Beyond allostatic load: Rethinking the role of stress in regulating human development

Effects of acute psychosocial stress on interpersonal cooperation and competition in young women

Although tend-and-befriend is believed to be the dominant stress response in women, little is known regarding the effects of acute psychosocial stress on different dynamic social interactions. To measure these effects, 80 female participants were recruited, paired into the dyads, and instructed to complete cooperative and competitive key-pressing tasks after experiencing acute stress or a control condition. Each dyad of participants should press the key synchronously when the signal was presented in the cooperative task and as fast as possible in the competitive task. During the tasks, brain activities of prefrontal and right temporo-parietal areas were recorded from each dyad using functional near-infrared spectroscopy (fNIRS). The results showed that acute psychosocial stress evidently promoted competitive behavior, accompanied by increased interpersonal neural synchronization (INS) in the right dorsolateral prefrontal cortex. Despite the lack of a significant difference in the overall cooperation rate, the response time difference between two stressed participants markedly declined over time with more widespread INS in the prefrontal cortex, suggesting that there ensued cooperative improvement among stressed women. These findings behaviorally and neurologically revealed context-dependent response patterns to psychosocial stress in women during dynamic social interactions.

Neural meaning making, prediction, and prefrontal-subcortical development following early adverse caregiving

Early adversities that are caregiving-related (crEAs) are associated with a significantly increased risk for mental health problems. Recent neuroscientific advances have revealed alterations in medial prefrontal cortex (mPFC)-subcortical circuitry following crEAs. While this work has identified alterations in affective operations (e.g., perceiving, reacting, controlling, learning) associated with mPFC-subcortical circuitry, this circuitry has a much broader function extending beyond operations. It plays a primary role in affective meaning making, involving conceptual-level, schematized knowledge to generate predictions about the current environment. This function of mPFC-subcortical circuitry motivates asking whether mPFC-subcortical phenotypes following crEAs support semanticized knowledge content (or the concept-level knowledge) and generate predictive models. I present a hypothesis motivated by research findings across four different lines of work that converge on mPFC-subcortical neuroanatomy, including (a) the neurobiology supporting emotion regulation processes in adulthood, (b) the neurobiology that is activated by caregiving cues during development, (c) the neurobiology that is altered by crEAs, and (d) the neurobiology of semantic-based meaning making. I hypothesize that the affective behaviors following crEAs result in part from affective semantic memory processes supported by mPFC-subcortical circuitry that over the course of development, construct affective schemas that generate meaning making and guide predictions. I use this opportunity to review some of the literature on mPFC-subcortical circuit development following crEAs to illustrate the motivation behind this hypothesis. Long recognized by clinical science and cognitive neuroscience, studying schema-based processes may be particularly helpful for understanding how affective meaning making arises from developmental trajectories of mPFC-subcortical circuitry.

Illness, Social Disadvantage, and Sexual Risk Behavior in Adolescence and the Transition to Adulthood

This study investigated the influence of illness on sexual risk behavior in adolescence and the transition to adulthood, both directly and through moderation of the impact of social disadvantage. We hypothesized positive effects for social disadvantages and illness on sexual risk behavior, consistent with the development of faster life history strategies among young people facing greater life adversity. Using the first two waves of the National Longitudinal Study of Adolescent to Adult Health, we developed a mixed-effects multinomial logistic regression model predicting sexual risk behavior in three comparisons: risky nonmonogamous sex versus safer nonmonogamous sex, versus monogamous sex, and versus being sexually inactive, by social characteristics, illness, interactions thereof, and control covariates. Multiple imputation was used to address a modest amount of missing data. Subjects reporting higher levels of illness had lower odds of having safer nonmonogamous sex (OR = 0.84, p < .001), monogamous sex (OR = 0.82, p < .001), and being sexually inactive (OR = 0.74, p < .001) versus risky nonmonogamous sex, relative to subjects in better health. Illness significantly moderated the sex (OR = 0.88, p < .01), race/ethnicity (e.g., OR = 1.21, p < .001), and childhood SES (OR = 0.94; p < .01) effects for the sexually inactive versus risky nonmonogamous sex comparison. Substantive findings were generally robust across waves and in sensitivity analyses. These findings offer general support for the predictions of life history theory. Illness and various social disadvantages are associated with increased sexual risk behavior in adolescence and the transition to adulthood. Further, analyses indicate that the buffering effects of several protective social statuses against sexual risk-taking are substantially eroded by illness.

Can some microbes promote host stress and benefit evolutionarily from this strategy?

Microbes can influence host physiology and behavior in many ways. Here we review evidence suggesting that some microbes can contribute to host stress (and other microbes can contribute to increased resilience to stress). We explain how certain microbes, which we call "stress microbes," can potentially benefit evolutionarily from inducing stress in a host, gaining access to host resources that can help fuel rapid microbial replication by increasing glucose levels in the blood, increasing intestinal permeability, and suppressing the immune system. Other microbes, which we term "resilience microbes," can potentially benefit from making hosts more resilient to stress. We hypothesize that "stress microbes" use a fast life history strategy involving greater host exploitation while "resilience microbes" use a slow life history strategy characterized by more aligned evolutionary interests with the host. In this paper, we review the evidence that microbes affect host stress and explain the evolutionary pressures that could lead microbes to manipulate host stress, discuss the physiological mechanisms that are known to be involved in both stress and microbial activity, and provide some testable predictions that follow from this hypothesis.

Biological sensitivity to context: A test of the hypothesized U-shaped relation between early adversity and stress responsivity

We conducted signal detection analyses to test for curvilinear, U-shaped relations between early experiences of adversity and heightened physiological responses to challenge, as proposed by biological sensitivity to context theory. Based on analysis of an ethnically diverse sample of 338 kindergarten children (4-6 years old) and their families, we identified levels and types of adversity that, singly and interactively, predicted high (top 25%) and low (bottom 25%) rates of stress reactivity. The results offered support for the hypothesized U-shaped curve and conceptually replicated and extended the work of Ellis, Essex, and Boyce (2005). Across both sympathetic and adrenocortical systems, a disproportionate number of children growing up under conditions characterized by either low or high adversity (as indexed by restrictive parenting, family stress, and family economic condition) displayed heightened stress reactivity, compared with peers growing up under conditions of moderate adversity. Finally, as hypothesized by the adaptive calibration model, a disproportionate number of children who experienced exceptionally stressful family conditions displayed blunted cortisol reactivity to stress.

Association of Early-Life Adversity With Measures of Accelerated Biological Aging Among Children in China

IMPORTANCE

A growing body of literature suggests that exposure to early-life adversity (ELA) is associated with accelerated biological aging, offering 1 mechanism through which ELA may be associated with an increased risk for age-related disease. These investigations, however, have been predominantly cross-sectional and focused on adults and females.

OBJECTIVE

To evaluate associations of threat-related (ie, physical abuse) and deprivation-related (ie, emotional neglect) ELA exposure with cellular and reproductive strategy metrics of biological aging among boys and girls with specific genetic backgrounds around the period of pubertal onset.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study, 997 boys and girls in grade 1 to grade 3 from 3 large elementary schools were recruited from Bengbu, Anhui Province, China, and were followed up from March 21, 2016 (baseline; wave 1), for 4 consecutive years, through March 25, 2019.

MAIN OUTCOMES AND MEASURES

The outcome was accelerated biological aging in both cellular and reproductive strategy metrics: telomere attrition and age at thelarche (for girls) and testicular maturation (for boys). Multi-informant assessment of exposure to threat-related and deprivation-related ELA was done at baseline (wave 1) and 1-year follow-up (wave 2). The polygenic risk score (PRS) was computed based on 17 single-nucleotide variations for early pubertal timing.

RESULTS

Of the 997 participants (579 girls [58.1%]; mean [SD] age at baseline, 8.0 [0.8] years), 550 (55.2%) reported exposure to threat-related ELA and 443 (44.4%) reported exposure to deprivation-related ELA. Threat-related ELA was associated with onset of thelarche 2.6 months earlier and deprivation-related ELA with onset of thelarche 3.3 months earlier in exposed girls than in unexposed peers; these associations were observed only among girls with a low PRS. Among boys, a similar pattern was found. Threat-related ELA was associated with testicular volume of 4 mL or more 1.4 months earlier and deprivation-related ELA was associated with testicular volume of 4 mL or more 2.3 months earlier than in unexposed peers but only among those with a low PRS. Boys and girls with greater exposure to threats showed a significantly higher percentage of telomere length change during 1-year follow-up, but only among those with low PRS (boys: β = 1.50; 95% CI, 0.80-2.21; P < .001; girls: β = 2.40; 95% CI, 1.78-3.05; P < .001) and moderate PRS (boys: β = 1.09; 95% CI, 0.43-1.75; P = .001; and girls: β = 1.27; 95% CI, 0.77-1.77; P < .001). No associations of deprivation-related ELA with percentage of telomere length change were found.

CONCLUSIONS AND RELEVANCE

This study suggests that the accelerating association of ELA with biological aging might occur at an earlier age and in a genetic background-dependent and dimension-specific manner.

Early external-environmental and internal-health predictors of risky sexual and aggressive behavior in adolescence: An integrative approach

External predictive adaptive response (PAR) models assume that developmental exposures to stress carry predictive information about the future state of the environment, and that development of a faster life history (LH) strategy in this context functions to match the individual to this expected harsh state. More recently internal PAR models have proposed that early somatic condition (i.e., physical health) critically regulates development of LH strategies to match expected future somatic condition. Here we test the integrative hypothesis that poor physical health mediates the relation between early adversity and faster LH strategies. Data were drawn from a longitudinal study (birth to age 16; N = 1,388) of mostly African American participants with prenatal substance exposure. Results demonstrated that both external environmental conditions early in life (prenatal substance exposure, socioeconomic adversity, caregiver distress/depression, and adverse family functioning) and internal somatic condition during preadolescence (birthweight/gestational age, physical illness) uniquely predicted the development of faster LH strategies in adolescence (as indicated by more risky sexual and aggressive behavior). Consistent with the integrative hypothesis, the effect of caregiver distress/depression on LH strategy was mostly mediated by worse physical health. Discussion highlights the implications of these findings for theory and research on stress, development, and health.

Chronic stress, executive functioning, and real-life self-control: An experience sampling study

OBJECTIVE

To test the hypothesis that chronic stress impairs the use of cognitive control for self-control, we examined how chronic stress affects the relation between individual differences in general executive functioning (GEF) and self-control in real-life situations.

METHOD

About 338 young adults with varying degrees of chronic stress underwent experience sampling of real-life self-control for 7 days and completed a battery of nine executive function tasks from which a latent variable representing individual differences in GEF was derived.

RESULTS

Structural equation models showed that higher levels of chronic stress were associated with stronger desires and a less negative relationship between GEF and desire strength. Chronic stress and GEF did not predict desire enactment in situations where effortful resistance was attempted.

CONCLUSIONS

These findings suggest that chronic stress may impair self-control by reducing the use of cognitive control for "early" desire regulation strategies while leaving "late" resistance strategies unaffected. That relationships between executive functioning and real-life self-control can be moderated by third factors such as chronic stress may to some extent explain the common finding of weak or missing associations between laboratory measures of executive functioning and real-life self-control.

Molecular and cellular mechanisms underlying the pathogenesis of Alzheimer's disease

Alzheimer’s disease (AD) is the most common neurodegenerative disorder seen in age-dependent dementia. There is currently no effective treatment for AD, which may be attributed in part to lack of a clear underlying mechanism. Studies within the last few decades provide growing evidence for a central role of amyloid β (Aβ) and tau, as well as glial contributions to various molecular and cellular pathways in AD pathogenesis. Herein, we review recent progress with respect to Aβ- and tau-associated mechanisms, and discuss glial dysfunction in AD with emphasis on neuronal and glial receptors that mediate Aβ-induced toxicity. We also discuss other critical factors that may affect AD pathogenesis, including genetics, aging, variables related to environment, lifestyle habits, and describe the potential role of apolipoprotein E (APOE), viral and bacterial infection, sleep, and microbiota. Although we have gained much towards understanding various aspects underlying this devastating neurodegenerative disorder, greater commitment towards research in molecular mechanism, diagnostics and treatment will be needed in future AD research.

Hidden talents in harsh environments

Although early-life adversity can undermine healthy development, children growing up in harsh environments may develop intact, or even enhanced, skills for solving problems in high-adversity contexts (i.e., “hidden talents”). Here we situate the hidden talents model within a larger interdisciplinary framework. Summarizing theory and research on hidden talents, we propose that stress-adapted skills represent a form of adaptive intelligence that enables individuals to function within the constraints of harsh, unpredictable environments. We discuss the alignment of the hidden talents model with current knowledge about human brain development following early adversity; examine potential applications of this perspective to multiple sectors concerned with youth from harsh environments, including education, social services, and juvenile justice; and compare the hidden talents model with contemporary developmental resilience models. We conclude that the hidden talents approach offers exciting new directions for research on developmental adaptations to childhood adversity, with translational implications for leveraging stress-adapted skills to more effectively tailor education, jobs, and interventions to fit the needs and potentials of individuals from a diverse range of life circumstances. This approach affords a well-rounded view of people who live with adversity that avoids stigma and communicates a novel, distinctive, and strength-based message.

Family Environment, Neurodevelopmental Risk, and the Environmental Influences on Child Health Outcomes (ECHO) Initiative: Looking Back and Moving Forward

The family environment, with all its complexity and diverse components, plays a critical role in shaping neurodevelopmental outcomes in children. Herein we review several domains of the family environment (family socioeconomic status, family composition and home environment, parenting behaviors and interaction styles, parental mental health and functioning, and parental substance use) and discuss how these domains influence neurodevelopment, with particular emphasis on mental health outcomes. We also highlight a new initiative launched by the National Institutes of Health, the Environmental influences on Child Health Outcomes (ECHO) program. We discuss the role that ECHO will play in advancing our understanding of the impact of the family environment on children's risk for psychiatric outcomes. Lastly, we conclude with important unanswered questions and controversies in this area of research, highlighting how ECHO will contribute to resolving these gaps in our understanding, clarifying relationships between the family environment and children's mental health.

Childhood Maltreatment and Impulsivity: A Meta-Analysis and Recommendations for Future Study

Both childhood maltreatment and impulsivity have been implicated in a broad array of negative public health outcomes and have been much studied in relation to each other. Characterizing this relationship, and the processes underlying it, are important for informing intervention efforts targeting this association and its psychopathological sequelae. The current review presented a systematic meta-analysis of the empirical literature on childhood maltreatment and impulsivity. In all, 55 eligible studies were identified and included in this review. General support was found for a positive association between childhood maltreatment, including its specific subtypes, and general trait impulsivity, with pooled effect sizes ranging from small in the case of childhood sexual abuse (OR = 1.59 [95% CI = 1.38-1.84]) to medium-to-large in the case of childhood emotional abuse (OR = 3.10 [95% CI = 2.27-4.23]). Support for a relationship between childhood maltreatment and laboratory-based measures of impulsive behavior was generally lacking. The current findings must be interpreted with a degree of caution, given several methodological limitations characterizing much of the empirical literature. Recommendations for addressing these limitations and directions for future research are provided.

Synthesizing Views to Understand Sex Differences in Response to Early Life Adversity

Sex as a biological variable (SABV) is critical for understanding the broad range of physiological, neurobiological, and behavioral consequences of early life adversity(ELA). The study of the interaction of SABV and ELA ties into several current debates, including the importance of taking into account SABV in research, differing strategies employed by males and females in response to adversity, and the possible evolutionary and developmental mechanisms of altered development in response to adversity. This review highlights the importance of studying both sexes, of understanding sex differences (and similarities) in response to ELA, and provides a context for the debate surrounding whether the response to ELA may be an adaptive process.

Effortful Control Development in the Face of Harshness and Unpredictability

Using psychosocial acceleration theory, this multimethod, multi-reporter study examines how early adversity adaptively shapes the development of a self-regulation construct: effortful control. Investigation of links between early life harshness and unpredictability and the development of effortful control could facilitate a nuanced understanding of early environmental effects on cognitive and social development. Using the Building Strong Families national longitudinal data set, aspects of early environmental harshness and early environmental unpredictability were tested as unique predictors of effortful control at age 3 using multiple regression. Early harshness variables were financial harshness, mothers' and fathers' observed parenting, mothers' and fathers' reported use of harsh discipline, and harsh neighborhood conditions. Early unpredictability was measured by number of paternal transitions. Cues of harshness, specifically observed unresponsive parenting, observed harsh parenting, and neighborhood harshness, did significantly negatively predict effortful control. Paternal transitions also significantly predicted effortful control, but in the opposite (i.e., positive) direction. The results corroborate previous research linking quality of parenting to the development of children's effortful control and place it within an evolutionary-developmental theoretical framework. Further, the results suggest that neighborhood harshness may also direct developmental trajectories of effortful control in young children, though the mechanisms through which this occurs are still unclear. This is the first study to explicitly investigate effortful control development in early childhood within the harshness and unpredictability framework.

Cohort profile: the DANish LIFE course (DANLIFE) cohort, a prospective register-based cohort of all children born in Denmark since 1980

PURPOSE

The DANish LIFE course (DANLIFE) cohort is a prospective register-based study set up to investigate the complex life course mechanisms linking childhood adversities to health and well-being in childhood, adolescence and young adulthood including cumulative and synergistic actions and potentially sensitive periods in relation to health outcomes.

PARTICIPANTS

All children born in Denmark in 1980 or thereafter have successively been included in the cohort totalling more than 2.2 million children. To date, the study population has been followed annually in the nationwide Danish registers for an average of 16.8 years with full data coverage in the entire follow-up period. The information is currently updated until 2015.

FINDINGS TO DATE

DANLIFE provides information on a wide range of family-related childhood adversities (eg, parental separation, death of a parent or sibling, economic disadvantage) with important psychosocial implications for health and well-being in childhood, adolescence and young adulthood. Measurement of covariates indicating demographic (eg, age, sex), social (eg, parental education) and health-related factors (eg, birth weight) has also been included from the nationwide registers. In this cohort profile, we provide an overview of the childhood adversities and covariates included in DANLIFE. We also demonstrate that there is a clear social gradient in the exposure to childhood adversities confirming clustering of adverse experiences within individuals.

FUTURE PLANS

DANLIFE provides a valuable platform for research into early life adversity and opens unique possibilities for testing new research ideas on how childhood adversities affect health across the life course.

Early Environmental Unpredictability: Implications for Youth's Perceptions and Social Functioning

According to an evolutionary perspective, early environmental unpredictability induces expectations in youth that their future is uncertain and increases their likelihood of engaging in opportunistic, impulsive, and aggressive behaviors. Although considerable evidence supports the links between environmental unpredictability and such behaviors, less is known about how youth growing up in volatile environments actually perceive their lives and how these perceptions relate to their behavior. In this study, two samples of 10-17 year-olds, one with a history of maltreatment and removal from home (n = 90; 52% female; 67% Hispanic-American) and one without (n = 80; 54% female; 69% Hispanic-American), reported on their perceptions of unpredictability and social functioning. Maltreated youth endorsed greater perceptions of unpredictability than non-maltreated youth. For both groups, greater perceptions of unpredictability were associated with increased aggression and conduct problems and decreased prosociality. Findings advance understanding of a developmental pathway contributing to opportunistic and risky social behavior in youth.

The Evolution of Prosocial and Antisocial Competitive Behavior and the Emergence of Prosocial and Antisocial Leadership Styles

Evolutionary analysis focuses on how genes build organisms with different strategies for engaging and solving life's challenges of survival and reproduction. One of those challenges is competing with conspecifics for limited resources including reproductive opportunities. This article suggests that there is now good evidence for considering two dimensions of social competition. The first, has been labeled as antisocial strategies, to the extent that they tend to be self-focused, threat sensitive and aggressive, and use tactics of bulling, threatening, and intimidating subordinates, or even injuring/killing competitors. Such strategies can inhibit care and affiliative social interactions and motivation. The social signals emitted stimulate threat processing in recipients and can create stressed and highly stratified groups with a range of detrimental psychological and physiological effects. Second, in contrast, prosocial strategies seek to create relaxed and secure social interactions that enable sharing, cooperative, mutually supportive and beneficial relationships. The friendly and low/no threat social signals emitted in friendly cooperative and affiliative relationships stimulate physiological systems (e.g., oxytocin, the vagus nerve of the parasympathetic system) that downregulates threat processing, enhances the immune system, and facilitates frontal cortical processes and general wellbeing. This article reviews the literature pertaining to the evidence for these two dimensions of social engagement.

Impact of a social skills program on children's stress: A cluster randomized trial

BACKGROUND

Most preschool children in Western industrialized countries attend child care during the day while parents work. Studies suggest that child care may be stressful to young children, perhaps because they still lack the social skills to interact daily in a group setting away from parents. This gap in social abilities may be greater for children in lower-income families, who may face more adversity at home, with fewer resources and more social isolation.

METHODS

We conducted a cluster-randomized controlled trial in 2013-2014 to test whether a social skills intervention led by early childhood educators within the child care center could reduce diurnal cortisol levels to more typical patterns expected of children this age. We randomized 19 public child care centers (n = 361 children) in low-income neighborhoods of Montreal, Canada, to either: 1) the Minipally program - intervention group (n = 10 centers; 186 children), or 2) waiting list - control group (n = 9 centers; 175 children). Saliva samples for cortisol levels were collected 3 times/day, pre- and post-implementation. The Minipally puppet program consists of 2 workshops/month for 8 months for the development of social skills and self-regulation in 2-5-year-olds, with reinforcement activities between workshops. Educators received 2-days' training and 12 h' supervision in Minipally.

RESULTS

Linear mixed models for repeated measures revealed a significant interaction between intervention status and time of day of cortisol sampling (β = -0.18, p =  0.04). The intervention group showed patterns of decreasing diurnal cortisol secretion (β = -0.32, p < 0.01), whereas the control group showed increasing slopes (β = 0.20, p < 0.01). Moreover, family income was a moderator; children in lower-income families benefited most from the intervention.

CONCLUSION

Results suggest that a social skills training program, when integrated into a preschool education curriculum, can foster an environment more conducive to typical childhood patterns of cortisol secretion.

What Is Stress? A Systems Perspective

The term "stress" is used to describe important phenomena at multiple levels of biological organization, but finding a general and rigorous definition of the concept has proven challenging. Current models in the behavioral literature emphasize the cognitive aspects of stress, which is said to occur when threats to the organism are perceived as uncontrollable and/or unpredictable. Here we adopt the perspective of systems biology and take a step toward a general definition of stress by unpacking the concept in light of control theory. Our goal is to clarify the concept so as to facilitate integrative research and formal analysis. We argue that stress occurs when a biological control system detects a failure to control a fitness-critical variable, which may be either internal or external to the organism. Biological control systems typically include both feedback (reactive, compensatory) and feedforward (predictive, anticipatory) components; their interplay accounts for the complex phenomenology of stress in living organisms. The simple and abstract definition we propose applies to animals, plants, and single cells, highlighting connections across levels of organization. In the final section of the paper we explore some extensions of our approach and suggest directions for future research. Specifically, we discuss the classic concepts of conditioning and hormesis and review relevant work on cellular stress responses; show how control theory suggests the existence of fundamental trade-offs in the design of stress responses; and point to potential insights into the effects of novel environmental conditions, including those resulting from anthropogenic change.

Evolutionary and developmental mismatches are consequences of adaptive developmental plasticity in humans and have implications for later disease risk

A discrepancy between the phenotype of an individual and that which would confer optimal responses in terms of fitness in an environment is termed 'mismatch'. Phenotype results from developmental plasticity, conditioned partly by evolutionary history of the species and partly by aspects of the developmental environment. We discuss two categories of such mismatch with reference primarily to nutrition and in the context of evolutionary medicine. The categories operate over very different timescales. A developmental mismatch occurs when the phenotype induced during development encounters a different environment post-development. This may be the result of wider environmental changes, such as nutritional transition between generations, or because maternal malnutrition or placental dysfunction give inaccurate information about the organism's likely future environment. An evolutionary mismatch occurs when there is an evolutionarily novel environment. Developmental plasticity may involve immediate adaptive responses (IARs) to preserve survival if an environmental challenge is severe, and/or predictive adaptive responses (PARs) if the challenge does not threaten survival, but there is a fitness advantage in developing a phenotype that will be better adapted later. PARs can have long-term adverse health consequences if there is a developmental mismatch. For contemporary humans, maternal constraint of fetal growth makes PARs likely even if there is no obvious IAR, and this, coupled with the pervasive nutritionally dense modern environment, can explain the widespread observations of developmental mismatch, particularly in populations undergoing nutritional transition. Both developmental and evolutionary mismatch have important public health consequences and implications for where policy interventions may be most effective. This article is part of the theme issue 'Developing differences: early-life effects and evolutionary medicine'.

Ecological Stoichiometry: A Link Between Developmental Speed and Physiological Stress in an Omnivorous Insect

The elemental composition of organisms belongs to a suite of functional traits that may adaptively respond to fluctuating selection pressures. Life history theory predicts that predation risk and resource limitations impose selection pressures on organisms’ developmental time and are further associated with variability in energetic and behavioral traits. Individual differences in developmental speed, behaviors and physiology have been explained using the pace-of-life syndrome (POLS) hypothesis. However, how an organism’s developmental speed is linked with elemental body composition, metabolism and behavior is not well understood. We compared elemental body composition, latency to resume activity and resting metabolic rate (RMR) of western stutter-trilling crickets (Gryllus integer) in three selection lines that differ in developmental speed. We found that slowly developing crickets had significantly higher body carbon, lower body nitrogen and higher carbon-to-nitrogen ratio than rapidly developing crickets. Slowly developing crickets had significantly higher RMR than rapidly developing crickets. Male crickets had higher RMR than females. Slowly developing crickets resumed activity faster in an unfamiliar relative to a familiar environment. The rapidly developing crickets did the opposite. The results highlight the tight association between life history, physiology and behavior. This study indicates that traditional methods used in POLS research should be complemented by those used in ecological stoichiometry, resulting in a synthetic approach that potentially advances the whole field of behavioral and physiological ecology.

Early Life Stress Delays Sexual Maturation in Female Mice

In humans, some forms of early life stress (ELS) have been linked with precocious puberty, altered brain maturation, and increased risk for a variety of forms of pathology. Interestingly, not all forms of ELS have been found to equally impact these metrics of maturation. In recent work, we have found that ELS in the form of limited bedding (LB) from P4 to P11, was associated with precocious hippocampus maturation in males and increased risk for depressive-like pathology and attentional disturbance in female mice. Here, we sought to test whether ELS in the form of LB also impacted the timing of sexual maturation in female mice. To establish rate of somatic and sexual development, distinct cohorts of mice were tested for weight gain, timing of vaginal opening, and development of estrous cycling. ELS animals weighed significantly less than controls at every timepoint measured. Onset of vaginal opening was tracked from P21 to 40, and ELS was found to significantly delay the onset of vaginal opening. To test the impact of ELS on estrous cycle duration and regularity, vaginal cytology was assessed in independent groups of animals using either a continuous sampling (daily from P40 to P57) or random sampling approach (single swab at P35, P50, or P75). ELS did impact measures of estrous cycling, but these effects were dependent upon the sampling method used. We also tested the impact of ELS on anxiety-like behaviors over development and across the estrous cycle. We observed a developmental increase in anxiety-like behavior in control but not ELS mice. No effect of estrous cycle stage was found on anxiety-like behavior for either group of mice. Together these results provide evidence that ELS in the form of LB delays somatic and sexual development. Additional work will be required to determine the mechanism by which ELS impacts these measures, and if these effects are common to other models of ELS in rodents.

Early Experiences of Threat, but Not Deprivation, Are Associated With Accelerated Biological Aging in Children and Adolescents

BACKGROUND

Recent conceptual models argue that early life adversity (ELA) accelerates development, which may contribute to poor mental and physical health outcomes. Evidence for accelerated development in youths comes from studies of telomere shortening or advanced pubertal development following circumscribed ELA experiences and neuroimaging studies of circuits involved in emotional processing. It is unclear whether all ELA is associated with accelerated development across global metrics of biological aging or whether this pattern emerges following specific adversity types.

METHODS

In 247 children and adolescents 8 to 16 years of age with wide variability in ELA exposure, we evaluated the hypothesis that early environments characterized by threat, but not deprivation, would be associated with accelerated development across two global biological aging metrics: DNA methylation (DNAm) age and pubertal stage relative to chronological age. We also examined whether accelerated development explained associations of ELA with depressive symptoms and externalizing problems.

RESULTS

Exposure to threat-related ELA (e.g., violence) was associated with accelerated DNAm age and advanced pubertal stage, but exposure to deprivation (e.g., neglect, food insecurity) was not. In models including both ELA types, threat-related ELA was uniquely associated with accelerated DNAm age (β = .18) and advanced pubertal stage (β = .28), whereas deprivation was uniquely associated with delayed pubertal stage (β = -.21). Older DNAm age was related to greater depressive symptoms, and a significant indirect effect of threat exposure on depressive symptoms was observed through DNAm age.

CONCLUSIONS

Early threat-related experiences are particularly associated with accelerated biological aging in youths, which may be a mechanism linking ELA with depressive symptoms.

Developmental Adaptation to Stress: An Evolutionary Perspective

The assumption that early stress leads to dysregulation and impairment is widespread in developmental science and informs prevailing models (e.g., toxic stress). An alternative evolutionary–developmental approach, which complements the standard emphasis on dysregulation, proposes that early stress may prompt the development of costly but adaptive strategies that promote survival and reproduction under adverse conditions. In this review, we survey this growing theoretical and empirical literature, highlighting recent developments and outstanding questions. We review concepts of adaptive plasticity and conditional adaptation, introduce the life history framework and the adaptive calibration model, and consider how physiological stress response systems and related neuroendocrine processes may function as plasticity mechanisms. We then address the evolution of individual differences in susceptibility to the environment, which engenders systematic person–environment interactions in the effects of stress on development. Finally, we discuss stress-mediated regulation of pubertal development as a case study of how an evolutionary–developmental approach can foster theoretical integration.

Animal models of PTSD: a challenge to be met

Recent years have seen increased interest in psychopathologies related to trauma exposure. Specifically, there has been a growing awareness to posttraumatic stress disorder (PTSD) in part due to terrorism, climate change-associated natural disasters, the global refugee crisis, and increased violence in overpopulated urban areas. However, notwithstanding the increased awareness to the disorder, the increasing number of patients, and the devastating impact on the lives of patients and their families, the efficacy of available treatments remains limited and highly unsatisfactory. A major scientific effort is therefore devoted to unravel the neural mechanisms underlying PTSD with the aim of paving the way to developing novel or improved treatment approaches and drugs to treat PTSD. One of the major scientific tools used to gain insight into understanding physiological and neuronal mechanisms underlying diseases and for treatment development is the use of animal models of human diseases. While much progress has been made using these models in understanding mechanisms of conditioned fear and fear memory, the gained knowledge has not yet led to better treatment options for PTSD patients. This poor translational outcome has already led some scientists and pharmaceutical companies, who do not in general hold opinions against animal models, to propose that those models should be abandoned. Here, we critically examine aspects of animal models of PTSD that may have contributed to the relative lack of translatability, including the focus on the exposure to trauma, overlooking individual and sex differences, and the contribution of risk factors. Based on findings from recent years, we propose research-based modifications that we believe are required in order to overcome some of the shortcomings of previous practice. These modifications include the usage of animal models of PTSD which incorporate risk factors and of the behavioral profiling analysis of individuals in a sample. These modifications are aimed to address factors such as individual predisposition and resilience, thus taking into consideration the fact that only a fraction of individuals exposed to trauma develop PTSD. We suggest that with an appropriate shift of practice, animal models are not only a valuable tool to enhance our understanding of fear and memory processes, but could serve as effective platforms for understanding PTSD, for PTSD drug development and drug testing.

Testing the indirect effects of somatic and parental effort on stress: the roles of worldviews and coping strategies

Life history theory (LHT) is a mid-level theory from evolutionary biology. LHT, adapted to humans, assumes that individuals can be placed along a single continuum of LH strategies referred to as the slow-to-fast LH continuum: faster life history strategists score higher on mating effort and lower on somatic and parental effort. In the present study we examine the hypothesis that worldview and coping strategies are mediators between somatic and parental effort (SPE) and current perceived stress. 226 participants completed a set of instruments: Mini-K, the World Assumptions Scale, Brief COPE, and the Perceived Stress Scale. In order to test the hypotheses about mediators, Structural Equation Modeling (SEM) was used. The results from the current study showed that individuals allocating their own resources to SPE experienced lower current stress, and felt positive about the benevolence and meaningfulness of the world as well as the worthiness of the self. A more complex linkage was also revealed: individuals displaying SPE endorsed stronger beliefs about self-worth, which in turn was associated with a lower tendency to use disengagement coping and which again translated into a lower level of perceived stress. Furthermore, females investing in SPE maintained a higher level of belief in the meaningfulness of the world, which translated into a higher tendency to use external support for coping.

Heart rate and hurtful behavior from teens to adults: Paths to adult health

A low resting heart rate across development from infancy to young adulthood relates to greater aggression/hostility. Adult aggression and a high heart rate relate to health risk. Do some aggressive individuals retain low heart rate and less health risk across development while others show high heart rate and more risk? A longitudinal sample of 203 men assessed as teens (age 16.1) and adults (mean age 32.0) permitted us to assess (a) stability of heart rate levels and reactivity, (b) stability of aggression/hostility, and (c) whether change or stability related to health risk. Adults were assessed with Buss-Perry measures of aggression/hostility; teens with the Zuckerman aggression/hostility measure. Mean resting heart rate, heart rate reactivity to speech preparation, and aggression/hostility were moderately stable across development. Within age periods, mean heart rate level, but not reactivity, was negatively related to hostility/aggression. Maintaining low heart rate into adulthood was related to better health among aggressive individuals relative to those with increasing heart rate into adulthood. Analyses controlled for weight gain, socioeconomic status, race, health habits, and medication. Low heart rate as a characteristic of hostile/aggressive individuals may continue to relate to better health indices in adulthood, despite possible reversal of this relationship with aging.

Child sex moderates the relationship between cortisol stress reactivity and symptoms over time

BACKGROUND

Past work suggests that individual differences in stress reactivity have implications for the development of psychopathology; in particular, females' stress reactivity appears more closely tied to internalizing symptoms than males' reactivity. Conversely, males who are under-reactive to threat may be at risk for externalizing problems. However, little is known about when such differences may emerge, although this knowledge could have implications for early prevention.

METHODS

Cortisol reactivity to a laboratory stressor was assessed in 409 three-year-old children (201 boys), along with parent-reported children's internalizing (anxiety and depression) and externalizing (oppositional-defiant and attention problems and hyperactivity) symptoms. Parent-reported symptoms were re-collected at child ages 5 (N = 379) and 8 (N = 364). Multilevel modelling was used to investigate whether the relationship between cortisol reactivity and symptoms differed between boys and girls over time.

RESULTS

Girls with lower cortisol reactivity showed a negative association between depressive symptoms and time, while girls with higher reactivity showed no such association. No interaction between sex and cortisol reactivity was found for anxious symptoms. Boys with higher cortisol reactivity showed a negative association between symptoms and time, while boys with lower cortisol reactivity showed no such association. Time and ADHD symptoms were unrelated for boys, regardless of their cortisol reactivity.

CONCLUSIONS

Findings suggest that the implications of stress reactivity indexed via cortisol vary for boys and girls, as well as for different symptom manifestations.

Chronic stress as a risk factor for Alzheimer's disease: Roles of microglia-mediated synaptic remodeling, inflammation, and oxidative stress

Microglia are the predominant immune cells of the central nervous system (CNS) that exert key physiological roles required for maintaining CNS homeostasis, notably in response to chronic stress, as well as mediating synaptic plasticity, learning and memory. The repeated exposure to stress confers a higher risk of developing neurodegenerative diseases including sporadic Alzheimer's disease (AD). While microglia have been causally linked to amyloid beta (Aβ) accumulation, tau pathology, neurodegeneration, and synaptic loss in AD, they were also attributed beneficial roles, notably in the phagocytic elimination of Aβ. In this review, we discuss the interactions between chronic stress and AD pathology, overview the roles played by microglia in AD, especially focusing on chronic stress as an environmental risk factor modulating their function, and present recently-described microglial phenotypes associated with neuroprotection in AD. These microglial phenotypes observed under both chronic stress and AD pathology may provide novel opportunities for the development of better-targeted therapeutic interventions.

Childhood Family Instability and Young Adult Health

American children live in a variety of family structures throughout their childhoods. Such instability in family arrangements is common and has important demonstrated implications for short-term child outcomes. However, it is not known whether family instability experienced in childhood has enduring health consequences across the life course. Using demographic, social, and biological data from the National Longitudinal Study of Adolescent to Adult Health, we investigate the family stress model, testing the relationship between parental family instability in childhood and four biological markers of health in young adulthood. This is the first study to examine whether the accumulation of family change in childhood leaves a lasting physiological residue. While family instability is associated with poorer short-term behavioral and socioeconomic outcomes as documented in previous research, we find no evidence of deleterious young adult health consequences. These findings are robust across different measures of physiological health risk and types of family transitions.

Atypical maternal cradling laterality in an impoverished South African population

Human studies consistently report a 60%-80% maternal left cradling preference. The dominant explanation points to an engagement of the emotionally more-attuned right brain. In contrast, we found equal incidences of left (31.3%), right (34.3%) and no-preference (34.3%) cradling in an impoverished South African population living under adverse conditions characterized by extreme dangers. We found striking differences on the Parenting Stress Index (PSI) between mothers with no cradling laterality preference and mothers with either a left or right preference. In several mammals a homologous left preference becomes stronger when acute threats prevail, rendering the rightwards shift we observed under dangerous conditions seemingly paradoxical. We propose this paradox can be resolved in terms of life-history strategy theory which predicts reduced parental investment in chronically dangerous environments. We interpret our high PSI score findings in no-preference cradlers as indicative of poorer, or at least ambivalent, maternal coping which many studies show is typically associated with reduced emotional sensitivity and responsiveness. We suggest that the latter may be a psychological mechanism mediating a partial withdrawal of parental investment in response to an enduringly adverse environment. To the best of our knowledge, this is the first study investigating cradling laterality preferences in an adverse socioeconomic environment.

Incorporating epigenetic mechanisms to advance fetal programming theories

Decades of fetal programming research indicates that we may be able to map the origins of many physical, psychological, and medical variations and morbidities before the birth of the child. While great strides have been made in identifying associations between prenatal insults, such as undernutrition or psychosocial stress, and negative developmental outcomes, far less is known about how adaptive responses to adversity regulate the developing phenotype to match stressful conditions. As the application of epigenetic methods to human behavior has exploded in the last decade, research has begun to shed light on the role of epigenetic mechanisms in explaining how prenatal conditions shape later susceptibilities to mental and physical health problems. In this review, we describe and attempt to integrate two dominant fetal programming models: the cumulative stress model (a disease-focused approach) and the match-mismatch model (an evolutionary-developmental approach). In conjunction with biological sensitivity to context theory, we employ these two models to generate new hypotheses regarding epigenetic mechanisms through which prenatal and postnatal experiences program child stress reactivity and, in turn, promote development of adaptive versus maladaptive phenotypic outcomes. We conclude by outlining priority questions and future directions for the fetal programming field.

Projected Behavioral Impacts of Global Climate Change

The projected behavioral impacts of global climate change emanate from environmental changes including temperature elevation, extreme weather events, and rising air pollution. Negative affect, interpersonal and intergroup conflict, and possibly psychological distress increase with rising temperature. Droughts, floods, and severe storms diminish quality of life, elevate stress, produce psychological distress, and may elevate interpersonal and intergroup conflict. Recreational opportunities are compromised by extreme weather, and children may suffer delayed cognitive development. Elevated pollutants concern citizens and may accentuate psychological distress. Outdoor recreational activity is curtailed by ambient pollutants. Limitations and issues in need of further investigation include the following: lack of data on direct experience with climate change rather than indirect assessments related to projected changes; poor spatial resolution in environmental exposures and behavioral assessments; few rigorous quasi-experimental studies; overreliance on self-reports of behavioral outcomes; little consideration of moderator effects; and scant investigation of underlying psychosocial processes to explain projected behavioral impacts.

Childhood physical maltreatment with physical injuries is associated with higher adult psychopathology symptoms

BACKGROUND

Previous research has neglected the distinction between childhood physical maltreatment (CPM) behaviors and the physical sequelae resulting from CPM. Prior empirical work has combined CPM behaviors (e.g., beat, hit with a belt) and CPM physical sequelae (e.g., bruises, fractures) into a single conceptual category to predict adverse psychological consequences in adults. This is preventing the examination whether specific subgroups of CPM exposure may report a higher risk of psychopathology symptoms in adulthood. The aim of this study was to examine whether distinct experiences of CPM histories (no physical maltreatment, physical maltreatment only, and physical maltreatment with physical sequelae) would be differentially associated with specific psychopathology dimensions in adulthood. symptoms METHOD: Data were drawn from the Portuguese National Representative Study of Psychosocial Context of Child Abuse and Neglect (N = 941). Participants completed the Childhood History Questionnaire and the Brief Symptom Inventory.

RESULTS

Three groups were created based on participants' experience of CPM assessed by the Childhood History Questionnaire. Participants who reported that suffered physical sequelae of the CPM exhibited significantly higher symptoms in all psychopathology dimensions than participants with no history of CPM and participants that were exposed to physical maltreatment without sequelae.

CONCLUSIONS

These findings suggest that clinicians should discriminate CPM behavior from CPM physical sequelae in order to increase effectiveness of mental health treatment with adults with history of CPM. Our findings are discussed in light of the evolutionary-developmental frameworks of adaptative development and cumulative risk hypothesis.

[A Patient´s Personality: A Frequently Ignored but Important Component in General Medical Practice]

A Patient´s Personality: A Frequently Ignored but Important Component in General Medical Practice Abstract. In general medical practice, a patient's personality is hardly considered and assessed. In this mini-review the author summarises how a comprehensive personality assessment may provide valuable patient information. Prospective effects of personality traits on general lifestyle as well as mental and physical health are presented. In addition, original research is introduced that shows meaningful associations between personality traits, clinical disease markers, and all-cause mortality. These findings are discussed with respect to selected etiological models. The studies illustrate that a personality assessment could be a useful aid for diagnosis, prognosis, and treatment planning.

Does Exposure to Hostile Environments Predict Enhanced Emotion Detection?

We used a Face-in-the-Crowd task to examine whether hostile environments predict enhanced detection of anger, and whether such enhanced cognition occurs for a different negative emotion, sadness, as well. We conducted a well-powered, preregistered study in 100 college students and 100 individuals from a community sample with greater exposure to hostile environments. At the group level, the community sample was less accurate at detecting both angry and sad faces than students; and, only students discriminated anger more accurately than sadness. At the individual level, having experienced more violence did not predict enhanced anger detection accuracy. In general, participants had a lower threshold (i.e., a more liberal criterion) for detecting emotion in response to anger than sadness. And, students had a higher threshold (i.e., a more conservative criterion) for detecting emotion than the community sample in response to both anger and sadness. Overall, these findings contradict our hypothesis that exposure to hostile environments predicts enhanced danger detection. Rather, our community sample was more prone to over-perceiving emotions, consistent with previous studies showing bias in threat-exposed populations. Future work is needed to tease apart the conditions in which people exposed to social danger show enhanced accuracy or bias in their perception of emotions.

A Salutogenic Perspective on Adverse Experiences

Abstract. Research has predominantly focused on the negative effects of adversity on health and well-being. However, the salutogenic perspective suggests that adversity may not always be detrimental ( Antonovsky, 1996 ). In fact, under certain circumstances, adversity may have the potential for positive outcomes, such as increased resilience and thriving ( Carver, 1998 ; Rutter, 1987 ). The “steeling effect” suggests that past experiences of adversity may increase resistance to later adversities. It proposes that moderate adversity may facilitate more adaptive functioning than no adversity or high levels of adversity ( Rutter, 2006 , 2012 ). The relationship between adversity and health may be optimally assessed using curvilinear models, yet the majority of previous studies have examined linear associations ( Masten & Cicchetti, 2016 ). It is therefore the aim of this review to determine whether moderate adversity is associated with more adaptive functioning when compared to no and high levels of adversity. Practical implications and future research are also discussed.