Cognition at Altitude: Impairment in Executive and Memory Processes Under Hypoxic Conditions

Asmaro, Deyar; Mayall, James; Ferguson, Sherri

doi:10.3357/asem.3661.2013

Cited by 73 publications

(65 citation statements)

References 22 publications

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“…The results from RMCPT are in agreement previous studies, indicating that participants made more errors and increased mean reaction time in hypoxic conditions (Van Diest et al, 2000). Results from Asmaro et al, (2013) also supports these findings in that reaction time and correct responses were decreased on the Word-Color Stroop task, which includes attention and concentration rather than simply reaction time.…”

Section: Cognitive and Physiological Measurements At Rest In Hypoxiasupporting

confidence: 92%

The Influence of Exercise on Cognitive Performance in Normobaric Hypoxia

Seo

Burns

Fennell

et al. 2015

High Altitude Medicine & Biology

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Although previous reports indicate that exercise improves cognitive function in normoxia, the influence of exercise on cognitive function in hypoxia is unknown. The purpose of this study was to determine if the impaired cognitive function in hypoxia can be restored by low to moderate intensity exercise. Sixteen young healthy men completed the ANAM versions of the Go/No-Go task (GNT) and Running Memory Continuous Performance Task (RMCPT) in normoxia to serve as baseline (B-Norm) (21% O2). Following 60 minutes of exposure to normobaric hypoxia (B-Hypo) (12.5% O2), these tests were repeated at rest and during cycling exercise at 40% and 60% of adjusted Vo2max. At B-Hypo, the % correct (p≤0.001) and throughput score (p≤0.001) in RMCPT were significantly impaired compared to B-Norm. During exercise at 40% (p=0.023) and 60% (p=0.006) of adjusted Vo2max, the throughput score in RMCPT improved compared to B-Hypo, and there was no significant difference in throughput score between the two exercise intensities. Mean reaction time also improved at both exercise intensities compared to B-Hypo (p≤0.028). Both peripheral oxygen saturation (Spo2) and regional cerebral oxygen saturation (rSo2) significantly decreased during B-Hypo (p≤0.001) and further decreased at 40% (p≤0.05) and 60% (p≤0.039) exercise. There was no significant difference in Spo2 or rSo2 between two exercise intensities. These data indicate that low to moderate exercise (i.e., 40%-60% adjusted Vo2max) may attenuate the risk of impaired cognitive function that occurs in hypoxic conditions.

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Section: Cognitive and Physiological Measurements At Rest In Hypoxiasupporting

confidence: 92%

The Influence of Exercise on Cognitive Performance in Normobaric Hypoxia

Seo

Burns

Fennell

et al. 2015

High Altitude Medicine & Biology

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“…Exposure to high altitude can cause a number of hypoxia‐induced physiological complications such as acute mountain sickness, pulmonary and/or cerebral oedema, and impairment of cognitive function (Hackett & Roach, ). Individuals become quickly aware of physical symptoms such as dizziness, headaches and nausea at altitude (Hackett & Roach, ), but they are less aware of the impairment to their cognitive function (Asmaro, Mayall, & Ferguson, ). The degree to which cognitive function is impaired is related to the severity of the hypoxic stimulus, particularly for tasks that require a higher order of cognitive ability (Petrassi, Hodkinson, Walters, & Gaydos, ; Yan, ).…”

Section: Introductionmentioning

confidence: 99%

Isolating the independent effects of hypoxia and hyperventilation‐induced hypocapnia on cerebral haemodynamics and cognitive function

Friend

Balanos

Lucas

2019

Experimental Physiology

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New Findings What is the central question of this study?What are the independent effects of hypoxia and hypocapnia on cerebral haemodynamics and cognitive function? What is the main finding and its importance?Exposure to hyperventilation‐induced hypocapnia causes cognitive impairment in both normoxia and hypoxia. In addition, supplementation of carbon dioxide during hypoxia alleviates the cognitive impairment and reverses hypocapnia‐induced vasoconstriction of the cerebrovasculature. These data provide new evidence for the independent effect of hypocapnia on the cognitive impairment associated with hypoxia. Abstract Hypoxia, which is accompanied by hypocapnia at altitude, is associated with cognitive impairment. This study examined the independent effects of hypoxia and hypocapnia on cognitive function and assessed how changes in cerebral haemodynamics may underpin cognitive performance outcomes. Single reaction time (SRT), five‐choice reaction time (CRT) and spatial working memory (SWM) tasks were completed in 20 participants at rest and after 1 h of isocapnic hypoxia (IH, end‐tidal oxygen partial pressure (P ET O2) = 45 mmHg, end‐tidal carbon dioxide partial pressure (P ETC O2) clamped at normal) and poikilocapnic hypoxia (PH, P ET O2 = 45 mmHg, P ETC O2 not clamped). A subgroup of 10 participants were also exposed to euoxic hypocapnia (EH, P ET O2 = 100 mmHg, P ETC O2 clamped 8 mmHg below normal). Middle cerebral artery velocity (MCAv) and prefrontal cerebral haemodynamics were measured with transcranial Doppler and near infrared spectroscopy, respectively. IH did not affect SRT and CRT performance from rest (566 ± 50 and 594 ± 70 ms), whereas PH (721 ± 51 and 765 ± 48 ms) and EH (718 ± 55 and 755 ± 34 ms) slowed response times (P < 0.001 vs. IH). Performance on the SWM task was not altered by condition. MCAv increased during IH compared to PH (P < 0.05), which was unchanged from rest. EH caused a significant fall in MCAv and prefrontal cerebral oxygenation (P < 0.05 vs. baseline). MCAv was moderately correlated to cognitive performance (R2 = 0.266–0.289), whereas prefrontal cerebral tissue perfusion and saturation were not (P > 0.05). These findings reveal a role of hyperventilation‐induced hypocapnia per se on the development of cognitive impairment during normoxic and hypoxic exposures.

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“…Review of extant literature indicates possible effects on a variety of cognitive abilities (Petrassi, Hodkinson, Walters, & Gaydos, 2012; Virues-Ortega et al, 2004), including motor learning and memory (Denison, Ledwith, & Poulton, 1966), decision-making (Frisby, Barrett, & Thornton, 1973), reaction time (Kida & Imai, 1993; McCarthy, Corban, Legg, & Faris, 1995), attention and working memory (Malle et al, 2013), and cognitive flexibility and executive functions (Asmaro, Mayall, & Ferguson, 2013). …”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Memory Dysfunction during High Altitude Hypoxia Training in Military Aircrew

Nation

Bondi

Gayles

et al. 2016

J Int Neuropsychol Soc

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Objectives Cognitive dysfunction from high altitude exposure is a major cause of civilian and military air disasters. Pilot training improves recognition of the early symptoms of altitude exposure so that countermeasures may be taken before loss of consciousness. Little is known regarding the nature of cognitive impairments manifesting within this critical window when life-saving measures may still be taken. Prior studies evaluating cognition during high altitude simulation have predominantly focused on measures of reaction time and other basic attention or motor processes. Memory encoding, retention, and retrieval represent critical cognitive functions that may be vulnerable to acute hypoxic/ischemic events and could play a major role in survival of air emergencies, yet these processes have not been studied in the context of high altitude simulation training. Methods In a series of experiments, military aircrew underwent neuropsychological testing before, during, and after brief (15 min) exposure to high altitude simulation (20,000 ft) in a pressure-controlled chamber. Results Acute exposure to high altitude simulation caused rapid impairment in learning and memory with relative preservation of basic visual and auditory attention. Memory dysfunction was predominantly characterized by deficiencies in memory encoding, as memory for information learned during high altitude exposure did not improve after washout at sea level. Retrieval and retention of memories learned shortly before altitude exposure were also impaired, suggesting further impairment in memory retention. Conclusions Deficits in memory encoding and retention are rapidly induced upon exposure to high altitude, an effect that could impact life-saving situational awareness and response.

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Cognition at Altitude: Impairment in Executive and Memory Processes Under Hypoxic Conditions

Cited by 73 publications

References 22 publications

The Influence of Exercise on Cognitive Performance in Normobaric Hypoxia

The Influence of Exercise on Cognitive Performance in Normobaric Hypoxia

Isolating the independent effects of hypoxia and hyperventilation‐induced hypocapnia on cerebral haemodynamics and cognitive function

Mechanisms of Memory Dysfunction during High Altitude Hypoxia Training in Military Aircrew

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