Cosmic radiation exposure and persistent cognitive dysfunction

Abstract

The Mars mission will result in an inevitable exposure to cosmic radiation that has been shown to cause cognitive impairments in rodent models, and possibly in astronauts engaged in deep space travel. Of particular concern is the potential for cosmic radiation exposure to compromise critical decision making during normal operations or under emergency conditions in deep space. Rodents exposed to cosmic radiation exhibit persistent hippocampal and cortical based performance decrements using six independent behavioral tasks administered between separate cohorts 12 and 24 weeks after irradiation. Radiation-induced impairments in spatial, episodic and recognition memory were temporally coincident with deficits in executive function and reduced rates of fear extinction and elevated anxiety. Irradiation caused significant reductions in dendritic complexity, spine density and altered spine morphology along medial prefrontal cortical neurons known to mediate neurotransmission interrogated by our behavioral tasks. Cosmic radiation also disrupted synaptic integrity and increased neuroinflammation that persisted more than 6 months after exposure. Behavioral deficits for individual animals correlated significantly with reduced spine density and increased synaptic puncta, providing quantitative measures of risk for developing cognitive impairment. Our data provide additional evidence that deep space travel poses a real and unique threat to the integrity of neural circuits in the brain.

Whole-Body Exposure to28Si-Radiation Dose-Dependently Disrupts Dentate Gyrus Neurogenesis and Proliferation in the Short Term and New Neuron Survival and Contextual Fear Conditioning in the Long Term

“…(28)], as lower-energy particles can be more damaging than higher-energy particles (9). Of course, age at time of exposure plays a role in the behavioral effects of 28 Si radiation, as has also been shown with other ions (87, 89). For example, mice exposed to 28 Si radiation at 6–7 months old were resistant to radiation-induced deficits in CFC at doses <1.6 Gy (90).…”

“…These data raise several discussion points. First, while these data suggest a 28 Si radiation dose-dependent effect on memory and/or anxiety, a HZE-induced effect has also been observed at low doses with titanium-48 [ 48 Ti (0.3 Gy)] but not 56 Fe (0.1, 0.5 and 2 Gy) (87, 88). Importantly, these data indicate the utility of employing the cued FC as well as CFC testing, because without the cued FC we might have concluded that 1-Gyirradiated mice had “normal” hippocampal-dependent function, while only the 0.2-Gy-irradiated mice had worse hippocampal function.…”

The Role of the Nuclear Factor κB Pathway in the Cellular Response to Low and High Linear Energy Transfer Radiation

“…Indeed, Parihar et al found increased numbers of activated microglia in the perirhinal cortex of rodents exposed to low doses of helium and other space-relevant accelerated ions, indicating neuroinflammation [86,87]. …”

The effect of simulated space radiation on the N‐glycosylation of human immunoglobulin G1

“…Parihar et al. simulated high atomic number and high energy particle irradiation for deep space missions (1+ years), which take up to 1% of the GCR spectra and apparently might cause dementia in rodent models. Fifteen weeks after exposure to 5 cGy of 16 O or 48 Ti particles, dendritic length and branching was significantly reduced in the central nervous systems of mice .…”