Social deprivation and the HPA axis in early development

Peer Problems Among Postinstitutionalized, Internationally Adopted Children: Relations to Hypocortisolism, Parenting Quality, and ADHD Symptoms

Seventy-eight postinstitutionalized (PI) children adopted at ages 17-36 months were assessed 2, 8, 16, and 24 months postadoption on measures of cortisol and parenting quality, and compared to same-aged children adopted from foster care (FC, n = 45) and nonadopted children (NA, n = 45). In kindergarten (M_age  = 6.0 years), teachers, parents, and trained observers completed measures of peer relationships and attention deficit hyperactivity disorder (ADHD) symptoms. PI children had more peer problems and ADHD symptoms according to teachers and observers than NA children with FC children in between, whereas both PI and FC children were at significantly greater risk of hypocortisolism (i.e., blunted cortisol diurnal rhythm and reactivity). Hypocortisolism and ADHD symptoms mediated the association between preadoption adversity and peer difficulties. Higher postadoption parenting quality was protective.

Developmental psychoneuroendocrine and psychoneuroimmune pathways from childhood adversity to disease

Childhood adversity has been repeatedly and robustly linked to physical and mental illness across the lifespan. Yet, the biological pathways through which this occurs remain unclear. Functioning of the inflammatory arm of the immune system and the hypothalamic-pituitary-adrenal (HPA)-axis are both hypothesized pathways through which childhood adversity leads to disease. This review provides a novel developmental framework for examining the role of adversity type and timing in inflammatory and HPA-axis functioning. In particular, we identify elements of childhood adversity that are salient to the developing organism: physical threat, disrupted caregiving, and unpredictable environmental conditions. We propose that existing, well-characterized animal models may be useful in differentiating the effects of these adversity elements and review both the animal and human literature that supports these ideas. To support these hypotheses, we also provide a detailed description of the development and structure of both the HPA-axis and the inflammatory arm of the immune system, as well as recent methodological advances in their measurement. Recommendations for future basic, developmental, translational, and clinical research are discussed.

Adolescent Chronic Unpredictable Stress Exposure Is a Sensitive Window for Long-Term Changes in Adult Behavior in Mice

Adolescence is a time period in development when the brain undergoes substantial remodeling in response to the environment. To determine whether a stressful experience during adolescence affects adult behavior, we exposed adolescent male and female C57BL/6J mice to chronic unpredictable stress (CUS) for 12 days starting at postnatal day 28 (PND28). We also exposed adult male and female mice to CUS for 12 days beginning at PND70 to determine whether adolescence is a sensitive time period when stress can have long-lasting effects on behavior. Regardless of when mice were exposed to stress, they were all tested exactly 30 days later in the marble burying task, elevated zero maze, acoustic startle response, and forced swim test. Adolescent stress exposure increased anxiety-like behaviors in adult male and female mice and decreased acoustic startle response in a sex-dependent manner. However, adult stress exposure did not change anxiety or response to an acoustic tone in adult male or female mice as compared with nonstressed animals. Of interest, increased depression-like behavior in the forced swim test was observed in all mice, regardless of when the stress occurred. Gene expression analysis showed significant upregulation of corticotropin releasing factor receptor 2 (CrfR2) in the amygdala of males subjected to CUS during adolescence, but not in males that experienced CUS during adulthood. In contrast, females, regardless of when they were exposed to CUS, were not affected. These data support clinical evidence suggesting that early-life stress may predispose individuals to increased anxiety and depression later in life.

Sensitive Periods of Emotion Regulation: Influences of Parental Care on Frontoamygdala Circuitry and Plasticity

Early caregiving experiences play a central role in shaping emotional development, stress physiology, and refinement of limbic circuitry. Converging evidence across species delineates a sensitive period of heightened neuroplasticity when frontoamygdala circuitry is especially amenable to caregiver inputs early in life. During this period, parental buffering regulates emotional behaviors and stress physiology as emotion regulation circuitry continues to mature. By contrast, disorganized or poor quality caregiving has profound and lasting consequences on the maturation of frontoamygdala circuitry essential for emotion regulation, even following termination of this early life stressor (e.g., adoption from orphanage). This article highlights how interactions between caregiving experiences and the biological state of the developing brain have broad implications for long-term health.

Association Between Neighborhood Violence and Biological Stress in Children

Importance

Exposure to violence continues to be a growing epidemic, particularly among children. An enhanced understanding of the biological effect of exposure to violence is critical.

Objective

To examine the association between neighborhood violence and cellular and biological stress in children.

Design, Setting, and Participants

A matched, cross-sectional study of 85 black children aged 5 to 16 years from 52 neighborhoods took place in the greater New Orleans, Louisiana, area between January 1, 2012, and July 31, 2013.

Exposures

Density of businesses where individuals can purchase alcohol as measured by rates per capita of liquor or convenience stores, and violence as measured by reports of violent crime and reports of domestic violence, operationalized as reports per capita of crime and domestic violence. Rates of exposure within a 500-, 1000-, and 2000-m radius from the child's home were calculated.

Main Outcomes and Measures

Primary biological outcomes were telomere length and cortisol functioning.

Results

Among the 85 children in the study, (mean [SD] age, 9.8 [3.1] years; 50 girls and 35 boys) significant variation in telomere length and cortisol functioning was observed at the neighborhood level, with intraclass correlation coefficients of 6% for telomere length, 3.4% for waking cortisol levels, and 5.5% for peak cortisol levels following a stressor. Density of liquor or convenience stores within a 500-m radius of a child's home was associated with a decrease in mean telomere length by 0.004 for each additional liquor store or convenience store (β [SE], -0.004 [0.002]; P = .02). The rate of domestic violence was significantly and inversely associated with a decrease in mean telomere length by 0.007 for each additional report of domestic violence in a 500-m radius of a child's home (β [SE], -0.007 [0.001]; P < .001). The rate of violent crime was significantly associated with a decrease in mean telomere length by 0.006 for each additional report of violent crime in a 500-m radius of a child's home (β [SE], -0.006 [0.002]; P < .001). Children exposed to more liquor and convenience stores within 500 m of their home were significantly less likely to reduce cortisol levels after a reactivity test (β, 0.029; P = .047), as were children exposed to high rates of domestic violence (β, 0.088; P = .12) and violent crime (β, 0.029; P = .006). Children exposed to more liquor and convenience stores within 500 m of their home had a steeper diurnal decline in cortisol levels during the day (β [SE], -0.002 [0.001]; P = .04), as did children exposed to more violent crime within 500 m of their home (β [SE] -0.032 [0.014]; P = .02).

Conclusions and Relevance

Neighborhoods are important targets for interventions to reduce the effect of exposure to violence in the lives of children. These findings provide the first evidence that objective exposures to neighborhood-level violence influence both physiological and cellular markers of stress, even in children.

Adopted youth and sleep difficulties

Sleep is a critical component of healthy development for youth, with cascading effects on youth’s biological growth, psychological well-being, and overall functioning. Increased sleep difficulties are one of many disruptions that adopted youth may face throughout the adoption process. Sleep difficulties have been frequently cited as a major concern by adoptive parents and hypothesized in the literature as a problem that may affect multiple areas of development and functioning in adopted youth. However, there is limited research exploring this relationship. Using a biopsychosocial framework, this paper reviews the extant literature to explore the development, maintenance, and impact of sleep difficulties in adopted youth. Finally, implications for future research and clinical interventions are outlined.

Differential DNA methylation in peripheral blood mononuclear cells in adolescents exposed to significant early but not later childhood adversity

Internationally adopted adolescents who are adopted as young children from conditions of poverty and deprivation have poorer physical and mental health outcomes than do adolescents conceived, born, and raised in the United States by families similar to those who adopt internationally. Using a sample of Russian and Eastern European adoptees to control for Caucasian race and US birth, and nonadopted offspring of well-educated and well-resourced parents to control for postadoption conditions, we hypothesized that the important differences in environments, conception to adoption, might be reflected in epigenetic patterns between groups, specifically in DNA methylation. Thus, we conducted an epigenome-wide association study to compare DNA methylation profiles at approximately 416,000 individual CpG loci from peripheral blood mononuclear cells of 50 adopted youth and 33 nonadopted youth. Adopted youth averaged 22 months at adoption, and both groups averaged 15 years at testing; thus, roughly 80% of their lives were lived in similar circumstances. Although concurrent physical health did not differ, cell-type composition predicted using the DNA methylation data revealed a striking difference in the white blood cell-type composition of the adopted and nonadopted youth. After correcting for cell type and removing invariant probes, 30 CpG sites in 19 genes were more methylated in the adopted group. We also used an exploratory functional analysis that revealed that 223 gene ontology terms, clustered in neural and developmental categories, were significantly enriched between groups.

Antenatal glucocorticoid treatment is associated with diurnal cortisol regulation in term-born children

Due to the rapid developmental changes that occur during the fetal period, prenatal influences can affect the developing central nervous system with lifelong consequences for physical and mental health. Glucocorticoids are one of the proposed mechanisms by which fetal programing occurs. Glucocorticoids pass through the blood-brain barrier and target receptors throughout the central nervous system. Unlike endogenous glucocorticoids, synthetic glucocorticoids readily pass through the placental barrier to reach the developing fetus. The synthetic glucocorticoid, betamethasone, is routinely given prenatally to mothers at risk for preterm delivery. Over 25% of the fetuses exposed to betamethasone will be born at term. Few studies have examined the lasting consequences of antenatal treatment of betamethasone on the regulation of the hypothalamic-pituitary-adrenal (HPA) axis. The purpose of this study is to examine whether antenatal exposure to betamethasone alters circadian cortisol regulation in children who were born full term. School-aged children prenatally treated with betamethasone and born at term (n=19, mean (SD)=8.1 (1.2) years old) were compared to children not treated with antenatal glucocorticoids (n=61, mean (SD)=8.2 (1.4) years old). To measure the circadian release of cortisol, saliva samples were collected at awakening; 30, 45, and 60min after awakening; and in the evening. Comparison children showed a typical diurnal cortisol pattern that peaked in the morning (the cortisol awakening response) and gradually decreased throughout the day. In contrast, children exposed to antenatal betamethasone lacked a cortisol awakening response and had a flatter diurnal slope (p's<0.01). These data suggest that antenatal glucocorticoid treatment may disrupt the circadian regulation of the HPA axis among children born at term. Because disrupted circadian regulation of cortisol has been linked to mental and somatic health problems, future research is needed to determine whether children exposed to antenatal synthetic glucocorticoids are at risk for poor mental and physical health.

Childhood Adversity, Self-Esteem, and Diurnal Cortisol Profiles Across the Life Span

Childhood adversity is associated with poor health outcomes in adulthood; the hypothalamic-pituitary-adrenal (HPA) axis has been proposed as a crucial biological intermediary of these long-term effects. Here, we tested whether childhood adversity was associated with diurnal cortisol parameters and whether this link was partially explained by self-esteem. In both adults and youths, childhood adversity was associated with lower levels of cortisol at awakening, and this association was partially driven by low self-esteem. Further, we found a significant indirect pathway through which greater adversity during childhood was linked to a flatter cortisol slope via self-esteem. Finally, youths who had a caregiver with high self-esteem experienced a steeper decline in cortisol throughout the day compared with youths whose caregiver reported low self-esteem. We conclude that self-esteem is a plausible psychological mechanism through which childhood adversity may get embedded in the activity of the HPA axis across the life span.

Multilevel developmental approaches to understanding the effects of child maltreatment: Recent advances and future challenges

Recent research in the field of child maltreatment has begun to shed new light on the emergence of health problems in children by emphasizing the responsiveness of developmental processes to children's environmental and biological contexts. Here, I highlight recent trends in the field with an emphasis on the effects of early life stress across multiple levels of developmental domains.

DNA methylation at stress-related genes is associated with exposure to early life institutionalization

OBJECTIVES

Differences in DNA methylation have been associated with early life adversity, suggesting that alterations in methylation function as one pathway through which adverse early environments are biologically embedded. This study examined associations between exposure to institutional care, quantified as the proportion of time in institutional care at specified follow-up assessment ages, and DNA methylation status in two stress-related genes: FKBP5 and SLC6A4.

MATERIALS AND METHODS

We analyzed data from the Bucharest Early Intervention Project, which is a prospective study in which children reared in institutional settings were randomly assigned (mean age 22 months) to either newly created foster care or care as usual (to remain in their current placement) and prospectively followed. A group of children from the same geographic area, with no history of institutionalized caregiving, were also recruited. DNA methylation status was determined in DNA extracted from buccal epithelial cells of children at age 12.

RESULTS

An inverse association was identified such that more time spent in institutional care was associated with lower DNA methylation at specific CpG sites within both genes.

DISCUSSION

These results suggest a lasting impact of early severe social deprivation on methylation patterns in these genes, and contribute to a growing literature linking early adversity and epigenetic variation in children. Am J Phys Anthropol 161:84-93, 2016.. © 2016 Wiley Periodicals, Inc.

Differential sensitization of parenting on early adolescent cortisol: Moderation by profiles of maternal stress

The hypothalamic-pituitary-adrenal (HPA) axis is a critical component of the body's stress-response neurobiological system, and its development and functioning are shaped by the social environment. Much of our understanding of the effects of the caregiving environment on the HPA axis is based on (a) parenting in young children and (b) individual maternal stressors, such as depression. Yet, less is known about how parenting behaviors and maternal stressors interact to influence child cortisol regulation, particularly in older children. With an ethnically diverse sample of 199 mothers and their early adolescent children (M=11.00years; 54% female), a profile analytic approach was used to investigate how multiple phenotypes of maternal stress co-occur and moderate the relation between parenting behaviors and youths' diurnal cortisol rhythms. Latent profile analysis yielded 4 profiles: current parenting stress, concurrent parenting and childhood stress, childhood stress, and low stress. For mothers with the concurrent parenting and childhood stress profile, inconsistent discipline, poor parental supervision, and harsh caregiving behaviors each were related to flattened diurnal cortisol rhythms in their adolescents. For mothers with the current parenting stress and childhood stress profiles, their use of inconsistent discipline was associated with flattened diurnal cortisol rhythms in their adolescents. For mothers with the low stress profile, none of the parenting behaviors was related to their adolescents' cortisol regulation. Findings suggest that based on mothers' stress profile, parenting behaviors are differentially related to youths' diurnal cortisol rhythms. Implications for parenting interventions are discussed.

Early adversity, hypocortisolism, and behavior problems at school entry: A study of internationally adopted children

The hypothalamic-pituitary-adrenal (HPA) axis is influenced by early life adversity; however, less is known about the potential for recovery following marked improvements in care. The present study examined longitudinal changes in children's cortisol reactivity in the laboratory (4 assessments over 2 years) after adoption. Post-institutionalized (N=65) and post-foster care children (N=49) demonstrated blunted reactivity relative to non-adopted peers (N=53). Furthermore, post-institutionalized children exhibited no evidence of expected adaptation to repeated sessions in the 2 years following adoption. As evidenced by blunted cortisol reactivity, flatter diurnal slope, and lower home morning cortisol, we found support for hypocortisolism among children experiencing adverse early care. Hypocortisolism served as a mediator between adversity and teacher-reported attention and externalizing problems during kindergarten. Early adversity appears to contribute to the down-regulation of the HPA axis under both basal and stress conditions.

Child Poverty and the Promise of Human Capacity: Childhood as a Foundation for Healthy Aging

The effect of child poverty and related early life experiences on adult health outcomes and patterns of aging has become a central focus of child health research and advocacy. In this article a critical review of this proliferating literature and its relevance to child health programs and policy are presented. This literature review focused on evidence of the influence of child poverty on the major contributors to adult morbidity and mortality in the United States, the mechanisms by which these associations operate, and the implications for reforming child health programs and policies. Strong and varied evidence base documents the effect of child poverty and related early life experiences and exposures on the major threats to adult health and healthy aging. Studies using a variety of methodologies, including longitudinal and cross-sectional strategies, have reported significant findings regarding cardiovascular disorders, obesity and diabetes, certain cancers, mental health conditions, osteoporosis and fractures, and possibly dementia. These relationships can operate through alterations in fetal and infant development, stress reactivity and inflammation, the development of adverse health behaviors, the conveyance of child chronic illness into adulthood, and inadequate access to effective interventions in childhood. Although the reviewed studies document meaningful relationships between child poverty and adult outcomes, they also reveal that poverty, experiences, and behaviors in adulthood make important contributions to adult health and aging. There is strong evidence that poverty in childhood contributes significantly to adult health. Changes in the content, financing, and advocacy of current child health programs will be required to address the childhood influences on adult health and disease. Policy reforms that reduce child poverty and mitigate its developmental effects must be integrated into broader initiatives and advocacy that also attend to the health and well-being of adults.

Early deprivation and autonomic nervous system functioning in post-institutionalized children

The relations between early deprivation and the development of the neuroendocrine and central components of the mammalian stress response have been examined frequently. However, little is known about the impact of early deprivation on the developmental trajectories of autonomic function. Children adopted between 15-36 months from institutional care were examined during their first 16 months post-adoption (N = 60). Comparison groups included same-aged peers reared in their birth families (N = 50) and children adopted internationally from overseas foster care (N = 46). The present study examined trajectories of baseline autonomic nervous system function longitudinally following entry into adopted families. Post-institutionalized children had higher sympathetic tone, measured by pre-ejection period (PEP). Individual differences in PEP soon after adoption served as a mediator between early deprivation and parent-reported behavioral problems 2 years post-adoption. There were no group differences in parasympathetic function, indexed by respiratory sinus arrhythmia. All three groups showed similar trajectories of ANS function across the 16 month period.

Developmental psychopathology: recent advances and future challenges

The integrative field of developmental psychopathology is having a huge impact on our understanding of human health and behavior. In this paper, I use the example of children's early stress exposure to illustrate how developmental psychopathologists now tend to deemphasize diagnostic categories and, instead, emphasize the social and biological contexts, events and circumstances that have created opportunities for maladaptive responses and health problems in youth. This example shows that developmental psychopathology is increasing understanding of how children develop the abilities that allow them to cope effectively with challenges and what leads to failures in development of these abilities. Integrating research about the neurobiology of learning may prove to be a powerful future direction to understand how the environment regulates behavior. Learning processes become increasingly intricate and fine-tuned as relevant neuroanatomical systems develop, and as the range, complexity and amount of environmental information increases for the developing child. A focus on these processes allows psychopathologists to formulate questions about which neural mechanisms children use to process information, how these mechanisms are themselves shaped by social context, why adverse social environments confer risk for children, and, perhaps, what sorts of neutrally informed interventions might remediate the deficits in self-regulation that underlie common psychopathologies.

Social scaffolding of human amygdala-mPFCcircuit development

Strong evidence indicates that reciprocal connections between the amygdala and the medial prefrontal cortex (mPFC) support fundamental aspects of emotional behavior in adulthood. However, this circuitry is slow to develop in humans, exhibiting immaturity in childhood. The argument is made that the development of this circuitry in humans is intimately associated with caregiving, such that parental availability during childhood provides important and enduring scaffolding of neuroaffective processes that ultimately form of the nature of the adult phenotype.

Social scaffolding of human amygdala-mPFCcircuit development

Strong evidence indicates that reciprocal connections between the amygdala and the medial prefrontal cortex (mPFC) support fundamental aspects of emotional behavior in adulthood. However, this circuitry is slow to develop in humans, exhibiting immaturity in childhood. The argument is made that the development of this circuitry in humans is intimately associated with caregiving, such that parental availability during childhood provides important and enduring scaffolding of neuroaffective processes that ultimately form of the nature of the adult phenotype.

Social Support Can Buffer against Stress and Shape Brain Activity

Social support from close relationship partners is an important resource for coping with stress, particularly during childhood. We discuss ethical challenges associated with studying stress and its social buffering in the laboratory, as well as emerging evidence regarding two potential neural substrates for the social buffering of stress: hypothalamic oxytocin activity and activation of areas in the prefrontal cortex associated with effective self-regulation. We also address the role of early-life social experiences in shaping brain development, as well as recommendations for practice and policy that would advance the ethical treatment of children and reduce social inequalities in early-life experiences and opportunities-e.g., investing in programs that prevent child maltreatment and facilitating access to high-quality child care for economically disadvantaged families. We also debate the ethical implications of using oxytocin nasal sprays to simulate the stress-reducing properties of social support and advise waiting for more evidence before recommending their use.