Long-duration spaceflight alters the fluid-filled spaces along veins and arteries in the brain, according to new research from Oregon Health & Science University and scientists across the country.
“These findings have important implications as we continue space exploration,” said the lead author. Juan Piantino, MD, Assistant Professor of Pediatrics (Neurology) at OHSU School of Medicine. “It also forces you to think about some fundamental fundamental questions in science and how life evolved here on Earth.”
The research involved imaging the brains of 15 astronauts before and after long periods of service on the International Space Station.
The researchers used magnetic resonance imaging to measure the perivascular space – or the space around blood vessels – in the astronauts’ brains before they launched and again immediately after they returned. They also repeated MRI measurements one, three and six months after their return. The astronauts’ images were compared to those taken from the same perivascular space in the brains of 16 Earth-bound control subjects.
Comparing before and after images, they found increased perivascular spaces in the brains of astronauts for the first time, but no difference between astronauts who had previously served on the space station orbiting Earth.
“Experienced astronauts may have reached a kind of homeostasis,” Piantino said.
In any case, the scientists found no problems with balance or visual memory that could suggest neurological deficits in the astronauts, despite the differences measured in the perivascular spaces of their brains.
By comparing a large group of anonymized astronauts, the study is among the first to comparatively assess an important aspect of brain health in space.
brains in space
Human physiology is based on the fact that life has evolved over millions of years while tethered to Earth’s gravitational pull. Unbound by the forces of gravity, the normal flow of cerebrospinal fluid in the brain is altered in space.
“We’ve all adapted to use gravity to our advantage,” Piantino said. “Nature didn’t put our brains in our feet, it put them high. Once you remove gravity from the equation, what does that do to human physiology? »
The researchers set out to find out by measuring the perivascular spaces, where cerebrospinal fluid circulates in the brain.
These spaces are part of a natural brain cleansing system that occurs during sleep. Known as the glymphatic system, this brain-wide network removes metabolic proteins that would otherwise accumulate in the brain. Scientists say this system seems to work best during deep sleep.
The perivascular spaces measured in the brain constitute the underlying “hardware” of the glymphatic system. Enlargement of these spaces occurs with aging and has also been linked to the development of dementia.
The researchers used a technique developed in the co-author’s lab Lisa C. Silvert, MD, MCRprofessor of neurology at the OHSU School of Medicine, to measure changes in these perivascular spaces through MRI scans.
Piantino said the study could be useful in helping to diagnose and treat Earth-bound disorders involving the cerebrospinal fluid, such as hydrocephalus.
“These findings not only help understand the fundamental changes that occur during spaceflight, but also for people on Earth who suffer from diseases that affect cerebrospinal fluid circulation,” Piantino said.
In addition to Piantino and Silbert, co-authors included first authors Kathleen E. Hupfeld and Sutton B. Richmond from the University of Florida; Heather R. McGregor and Rachel D. Seidler from the University of Florida; Daniel L. Schwartz and Madison N. Luther from OHSU; Nichole E. Beltran, Igor S. Kofman, Yiri E. De Dios and Ajitkumar P. Mulavara from PBR in Houston; Roy F. Riascos the University of Texas Health Sciences Center; Scott J. Wood and Jacob J. Bloomberg from NASA; and Jeffrey J. Iliff from the University of Washington School of Medicine and the VA Puget Sound Health Care System.
The research was supported by the National Aeronautics and Space Administration, grant NNX11AR02G; the National Institute for Space Biomedical Research, NCC 9-58 award; the National Science Foundation Graduate Research Fellowship, grants DGE-1315138 and DGE-1842473; the National Institute of Neurological Disorders and Stroke, grant T32-NS082128; National Institute on Aging Fellowship 1F99AG068440 and Fellowships R01AG056712, P30AG008017, and P30AG066518; and the National Heart Lung and Blood Institute, grant K23HL150217-01.
The co-authors also thank all the astronauts who gave their time, without whom this project would not have been possible.