Effects of Age on the Disruption of Cognitive Performance by Exposure to Space Radiation

Abstract

Exposure to low doses of heavy particles and protons, which will be encountered during long-term exploratory class missions to other planets, can cause deficits in cognitive performance. These deficits are similar to those observed in aged animals. The long-term effects of such exposures and their relationship to the short-term effects and to aging remain to be established. Two-month old rats were exposed to a variety of heavy particles and protons. Recognition memory was tested at two time points following irradiation. The results showed that exposure to doses of radiation that did not disrupt cognitive performance in the younger animals, disrupted performance when the subjects were re-tested at an older age. These results indicate that there is an interaction between the age of the organism and the effects of exposure to space radiation on cognitive performance, such that exposure to doses of heavy particles or protons that may not produce an initial effect on cognitive performance may produce an effect as the organism ages. Because of the interaction between exposure to the types of radiation encountered in space and age, it is possible that participating in exploratory class missions may have consequences for the quality of life after the conclusion of the mission.

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).…”

“…However, it is important that future work examine whether older mice, which are closer in age to that of astronauts, are similarly influenced by 28 Si (89). Indeed, as mentioned above, previous work with another mouse strain has revealed that these animals, which were 6–7 months old at time of exposure, were unimpaired in CFC at low doses of 28 Si and only showed impairment after 1.6 Gy 28 Si irradiation (90).…”

16 Oxygen irradiation enhances cued fear memory in B6D2F1 mice

“…Published by Elsevier Ltd. All rights reserved. later for doses between 0.5 and 5 cGy, but not at 0.1 or 10 cGy (Rabin et al, 2014). 16 O ion irradiation (1000 MeV/amu) at two months of age impaired novel object recognition four months later at doses of 5 and 10 cGy, but not at 25 cGy (Rabin et al, 2014).…”

“…To date, the most comprehensive set of data regarding the behavioral effects of space flight radiation have come from studies in rats, including effects from low to moderate doses of various ions, including 16 O ions (Poulose et al, 2011;Rabin et al, 2011;Rabin et al, 2014). In rats, 16 O ion exposure (600 MeV/amu) at two months of age impaired novel object recognition two months http://dx.doi.org/10.1016/j.lssr.2015.10.004 2214-5524/© 2015 The Committee on Space Research (COSPAR).…”

Multi-domain cognitive assessment of male mice reveals whole body exposure to space radiation is not detrimental to high-level cognition and actually improves pattern separation

“…Third, breadth of testing matters. Preclinical studies on space radiation typically assess one or two cognitive domains 4 (24,(44)(45)(46)(47) . In contrast, astronauts repeatedly undergo test batteries -often on a touchscreen platform -to assess integrity of many cognitive domains over time (39,48,49) .…”