Extreme Environment Effects on Cognitive Functions: A Longitudinal Study in High Altitude in Antarctica

Night work, season and alertness as occupational safety hazards in the Arctic: protocol for the Noralert observational crossover study among Norwegian process operators

INTRODUCTION

The objective of this study is to determine the effects of night work, Arctic seasonal factors and cold working environments on human functions relevant to safety. The study aims to quantify the contribution of (1) several consecutive night shifts, (2) seasonal variation on sleepiness, alertness and circadian rhythm and (3) whether a computational model of sleep, circadian rhythms and cognitive performance can accurately predict the observed sleepiness and alertness.

METHODS AND ANALYSIS

In an observational crossover study of outdoor and indoor workers (n=120) on a three-shift schedule from an industrial plant in Norway (70 °N), measurements will be conducted during the summer and winter. Sleep duration and quality will be measured daily by smartphone questionnaire, aided by actigraphy and heart rate measurements. Sleepiness and alertness will be assessed at regular intervals by the Karolinska Sleepiness Scale and the psychomotor vigilance test, respectively. Saliva samples will assess melatonin levels, and a blood sample will measure circadian time. Thermal exposures and responses will be measured by sensors and by thermography.

ETHICS AND DISSEMINATION

All participants will give written informed consent to participate in the study, which will be conducted in accordance with the Declaration of Helsinki. The Norwegian Regional Committee for Medical Research Ethics South-East D waivered the need for ethics approval (reference 495816). Dissemination plans include academic and lay publications, and partnerships with national and regional policymakers.

The change of attention network functions and physiological adaptation during high-altitude hypoxia and reoxygenation

Previous studies have not reached a definitive conclusion regarding the effect of high-altitude hypoxia and reoxygenation on attention. To clarify the influence of altitude and exposure time on attention and the relations between physiological activity and attention, we conducted a longitudinal study to track attention network functions in 26 college students. The scores on the attention network test and physiological data, including heart rate, percutaneous arterial oxygen saturation (SpO₂), blood pressure, and vital capacity in pulmonary function measurement, were collected at five time-points: two weeks before arriving at high altitude (baseline), within 3 days after arriving at high altitude (HA3), 21 days after arriving at high altitude (HA21), 7 days after returning to sea level (POST7) and 30 days after returning to sea level (POST30). The alerting scores at POST30 were significantly higher than those at baseline, HA3 and HA21; the orienting scores at HA3 were lower than those at POST7 and POST30; the executive control scores at POST7 were significantly lower than those at baseline, HA3, HA21, and POST30; and the executive control scores at HA3 were significantly higher than those at POST30. The change in SpO₂ during high-altitude acclimatization (from HA3 to HA21) was positively correlated with the orienting score at HA21. Vital capacity changes during acute deacclimatization positively correlated with orienting scores at POST7. Attention network functions at the behavioral level did not decline after acute hypoxia exposure compared with baseline. Attention network functions after returning to sea level were improved compared with those during acute hypoxia; additionally, alerting and executive function scores were improved compared with those at baseline. Thus, the speed of physiological adaptation could facilitate the recovery of orienting function during acclimatization and deacclimatization.

Human challenges to adaptation to extreme professional environments: A systematic review

NASA is planning human exploration of the Moon, while preparations are underway for human missions to Mars, and deeper into the solar system. These missions will expose space travelers to unusual conditions, which they will have to adapt to. Similar conditions are found in several analogous environments on Earth, and studies can provide an initial understanding of the challenges for human adaptation. Such environments can be marked by an extreme climate, danger, limited facilities and supplies, isolation from loved ones, or mandatory interaction with others. They are rarely encountered by most human beings, and mainly concern certain professions in limited missions. This systematic review focuses on professional extreme environments and captures data from papers published since 2005. Our findings provide an insight into their physiological, biological, cognitive, and behavioral impacts for better understand how humans adapt or not to them. This study provides a framework for studying adaptation, which is particularly important in light of upcoming longer space expeditions to more distant destinations.

Short-term isolation effects on the brain, cognitive performance, and sleep-The role of exercise

Isolation is stressful and negatively affects sleep and mood and might also affect the structure and function of the brain. Physical exercise improves brain function. We investigated the influence of physical exercise during isolation on sleep, affect, and neurobehavioral function. N = 16 were isolated for 30 days with daily exercise routines (ISO₁₀₀) and n = 16 isolated for 45 days with every second day exercise (ISO₅₀). N = 27 were non-isolated controls who either exercised on a daily basis (CTRL_Ex) or refused exercise (CTRL_NonEx) for 30 days. At the beginning and the end of each intervention, intravenous morning cortisol, melatonin, brain-derived neurotrophic factor and IGF-1, positive and negative affect scales, electroencephalography, cognitive function, and sleep patterns (actigraphy) were assessed. High levels of cortisol were observed for the isolated groups (p < .05) without negative effects on the brain, cognitive function, sleep, and mood after 4 to 6 weeks of isolation, where physical exercise was performed regularly. An increase in cortisol and impairments of sleep quality, mood, cognitive function, and neurotrophic factors (p < .05) were observed after 4 weeks of absence of physical exercise in the CTRL_NonEx group. These findings raise the assumption that regular physical exercise routines are a key component during isolation to maintain brain health and function.

Intensity-dependent acute aerobic exercise: Effect on reactive control of attentional functions in acclimatized lowlanders at high altitude

Human attentional function is sensitive to hypoxia. However, little is known about whether and how attentional function is altered after acute aerobic exercise at high altitude, especially for acclimatized lowlanders. In this study, we used the Attention Network Test (ANT) to measure alerting, orienting, and executive control functions and the Stroop Color and Word Test (SCWT) with a different proportion of incongruent trials to investigate proactive and reactive control of executive function. We randomly divided the sample of 160 Tibetan lowlanders who had lived in the highlands for more than two years into four groups. Each of three groups performed 20 min of low-, moderate-, or high-intensity acute aerobic exercise, separately, and a control group watched a 20-min documentary. The ANT and SCWT were conducted before and after exercise or watching the documentary. The results indicated that the executive control effects of the three experimental groups significantly decreased and, in the posttest, the executive control effects of the high-intensity group were lower than those of the low-intensity group. Furthermore, the accuracy of the moderate- and high-intensity groups was increased significantly in the blocks containing 25% incongruent trials of SCWT task. These results suggest that the acute aerobic exercise at high altitude will improve the reactive control of attentional functions in acclimatized lowlanders, and the intensity may play an important role in the exercise-cognition interaction at high altitude.

Psychosocial issues in isolated and confined extreme environments

PALINKAS, L.A., and P. SUEDFELD. Psychosocial Issues in Isolated and Confined Extreme Environments. NEUROSCI BIOBEHAV REV (1) XXX-XXX, 2020. Psychosocial elements of behavior and performance will significantly impact the outcomes of long duration missions in space, ranging from individual and team decrements to positive benefits associated with successful adaptation. This paper reviews our current understanding of the individual, interpersonal and organizational issues related to living and working in isolated and confined extreme (ICE) environments. Individual issues include changes in emotions and cognitive performance; seasonal syndromes linked to changes in the physical environment; and positive effects of adapting to ICE environments. Interpersonal issues include processes of crew cohesion, tension and conflict; interpersonal relations and social support; the impact of group diversity and leadership styles on small group dynamics; and crew-mission control interactions. Organizational issues include the influence of organizational culture and mission duration on individual and group performance, crew autonomy, and managerial requirements for long duration missions. Improved screening and selection, leadership, coping and interpersonal skills training, and organizational change are key elements to optimizing adjustment to the environment and preventing decrements during and after long duration missions.

'White Mars' - nearly two decades of biomedical research at the Antarctic Concordia station

NEW FINDINGS

What is the topic of this review? Biomedical research at the Antarctic Concordia Station. What advances does it highlight? Overview of findings in psychology, neuroscience, sleep, cardiovascular physiology and immune system, relevant in isolated, confined and extreme environments and spaceflight.

ABSTRACT

Extended stays in isolated, confined and extreme (ICE) environments like Antarctica are associated with a whole set of psychological and physiological challenges for the crew. As such, winter-over stays at Antarctica provide an important opportunity to acquire knowledge into the physiological and psychological changes that ICE environments inevitably bring. The European Space Agency (ESA) is particularly interested in conducting research in such an environment, as it is a unique opportunity to translate these results to space crews experiencing very similar issues. In the past two decades, the ESA has supported a total of 36 biomedical research projects at the Concordia station in collaboration with the French and Italian polar institutes. More specifically, studies in the areas of psychology, neuroscience, sleep physiology, cardiovascular physiology and immunology were performed. The outcomes of these studies are directly relevant for people working in ICE environments, but also help to better understand the biomedical challenges of those environments. Consequently, they can help to better prepare for human space exploration and to identify countermeasures to minimize the adverse effects of space environments on astronaut health. The aim of this review is to provide an overview of the biomedical studies that have taken place in the past two decades at the Antarctic Concordia station and to summarize the results and their implication for human spaceflight.

Genomic and physiological resilience in extreme environments are associated with a secure attachment style

Understanding individual capability to adjust to protracted confinement and isolation may inform adaptive plasticity and disease vulnerability/resilience, and may have long-term implications for operations requiring prolonged presence in distant and restricted environments. Individual coping depends on many different factors encompassing psychological dispositional traits, endocrine reactivity and their underlying molecular mechanisms (e.g. gene expression). A positive view of self and others (secure attachment style) has been proposed to promote individual resilience under extreme environmental conditions. Here, we tested this hypothesis and investigated the underlying molecular mechanisms in 13 healthy volunteers confined and isolated for 12 months in a research station located 1670 km away from the south geographic pole on the Antarctic Plateau at 3233 m above sea level. Study participants, stratified for attachment style, were characterised longitudinally (before, during and after confinement) for their psychological appraisal of the stressful nature of the expedition, diurnal fluctuations in endocrine stress reactivity, and gene expression profiling (transcriptomics). Predictably, a secure attachment style was associated with reduced psychological distress and endocrine vulnerability to stress. In addition, while prolonged confinement and isolation remarkably altered overall patterns of gene expression, such alteration was largely reduced in individuals characterised by a secure attachment style. Furthermore, increased resilience was associated with a reduced expression of genes involved in energy metabolism (mitochondrial function and oxidative phosphorylation). Ultimately, our data indicate that a secure attachment style may favour individual resilience in extreme environments and that such resilience can be mapped onto identifiable molecular substrates.

Subjective time estimation in Antarctica: The impact of extreme environments and isolation on a time production task

Interval timing measures time estimation in the seconds-to-minutes range. Antarctica provides a real-world context to study the effect of extreme photoperiods and isolation on time perception. The aim of this study was to explore interval timing as a cognitive measure in the crew of Belgrano II Argentine Antarctic Station. A total of 13 subjects were assessed for interval timing in short (3 s), intermediate (6 s) and long (12 s) duration stimuli. Measures were taken during the morning and evening, five times along the year. Significant variations were found for 3 s and 6 s during the morning and 6 s during the evening. Results suggest an impact of isolation on morning performances and an effect of the polar night on evening measures. These findings shed some light on the use of interval timing as a cognitive test to assess performance in extreme environments.

Differential impact of acute hypoxia on event related potentials: impaired task-irrelevant, but preserved task-relevant processing and response inhibition

The current study investigated how experimentally induced acute normobaric hypoxia affects attentional control functions during easy, monotonous visual sustained attention and response inhibition (modified Continuous Performance Task) and executive control tasks (number-size Stroop task). Along with behavioral efficiency, task-relevant and task-irrelevant information processing were investigated by measuring event related brain potentials (ERP) evoked by target stimuli (Target P3), task-relevant stimuli with no response needed (NoGo P3), and task-irrelevant novel stimuli (Novelty P3) during acute hypoxia exposure. Normobaric hypoxia was induced by adjusting the O₂ content of the breathing mixture to obtain 80% peripheral oxygen saturation, equivalent of 5500 m above sea level. Here we report decreased Novelty P3 during acute normobaric hypoxia exposure, while Target P3 and NoGo P3, as well as behavioral efficiency remained intact. Our paper is the first to provide evidence for impaired novelty processing along with intact task-relevant information processing and response inhibition during normobaric hypoxic exposure.

Psychological Hibernation in Antarctica

Human activity in Antarctica has increased sharply in recent years. In particular during the winter months, people are exposed to long periods of isolation and confinement and an extreme physical environment that poses risks to health, well-being and performance. The present study aimed to gain a better understanding of processes contributing to psychological resilience in this context. Specifically, the study examined how the use of coping strategies changed over time, and the extent to which changes coincided with alterations in mood and sleep. Two crews (N = 27) spending approximately 10 months at the Concordia station completed the Utrecht Coping List, the Positive and Negative Affect Schedule (PANAS), and a structured sleep diary at regular intervals (x 9). The results showed that several variables reached a minimum value during the midwinter period, which corresponded to the third quarter of the expedition. The effect was particularly noticeable for coping strategies (i.e., active problem solving, palliative reactions, avoidance, and comforting cognitions). The pattern of results could indicate that participants during Antarctic over-wintering enter a state of psychological hibernation as a stress coping mechanism.

Cognitive resilience after prolonged task performance: an ERP investigation

Deleterious consequences of cognitive fatigue might be avoided if people respond with increased effort to increased demands. In this study, we hypothesized that the effects of fatigue would be more pronounced in cognitive functions reflecting compensatory effort. Given that the P3a event-related potential is sensitive to the direction and amount of attention allocated to a stimulus array, we reasoned that compensatory effort would manifest in increased P3a amplitudes. Therefore, we compared P3a before (pre-test) and after (post-test) a 2 h long cognitively demanding (fatigue group, n = 18) or undemanding task (control group, n = 18). Two auditory tasks, a three-stimulus novelty oddball and a duration discrimination two-choice response task were presented to elicit P3a. In the fatigue group, we used the multi-attribute task battery as a fatigue-inducing task. This task draws on a broad array of attentional functions and imposed considerable workload. The control group watched mood-neutral documentary films. The fatigue manipulation was effective as subjective fatigue increased significantly in the fatigue group compared to controls. Contrary to expectations, however, fatigue failed to affect P3a in the post-test phase. Similar null effects were obtained for other neurobehavioral measures (P3b and behavioral performance). Results indicate that a moderate increase in subjective fatigue does not hinder cognitive functions profoundly. The lack of objective performance loss in the present study suggests that the cognitive system can be resilient against challenges instigated by demanding task performance.