The human body is not designed for space. Space travel can cause bone decalcification, muscle atrophy, fluctuating blood pressure, irregular heart rate, and fluid buildup in the head, resulting in pain, congestion, vision problems, and even kidney stones. While exercise and hydration help mitigate some issues, long space missions (six to twelve months) take a significant toll, particularly on the brain. The effects of long-duration spaceflight on cognitive function are less understood but equally concerning.
A new study published in Frontiers in Physiology offers reassuring findings. While space travel can impact the brain, astronauts generally maintain their cognitive and behavioral abilities, adapting effectively, albeit sometimes slowly, to the space environment.
Led by neuropsychologist Sheena Dev of NASA’s behavioral health and performance laboratory, this extensive research involved 25 astronauts who underwent ten cognitive tests before, during, and after six-month stays on the International Space Station. Baseline tests were conducted 90 days pre-flight, followed by tests during the first and last months in space, and ten and thirty days post-flight.
Several factors were considered as potential contributors to cognitive decline, including isolation, confinement, distance from home, overwork, disrupted circadian rhythms, and sleep deprivation.
“Even on Earth, processing speed, working memory, and attention can temporarily decline under stress,” Dev stated. “A busy day with little sleep can impair attention and task completion.”
Microgravity and cosmic radiation were also considered potential contributors, though the study didn’t speculate on the mechanisms, acknowledging the possibility of brain and central nervous system damage.
Before each cognitive test, astronauts reported their sleep hours and alertness level (0-10). This helped determine if performance deficits stemmed from immediate factors or longer-term stressors. Each test assessed a specific cognitive skill.
One test, the Visual Object Learning Task, involved memorizing and identifying 3D shapes. The Emotion Recognition Task required identifying emotions in photographs. The Matrix Reasoning Task tested pattern recognition, and the Balloon Analog Risk Task measured risk tolerance in a simulated game.
Encouragingly, astronaut cognitive abilities didn’t significantly decline across the pre-flight, in-orbit, and post-flight periods. “Astronaut performance was stable throughout the flight,” Dev reported, “with no evidence of significant impairment or neurodegenerative decline.”
However, space travel did impact performance. Processing speed, working memory, and attention were slower in space but accuracy remained consistent. Recovery varied; attention returned to normal earlier than processing speed. Performance on the emotion recognition task improved during the mission. Risk tolerance decreased, possibly reflecting cautiousness in a hazardous environment. Matrix Reasoning performance improved steadily.
“Even with observed declines, astronauts compensated and effectively completed tasks,” Dev noted.
While six months is a fraction of future mission durations (a Mars trip alone is at least eight months), the findings suggest humans possess the cognitive and emotional resilience for extended space travel.
As Dev concluded, “Living and working in space wasn’t associated with widespread cognitive impairment suggestive of significant brain damage.”
