Earth. Not so promisingly, they believe that the pathways that cause the changes might linger for longer. To that end, the team hopes to conduct follow up studies six months after spaceflight to investigate the longer term effects.
The scientists even draw parallels to our sedentary lifestyles here on Earth, contending that the lack of gravitational pull on arms and legs bound to the couch means less and less sensory input is pushed to the brain, possibly rewiring the brain's pathways that process that information.
"We have an increasingly sedentary lifestyle," Seidler points out. "It's not the same as the effects on limbs in space, but if we're laying around and not using our bodies, could the integrity of white matter pathways in the brain be affected? Another reason for an active lifestyle."
The research was published in the journal JAMA Neurology.
Source: University of Florida