Spending months in space changes the brain and can increase the risk of developing brain damage and dementia, a new study revealed.
Researchers from the University of Texas studied brain scans of astronauts a year after they returned from the International Space Station for signs of damage.
The lack of gravity experienced by humans in space redirects blood away from arms and legs to the brain – causing a build up of pressure inside the skull.
It was already known that extended spells in space causes vision problems in astronauts but this new study shows that the impact ‘could be far worse’.
This image shows an astronauts brain before (left) and after (right) spaceflight with the dark arrows in picture b pointing to an expansion of parts of the brain
Researchers are studying ways to counter the effects of microgravity – something that will be needed before humans make the nine month or more journey to Mars.
The Texas researchers believe that the process of blood being redirected to the brain could cause its volume to balloon and the pituitary gland to shrink down.
The team suspect could cause difficulty walking, problems with bladder control and an increase risk of developing dementia.
The pituitary gland is part of the body’s endocrine system, releasing hormones into the blood and the damage could be irreparable.
Researchers compared the brains of astronauts before and after their stay on the ISS as well as at several points up to a year following their journey. They found a number of changes, including an expansion of parts of the brain
Study lead author Dr Larry Kramer, from the University of Texas, said when you’re in microgravity fluid no longer pools towards lower extremities.
‘That movement of fluid toward your head may be one of the mechanisms causing changes we are observing in the eye and intracranial compartment,’ he said.
To find out more, Dr Kramer’s team took MRI scans of 11 astronauts’ brains, including 10 men and one woman.
The scans were taken before and directly after their trips to the International Space Station, and then at several points during the following year.
The results showed that long periods of exposure to weak gravity caused the volume of astronauts’ brain and cerebrospinal fluids to expand.
‘What we identified that no one has really identified before is that there is a significant increase of volume in the brain’s white matter from preflight to postflight.
‘White matter expansion in fact is responsible for the largest increase in combined brain and cerebrospinal fluid volumes postflight,’ said Kramer.
MRI also showed alterations to the pituitary gland, a pea-sized ‘master gland’ at the base of the skull that governs vital bodily functions from growth to temperature.
Dr Kramer added: ‘We found that the pituitary gland loses height and is smaller postflight than it was preflight.
‘In addition, the dome of the pituitary gland is predominantly convex in astronauts without prior exposure to microgravity but showed evidence of flattening or concavity postflight.
‘This type of deformation is consistent with exposure to elevated intracranial pressures,’ said Kramer.
The researchers also observed that cerebrospinal fluids flowed through the brain faster than before the space flight.
They linked the result to hydrocephalus, a condition also affecting earth dwellers in which the ventricles in the brain are abnormally enlarged.
The names of astronauts involved in the study haven’t been revealed and it isn’t clear whether it included Scott Kelly – pictured. Mission Commander Kelly held the record for the longest stay on the ISS
So far hydrocephalus’ symptoms, which include a decline in brain function, have not been observed in astronauts.
The researchers are now studying ways to counter the impact of microgravity.
One option they are probing is artificial gravity, which they could create using a large centrifuge that can spin people in either a sitting or prone position.
They are also investigating applying negative pressure to the lower extremities to counteract the headward flow of fluid in space.
Dr Kramer hopes the research could be applied to non-astronauts to better understand the way the body changes under different conditions.
‘If we can better understand the mechanisms that cause ventricles to enlarge in astronauts and develop suitable countermeasures,’ he said.
‘Then maybe some of these discoveries could benefit patients with normal pressure hydrocephalus and other related conditions.’
Researchers are studying ways to counter the effects of microgravity – something that will be needed before humans make the nine month or more journey to Mars.
One option being considered to counter the impact of microgravity on the human body is the creation of artificial gravity using a large centrifuge to spin people.
They are also looking at using negative pressure on the lower limbs to counteract the shift of blood to the brain.
The study was published in the journal Radiology.