Neurocognitive Vulnerability to Hypoxia Across Cognitive Domains: A Systematic Review and Meta-Analysis

Hypoxia challenges brain function because of the high metabolic demands required to sustain cognition, yet its effects across cognitive abilities remain incompletely understood. We conducted a systematic review and meta-analysis of 46 studies comprising 152 effect sizes to quantify the impact of hypoxia on human cognitive performance and identify factors that moderate these effects. Overall, hypoxia was associated with a significant reduction in cognitive performance, Hedges g = -0.42, 95% CI [-0.53, -0.31]. Domain-specific analyses indicated the largest pooled impairments for processing speed (Gs; g = -0.62, 95% CI [-0.98, -0.26]), long-term storage and retrieval (Glr; g = -0.60, 95% CI [-1.03, -0.17]), and psychomotor speed (Gps; g = -0.50, 95% CI [-0.96, -0.05]), while smaller impairments for fluid reasoning (Gf; g = -0.36, 95% CI [-.55, -0.16]), short-term memory (Gsm; g = -0.36, 95% CI [-.56, -0.15]), and decision speed/reaction time (Gt; g = -0.33, 95% CI [-.55, -0.12]). Visual processing (Gv) was not significantly affected. Greater hypoxic severity, reflected by lower fraction of inspired oxygen (FiO2), was associated with larger cognitive impairments. In contrast, exposure duration, participant age, and hypoxic type were not consistently associated with cognitive effect size. Substantial heterogeneity remained across analyses, indicating considerable variability in cognitive responses to hypoxia. These findings demonstrate that hypoxia is associated with broad but heterogeneous reductions in cognitive performance, with processing speed, long-term storage and retrieval, and psychomotor speed showing the largest pooled effects. This synthesis provides a framework for investigating the neurophysiological mechanisms and individual factors underlying variability in cognitive responses to hypoxia.