Effects of -12° Head-Down Tilt with and without Elevated Levels of CO2 on Cognitive Performance: the SPACECOT study

Microgravity and elevated levels of CO2 are two common environmental stressors in spaceflight that may affect cognitive performance of astronauts. In this randomized, double-blind, cross-over trial (SPACECOT), N=6 healthy males (mean{plus minus}SD age: 41{plus minus}5yr) were exposed to 0.04% (ambient air) and 0.5% CO2 concentrations during 26.5-hour periods of -12{degree sign} head-down tilt (HDT) bed rest with a one-week washout period between exposures. Subjects performed the 10 tests of the Cognition Test Battery before and on average 0.1, 5.2, and 21.0 hours after the initiation of HDT bed rest. HDT in ambient air induced a change in response strategy, with increased response speed (+0.19 SD; p=0.0254) at the expense of accuracy (-0.19 SD; 0.2867), resulting in comparable cognitive efficiency. The observed effects were small and statistically significant for cognitive speed only. However, even small declines in accuracy can potentially cause errors during mission-critical tasks in spaceflight. Unexpe...