Caudwell Xtreme Everest: A prospective study of the effects of environmental hypoxia on cognitive functioning di Griva, K, Stygall, J, Wilson, M, Martin, D, Levett, D, Mitchell, K, Mythen, M, Montgomery, H, Grocott, M, Aref-Adib, G, Edsell, M, Plant, T, Imray, C, Cooke, D, Harrington, J, Khosravi, M, Newman, S, Basnyat, B, Caudwell Xtreme Everest Research Group