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NPJ Microgravity. 2019 Jun 19;5:17. doi: 10.1038/s41526-019-0071-6. eCollection 2019.

Effects of acute exposures to carbon dioxide on decision making and cognition in astronaut-like subjects.

Author information

1Biomedical Research and Environmental Sciences, KBRwyle, Houston, TX 77058 USA.
2Biomedical Research and Environmental Sciences Division, Human Health and Performance Directorate, NASA Lyndon B. Johnson Space Center, Houston, TX 77058 USA.
3Unit for Experimental Psychiatry, Division of Sleep and Chronobiology, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 USA.
4Brain Behavior Laboratory, Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104 USA.
5Space Medicine Operations Division, Human Health and Performance Directorate, NASA Lyndon B. Johnson Space Center, Houston, TX 77058 USA.
6Department of Psychiatry and Behavioral Science, Upstate Medical University State University of New York, Syracuse, NY 13210 USA.
Contributed equally


Acute exposure to carbon dioxide (CO2) concentrations below those found on the International Space Station are reported to deteriorate complex decision-making. Effective decision-making is critical to human spaceflight, especially during an emergency response. Therefore, effects of acutely elevated CO2 on decision-making competency and various cognitive domains were assessed in astronaut-like subjects by the Strategic Management Simulation (SMS) and Cognition test batteries. The double-blind cross-over study included 22 participants at the Johnson Space Center randomly assigned to one of four groups. Each group was exposed to a different sequence of four concentrations of CO2 (600, 1200, 2500, 5000 ppm). Subjects performed Cognition before entering the chamber, 15 min and 2.5 h after entering the chamber, and 15 min after exiting the chamber. The SMS was administered 30 min after subjects entered the chamber. There were no clear dose-response patterns for performance on either SMS or Cognition. Performance on most SMS measures and aggregate speed, accuracy, and efficiency scores across Cognition tests were lower at 1200 ppm than at baseline (600 ppm); however, at higher CO2 concentrations performance was similar to or exceeded baseline for most measures. These outcomes, which conflict with those of other studies, likely indicate differing characteristics of the various subject populations and differences in the aggregation of unrecognized stressors, in addition to CO2, are responsible for disparate outcomes among studies. Studies with longer exposure durations are needed to verify that cognitive impairment does not develop over time in crew-like subjects.


Psychology; Risk factors

Conflict of interest statement

Competing interestsThe authors declare no competing interests.

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