Space Travel Damages the Brain (This Finding Could Lead to New Answers for Dementia)

What if the key to understanding Alzheimer’s disease wasn’t found in a lab on Earth—but in the brains of astronauts floating hundreds of miles above it? As scientists study what happens to the human body during long missions in space, they’re uncovering something unexpected—and potentially groundbreaking. The same forces that reshape the brain in microgravity may also reveal early clues about cognitive decline, opening the door to entirely new ways of understanding—and possibly treating—dementia.

Key Takeaways

• Microgravity causes measurable brain changes, including swelling and increased cerebrospinal fluid

• White matter expansion—linked to Alzheimer’s risk—was observed in astronauts

• Space research may help uncover new pathways for treating cognitive decline on Earth

Could Space Travel Unlock the Secret to Dementia?

Up until a few years ago, few men or women had remained in space long enough to know how the body would respond to a journey of nine months or longer. But research has identified some important indicators. These show, at least as far as the brain is concerned, space travel is not all sweetness and light. In fact, the changes that occur within the body, especially the brain, could one day help researchers understand the development of dementia and lead to new treatments.

Microgravity is Like Standing on Your Hands

Astronauts in space experience microgravity, or weightlessness, since they’re away from the gravitational pull people experience living on Earth. The health effects of living in microgravity seem to be all bad news, as the research shows it weakens bones, lowers muscle mass, reduces weight, and causes fatigue.  

Fortunately, these are all short-term effects and can be reversed when astronauts return to Earth. However, there are also long-term health problems. One is that astronauts are at a greater risk of heart disease. Another problem relates to changes in vision. Apparently, spending extended periods in space swells the optic nerve and causes retinal bleeding and structural changes in the eye. These visual changes can persist for years after astronauts return. 

Dr. Larry Kramer from the University of Texas has a hypothesis on why this happens: "When you're in microgravity, fluid such as your venous blood no longer pools toward your lower extremities but redistributes headward. "That movement of fluid toward your head may be one of the mechanisms causing changes we are observing in the eye and intracranial compartment. "It's not something that we normally experience on Earth unless you're sort of standing on your hands." Then there are the changes microgravity causes within the brain.

Microgravity Causes the Brain to Swell

Dr. Kramer and his research team scanned the brains of 11 astronauts at different points in time: before space travel, the day after they returned, and then at regular intervals up to a year later. What they could see on the scans was swelling of the astronauts' brains. 

The cerebrospinal fluid (CSF), which flows in and around the hollow spaces of the brain and spinal cord, also increased in volume. Even a year after returning to Earth, both remained expanded. These effects could potentially elevate intracranial pressure – pressure inside the skull. "What we identified, that no one has really identified before, is that there is a significant increase in volume in the brain's white matter from pre-flight to post-flight,” reports Dr. Kramer. 

“White matter expansion, in fact, is responsible for the largest increase in combined brain and cerebrospinal fluid volumes post-flight." It will be interesting to see if any of these astronauts develop cognitive decline or dementia as they age. That’s because much of the latest research points to white matter degeneration as an early marker of Alzheimer’s disease.  

Researchers from Columbia University reported that Alzheimer’s disease impacts the brain’s white matter before impacting grey matter with the development of amyloid plaques and neurofibrillary tangles. What’s more, white matter changes have also been associated with a decline in motor function and fine motor coordination.

The Pituitary Gland Shrinks

These studies also showed that the pituitary gland at the base of the skull, which governs the function of many other hormone-secreting glands, had flattened and shrunk. This is consistent with elevated intracranial pressure. The spaces in the brain that carry CSF, called the lateral ventricles, also expanded, and the fluid flowed faster. Enlarged ventricles are seen in normal pressure hydrocephalus (NPH), a condition in which patients develop a shuffling gait, forgetfulness, and confusion. It's treatable, but is commonly misdiagnosed as Alzheimer's. 

Dr. Kramer said that focusing research on why astronauts’ ventricles enlarge in microgravity could improve understanding of the mechanisms involved in NPH. Perhaps one day, even Alzheimer’s.  

Meanwhile, scientists now need to find ways to mitigate the intracranial effects of microgravity. One option is to spin the astronauts in a chair for part of the day to move the blood back towards the legs. Another is a specialized suit for the lower half of the body to counteract fluid that heads upward.

Summary

New research on astronauts exposed to long-term microgravity reveals significant changes in brain structure, including swelling, increased cerebrospinal fluid, and expansion of white matter. These changes may elevate intracranial pressure and mimic early markers of neurological conditions like Alzheimer’s disease and normal pressure hydrocephalus. Scientists believe studying these effects could provide valuable insights into how cognitive decline develops—and potentially lead to new treatment strategies on Earth. 

Frequently Asked Questions

How does space travel affect the brain?

Microgravity can cause brain swelling, increased cerebrospinal fluid, and structural changes that may persist after returning to Earth.

What is white matter and why does it matter?

White matter connects brain regions and is crucial for communication; changes in it are linked to cognitive decline and Alzheimer’s.

Can space research help treat Alzheimer’s?

Yes, studying brain changes in astronauts may reveal early mechanisms of neurodegenerative diseases.

What is intracranial pressure?

It’s the pressure inside the skull, which can increase due to fluid buildup and affect brain function.

Are these brain changes permanent?

Some effects may persist for months or longer, but research is ongoing to determine long-term outcomes.