Effect of acute hypoxia on cognition: A systematic review and meta-regression analysis. (March 2017) - McMorris, Terry
Highlights: Hypoxia has a negative effect on cognition. Effect on central executive and non-executive tasks did not differ significantly. Low (<60 mmHg) arterial partial pressure of oxygen predicts poor cognition. Hypobaric versus normobaric hypoxic conditions was not a significant moderator. Abstract: A systematic meta-regression analysis of the effects of acute hypoxia on the performance of central executive and non-executive tasks, and the effects of the moderating variables, arterial partial pressure of oxygen (PaO2 ) and hypobaric versus normobaric hypoxia, was undertaken. Studies were included if they were performed on healthy humans; within-subject design was used; data were reported giving the PaO2 or that allowed the PaO2 to be estimated (e.g. arterial oxygen saturation and/or altitude); and the duration of being in a hypoxic state prior to cognitive testing was ≤6 days. Twenty-two experiments met the criteria for inclusion and demonstrated a moderate, negative mean effect size (g = −0.49, 95% CI −0.64 to −0.34, p < 0.001). There were no significant differences between central executive and non-executive, perception/attention and short-term memory, tasks. Low (35–60 mmHg) PaO2 was the key predictor of cognitive performance (R 2 = 0.45, p < 0.001) and this was independent of whether the exposure was in hypobaric hypoxic or normobaric hypoxic conditions.