NOTE: End date changed to 7/31/2023 per L. Barnes-Moten/JSC (Ed., 4/7/21)

This NASA Specialized Center of Research (NSCOR) sought to characterize the three less well-understood National Institute of Mental Health (NIMH) Research Domain Criteria (RDoC) domains of positive valence, negative valence, and social processes as they relate to performance, adaptation, and resilience of individuals living and working in ICC/ICE environments. This study further sought to identify biomarkers of resilience and determine the neurobiological and cellular/molecular mechanisms that underlie resilience and adaptation. The NSCOR aimed to elucidate key promoters of resiliency, including social support and meaningfulness of work. To achieve these objectives, this study investigated the biological and behavioral responses of N=93 astronaut-like individuals who were living and working in one of three spaceflight analog environments: 1) 7-day missions in the Isolation, Confinement, Analog Research Unit for Spaceflight (ICARUS) at the University of Pennsylvania; 2) 45-day missions in the Human Exploration Research Analog (HERA) at NASA Johnson Space Center (JSC); and 3) 14-month winter-over missions at the Neumayer III station in Antarctica. Structural and functional neuroimaging were obtained before and after each analog mission. Extensive biological and behavioral data were collected across all three phases of the missions, including pre-, in-, and post-mission. Crewmembers completed a series of surveys before and after their respective missions reporting on their social and emotional processes, affective functioning, personality, emotion regulation, resilience, exposure to life-course adversity, psychological well-being, etc. Throughout analog missions, crewmember sleep-wake behaviors were measured continuously using actigraphy and periodic measures of cognitive (Cognition test battery) and spatial cognitive performance, spaceflight-relevant operational performance (Robotic-Onboard Trainer for Research), surveys of anxiety and depression, as well as effective functioning were collected. At four times during analog missions, crewmembers provided blood, urine, and saliva samples to measure biomarkers of resilience and wore electrocardiographs for 24 hours continuously to evaluate heart rate variability. This NSCOR had the following Specific Aims:

Specific Aim 1 is to identify and quantify individual differences in adaptation and resilience, key threats to and promoters of mission-relevant behavioral health and performance (BMed 1 Gap). We will use components of the RDoC framework to look across individual risk factors in order to identify and validate molecular, circuitry, and physiological measures that can be used for monitoring and selection of individuals who are highly resilient to the key behavioral health and performance threats during autonomous, long-duration and/or long-distance exploration missions (BMed 2 & 5 Gaps). Aim 1a. Perform a comprehensive literature review of the RDoC framework to identify the units of analysis (e.g., cells, etc.) of the individual risk factors most related to LDEMs and positive valence, negative valence, and social processes domains. Aim 1b. Identify how the risk factors within those three RDoC domains relate to performance outcomes, resiliency, and adaptation in LDEMs.

Specific Aim 2 is to identify neural circuits and molecular/cellular mechanisms underlying adaptation and resilience in a rodent model using cross-species equivalency (i.e., mice exposed for “human” equivalent time). Hypothesis 2a. The human vs rodent ICC exposures will reveal “adaptations” of neural circuitry and biomarkers related to the length of human and human-equivalent rodent exposures. Hypothesis 2b. The rodent model circuitry results will provide cellular/molecular/structural targeting for pre-/post-mission MRI scans for human analogs. Hypothesis 2c. Molecular/cellular biomarkers of stress, adaptability, and resiliency will correlate with neural circuitry changes using structural and functional neuroimaging. Hypothesis 2d. Biomarkers related to stress, adaptability, and resiliency will reveal intraindividual differences that correspond to individual/team performance and self-report measures.

Specific Aim 3 encompasses the biological basis of social support to assess individual sociability and the neurobehavioral contributions to resiliency and/or adaptability of engaging positively in social interactions, tolerance, and awareness (e.g., affiliation, attachment). Hypothesis 3a. Cellular and molecular biomarkers related to social systems (e.g., oxytocin) will reveal changes in the underlying neurobiological systems as a function of social support, before, during, and after being in an ICC/ICE environment. Hypothesis 3b. Individual differences in indicators of resilience measured before isolation will predict loneliness, perceived social support, and healthier social neurobiology during isolation. Hypothesis 3c. Individual differences in emotional regulation will provide the most robust evidence for how the neural circuitry moves up to behavior and social processes in self-report and interactions, as well as downward toward cellular/molecular biomarkers (e.g., cortisol, BDNF, oxytocin, etc.), with structural changes revealed by the MRI.

Specific Aim 4 will identify how meaningful work mediates the relationship among risk factors, the valence and social process domains, and operational outcomes, as well as the direct effects of meaningful work on performance. The intent is to identify a sensitive, reliable, valid, and feasible set of measures for measuring and monitoring the meaningfulness of work in spaceflight. Hypothesis 4a. Leveraging the review of the extant literature to address Specific Aim 1, candidate measures of meaningfulness of work will be identified and adapted into a single meaningful work battery for use in the study data collection. Hypothesis 4b. The use of this meaningful work battery in study analogs will provide evidence for the sensitivity, reliability, validity, and feasibility of the battery for use in the spaceflight context.

Specific Aim 5 encompasses the need to identify how positive and negative valence systems impact psychological well-being and performance when confronted with the adverse conditions found in prolonged spaceflight. We will identify biomarkers and psychological report measures associated with the effects of well-being on performance and determine their contribution to the positive/negative valence systems involved in individual adaptation and resilience. Hypothesis 5a. Leveraging the review of extant literature to address Specific Aim 1, candidate measures of well-being that incorporate the three-factor model of well-being put forth by the NASA review 11 will be identified and adapted into a single well-being battery to feasible and acceptable measure of well-being in the context of spaceflight. Hypothesis 5b. The use of this well-being battery in the study analogs will provide evidence for the sensitivity, reliability validity, and feasibility of the battery for use in the spaceflight context. Hypothesis 5c. Self-report measures of well-being will correlate with performance outcomes and biomarkers. Hypothesis 5d. Both intra- and inter-individual differences in molecular, circuitry, physiological, and behavioral domains will reflect adaptability/tolerance (i.e., endurance/coping) within positive and negative valence systems and social processes with the most pronounced threat to well-being and performance under the adverse conditions of the extended ICE.

A total of N=93 crewmembers participated in the NSCOR study and across studies in the three analog environments, a total of N=14,653 crewmember-mission-days were completed (n=9,273 original NSCOR study and n=5,380 Neumayer supplement), including N=201 in ICARUS, N=1,440 in HERA, and N=13,012 in Neumayer. Data collection yields in the NSCOR study were high across biological measures of interest. For biomarker collection, there were a total of N=371 (n=315 from original NSCOR cohort and n=56 from Neumayer supplement) blood, saliva, and urine biospecimen collections across missions in the three analog environments; crewmembers in the original NSCOR cohort’s biosamples were assayed for 20 biomarkers and crewmembers in the Neumayer supplement biosamples were assayed for 17 biomarkers with relevance for resilience and adaptation in ICC/ICE environments. From these biospecimens, a total of N=8,465 biomarker measurements (98.4% of expected) were generated. For neuroimaging data collection, a total of N=176 MRI scans were collected; missing data were due to participant withdraws or MRI contraindications. Crewmembers underwent five imaging modalities including both structural and functional MRI, as well as diffusion-weighted imaging. For heart rate variability data, a total of N=300 24-h ECG recordings were collected across mission phases.

The translational rodent model elucidated the neurobiological mechanisms through which exposure to early life stress (ELS) leads to persistent cognitive deficits, which were found to be biologically embedded by distinct, reversible mechanisms in males and females. A deeper understanding of the sex-specific cognitive consequences of ELS, thus, identifies Adverse Childhood Experiences (ACEs) as a potentially important criterion for selection of crew members performing specific tasks under prolonged spaceflight conditions, validates peripheral measures of oxidative stress as a proxy for prefrontal stress burden, and reveals novel strategies for overcoming them which may acutely improve performance under chronic space mission stress. Baseline behavioral differences induced by ELS align with human studies indicating a gender bias for externalizing (male) and internalizing (female) symptomatology.

The human studies lead to the development and quantification of a novel spaceflight-relevant objective measure of resilience. To define resilience, 36 measures across five measurement domains with potential relevance to resilience/adaptation in ICC/ICE environments were identified. To determine the magnitude of each measure’s relevance for resilience, each measure was assigned a ranking of relevance for resilience, which was accomplished through the paired comparisons method where subject matter experts rated each item relative to all others (630 paired comparisons). This measure of resilience reflects the multidimensionality of the construct and was associated with both biological and behavioral measures.

For the biomarker prediction of resilience in humans during ICC/ICE missions, biological and behavioral measures collected prior to analog missions differed in their prediction of in-mission resilience. Pre-mission concentrations of peripheral biomarkers were largely not predictive of in-mission resilience with testosterone being the only biomarker of modest predictive utility.

On the other hand, pre-mission heart rate variability (HRV) significantly predicted average resilience and was the strongest biological predictor of in-mission resilience. The HRV metrics that predicted resilience were primarily non-linear HRV metrics, accounting for 26.2% of the variance in resilience.

The prediction of resilience by structural MRI data revealed that gray matter volume in the hippocampus and hippocampal subfields was the strongest pre-mission neurostructural predictor of in-mission resilience; however, the explanatory value of these predictions was modest. No microstructural or white matter tract outcomes, measured by diffusion-weighted imaging, were significant predictors of resilience accounting for only 6.8% of the in-mission variance.

For the cross-domain biological and behavioral prediction of resilience, the combination of pre-mission biological measures (biomarkers, HRV, and structural MRI) and pre-mission surveys of individual characteristics (personality, grit, psychological wellbeing, attachment styles, anxiety, etc.) demonstrated the strongest prediction of in-mission resilience, accounting for 40.4% of the variance. The predictors that had explanatory value were the HRV metrics, anxiety, and the need for approval (attachment style). The exclusion of three predictors that did not significantly contribute to the prediction model produced a parsimonious prediction model that included seven predictors (5 HRV metrics and 2 surveys) and increased the adjusted r-squared to 46.5%. The use of both biological and behavioral measures in the prediction of resilience explained the most variance of all prediction models built suggesting that resilience is a multidimensional construct that is best predicted by a variety of measurement domains.

The COVID-19 pandemic resulted in a mandated cessation of scheduled NSCOR data acquisition at the Isolation and Confinement Analog Research Unit for Spaceflight (ICARUS) facility at the University of Pennsylvania. Data acquisition is scheduled to recommence this year, if the University of Pennsylvania Perelman School of Medicine approves the updated research resumption plan. The team at Penn has continued to work with the statistician, Dr. Warren Bilker, to create a resilience score for the NSCOR across analog sites. Data acquisition for Campaign 6 in Human Exploration Research Analog (HERA) is postponed due to the COVID-19 pandemic. Campaign 6 is currently scheduled to begin this year. Data acquisition for the second 14 month mission in Neumayer is complete.

During the past year in the mouse model, Dr. Hensch and colleagues identified sex-specific consequences of early life adversity in an adult mouse model. These results may impact the selection of candidates or optimal environments for long-term spaceflight confinement stress in humans based on their adverse childhood experience (ACE) scores. To capture the true complexity of social behaviors that occur in groups, they established a Social Network Analysis (SNA) approach to define objective parameters associated with sociability and its plasticity by sex. This analytical approach can identify, for example, network participants who are more effective teammates or more likely to generate new social relationships. Anticipated baseline behavior was further compared to novel and established molecular biomarkers to be assessed in peripheral samples (e.g., urine, blood), including autoantibodies and oxidative stress markers. Importantly, the ability to overcome impairments of sociability with acute antioxidant (or other) treatments can now be tested in animal models.

During the past year in the animal model at Harvard, Hensch and colleagues identified sex-specific consequences of early life adversity on adult behavior. To capture the true complexity of social behaviors that occur in groups, they established a Social Network Analysis (SNA) approach to define objective parameters associated with sociability and its plasticity by sex. This analytical approach can identify, for example, network participants who are more effective teammates or more likely to generate new social relationships. Anticipated baseline behavior was further compared to novel and established molecular biomarkers to be assessed in peripheral samples (e.g., urine, blood), including autoantibodies and oxidative stress markers. Importantly, the ability to overcome impairments of sociability with acute antioxidant (or other) treatments can now be tested in animal models.

During the past year, Hensch and colleagues established molecular and behavioral biomarkers to assess confinement stress. First, we validated the accuracy with which peripheral measures of oxidative stress reflect brain levels. Isoprostanes are prostaglandin-like compounds detectable in urine formed from the free radical-catalyzed peroxidation of essential fatty acids such as lipids in both animal and human models of oxidative stress. Second, using a machine learning approach, we defined objective parameters associated with sociability. While dyadic assays have been used as a proxy of sociability in mice, this standardized test does not capture the true complexity of social behaviors that occur in groups. Social network analysis (SNA) uses graph theory to investigate the structure of social groups. This analytical approach is capable, for example, of identifying network participants that are more sociable or more likely to generate new social relationships.

Human Analogs:

Over the 4-year project period, N=90 healthy adult subjects (male and female, aged 30-55 years) will have been exposed to stressors that vary in intensity and duration, while living in one of the three ICC/ICE sites. Site 1 is the Isolation, Confinement, Analog Research Unit for Spaceflight (ICARUS) located at the University of Pennsylvania (Penn). Site 2 is NASA’s Human Exploration Research Analog (HERA) at Johnson Space Center (JSC). Site 3 is the German Antarctic station Neumayer-Station III (Neumayer). By having three analogs that vary in key ways relative to spaceflight stressors, we will be able to determine whether RDoC assessments of neural circuitry and biomarkers will vary with indices of adaptability and resilience by analog context and conditions.

During the reporting period for this Annual Report (9/5/2018-9/5/2019), all three human research sites (and the animal site at Harvard) initiated data collection. The investigator team held weekly/bi-weekly telecons (N=28) to discuss and resolve important issues related to data acquisition. This enabled the team to update its scheduled study runs as well as refine its list of biological biomarkers and questionnaires. Thus, in the past year, the NSCOR team finalized protocols, secured IRB (Institutional Review Board) approvals, implemented measures at each site, ordered essential materials and equipment, screened and empaneled study participants, and initiated data collection. There have been a total of n=29 human subjects run through this NSCOR project across all three sites over the past year. This includes n=2 subjects who withdrew resulting in an overall completion rate of 93%. Across NSCOR human research sites there has been a high rate of subject compliance to biological measures including MRI scans, blood draws, urine samples, and saliva collection.

During the Definition Phase of this NSCOR project (10/5/17-4/5/18), a literature review was conducted to select biological biomarkers. Blood and saliva samples will be analyzed (to the extent funding is available), and urine samples will be collected and analyzed (to the extent funding is available) for these biomarkers, which the scientific literature indicates are associated with stress, emotional, and/or immune responses.

During the Definition Phase of this NSCOR project (10/5/17-4/5/18), a literature review was conducted to select and adapt questionnaires. Selected questionnaires will be administered as screening measures (administered pre-mission), characterization measures (administered pre/post-mission), and/or state-based measures (administered in-mission).

Selection, refinement, and development of relevant measures was also major goal of the NSCOR year-1 and Definition Phase activities. For the human research components, the BHP (Behavioral Health & Performance) Laboratory’s major contributions were in the domains of meaningful work and social support.

The following biomarkers, which have all been associated with stress, emotional, or immune responses in prior research, will be determined in venous blood samples (8 ml serum) collected at baseline and on a regular basis throughout the 3 ICC/E environments: Brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), insulin-like growth factor 1 (IGF-1) (Lin, Suhr et al. 2014) , Neuropeptide Y (NPY), Ghrelin and oxytocin, tumor necrosis factor (TNF) (Beste, Baune et al. 2010; Hodes, Pfau et al. 2014; van Zuiden, Kavelaars et al. 2015), interleukin-1 (IL-1), interleukin-6 (IL-6) (Valkanova, Ebmeier et al. 2013), interleukin-10 (IL-10), and vitamin D. Blood samples will be taken by venipuncture in the morning after overnight fasting between 7 and 8 am to avoid circadian rhythm confounds. The Vacutainer® Safety-Lok TM Blood Collection Set and SST TM Tubes with Silica Clot Activator (Beckton, Dickinson & Company) from clinical suppliers certified as medical products (Sarstedt system) will be used to perform the blood draw. Immediately after collection serum samples will be centrifuged for 10 min at 1000 g, and then aliquoted in 8 cryovials of 250 µl each and then stored at -80°C. Serum parameters will be analyzed by ELISA (enzyme-linked immunoarbsorbat assay) kits (R&D Systems GmbH, Wiesbaden, Germany / IBL International GmbH, Hamburg, Germany). Cortisol will be determined from morning collections of saliva specimens, which will be collected by chewing on a salivette for approximately 3 minutes until it is soaked (Salivette; Sarsted, Rommelsdorf, Germany). Samples are immediately centrifuged at 1500 g for 15 min, and will then be stored at –80°C until shipping to Germany. Samples are analyzed for free cortisol by ELISA in accordance with the manufacturer’s instructions (IBL International GmbH, Hamburg, Germany). On the same days as blood draws, we will gather 24 h ECG data (e.g., with the eMotion FAROS sensor (Mega Electronics Ltd., Kuopio, Finland) to derive heart rate and heart rate variability measures as a peripheral index of emotion regulatory processes that are affected by prefrontal mechanisms.

Analysis will encompass the biological basis of social support to assess individual sociability and the neurobehavioral contributions to resiliency and/or adaptability of engaging positively in social interactions, tolerance, and awareness (e.g., affiliation, attachment). Cellular and molecular biomarkers related to social systems (e.g., oxytocin) will reveal changes in the underlying neurobiological systems as a function of social support, before, during, and after being in an ICC/ICE environment. Individual differences in indicators of resilience measured before isolation will predict reported loneliness, higher perceived social support, and healthier social neurobiological systems. Individual differences in emotional regulation will provide the most robust evidence for how the neural circuitry moves up to behavior and social processes in self-report and interactions as well as downward toward cellular/molecular biomarkers (e.g., cortisol, BDNF, oxytocin, etc) with structural changes revealed by the fMRI.

Biomarkers of human performance optimization (Dr. Nindl’s Lab) will be tested prospectively within the Neumayer ICE analog. The extensive biomarker panel, analyzed in three separate isolation analogs, will provide insight to the most pertinent biological signatures of resiliency. This information will help guide the down-selection of biomarkers used in the selection of astronauts mostly likely to maintain health and performance in long-duration exploration missions.

During the Definition Phase of this NSCOR project (10/5/17-4/5/18), a literature review was conducted to select and adapt questionnaires. Selected questionnaires will be administered as screening measures (administered pre-mission), characterization measures (administered pre/post-mission), and/or state-based measures (administered in-mission).

The refinement of the biological biomarkers to be measured by blood, saliva, and urine (as funding permits) and refinement of questionnaires to be administered are vital to prepare for the Study Campaigns in each human analog (Neumayer, ICARUS, and HERA). Furthermore, the Meaningfulness of Work Battery that will be implemented in the analogs is crucial for Specific Aim 4.

References

Lin, F., J. Suhr, S. Diebold, and K.L. Heffner, Associations between depressive symptoms and memory deficits vary as a function of insulin-like growth factor (IGF-1) levels in healthy older adults. Psychoneuroendocrino, 2014. 42: p. 118-123

Beste, C., Baune, B. T., Falkenstein, M., & Konrad, C. (2010). Variations in the TNF-a gene (TNF-a-308G-->A) affect attention and action selection mechanisms in a dissociated fashion. Journal of neurophysiology, 104(5), 2523-2531

Hodes, G. E., Pfau, M. L., Leboeuf, M., Golden, S. A., Christoffel, D. J., Bregman, D., ... & Labonté, B. (2014). Individual differences in the peripheral immune system promote resilience versus susceptibility to social stress. Proceedings of the National Academy of Sciences, 111(45), 16136-16141

van Zuiden, M., Kavelaars, A., Vermetten, E., Olff, M., Geuze, E., & Heijnen, C. (2015). Pre-deployment differences in glucocorticoid sensitivity of leukocytes in soldiers developing symptoms of PTSD, depression or fatigue persist after return from military deployment. Psychoneuroendocrinology, 51, 513-524

Valkanova, V., Ebmeier, K. P., & Allan, C. L. (2013). CRP, IL-6 and depression: a systematic review and meta-analysis of longitudinal studies. Journal of affective disorders, 150(3), 736-744