University of Alabama at Birmingham Birmingham, Alabama, United States
Objectives: Spaceflight causes multisystem adaptations – muscle atrophy, bone loss, orthostatic intolerance, decreased endurance, and cognitive impairment – that persist after return to Earth and require rehabilitation. Longer-duration missions are expected to exacerbate these effects with long-term sequelae. This narrative review synthesizes musculoskeletal, cardiovascular, performance, and neurocognitive changes, emphasizing recovery patterns and long-term health consequences.
Design: A PubMed and open-access NASA resources search was conducted to identify literature on neurocognitive and physiological adaptations to long-duration spaceflight with attention to long-term health and recovery.
Results: Astronauts lose 20% muscle volume, 24% strength, and 9% paraspinal muscle density with fatty infiltration persisting 2-4 years. Bone mineral density decreases 3.5% with 9% trabecular loss. 50% sustain musculoskeletal injuries within 1 year, 33% report chronic pain, and disc herniation is 4.3-fold higher, including one inflight cervical case. Cardiovascular adaptations include 30% increased arterial stiffness, 12 mL left atrial enlargement, 15% blood volume reduction, and 48% with postflight anemia and 30% increased hemolysis and progressive hemoglobin decline (-0.73 g/dL women, -0.36 g/dL men per year in space). Cardiovascular disease incidence rises to 1.90 events per 1000 person-years. Functionally, 17% may lose ≥20% performance, task times increase 48% on postflight day-1 with 95% recovery by day-15. Neurocognitive changes include mild impairments in memory, processing speed, and attention, with no headaches postflight. Most systems recover within 2 months, though paraspinal atrophy, bone loss, and anemia persist beyond 1-year postflight.
Conclusions: Long-duration spaceflight induces multisystem changes resembling accelerated aging. Most impairments recover within 2 months, though paraspinal atrophy, bone loss, hemolysis, and lifelong hemoglobin decline persist. The high prevalence of musculoskeletal injury, cardiovascular disease, and neurocognitive deficits underscores the need for improved countermeasures and rehabilitation, particularly for exploration-class missions and commercial astronauts with comorbidities.
