title: Cognitive performance in high-altitude climbers: a comparative study of saccadic eye movements and neuropsychological tests.
abstract: Impairment of cognitive performance during and after high-altitude climbing has been described in numerous studies and has mostly been attributed to cerebral hypoxia and resulting functional and structural cerebral alterations. To investigate the hypothesis that high-altitude climbing leads to cognitive impairment, we used of neuropsychological tests and measurements of eye movement (EM) performance during different stimulus conditions. The study was conducted in 32 mountaineers participating in an expedition to Muztagh Ata (7,546 m). Neuropsychological tests comprised figural fluency, line bisection, letter and number cancellation, and a modified pegboard task. Saccadic performance was evaluated under three stimulus conditions with varying degrees of cortical involvement: visually guided pro- and anti-saccades, and visuo-visual interaction. Typical saccade parameters (latency, mean sequence, post-saccadic stability, and error rate) were computed off-line. Measurements were taken at a baseline level of 440 m and at altitudes of 4,497, 5,533, 6,265, and again at 440 m. All subjects reached 5,533 m, and 28 reached 6,265 m. The neuropsychological test results did not reveal any cognitive impairment. Complete eye movement recordings for all stimulus conditions were obtained in 24 subjects at baseline and at least two altitudes and in 10 subjects at baseline and all altitudes. Measurements of saccade performances showed no dependence on any altitude-related parameter and were well within normal limits. Our data indicates that acclimatized climbers do not seem to suffer from significant cognitive deficits during or after climbs to altitudes above 7,500 m. We demonstrated that investigation of EMs is feasible during high-altitude expeditions.
authors.affiliation: Department of Intensive Care Medicine, Bern University Hospital and University of Bern, Bern, Switzerland. tobias.merz@insel.ch
authors.forename: Tobias M
authors.initials: TM
authors.lastname: Merz
authors.forename: Martina M
authors.initials: MM
authors.lastname: Bosch
authors.forename: Daniel
authors.initials: D
authors.lastname: Barthelmes
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Pichler
authors.forename: Urs
authors.initials: U
authors.lastname: Hefti
authors.forename: Kai-Uwe
authors.initials: KU
authors.lastname: Schmitt
authors.forename: Konrad E
authors.initials: KE
authors.lastname: Bloch
authors.forename: Otto D
authors.initials: OD
authors.lastname: Schoch
authors.forename: Thomas
authors.initials: T
authors.lastname: Hess
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Turk
authors.forename: Urs
authors.initials: U
authors.lastname: Schwarz
mesh_terms: D000328:Adult; D000531:Altitude; D003071:Cognition; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009051:Mountaineering / Q000502:physiology*; D009483:Neuropsychological Tests; D012438:Saccades
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