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Background: Postpartum maternal distress has been associated with adverse infant outcomes. A potential pathway of how maternal distress affects infant outcomes could be alterations in maternal caregiving behavior. However, the associations between maternal distress, caregiving behavior, and infant outcomes have never been tested in a controlled experiment. This preregistered study utilized an experimental design to investigate the effects of an acute maternal stressor on infant cortisol and crying and the possible mediating role of maternal caregiving behavior., Methods: Mother-infant dyads (N = 91) participated in a lab visit at 8 weeks postpartum, where mothers were separated from their infants to either perform a Trier Social Stress Test (TSST) or a control task. The task was immediately followed by a mother-infant interaction to assess maternal caregiving behavior and infant cortisol and crying., Results: Our structural equation model found no differences between conditions (stressor/control) on maternal caregiving behavior and infant response to maternal stress. Secondary findings revealed that higher quality of maternal caregiving behavior was related to lower levels of infant crying and lower cortisol levels at the end of the visit, but not cortisol at reunion., Conclusions: Our findings do not support the occurrence of mother-infant stress contagion in this experimental setting but do indicate a link between maternal caregiving behavior and infant behavioral and cortisol responses. Given the high prevalence of maternal mental health problems and their possible negative association with offspring development, further (experimental) research is needed to understand just how maternal postpartum distress affects young infants., (© 2025 The Author(s). Journal of Child Psychology and Psychiatry published by John Wiley & Sons Ltd on behalf of Association for Child and Adolescent Mental Health.)

Aside from stressors that each of us experience directly, we also share the stress of the people around us. Such empathic stress exists on psychological and physiological levels, including subjective, sympathetic, parasympathetic and endocrine activation. The objective of this review is to offer an overview of methodology over the past fifteen years of empathic stress research and derive practical considerations for future research endeavors in the field. We used a keyword search strategy in the databases Web of Science, PsycInfo and PubMed to find empathic stress studies published until December 2023, and included 17 studies into our review. The reviewed laboratory studies provide initial yet consistent evidence for the existence of empathic stress across different populations, in intimate and stranger dyads, with direct and virtual contact, across multiple levels of the stress system, and based on diverse statistical analysis methods. We discuss all findings and derive practical considerations for future empathic stress research. The diversity of methods established provides a solid foundation upon which future studies can expand., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The observation of a stressed individual can trigger a stress response in a passive observer. Little is known about the mechanisms of this so-termed empathic stress, including the observer's empathic involvement with the stressful situation. In 108 opposite-sex stranger dyads, we expected to increase the observer's empathic involvement with a stressed target performing a standardized laboratory stressor (Trier Social Stress Test, TSST; Kirschbaum et al., 1993) by exposing observers themselves to the TSST one week earlier. Conversely, we intended to decrease empathic involvement by granting observers a powerful position over the targets (by asking them to evaluate the targets' TSST performance and allegedly decide on their financial compensation). A control group without any manipulation was also included. In the preregistered data analysis, two types of empathic stress were investigated: vicarious stress, which evolves irrespective of the target's stress response, and stress resonance, which is proportional to the target's stress response. Irrespective of manipulation, observers exhibited vicarious stress in subjective and high-frequency heart rate variability (HF-HRV), and synchronized with the targets' stress reactivity in cortisol release. Prior TSST experience unexpectedly decreased observers' self-reported empathy and vicarious cortisol stress reactivity. The power manipulation, conversely, led to stronger observer vicarious stress in overall heart rate and HF-HRV reactivity. Based on Wondra and Ellsworth's (2015) appraisal theory, we propose that, due to their prior stressor exposure, observers habituated to said stressor, and consequently changed their evaluation of the target's stressful situation. In contrast, observers in the powerful position may have felt responsible for the targets, triggering a stronger vicarious stressful experience., Competing Interests: Declaration of competing interest None., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Social environments modulate endocrine function, yet it is unclear whether individuals can become like their social partners in how they physiologically respond to stressors. This social transmission of hypothalamic-pituitary-adrenal (HPA) axis reactivity could have long-term consequences for health and lifespan of individuals if their social partners react to stressors with an exaggerated HPA axis response. We tested whether glucocorticoid levels in response to stress of breeding partners changes after breeding depending on whether partners had similar or dissimilar postnatal conditions. We manipulated postnatal conditions by mimicking early life stress in zebra finch chicks (Taeniopygia guttata) via postnatal corticosterone exposure. When they reached adulthood, we created breeding pairs where the female and male had experienced either the same or different early life hormonal treatment (corticosterone or control). Before and after breeding, we obtained blood samples within 3 min and after 10 min or 30 min of restraint stress (baseline, cort10, cort30). We found that corticosterone levels of individuals in response to restraint were affected by their own and their partner's early life conditions, but did not change after breeding. However, across all pairs, partners became more similar in cort30 levels after breeding, although differences between partners in cort10 remained greater in pairs with a corticosterone-treated female. Thus, we show that HPA axis response to stressors in adulthood can be modulated by reproductive partners and that similarity between partners is reduced when females are postnatally exposed to elevated glucocorticoids., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Rodents are sensitive to the emotional state of conspecifics. While the presence of affiliative social partners mitigates the physiological response to stressors (buffering), the partners of stressed individuals show behavioral and endocrine changes indicating that stress parameters can be transmitted across the group members (contagion). In this study, we investigated the social contagion/buffering phenomena in behavior and neuroendocrine mechanisms after exposure to chronic stress, in groups of rats living in the PhenoWorld (PhW). Three groups were tested (8 stressed rats, 8 unstressed rats, and a mixed group with 4 and 4) and these were analyzed under 4 conditions: stressed (pure stress group, n = 8), unstressed (naive control group, n = 8), stressed from mixed group (stressed companion group, n = 8), unstressed from mixed group (unstressed companion group, n = 8. While naive control animals remained undisturbed, pure stress group animals were all exposed to stress. Half of the animals under the mixed-treatment condition were exposed to stress (stressed companion group) and cohabitated with their unstressed partners (unstressed companion group). We confirmed the well-established chronic unpredictable stress (CUS) effects in physiological, behavioral, and neuroendocrine endpoints; body weight gain, open arm entries and time in EPM, and oxytocin receptor expression levels in the amygdala decreased by stress exposure, whereas adrenal weight was increased by stress. Furthermore, we found that playing, rearing and solitary resting behaviors decreased, whereas huddling behavior increased by CUS. In addition, we detected significant increases (stress-buffering) in body weight gain and huddling behaviors between pure stress and stress companion animals, and significant stress contagion effects in emotional behavior and oxytocin receptor expression levels between naive control and control companion groups. Hence, we demonstrate buffering and contagion effects were evident in physiological parameters, emotional behaviors, and social home-cage behaviors of rats and we suggest a possible mediation of these effects by oxytocin neurotransmission. In conclusion, the results herein suggest that the stress status of animals living in the same housing environment influences the behavior of the group., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Background & Objectives: Existing research indicates that not only own stress leads to physiological stress reactions, but also observing stress in others. So far, a standardized paradigm to reliably induce physiological stress contagion based on direct face-to-face stress observation compared to an active placebo-stress observing control condition is lacking. Here, we tested a standardized randomized placebo-controlled experimental paradigm to investigate physiological reactivity to direct stress observation and characterized the stress contagion response of the major endocrine stress systems, including full reactivity kinetics., Methods: Healthy young male participants were randomly assigned to (1) undergo an adapted version of the Trier Social Stress Test ("TSST participants", n = 20), (2) observe it ("stress observers", n = 36), or (3) observe a corresponding placebo-stress control condition ("placebo-stress observers", n = 30). We repeatedly assessed heart rate, salivary alpha-amylase, salivary cortisol, and salivary aldosterone., Results: Stress observers exhibited greater physiological reactivity to stress observation as compared to placebo-stress observers to placebo-stress observation in heart rate, salivary alpha-amylase, and cortisol (p's ≤ .027), but not in aldosterone. We observed similar reactivity kinetics in TSST participants and stress observers but less pronounced in stress observers., Discussion: Extending previous literature, our findings indicate that independent of secondary effects of the observation setting, direct observation of stress in other individuals induces activation of the hypothalamus-pituitary-adrenal axis and the sympathetic-adrenal-medullary axis. Moreover, the physiological stress contagion response resembles the physiological reactivity to first-hand stress but is less pronounced. Potential implications of physiological stress contagion regarding health, cognition, or behavior, as well as modulating factors need to be further elucidated., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to declare., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Experiencing early life adversity (ELA) alters stress physiology and increases the risk for developing psychiatric disorders. The social environment can influence dynamics of stress responding and buffer and/or transfer stress across individuals. Yet, the impact of ELA on sensitivity to the stress of others and social behavior following stress is unknown. Here, to test the impact of ELA on social and physiological responses to stress, circulating blood corticosterone (CORT) and social behaviors were assessed in adult male and female mice reared under limited bedding and nesting (LBN) or control conditions. To induce stress, one cagemate of a pair-housed cage underwent a footshock paradigm and was then returned to their unshocked partner. CORT was measured in both groups of mice 20 or 90 min after stress exposure, and social behaviors were recorded and analyzed. ELA rearing influenced the CORT response to stress in a sex-specific manner. In males, both control and ELA-reared mice exhibited similar stress transfer to unshocked cagemates and similar CORT dynamics. In contrast, ELA females showed a heightened stress transfer to unshocked cagemates, and sustained elevation of CORT relative to controls, indicating enhanced stress contagion and a failure to terminate the stress response. Behaviorally, ELA females displayed decreased allogrooming and increased investigative behaviors, while ELA males showed reduced huddling. Together, these findings demonstrate that ELA influenced HPA axis dynamics, social stress contagion and social behavior. Further research is needed to unravel the underlying mechanisms and long-term consequences of ELA on stress systems and their impact on behavioral outcomes., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Occupational stress has immense economic and health-related consequences for individuals, organizations, and societies. In this context, the question of whether and how stress among managers transmits to their subordinates is highly interesting, yet not profoundly researched. This study aims to empirically investigate the effect of manager occupational stress on the development of subordinate stress and for how long such effects last in time. We exploit a unique panel dataset based on three different surveys among employees from a large Danish municipality, covering 5,688 employees and their 473 immediate managers between 2016 and 2020. We analyze this data using a fixed effects estimator with clustered robust standard errors, allowing us to significantly reduce potential endogeneity issues. The study shows that managers do in fact 'transmit' stress onto their employees, that the relationship is detectable a full year after the initial transmission of stress occurred, and that such an effect fades within additional two years. Our study serves to emphasize the great importance of the psychosocial wellbeing of managers as 'nerve centers' for entire job teams and urges organizations to treat stress among personnel on management levels with a high degree of concern., (© 2022. The Author(s).)

The stress systems are powerful mediators between the organism's systemic dynamic equilibrium and changes in its environment beyond the level of anticipated fluctuations. Over- or under-activation of the stress systems' responses can impact an animal's health, survival and reproductive success. While physiological stress responses and their influence on behaviour and performance are well understood at the individual level, it remains largely unknown whether-and how-stressed individuals can affect the stress systems of other group members, and consequently their collective behaviour. Stressed individuals could directly signal the presence of a stressor (e.g. via an alarm call or pheromones), or an acute or chronic activation of the stress systems could be perceived by others (as an indirect cue) and spread via social contagion. Such social transmission of stress responses could then amplify the effects of stressors by impacting social interactions, social dynamics and the collective performance of groups. As the neuroendocrine pathways of the stress response are highly conserved among vertebrates, transmission of physiological stress states could be more widespread among non-human animals than previously thought. We therefore suggest that identifying the extent to which stress transmission modulates animal collectives represents an important research avenue.

Physiological synchrony (PS) is defined as the co-occurrence and interdependence of physiological activity between interaction partners. Previous research has uncovered numerous influences on the extent of PS, such as relationship type or individual characteristics. Here, we investigate the influence of acute stress on PS. We do so in a setting in which PS was not promoted, but contact between group members was explicitly minimized. We reanalyzed cortisol, alpha-amylase, and subjective stress data from 138 participants (mean age = [Formula: see text], 47.1% female) who previously underwent the Trier Social Stress Test for groups (TSST-G) or a non-stressful control task together, collected as part of a larger project by Popovic et al. (Sci Rep 10: 7845, 2020). Using a stability and influence model, an established method to test for synchrony, we tested whether individuals' cortisol and alpha-amylase concentrations could be predicted by group members' levels. We found cortisol PS in participants who were in the same group, the extent of which was stronger in the non-stressful control condition. For alpha-amylase, participants were synchronized as well; furthermore, there was an interaction between previous stress levels and PS. This suggests that while synchrony of both stress markers can occur in group settings even with spurious interaction, stressor exposure might attenuate its extent. We argue that if PS occurs in a sample where interaction was minimal, the phenomenon might be more widespread than previously thought. Furthermore, stressor exposure might influence whether a situation allows for PS. We conclude that PS should be investigated within group settings with various degrees of social interaction to further expose mechanisms of and influence on PS., (© 2021. The Author(s).)

In the wake of the massive Canadian wildfire of May 2016 in the area of Fort McMurray Alberta, we observed increased rates of mental health problems, particularly post-traumatic stress disorder (PTSD), in school-aged adolescents (ages 11-19). Surprisingly, we did not see these rates decline over the 3.5-year follow-up period. Additionally, our research suggested that the impact of this mass incident resulted in other unanticipated effects, including the finding that children who were not present for and relatively unaffected by the wildfire showed a similar PTSD symptom profile to children more directly involved, suggesting some degree of spillover or stress contagion. A potential explanation for these high rates in individuals who were not present could be undiagnosed retraumatization in some of the students. To investigate this possibility, we compared two groups of students: those who reported the wildfire as their most significant trauma ( n = 740) and those who had their most significant trauma prior to the wildfire ( n = 295). Those with significant pre-existing trauma had significantly higher rates of both depression and PTSD symptoms, although, unexpectedly the groups exhibited no differences in anxiety level. Taken together, this evidence suggests retraumatization is both longer-lasting and more widespread than might be predicted on a case-by-case basis, suggesting the need to reconceptualize the role of past trauma history in present symptomatology. These findings point to the need to recognize that crises instigated by natural disasters are mass phenomena which expose those involved to numerous unanticipated risks. New trauma-informed treatment approaches are required that incorporate sensitivity to the collective impact of mass crises, and recognize the risk of poorer long-term mental health outcomes for those who experienced trauma in the past., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Pazderka, Brown, Agyapong, Greenshaw, McDonald-Harker, Noble, Mankowski, Lee, Drolet, Omeje, Brett-MacLean, Kitching and Silverstone.)

Theories such as social baseline theory have argued that social groups serve a regulatory function but have not explored whether this regulatory process carries costs for the group. Allostatic load, the wear and tear on regulatory systems caused by chronic or frequent stress, is marked by diminished stress system flexibility and compromised recovery. We argue that allostatic load may develop within social groups as well and provide a model for how relationship dysfunction operates. Social allostatic load may be characterized by processes such as groups becoming locked into static patterns of interaction and may ultimately lead to up-regulation or down-regulation of a group's set point, or the optimal range of arousal or affect around which the group tends to converge. Many studies of emotional and physiological linkage within groups have reported that highly correlated states of arousal, which may reflect failure to maintain a group-level regulatory baseline, occur in the context of stress, conflict, and relationship distress. Relationship strain may also place greater demands on neurocognitive regulatory processes. Just as allostatic load may be detrimental to individual health, social allostatic load may corrode relationship quality.

Observing another person in a stressful situation can cause a full-blown physiological stress response in the observer, which is referred to as empathic stress. One way through which stress-related information might be transmitted between individuals under conditions of empathic stress is chemosensory communication. In the present study, we investigated whether the odorant Hedione, as a potential chemosignal, affects the empathic stress response at a physiological and psychological level. For this purpose, two experiments were designed, each testing one group of participants in an odor-free room and a second group in a room scented with Hedione. In Experiment 1, 60 participants (25 males) watched a video of an unknown female participant in the Trier Social Stress Test (TSST). In Experiment 2, 37 free-cycling females watched a live video of a male participant in the TSST. Observers' psychological and physiological stress response was captured via repeated measurements of salivary cortisol, alpha-amylase, and self-report ratings. Empathy with the stressed participants was assessed on the dimensions of personal distress and empathic concern of the Emotional Response Scale (ERS). Our results show no substantial physiological stress response in the observers and no effect of Hedione on physiological stress measures. Further, in Experiment 1, there was no subjective stress elicited by the video and no effect of Hedione. In Experiment 2, the observation was perceived as stressful and Hedione reduced subjective vicarious stress. The subjective stress response was associated with the Observers' direct personal distress, but not with their empathic concern for the target in both experiments. Based on the findings presented above, we conclude that under conditions of empathic stress, Hedione alleviates subjectively perceived stress felt when observing another person being stressed, while leaving empathic concern for the target unaffected. In this regard, future research is warranted to clarify the underlying mechanisms of this effect., (Copyright © 2020 Pützer, Brüne, Hatt and Wolf.)

For many African American youth, the joint influences of economic and racial marginalization render the transition to stable adult roles challenging. We have gained much insight into how these challenges affect future life chances, yet we lack an understanding of what these challenges mean in the context of linked lives. Drawing on a life course framework, this study examines how young African Americans' experiences across a variety of salient domains during the transition to adulthood affect their mothers' health. Results suggest that stressors experienced by African Americans during the transition to adulthood (e.g., unemployment, troubled romantic relationships, arrest) heighten their mothers' cumulative biological risk for chronic diseases, or allostatic load, and reduce subjective health. These results suggest that the toll of an increasingly tenuous and uncertain transition to adulthood extends beyond young people to their parents. Hence, increased public investments during this transition may not only reduce inequality and improve life chances for young people themselves, but may also enhance healthy aging by relieving the heavy burden on parents to help their children navigate this transition.