The effects of spaceflight on the human mind is a somewhat futuristic question but one that’s become increasingly relevant. As we accelerate humanity’s focus on space exploration, we’re expanding our capacity to travel further and more frequently into the expanse. But as we continue to explore, we’re also extensively exposing the human body to the extreme conditions of space.

When humans leave Earth’s atmosphere, they’re subjected to hostile, unfamiliar space conditions. Increased radiation levels, changed fields of gravity, fluctuating levels of oxygen, changes in their own bodies and various psychological stressors are just a few challenges space travelers face from the outset. Extended exposure to all of these elements has an even more significant effect as time wears on, affecting the central nervous system and cognitive and behavioral health.

Physical Brain Changes in Space

The brain undergoes both functional and structural changes in space. According to a study published by the National Center for Biotechnology Information, the social isolation, immobilization, and altered gravity that go hand-in-hand with space travel can have profound effects on brain plasticity, particularly that associated with spatial navigation.

Neuroimaging of space travels after their earthly return revealed physical changes such as an upward shift of the brain, ventricular volume reduction, redistribution of cerebrospinal fluid and even decreases in gray matter volume. Structural changes to the brain after space flight are directly related to radiation, increased exposure to CO2, weightlessness and circadian disruption.

Cosmic radiation appears to cause significant damage to the hippocampus, associated with a wide range of adverse behavioral conditions, such as taste aversion, memory formation, spatial learning and disruption to reversal learning and reinforcement behavior.

Because of the limited capacity of air recycling systems aboard spacecraft, exposure to increased carbon dioxide levels can lead to hypoxia, acutely affecting cognitive performance. Gravity changes have great vestibular influence, affecting the ability to respond to physical tilt and ​​spatial learning and memory formation.

The lack of a regular 24-hour dark and light cycle significantly impacts a space traveler’s circadian rhythm, which can result in a severe disruption of a normal sleep cycle. This disruption, especially when severe, is associated with neurodegenerative and neuropsychiatric conditions and hippocampal atrophy. This effect also leads to the psychological elements at play during space travel, increasing stress and reducing cognitive ability.

Intangible Effects on the Brain

Other effects space travel has on the brain, most notably, include cognitive, behavioral or psychological changes. Decrements in manual dexterity, motion perception and virtual navigation (like that needed to drive a car) were notably reduced upon travelers’ return to Earth.

Although many of these symptoms tend to resolve over months, there is some concern for the immediate onset of these effects and how they might impede during missions that involve regular fluctuation and transitions between different levels of gravity. This questions the possible impact such changes could have on inflight tasks and missions, both in their safety and effectiveness.

Isolation, confinement, and sensory deprivation are the most significant factors that contribute to psychological or emotional distress aboard a space flight. These are all severe stressors that may lead to interpersonal tension and conflict, depression and anxiety, job-related errors, and even increased mortality.

Many countermeasures have already been implemented to help mitigate both the physiological and psychological effects of space travel for astronauts. Those measures include enhanced habitat design with better lighting and social spaces, means to exercise, workload variations to include more meaningful work, carefully constructed sleep schedules, relaxation techniques, plants, and entertainment such as video gaming and virtual reality. They also have strategies for helping crew members maintain group cohesion, psychological counseling, and family support.

Why Further Studies are Needed

It’s still reasonably unknown what adverse effects these brain changes might have on cognitive or behavioral function in the long term, one of the reasons researchers are feverishly pursuing further studies in this area. Exploratory missions planned for NASA’s future are expected to last considerably longer than current or past missions, with projects like a mission to Mars to comprise about 1100 days in total. This extended time in space flight will expose crew members to unprecedented risks, increasing their chances to develop adverse cognitive or behavioral fluctuations, a critical risk factor so long as their effects and prevention remain largely unknown.