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Caudwell Xtreme Everest: A prospective study of the effects of environmental hypoxia on cognitive functioning.

Griva, K; Stygall, J; Wilson, MH; Martin, D; Levett, D; Mitchell, K; Mythen, M; Montgomery, HE; Grocott, MP; Aref-Adib, G; et al. Griva, K; Stygall, J; Wilson, MH; Martin, D; Levett, D; Mitchell, K; Mythen, M; Montgomery, HE; Grocott, MP; Aref-Adib, G; Edsell, M; Plant, T; Imray, C; Cooke, D; Harrington, J; Khosravi, M; Newman, SP; Caudwell Xtreme Everest Research Group (2017) Caudwell Xtreme Everest: A prospective study of the effects of environmental hypoxia on cognitive functioning. PLoS One, 12 (3). ISSN 1932-6203 https://doi.org/10.1371/journal.pone.0174277
SGUL Authors: Edsell, Mark

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Abstract

BACKGROUND: The neuropsychological consequences of exposure to environmental hypobaric hypoxia (EHH) remain unclear. We thus investigated them in a large group of healthy volunteers who trekked to Mount Everest base camp (5,300 m). METHODS: A neuropsychological (NP) test battery assessing memory, language, attention, and executive function was administered to 198 participants (age 44.5±13.7 years; 60% male). These were studied at baseline (sea level), 3,500 m (Namche Bazaar), 5,300 m (Everest Base Camp) and on return to 1,300 m (Kathmandu) (attrition rate 23.7%). A comparable control group (n = 25; age 44.5±14.1 years; 60% male) for comparison with trekkers was tested at/or near sea level over an equivalent timeframe so as to account for learning effects associated with repeat testing. The Reliable Change Index (RCI) was used to calculate changes in cognition and neuropsychological function during and after exposure to EHH relative to controls. RESULTS: Overall, attention, verbal ability and executive function declined in those exposed to EHH when the performance of the control group was taken into account (RCI .05 to -.95) with decline persisting at descent. Memory and psychomotor function showed decline at highest ascent only (RCI -.08 to -.56). However, there was inter-individual variability in response: whilst NP performance declined in most, this improved in some trekkers. Cognitive decline was greater amongst older people (r = .42; p < .0001), but was otherwise not consistently associated with socio-demographic, mood, or physiological variables. CONCLUSIONS: After correcting for learning effects, attention, verbal abilities and executive functioning declined with exposure to EHH. There was considerable individual variability in the response of brain function to sustained hypoxia with some participants not showing any effects of hypoxia. This might have implications for those facing sustained hypoxia as a result of any disease.

Item Type: Article
Additional Information: © 2017 Griva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Keywords: General Science & Technology, MD Multidisciplinary
SGUL Research Institute / Research Centre: Academic Structure > Institute of Medical & Biomedical Education (IMBE)
Academic Structure > Institute of Medical & Biomedical Education (IMBE) > Centre for Clinical Education (INMECE )
Journal or Publication Title: PLoS One
Article Number: e0174277
ISSN: 1932-6203
Language: eng
Dates:
DateEvent
27 March 2017Published
5 March 2017Accepted
Publisher License: Creative Commons: Attribution 4.0
PubMed ID: 28346535
Go to PubMed abstract
URI: https://openaccess.sgul.ac.uk/id/eprint/108848
Publisher's version: https://doi.org/10.1371/journal.pone.0174277

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