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Cognitive performance in high-altitude climbers: a comparative study of saccadic eye movements and neuropsychological tests

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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.

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Acknowledgments

We are thankful to the 32 volunteers who participated in our studies during the expedition and the following members of the Swiss Muztagh Ata Expedition Team: Timothy Holmes, Gregor Schubiger, and Frédéric Truffer. Furthermore, we appreciate the efforts of Kari Kobler and his Swiss Mountain guides, as well as the porters from Pakistan, China and Tibet. We thank Jeannie Wurz for editorial help with the manuscript.

Conflict of interest

The authors declare that they have no conflict of interest.

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Authors and Affiliations

  1. Department of Intensive Care Medicine, Bern University Hospital and University of Bern, Bern, Switzerland

    Tobias M. Merz

  2. Department of Ophthalmology, University Hospital Zürich, Zurich, Switzerland

    Martina M. Bosch & Daniel Barthelmes

  3. Department of Pneumology, Bern University Hospital and University of Bern, Bern, Switzerland

    Jacqueline Pichler

  4. Swiss Sport Clinic, Stade de Suisse, Sempacherstr. 22, 3014, Bern, Switzerland

    Urs Hefti

  5. Institute for Biomedical Engineering, ETH Zürich and University of Zürich, Zurich, Switzerland

    Kai-Uwe Schmitt

  6. Pulmonary Division, Department of Internal Medicine, Cantonal Hospital, Winterthur, Switzerland

    Thomas Hess

  7. Pulmonary Division, Department of Internal Medicine, University Hospital of Zurich, Zurich, Switzerland

    Konrad E. Bloch & Alexander J. Turk

  8. Pulmonary Division, Kantonsspital, St. Gallen, Switzerland

    Otto D. Schoch

  9. Department of Neurology, University Hospital Zürich, Zurich, Switzerland

    Urs Schwarz

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  1. Tobias M. Merz
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  2. Martina M. Bosch
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  4. Jacqueline Pichler
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  7. Konrad E. Bloch
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  8. Otto D. Schoch
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  9. Thomas Hess
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  10. Alexander J. Turk
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  11. Urs Schwarz
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Correspondence to Tobias M. Merz.

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Communicated by Guido Ferretti.

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Merz, T.M., Bosch, M.M., Barthelmes, D. et al. Cognitive performance in high-altitude climbers: a comparative study of saccadic eye movements and neuropsychological tests. Eur J Appl Physiol 113, 2025–2037 (2013). https://doi.org/10.1007/s00421-013-2635-6

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  • DOI: https://doi.org/10.1007/s00421-013-2635-6

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