title: Acute hypoxic gas breathing severely impairs cognition and task learning in humans.
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.
authors: Exercise Neurometabolism Laboratory, Centre for Brain Research, The University of Auckland, New Zealand.
authors: Clare E
authors: CE
authors: Turner
authors: School of Psychology, Centre for Brain Research, The University of Auckland, New Zealand.
authors: Suzanne L
authors: SL
authors: Barker-Collo
authors: Exercise Neurometabolism Laboratory, Centre for Brain Research, The University of Auckland, New Zealand.
authors: Charlotte J W
authors: CJ
authors: Connell
authors: Exercise Neurometabolism Laboratory, Centre for Brain Research, The University of Auckland, New Zealand. Electronic address: n.gant@auckland.ac.nz.
authors: Nicholas
authors: N
authors: Gant
mesh_terms: D000208:Acute Disease; D000328:Adult; D001288:Attention; D001794:Blood Pressure / Q000502:physiology; D003071:Cognition; D003072:Cognition Disorders / Q000209:etiology* / Q000503:physiopathology; D056344:Executive Function; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology / Q000523:psychology*; D007858:Learning; D008297:Male; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D011214:Practice, Psychological; D011597:Psychomotor Performance; D011930:Reaction Time; D016037:Single-Blind Method; D013067:Speech Perception; D014796:Visual Perception; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: High-altitude; Hypoxic emergencies; Learning effects; Mild traumatic brain injury; Neurocognition; Oxygen deprivation