Study of cognitive performance and physiological effort at altitude

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Jan 052010

Next week, Spanish Highs Mountain Guides will be working in the Sierra Nevada with experimenters David Gallagher and Dr. Wael El-Deredy, from Manchester University, who are studying cognitive performance and physiological effort at altitude. This is the first time we have participated in such a study and the results should prove interesting and will hopefully lead to further research.

The research is best described by David Gallagher and Wael El-Deredy in their own words………..

Purpose and Study Focus

We aim to collect some pilot data for a research grant application.

It is known that cognitive performance is detrimentally affected by environmental stressors such as heat, cold and altitude. What is less clear is the relationship between cognitive processes and the physiological mechanisms that maintain body homeostasis as a consequence of environmental stress. The current study aims to focus on how sustained cognitive performance may be dependent on variations / compensations in physiological effort.

Research Strategy

The study will use existing paradigms that test different aspects of higher cognitive functioning including working memory, spatial navigation, visual search tasks tailored as relevant to a mountain scenario. Additional heart rate data will be collated at baseline (no tasks) and test to ascertain indices of physiological effort relative to cognitive task performance.

Study and Background

Research into cognitive performance under environmental stressors has established that extremes of heat, cold and altitude can have detrimental effects upon a range of cognitive processes that are typically optimum in the 18-27°C bandwidth, and below 3000m (Hancock and Vasmatzidis, 2003; Pilcher, Nadler, and Busch, 2002; Kramer, Coyne, and.Strayer, 1993). This is particularly true for higher level processes involving attention, working memory, and decision making. Such functions are critical to avoid errors in performance that could have potentially disastrous consequences. Physiological effects of exposure to such environments have also been well documented, concomitant with the effects of exercise intensity that tends to accompany exposure to extremes (as with mountaineering activities). Some attempts have been made to relate these to cognitive performance generally (Reilly and Waterhouse, 2005). For instance, once oxygen saturation starts to fall (about 2000 m), brain function is likely to be affected, and under exercise, cognitive function starts to deteriorate. It has been suggested that cognitive performance requires a certain amount of physiological effort, and given that stressful situations will entail an increased arousal and physiological strain, this may help explain why cognitive performance is likely to decrease with increased physiological stress (Hockey, 1997). Furthermore, Craig (2005) has proposed neurophysiological evidence for an integration of brain functions relevant to higher order cognitive / affective processes and physiological mechanisms governing bodily homeostasis. Given the importance of these different factors in successful decision making and good judgement we are interested in the relationship between brain functions that govern higher order cognition (Koechlin, Ody, and Kouneiher, 2003) and the physiological and homeostatic mechanisms alluded to. We propose to consider these theoretical frameworks as being relevant to a model for sustained cognitive performance under altitude stress. Our hypothesis is that cognitive performance may be sustained at increases in altitude (above 3000m) accounting for acclimatisation, but that this will incur a physiological cost, as the homeostasis mechanisms ‘redress the balance’ as it were. This should be observable as increases in heart rate compared to baseline in the course of cognitive testing, reflecting additional effort. Where physiological resources are no longer available to recruit additional compensatory effort (such as already high heart rate at baseline / physiological stress is unmanageable) it would be predicted that a detriment in cognitive performance will be observed.

Methodology/Procedure

Participants a small number of mountain guides and their clients (n=8) will be recruited in the Sierra Nevada mountain range in Spain. These will already be voluntarily engaged in activities in the mountain environment, and this study will align with their existing schedule.

The Procedure will be carried out in the field in the Sierra Nevada national park area at a location determined by the existing schedule of the mountain guides and clients. The study will be carried out at a base altitude 650m (at the location of the mountain guide company ‘Spanish Highs’ http://www.spanishhighs.co.uk/, Lanjaron), on day 1, then at around 3000m on the day 2 at the same time of day, and again at 3000m on day 3 following acclimatisation. The test will consist of a 2 minute heart rate baseline measure (participant sitting relaxed wearing a Suunto heart rate chest band) followed by a 2 minute period in which the cognitive tasks are administered whilst heart rate is again monitored. The tasks will be administered as pen and paper tests. Data captured will encompass baseline vs test heart rate averaged over 2 minutes; number of correct responses to tasks performed.

Analysis

A one way ANOVA with 3 levels will be performed on the mean correct responses data: at base altitude of 600m, at 3000m pre-acclimatisation, at 3000m post-acclimatization. A two way ANOVA with the factors Testing condition (baseline vs tasks) x Altitude (base 600m, pre-acclimatized 3000m, post-acclimatized 3000m) will be conducted on the mean heart rate data. Heart rate data will be correlated to task performance measures.

Potential Risks

The study will be aligned within the scheduling of existing mountain activities for which the mountain company will be already risk assessed and the participants already signed up for. No additional physical activity is required for this study.

The most southern high mountain range on mainland Europe, the Sierra Nevadas offer high altitude training without the risks associated with other European mountains. They have very stable weather systems, gentle slopes and no glaciers.

Purpose and Study Focus

We aim to collect some pilot data for a research grant application.

It is known that cognitive performance is detrimentally affected by environmental stressors such as heat, cold and altitude. What is less clear is the relationship between cognitive processes and the physiological mechanisms that maintain body homeostasis as a consequence of environmental stress. The current study aims to focus on how sustained cognitive performance may be dependent on variations / compensations in physiological effort.

Research Strategy

The study will use existing paradigms that test different aspects of higher cognitive functioning including working memory, spatial navigation, visual search tasks tailored as relevant to a mountain scenario. Additional heart rate data will be collated at baseline (no tasks) and test to ascertain indices of physiological effort relative to cognitive task performance.

Study and Background

Research into cognitive performance under environmental stressors has established that extremes of heat, cold and altitude can have detrimental effects upon a range of cognitive processes that are typically optimum in the 18-27°C bandwidth, and below 3000m (Hancock and Vasmatzidis, 2003; Pilcher, Nadler, and Busch, 2002; Kramer, Coyne, and.Strayer, 1993). This is particularly true for higher level processes involving attention, working memory, and decision making. Such functions are critical to avoid errors in performance that could have potentially disastrous consequences. Physiological effects of exposure to such environments have also been well documented, concomitant with the effects of exercise intensity that tends to accompany exposure to extremes (as with mountaineering activities). Some attempts have been made to relate these to cognitive performance generally (Reilly and Waterhouse, 2005). For instance, once oxygen saturation starts to fall (about 2000 m), brain function is likely to be affected, and under exercise, cognitive function starts to deteriorate. It has been suggested that cognitive performance requires a certain amount of physiological effort, and given that stressful situations will entail an increased arousal and physiological strain, this may help explain why cognitive performance is likely to decrease with increased physiological stress (Hockey, 1997). Furthermore, Craig (2005) has proposed neurophysiological evidence for an integration of brain functions relevant to higher order cognitive / affective processes and physiological mechanisms governing bodily homeostasis. Given the importance of these different factors in successful decision making and good judgement we are interested in the relationship between brain functions that govern higher order cognition (Koechlin, Ody, and Kouneiher, 2003) and the physiological and homeostatic mechanisms alluded to. We propose to consider these theoretical frameworks as being relevant to a model for sustained cognitive performance under altitude stress. Our hypothesis is that cognitive performance may be sustained at increases in altitude (above 3000m) accounting for acclimatisation, but that this will incur a physiological cost, as the homeostasis mechanisms ‘redress the balance’ as it were. This should be observable as increases in heart rate compared to baseline in the course of cognitive testing, reflecting additional effort. Where physiological resources are no longer available to recruit additional compensatory effort (such as already high heart rate at baseline / physiological stress is unmanageable) it would be predicted that a detriment in cognitive performance will be observed.

Methodology/Procedure

Participants a small number of mountain guides and their clients (n=8) will be recruited in the Sierra Nevada mountain range in Spain. These will already be voluntarily engaged in activities in the mountain environment, and this study will align with their existing schedule.

The Procedure will be carried out in the field in the Sierra Nevada national park area at a location determined by the existing schedule of the mountain guides and clients. The study will be carried out at a base altitude 650m (at the location of the mountain guide company ‘Spanish Highs’ http://www.spanishhighs.co.uk/, Lanjaron), on day 1, then at around 3000m on the day 2 at the same time of day, and again at 3000m on day 3 following acclimatisation. The test will consist of a 2 minute heart rate baseline measure (participant sitting relaxed wearing a Suunto heart rate chest band) followed by a 2 minute period in which the cognitive tasks are administered whilst heart rate is again monitored. The tasks will be administered as pen and paper tests. Data captured will encompass baseline vs test heart rate averaged over 2 minutes; number of correct responses to tasks performed.

Analysis

A one way ANOVA with 3 levels will be performed on the mean correct responses data: at base altitude of 600m, at 3000m pre-acclimatisation, at 3000m post-acclimatization. A two way ANOVA with the factors Testing condition (baseline vs tasks) x Altitude (base 600m, pre-acclimatized 3000m, post-acclimatized 3000m) will be conducted on the mean heart rate data. Heart rate data will be correlated to task performance measures.

Potential Risks

The study will be aligned within the scheduling of existing mountain activities for which the mountain company will be already risk assessed and the participants already signed up for. No additional physical activity is required for this study.

The most southern high mountain range on mainland Europe, the Sierra Nevadas offer high altitude training without the risks associated with other European mountains. They have very stable weather systems, gentle slopes and no glaciers.