Abstract
Introduction: Whilst it is generally accepted that cognition is impaired under hypoxia, the large disparity in methodologies employed in the existing literature has made drawing definitive conclusions problematic. Moreover, it is still unclear i) at what level of hypoxia cognitive impairment begins, ii) the cognitive domain(s) that is/are affected, and iii) the mechanism(s) responsible for these deteriorations. Therefore, the aim of this study was to assess a variety of central executive and non-executive tasks and the concurrent changes in physiology over a range of simulated altitudes. It was hypothesised that there would be a linear relationship between fraction of inspired oxygen (FiO2) and cognitive performance, with non-executive tasks displaying greater resilience to hypoxia than executive tasks.
Methods: A within participant, balanced, crossover design was employed. Twelve healthy male participants (mean [SD] 22[4] yrs, 75[9] kg, FEV1/FVC ratio 85[5] %) completed a 4-task cognitive testing battery designed to examine the cognitive domains of inhibition, selective attention (Eriksen Flanker), working memory (N-back) and simple and choice reaction time (Deary-Liewald). The battery was completed before and after 60 minutes of exposure to each of the following FiO2 values: 0.21 (sea level), 0.17 (~1600 m), 0.15 (~2800 m), and 0.12 (~4300 m). Peripheral oxygen saturation (SpO2), cerebral oxygenation (measured via near-infrared spectroscopy), minute ventilation, mood disturbance and acute mountain sickness were also recorded.
Results: As designed, SpO2 decreased as altitude increased (FiO2 0.21: 96[0] %, FiO2 0.17: 94[2] %, FiO2 0.145: 89[2] %, FiO2 12: 81[4] %, p < 0.05). Despite a significant reduction from baseline in cerebral oxygenation (-5.72[2.9] %, p < 0.001) and an increase in mood disturbance (p = 0.049) following exposure to FiO2 0.12, cognitive performance was maintained for both central executive and non-executive tasks across all conditions (all p > 0.05).
Conclusions: These results suggest that a simulated altitude of up to ~4300 m and the resultant physiological changes do not provide a sufficient stimulus to impair cognitive function at rest. These findings may have implications for those visiting and working at altitude.
Methods: A within participant, balanced, crossover design was employed. Twelve healthy male participants (mean [SD] 22[4] yrs, 75[9] kg, FEV1/FVC ratio 85[5] %) completed a 4-task cognitive testing battery designed to examine the cognitive domains of inhibition, selective attention (Eriksen Flanker), working memory (N-back) and simple and choice reaction time (Deary-Liewald). The battery was completed before and after 60 minutes of exposure to each of the following FiO2 values: 0.21 (sea level), 0.17 (~1600 m), 0.15 (~2800 m), and 0.12 (~4300 m). Peripheral oxygen saturation (SpO2), cerebral oxygenation (measured via near-infrared spectroscopy), minute ventilation, mood disturbance and acute mountain sickness were also recorded.
Results: As designed, SpO2 decreased as altitude increased (FiO2 0.21: 96[0] %, FiO2 0.17: 94[2] %, FiO2 0.145: 89[2] %, FiO2 12: 81[4] %, p < 0.05). Despite a significant reduction from baseline in cerebral oxygenation (-5.72[2.9] %, p < 0.001) and an increase in mood disturbance (p = 0.049) following exposure to FiO2 0.12, cognitive performance was maintained for both central executive and non-executive tasks across all conditions (all p > 0.05).
Conclusions: These results suggest that a simulated altitude of up to ~4300 m and the resultant physiological changes do not provide a sufficient stimulus to impair cognitive function at rest. These findings may have implications for those visiting and working at altitude.
| Original language | English |
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| Pages | 53 |
| Number of pages | 1 |
| Publication status | Published - Jul 2018 |
| Event | 3rd International Conference on Physical Employment Standards - Portsmouth, United Kingdom Duration: 17 Jul 2018 → 19 Jul 2018 |
Conference
| Conference | 3rd International Conference on Physical Employment Standards |
|---|---|
| Abbreviated title | PES 2018 |
| Country/Territory | United Kingdom |
| City | Portsmouth |
| Period | 17/07/18 → 19/07/18 |