Persistent cognitive impairment and bone health following helium ion exposure: implications for space travel

This study investigated the long-term neurobehavioral and physiological impacts of low-dose helium (⁴He) ion exposure-a key component of galactic cosmic radiation-on male Long Evans rats. After training on the rodent psychomotor vigilance test (rPVT), the rats were irradiated and monitored for up to 180 days to assess sustained attention and social recognition memory, alongside blood and bone analyses. Results showed that acute exposure to 25 cGy ⁴He ions significantly impaired sustained attention, increasing attention lapses and reaction times, and decreasing task accuracy. Exposure to 5 cGy only affected specific reaction time measures. However, both doses caused persistent social recognition memory impairments for 180 days. While overall bone mechanics remained largely unchanged, specific skeletal strength parameters were affected. Importantly, significant correlations emerged between behavioral performance and circulating cytokines (IL-1beta), undercarboxylated osteocalcin (ucOC), and bone biomechanics. This suggests these blood and bone targets could serve as diagnostic biomarkers for radiation-induced neurobehavioral deficits. The sustained and progressive nature of the neurobehavioral deficits observed underscores the critical need for effective countermeasures to protect astronaut health and performance during exploration-class missions.