Abstract:
Impairments in neural function are common when oxygen supply to the brain is reduced. This study examined neurocognitive processes that are vulnerable to oxygen deprivation. We induced moderate-to-severe hypoxia in healthy adults, thereby inducing impairments caused by low brain oxygen availability. 22 healthy adults participated in this matched-pairs study with a single-blind, randomised design. Baseline neurocognitive function was examined during a familiarisation trial and participants were assigned to hypoxia (10% O2) or sham (21% O2) groups. Neurocognitive performance was assessed via computerised test battery after 50 min of breathing a gas mixture that reduced arterial oxygen saturation by 20% (p < 0.01). Hypoxia severely reduced performance across all neurocognitive domain scores; with significant drops in neurocognitive index (− 20%), composite memory (− 30%), verbal memory (− 34%), visual memory (− 23%), processing speed (− 36%), executive function (− 20%), psychomotor speed (− 24%), reaction time (− 10%), complex attention (− 19%) and cognitive flexibility (− 18%; all p < 0.05). Practice effects were blocked by hypoxia but occurred in sham for information processing speed (+ 30%), executive function (+ 14%), psychomotor speed (+ 18%), reaction time (+ 5%), cognitive flexibility (+ 14%), and overall cognitive functioning (+ 9%; all p < 0.05). Neuropsychological performance decrements caused by acute experimental hypoxia are comparable to cognitive domains impaired with high altitude exposure and mild traumatic brain injury.