The Neuro-Environmental Loop of Plasticity: A Cross-Species Analysis of Parental Effects on Emotion Circuitry Development Following Typical and Adverse Caregiving

What was learned from studying the effects of early institutional deprivation

The effect of experiences in infancy on human development is a central question in developmental science. Children raised in orphanage-like institutions for their first year or so of life and then adopted into well-resourced and supportive families provide a lens on the long-term effects of early deprivation and the capacity of children to recover from this type of early adversity. While it is challenging to identify cause-and-effect relations in the study of previously institutionalized individuals, finding results that are consistent with animal experimental studies and the one randomized study of removal from institutional care support the conclusion that many of the outcomes for these children were induced by early institutional deprivation. This review examines the behavioral and neural evidence for altered executive function, declarative memory, affective disorders, reward processing, reactivity to threat, risk-taking and sensation-seeking. We then provide a brief overview of the neurobiological mechanisms that may transduce early institutional experiences into effects on brain and behavior. In addition, we discuss implications for policy and practice.

Adolescence as a pivotal period for emotion regulation development for consideration at current opinion in psychology

Adolescence is a dynamic period for the development of emotion regulation. For many individuals, emotion regulation skills improve dramatically during adolescence; however, for some youth, adolescence marks the beginning or worsening of psychopathology characterized by difficulties with emotion regulation. In the present review, I describe evidence that caregiving experiences play an outsized role in shaping interindividual variability in emotion regulation during adolescence. After describing work demonstrating links between caregiving - with an emphasis on parental socialization practices - and emotion regulation outcomes, I characterize our current understanding of how behavioral and neurobiological indices of emotion regulation develop normatively across adolescence. Using cognitive reappraisal as an exemplar emotion regulation strategy, I outline ways that caregiving might impact interindividual variability in emotion regulation neurodevelopment. I conclude by identifying two key future directions for adolescent emotion regulation research.

Caregiving Influences on Development: A Sensitive Period for Biological Embedding of Predictability and Safety Cues

Across species, caregivers exert a powerful influence on the neural and behavioral development of offspring. Increasingly, both animal and human research has highlighted specific patterns in caregivers' behavior that may be especially important early in life, as well as neurobiological mechanisms linking early caregiving experiences with long-term affective behavior. Here we delineate evidence for an early sensitive period during infancy and toddlerhood when caregiver inputs that are predictable and associated with safety may become biologically embedded via influences on corticolimbic circuitry involved in emotion regulation. We propose that these caregiver signals prime corticolimbic circuitry to be receptive to later stage-specific caregiver influences, such as caregivers' external regulation of children's emotional reactivity. Following caregiving adversity that disrupts predictability and safety associated with caregivers during this sensitive period, accelerated maturation of corticolimbic circuitry may foreshorten the protracted period of plasticity and caregiver influence that is characteristic of humans. This work has implications for both prevention and intervention efforts for children exposed to early life adversity.

Is left-behind a real reason for children's social cognition deficit? An fNIRS study on the effect of social interaction on left-behind preschooler's prefrontal activation

The left-behind phenomenon, caused by parent out-migration, has become a common social issue and might lead to long-term and potential risks for children in rural areas of China. It is important to investigate the effect of social interaction on prefrontal activation of left-behind children in China because of possible effects of parent out-migration on children’s social cognition. We recruited 81 rural Chinese preschoolers aged 52–76 months (mean = 64.98 ± 6.321 months) preschoolers with three different statuses of parental out-migration (including non-, partially, and completely left-behind children). Using functional Near-Infrared Spectroscopy (fNIRS), we compared behavior and brain activation and in three groups (non-, partially-, completely-left-behind children) under two different social interaction conditions (child-teacher and child-stranger situation). Results revealed that initiating joint attention (IJA) may evoke higher brain activation than responding to joint attention (RJA) in the prefrontal cortex (PFC), especially in the case of initiating joint attention with the stranger. In addition, the activation of joint attention was positively correlated with children’s language score, cognitive flexibility, and facial expression recognition. More importantly, partially-left-behind children evoked higher brain activation in the IJA condition and presented a higher language level than completely/non-left-behind children. The current study provides insight into the neural basis of left-behind children’s development and revealed for the first time that family economic level and left-behind status may contribute to the lower social cognition.

Prediction Along a Developmental Perspective in Psychiatry: How Far Might We Go?

Most mental disorders originate in childhood, and once symptoms present, a variety of psychosocial and cognitive maladjustments may arise. Although early childhood problems are generally associated with later mental health impairments and psychopathology, pluripotent transdiagnostic trajectories may manifest. Possible predictors range from behavioral and neurobiological mechanisms, genetic predispositions, environmental and social factors, and psychopathological comorbidity. They may manifest in altered neurodevelopmental trajectories and need to be validated capitalizing on large-scale multi-modal epidemiological longitudinal cohorts. Moreover, clinical and etiological variability between patients with the same disorders represents a major obstacle to develop effective treatments. Hence, in order to achieve stratification of patient samples opening the avenue of adapting and optimizing treatment for the individual, there is a need to integrate data from multi-dimensionally phenotyped clinical cohorts and cross-validate them with epidemiological cohort data. In the present review, we discuss these aspects in the context of externalizing and internalizing disorders summarizing the current state of knowledge, obstacles, and pitfalls. Although a large number of studies have already increased our understanding on neuropsychobiological mechanisms of mental disorders, it became also clear that this knowledge might only be the tip of the Eisberg and that a large proportion still remains unknown. We discuss prediction strategies and how the integration of different factors and methods may provide useful contributions to research and at the same time may inform prevention and intervention.

Within-person changes in basal cortisol and caregiving modulate executive attention across infancy

One pathway by which environments of socioeconomic risk are thought to affect cognitive development is through stress physiology. The biological systems underpinning stress and attention undergo a sensitive period of development during infancy. Psychobiological theory emphasizes a dynamic pattern of context-dependent development, however, research has yet to examine how basal cortisol and attention dynamically covary across infancy in ecologically valid contexts. Thus, to address these gaps, we leveraged longitudinal, multilevel analytic methods to disentangle between- from within-person associations of hypothalamic-pituitary-adrenal (HPA) axis activity and executive attention behaviors across infancy. We use data from a large longitudinal sample (N = 1,292) of infants in predominantly low-income, nonurban communities at 7-, 15-, and 24-months of age. Using multilevel models, we investigated longitudinal associations of infant attention and basal cortisol levels and examined caregiving behaviors as moderators of this relationship. Results indicated a negative between- and within-person association between attention and cortisol across infancy and a within-person moderation by caregiver responsiveness. In other words, on the within-person level, higher levels of cortisol were concomitantly associated with lower infant attention across the first 2 years of life. However, variation in the caregiver's level of responsiveness either buffered or sensitized the executive attention system to the negative effects of physiological stress.

Altered hippocampal microstructure and function in children who experienced Hurricane Irma

Hurricane Irma was the most powerful Atlantic hurricane in recorded history, displacing 6 million and killing over 120 people in the state of Florida alone. Unpredictable disasters like Irma are associated with poor cognitive and health outcomes that can disproportionately impact children. This study examined the effects of Hurricane Irma on the hippocampus and memory processes previously related to unpredictable stress. We used an innovative application of an advanced diffusion-weighted imaging technique, restriction spectrum imaging (RSI), to characterize hippocampal microstructure (i.e., cell density) in 9- to 10-year-old children who were exposed to Hurricane Irma relative to a non-exposed control group (i.e., assessed the year before Hurricane Irma). We tested the hypotheses that the experience of Hurricane Irma would be associated with decreases in: (a) hippocampal cellularity (e.g., neurogenesis), based on known associations between unpredictable stress and hippocampal alterations; and (b) hippocampal-related memory function as indexed by delayed recall. We show an association between decreased hippocampal cellularity and delayed recall memory in children who experienced Hurricane Irma relative to those who did not. These findings suggest an important role of RSI for assessing subtle microstructural changes related to functionally significant changes in the developing brain in response to environmental events.

Newborn white matter microstructure moderates the association between maternal postpartum depressive symptoms and infant negative reactivity

Maternal postpartum depression is a prominent risk factor for aberrant child socioemotional development, but there is little understanding about the neural phenotypes that underlie infant sensitivity to maternal depression. We examined whether newborn white matter fractional anisotropy (FA), a measure of white matter maturity, moderates the association between maternal postpartum depressive symptoms and infant negative reactivity at 6 months. Participants were 80 mother–infant dyads participating in a prospective population-based cohort, and included families whose newborns underwent a magnetic resonance/diffusion tensor imaging scan at 2–5 weeks of age and whose mothers reported their own depressive symptoms at 3 and 6 months postpartum and infant negative emotional reactivity at 6 months. The whole-brain FA moderated the association between maternal depressive symptoms and mother-reported infant negative reactivity at 6 months after adjusting for the covariates. Maternal depressive symptoms were positively related to infant negative reactivity among infants with high or average FA in the whole brain and in corpus callosum and cingulum, but not among those with low FA. The link between maternal depressive symptoms and infant negative reactivity was moderated by newborn FA. The variation in white matter microstructure might play a role in child susceptibility to parental distress.

Bidirectional and transactional relationships between parenting styles and child symptoms of ADHD, ODD, depression, and anxiety over 6 years

It is well established that mothers' parenting impacts children's adjustment. However, much less is known about how children's psychopathology impacts their mothers' parenting and how parenting and child symptoms relate either bidirectionally (i.e., a relationship in both directions over two time points) or transactionally (i.e., a process that unfolds over time) to one another over a span of several years. In addition, relatively little research addresses the role of fathers' parenting in the development of children's symptoms and, conversely, how children may elicit certain types of parenting from fathers. In this study, data were collected from 491 families on mothers' and fathers' parenting styles (authoritarianism, authoritativeness, permissiveness, and overprotectiveness) and children's symptoms of psychopathology (attention deficit, oppositional defiant, depression, and anxiety) when children were age 3, 6, and 9 years old. Cross-lagged panel analyses revealed that parents and children affected one another in a bidirectional and transactional fashion over the course of the six years studied. Results suggest that children's symptoms may compound over time partially because they reduce exposure to adaptive and increase exposure to maladaptive parenting styles. Likewise, maladaptive parenting may persist over time due to the persistence of children's symptoms.

Environmental influences on the pace of brain development

Childhood socio-economic status (SES), a measure of the availability of material and social resources, is one of the strongest predictors of lifelong well-being. Here we review evidence that experiences associated with childhood SES affect not only the outcome but also the pace of brain development. We argue that higher childhood SES is associated with protracted structural brain development and a prolonged trajectory of functional network segregation, ultimately leading to more efficient cortical networks in adulthood. We hypothesize that greater exposure to chronic stress accelerates brain maturation, whereas greater access to novel positive experiences decelerates maturation. We discuss the impact of variation in the pace of brain development on plasticity and learning. We provide a generative theoretical framework to catalyse future basic science and translational research on environmental influences on brain development.

Early life stress and neural development: Implications for understanding the developmental effects of COVID-19

Chronic and/or extreme stress in childhood, often referred to as early life stress, is associated with a wide range of long-term effects on development. Given this, the COVID-19 pandemic has led to concern about how stress due to the pandemic will affect children's development and mental health. Although early life stress has been linked to altered functioning of a number of neural and biological systems, there is a wide range of variability in children's outcomes. The mechanisms that influence these individual differences are still not well understood. In the past, studies of stress in childhood focused on the type of events that children encountered in their lives. We conducted a review of the literature to formulate a new perspective on the effects of early life stress on development. This new, topological model, may increase understanding of the potential effects of the COVID-19 pandemic on children's development. This model is oriented on children's perceptions of their environment and their social relationships, rather than specific events. These factors influence central and peripheral nervous system development, changing how children interpret, adapt, and respond to potentially stressful events, with implications for children's mental and physical health outcomes.

The importance of responsive parenting for vulnerable infants

The quality of the early caregiving context sets the stage for the developing child's long term developmental trajectory. Infants are born highly dependent on parents and other caregivers for critical input for developing brain and behavioral systems. When infants experience early adversity, they are at risk for difficulties regulating behavior, emotions, and physiology. Parenting interventions have been developed to enhance parental responsiveness, thereby enhancing child outcomes. One such program, Attachment and Biobehavioral Catch-up (ABC), is a home visiting intervention designed to enhance parenting nurturance and sensitivity. In this paper, we will consider the importance of parental sensitivity and developmental consequences of sensitive and insensitive care. We will then describe interventions that target parental responsiveness and intervention effectiveness, focusing primarily on ABC. Public policy recommendations related to the importance of parental responsiveness will then be discussed.

Maternal parenting behavior and functional connectivity development in children: A longitudinal fMRI study

Parenting behavior is associated with internalizing symptoms in children, and cross-sectional research suggests that this association may be mediated by the influence of parenting on the development of frontoamygdala circuitry. However, longitudinal studies are lacking. Moreover, there is a paucity of studies that have investigated parenting and large-scale networks implicated in affective functioning. In this longitudinal study, data from 95 (52 female) children and their mothers were included. Children underwent magnetic resonance imaging that included a 6 min resting state sequence at wave 1 (mean age = 8.4 years) and wave 2 (mean age = 9.9 years). At wave 1, observational measures of positive and negative maternal behavior were collected during mother-child interactions. Region-of-interest analysis of the amygdala, and independent component and dual-regression analyses of the Default Mode Network (DMN), Executive Control Network (ECN) and the Salience Network (SN) were carried out. We identified developmental effects as a function of parenting: positive parenting was associated with decreased coactivation of the superior parietal lobule with the ECN at wave 2 compared to wave 1. Thus our findings provide preliminary longitudinal evidence that positive maternal behavior is associated with maturation of the connectivity between higher-order control networks.

Child-parent cardiac transference is decreased following disrupted/absent early care

Parental input shapes youth self-regulation development, and a lack of sensitive caregiving is a risk factor for youth mental health problems. Parents may shape youth regulation through their influence over biological (including neural) and behavioral development during childhood at both micro (moment-to-moment) and macro (global) levels. Prior studies have shown that micro-level parent-child interactions shape youth's biology contributing to youth mental health. However, it remains unclear whether prior disrupted/absent care affects those moment-to-moment parent-youth interactions in ways that increase risk for youth psychopathology. In the current study, we calculated transfer entropy on cardiac data from parent-youth dyads where the youth had either been exposed to disrupted care prior to adoption or not. Transfer Entropy (TE) tracks information flow between two signals, enhancing quantification of directional coupling, allowing for the examination of parent-child and child-parent influences. Using this novel approach, we identified lower cardiac information transfer from youth-to-parents in dyads where the youth had been exposed to disrupted/absent early care. Moreover we showed that the degree to which the parent's physiology changed in response to youth's physiology was negatively related to the youth's mental health, representing a potential pathway for elevated mental health risk in populations exposed to disrupted/absent early care.

The Developmental Origins of Opioid Use Disorder and Its Comorbidities

Opioid use disorder (OUD) rarely presents as a unitary psychiatric condition, and the comorbid symptoms likely depend upon the diverse risk factors and mechanisms by which OUD can arise. These factors are heterogeneous and include genetic predisposition, exposure to prescription opioids, and environmental risks. Crucially, one key environmental risk factor for OUD is early life adversity (ELA). OUD and other substance use disorders are widely considered to derive in part from abnormal reward circuit function, which is likely also implicated in comorbid mental illnesses such as depression, bipolar disorder, and schizophrenia. ELA may disrupt reward circuit development and function in a manner predisposing to these disorders. Here, we describe new findings addressing the effects of ELA on reward circuitry that lead to OUD and comorbid disorders, potentially via shared neural mechanisms. We discuss some of these OUD-related problems in both humans and animals. We also highlight the increasingly apparent, crucial contribution of biological sex in mediating the range of ELA-induced disruptions of reward circuitry which may confer risk for the development of OUD and comorbid neuropsychiatric disorders.

Development and Validation of the Parental Assistance with Child Emotion Regulation (PACER) Questionnaire

Caregivers play a central role in promoting emotion regulation throughout infancy, childhood, and adolescence. However, there are no existing psychometric measures to assess how parents assist children in employing emotion regulation strategies for negative emotions. We therefore developed the Parental Assistance with Child Emotion Regulation (PACER) Questionnaire to assess the degree to which parents assist their children in their use of ten different regulation strategies. In this paper, we describe the development of the PACER and examine its psychometric properties (N = 407 parents of children ages birth to 17 years). In so doing, we also use the PACER to comprehensively explore the links between parent-assisted emotion regulation and indices of parent and child stress, symptomatology, and attachment. Confirmatory factor analyses of the PACER items supported its intended ten-factor structure (corresponding to ten specific regulation strategies), which was invariant across different child age and sex categories. PACER scale scores had excellent internal consistency and generally acceptable test-retest reliability over a one-week period. Convergent validity was established via correlations between PACER scales and indices of parental emotion sensitivity, expressivity, and regulation, as well as parents' perception of the efficacy of their assistance with children's execution of emotion regulatory strategies. Lower parental facilitation of stereotypically adaptive emotion regulatory strategies was associated with higher child internalizing and externalizing problems and with poorer parent-child relationship quality. Overall, these findings suggest that the PACER may be a useful tool for the assessment of parental assistance with child emotion regulation across development.

Initial Evidence for Symptoms of Postpartum Parent-Infant Relationship Obsessive Compulsive Disorder (PI-ROCD) and Associated Risk for Perturbed Maternal Behavior and Infant Social Disengagement From Mother

Infant socioemotional development and underlying brain maturation occur primarily within the context of early caregiver-infant relationships. Perinatal research demonstrates detrimental impact of postpartum pathology, including postnatal onset of maternal OCD-on the mother-infant relationship. The present study is the first to examine postnatal onset of a particular dimension of OCD symptoms focusing on close interpersonal relationships (relationship-OCD, i.e., ROCD) within a general population sample. Specifically, we assessed whether symptoms of Parent-Child ROCD (PC-ROCD), may onset postnatally, thus yielding symptoms of Parent-Infant ROCD (PI-ROCD). We adapted the previously validated Parent-Child ROCD measure for use during infancy to assess symptoms of PI-ROCD. The adapted measure, Parent-Infant Relationship Obsessive Compulsive Symptoms Inventory (PI-PROCSI), was administered to 143 mothers from the general population at 4-months postpartum. We investigated concurrent associations between postnatal onset of PI-ROCD, maternal depression and bonding, as well as longitudinal predictive associations with observed maternal and infant behaviors in dyadic interactions at 10 months. Due to dropout across the 1st year postpartum, the subsample with longitudinal data was substantially reduced compared to the full sample. PI-PROCSI scores explained unique variance in concurrent maternal depression over and above concurrent anxiety. PI-PROCSI scores also associated with concurrent impairments of maternal bonding. Moreover, unique associations emerged between maternal PI-ROCD scores and perturbations in both maternal and infant observable behaviors at 10-months. Specifically, observable perturbations in maternal behaviors mediated associations between symptoms of PI-ROCD at 4-months and observable infant avoidance of social engagement behaviors at 10-months. Findings suggest that parent-child ROCD symptoms may onset during the postnatal period, and that such symptoms may play a significant role in shaping quality of reciprocal caregiver-infant interactions. Theoretical and clinical implications are discussed.

Associations between developmental trajectories of peer victimization, hair cortisol, and depressive symptoms: a longitudinal study

BACKGROUND

Peer victimization has been associated with long-lasting risks for mental health. Prior research suggests that stress-related systems underlying adaptation to changing environments may be at play. To date, inconsistent findings have been reported for the hypothalamic-pituitary-adrenal (HPA) axis, and its end product cortisol. This study tested whether peer victimization was associated with hair cortisol concentrations (HCC), and whether this association varied according to sex, timing, and changes in exposure. We also examined whether peer victimization differentially predicted depressive symptoms according to HCC.

METHODS

The sample comprised 556 adolescents (42.0%; 231 males) who provided hair for cortisol measurement at 17 years of age. Peer victimization was reported at seven occasions between the ages of 6 and 15 years.

RESULTS

Peer victimization was nonlinearly associated with HCC for boys only, whereas changes in peer victimization were related to HCC for boys and girls. Peer victimization predicted more depressive symptoms for all participants, except those with lower HCC.

CONCLUSIONS

Our findings provide further support for persistent dysregulation of the HPA axis following exposure to chronic adversity, of which the expression may change according to sex and the severity of victimization.

Conceptual Analysis: A Social Neuroscience Approach to Interpersonal Interaction in the Context of Disruption and Disorganization of Attachment (NAMDA)

Humans are strongly dependent upon social resources for allostasis and emotion regulation. This applies especially to early childhood because humans-as an altricial species-have a prolonged period of dependency on support and input from caregivers who typically act as sources of co-regulation. Accordingly, attachment theory proposes that the history and quality of early interactions with primary caregivers shape children's internal working models of attachment. In turn, these attachment models guide behavior, initially with the set goal of maintaining proximity to caregivers but eventually paving the way to more generalized mental representations of self and others. Mounting evidence in non-clinical populations suggests that these mental representations coincide with differential patterns of neural structure, function, and connectivity in a range of brain regions previously associated with emotional and cognitive capacities. What is currently lacking, however, is an evidence-based account of how early adverse attachment-related experiences and/or the emergence of attachment disorganization impact the developing brain. While work on early childhood adversities offers important insights, we propose that how these events become biologically embedded crucially hinges on the context of the child-caregiver attachment relationships in which the events take place. Our selective review distinguishes between direct social neuroscience research on disorganized attachment and indirect maltreatment-related research, converging on aberrant functioning in neurobiological systems subserving aversion, approach, emotion regulation, and mental state processing in the wake of severe attachment disruption. To account for heterogeneity of findings, we propose two distinct neurobiological phenotypes characterized by hyper- and hypo-arousal primarily deriving from the caregiver serving either as a threatening or as an insufficient source of co-regulation, respectively.

Early life stress and development: potential mechanisms for adverse outcomes

BACKGROUND

Chronic and/or extreme stress in early life, often referred to as early adversity, childhood trauma, or early life stress, has been associated with a wide range of adverse effects on development. However, while early life stress has been linked to negative effects on a number of neural systems, the specific mechanisms through which early life stress influences development and individual differences in children's outcomes are still not well understood.

MAIN TEXT

The current paper reviews the existing literature on the neurobiological effects of early life stress and their ties to children's psychological and behavioral development.

CONCLUSIONS

Early life stress has persistent and pervasive effects on prefrontal-hypothalamic-amygdala and dopaminergic circuits that are at least partially mediated by alterations in hypothalamic-pituitary-adrenal axis function. However, to date, this research has primarily utilized methods of assessment that focus solely on children's event exposures. Incorporating assessment of factors that influence children's interpretation of stressors, along with stressful events, has the potential to provide further insight into the mechanisms contributing to individual differences in neurodevelopmental effects of early life stress. This can aid in further elucidating specific mechanisms through which these neurobiological changes influence development and contribute to risk for psychopathology and health disorders.

Caregiving influences on emotional learning and regulation: Applying a sensitive period model

Early caregiving experiences play a central role in shaping corticolimbic development and emotional learning and regulation. Given dynamic changes in corticolimbic maturation, the effects of caregiving experiences are likely to depend on the developmental timing of exposure. Cross-species evidence has identified timing-related differences in the effects of caregiving adversity. However, the extent to which developmental differences in associations between caregiving adversity and corticolimbic circuitry align with a sensitive period model has remained unclear. Converging evidence from studies of caregiver deprivation points to a sensitive period for caregiving influences on corticolimbic circuitry and emotional development during infancy. By contrast, differential associations between maltreatment and corticolimbic circuitry at specific ages in childhood and adolescence may reflect experience-dependent mechanisms of plasticity. Delineating sensitive periods of development and the precise experience-related mechanisms by which caregiving experiences influence corticolimbic development is essential for refining conceptual models and understanding risk and resilience following early adversity.

An exploration of amygdala-prefrontal mechanisms in the intergenerational transmission of learned fear

Humans learn about their environments by observing others, including what to fear and what to trust. Observational fear learning may be especially important early in life when children turn to their parents to gather information about their world. Yet, the vast majority of empirical research on fear learning in youth has thus far focused on firsthand classical conditioning, which may fail to capture one of the primary means by which fears are acquired during development. To address this gap in the literature, the present study examined observational fear learning in youth (n = 33; age range: 6-17 years) as they watched videos of their parent and an "unfamiliar parent" (i.e., another participant's parent) undergo fear conditioning. Youth demonstrated stronger fear learning when observing their parent compared to an unfamiliar parent, as indicated by changes in their self-reported liking of the stimuli to which their parents were conditioned (CS+, a geometric shape paired with an aversive noise; CS-, a geometric shape never paired with an aversive noise) and amygdala responses. Parent trait anxiety was associated with youth learning better (i.e., reporting a stronger preference for the CS- relative to CS+), and exhibiting stronger medial prefrontal-amygdala connectivity. Neuroimaging data were additionally acquired from a subset of parents during firsthand conditioning, and parental amygdala and mPFC activation were associated with youth's neural recruitment. Together, these results suggest that youth preferentially learn fears via observation of their parents, and this learning is associated with emotional traits and neural recruitment in parents.

[Cohort studies in child and adolescent psychiatry]

BACKGROUND

Longitudinal cohort studies with early start and life span perspectives are increasingly recognized as being crucial to uncover developmental trajectories as well as risk and resilience factors of psychiatric disorders.

OBJECTIVE

The importance of longitudinal studies is presented and the main findings of the Mannheim study of children at risk (MARS), the adolescent brain cognitive development (ABCD), the pediatric and adolescent health survey (Kinder- und Jugendgesundheitssurvey, KiGGS) and the AIMS longitudinal European autism project (LEAP) cohort studies are described.

MATERIAL AND METHODS

A literature search was carried out in MEDLINE.

RESULTS

The MARS followed participants with psychosocial and organic risks over more than 30 years starting from birth and showed the importance of early risk factors (prenatal period up to early childhood) for neuropsychosocial development. The ABCD cohort study (start 9-10 years old) underlined the developmental significance of early socioemotional and prenatal risks as well as toxin exposure. The KiGGS cohort followed children and adolescents from age 0-17 years up to the ages of 10-28 years. Main findings underline the importance of the socioeconomic status and gender-specific effects with respect to sensitive periods for the onset and trajectories of psychiatric disorders. The AIMS cohort followed patients with and without autism spectrum disorders aged between 6 and 30 years and first results revealed small effects regarding group differences. Further, cohort studies starting prenatally along with deep phenotyping are warranted to uncover the complex etiology of mental disorders.

CONCLUSION

Existing cohort studies on early mental development have shown specific focal points. To identify general and specific risk and resilience factors for psychiatric disorders and to model trajectories, there is a need for multimodal integration of data sets.

Neurodevelopmental Optimization after Early-Life Adversity: Cross-Species Studies to Elucidate Sensitive Periods and Brain Mechanisms to Inform Early Intervention

Human brain development is influenced by early-life experiences, particularly during sensitive periods, with impact on cognitive and emotional outcomes. Understanding how the timing and nature of such experiences (including adversity, trauma, and enrichment) govern their influence on brain organization is crucial for harnessing key environmental factors early in life to enhance brain development. Here we synthesize findings from human and animal studies focusing on sensitive periods and their regional and circuit specificity and highlight the challenge and power of such cross-species approaches in informing the 'next steps' to optimize cognitive and emotional health in developing children. We propose designs for neurodevelopmental optimization research programs utilizing randomized enhancement trials in early childhood to inform public health strategies on prevention and early intervention.

Neuronal changes and cognitive deficits in a multi-hit rat model following cumulative impact of early life stressors

Perinatal protein malnourishment (LP) is a leading cause for mental and physical retardation in children from poor socioeconomic conditions. Such malnourished children are vulnerable to additional stressors that may synergistically act to cause neurological disorders in adulthood. In this study, the above mentioned condition was mimicked via a multi-hit rat model in which pups born to LP mothers were co-injected with polyinosinic:polycytidylic acid (Poly I:C; viral mimetic) at postnatal day (PND) 3 and lipopolysaccharide (LPS; bacterial mimetic) at PND 9. Individual exposure of Poly I:C and LPS was also given to LP pups to correlate chronicity of stress. Similar treatments were also given to control pups. Hippocampal cellular apoptosis, β III tubulin catastrophe, altered neuronal profiling and spatial memory impairments were assessed at PND 180, using specific immunohistochemical markers (active caspase 3, β III tubulin, doublecortin), golgi studies and cognitive mazes (Morris water maze and T maze). Increase in cellular apoptosis, loss of dendritic arborization and spatial memory impairments were higher in the multi-hit group, than the single-hit groups. Such impairments observed due to multi-hit stress mimicked conditions similar to many neurological disorders and hence, it is hypothesized that later life neurological disorders might be an outcome of multiple early life hits.This article has an associated First Person interview with the first author of the paper.

Nested sensitive periods: how plasticity across the microbiota-gut-brain axis interacts to affect the development of learning and memory

There is a growing appreciation for the range of sensitive periods which occur across the brain. These sensitive periods give rise to sensory outcomes, as well as complex higher-order cognitive functions like learning and memory. More recently, an understanding that sensitive periods of development occur outside of the central nervous system (e.g., in the gastrointestinal microbiota) has emerged. Less well understood is how these peripheral sensitive periods may interact with those operating centrally to influence complex behavior. The goal of this paper is to put forward the view that sensitive periods of development occur across the entirety of the microbiota-gut-brain (MGB) axis, and that these nested sensitive periods may interact to influence learning and memory outcomes. Adopting this framework should promote a 'new wave' of thinking in the field which appreciates the complex central and peripheral forces acting on behavior, and uses that understanding to innovate therapies and interventions for disordered learning and memory systems.

Mind and gut: Associations between mood and gastrointestinal distress in children exposed to adversity

Gastrointestinal and mental disorders are highly comorbid, and animal models have shown that both can be caused by early adversity (e.g., parental deprivation). Interactions between the brain and bacteria that live within the gastrointestinal system (the microbiome) underlie adversity-gastrointestinal-anxiety interactions, but these links have not been investigated during human development. In this study, we utilized data from a population of 344 youth (3-18 years old) who were raised with their biological parents or were exposed to early adverse caregiving experiences (i.e., institutional or foster care followed by international adoption) to explore adversity-gastrointestinal-anxiety associations. In Study 1, we demonstrated that previous adverse care experiences were associated with increased incidence of gastrointestinal symptoms in youth. Gastrointestinal symptoms were also associated with concurrent and future anxiety (measured across 5 years), and those gastrointestinal symptoms mediated the adversity-anxiety association at Time 1. In a subsample of children who provided both stool samples and functional magnetic resonance imaging of the brain (Study 2, which was a "proof-of-principle"), adversity was associated with changes in diversity (both alpha and beta) of microbial communities, and bacteria levels (adversity-associated and adversity-independent) were correlated with prefrontal cortex activation to emotional faces. Implications of these data for supporting youth mental health are discussed.

Neurobiological Markers of Resilience to Early-Life Adversity During Adolescence

Early-life adversity (ELA) exposure (e.g., trauma, abuse, neglect, or institutional care) is a precursor to poor physical and mental health outcomes and is implicated in 30% of adult mental illness. In recent decades, ELA research has increasingly focused on characterizing factors that confer resilience to ELA and on identifying opportunities for intervention. In this review, we describe recent behavioral and neurobiological resilience work that suggests that adolescence (a period marked by heightened plasticity, development of key neurobiological circuitry, and sensitivity to the social environment) may be a particularly opportune moment for ELA intervention. We review intrapersonal factors associated with resilience that become increasingly important during adolescence (specifically, reward processing, affective learning, and self-regulation) and describe the contextual factors (family, peers, and broader social environment) that modulate them. In addition, we describe how the onset of puberty interacts with each of these factors, and we explore recent findings that point to possible "pubertal recalibration" of ELA exposure as an opportunity for intervention. We conclude by describing considerations and future directions for resilience research in adolescents, with a focus on understanding developmental trajectories using dimensional and holistic models of resilience.

Parent's anxiety links household stress and young children's behavioral dysregulation

Young children rely heavily on their caregivers to gain information about the environment, especially during times of duress. Therefore, considering parental assessments of behavior in the context of stressful environments may better facilitate our understanding of the longstanding association between early environmental stressors and changes in child behavior and physiology. Confirming many previous reports, a higher degree of household stress exposure was associated with elevated mental health symptoms in 2- to 6-year-old children (N = 115; anxiety and externalizing behaviors), which were verified in a subset of children with laboratory-based behaviors (N = 46). However, these associations were mediated by parental anxiety symptoms, which were also associated with increased cortisol levels in children. A closer look at the stressors indicated that it was the adult-targeted, and not the child-targeted, stressors that correlated most with children's behavior problems. These results highlight the importance of considering the mediating effect of parents, when examining associations between household stress and young children's behavioral development.

Rethinking Concepts and Categories for Understanding the Neurodevelopmental Effects of Childhood Adversity

Discovering the processes through which early adverse experiences affect children’s nervous-system development, health, and behavior is critically important for developing effective interventions. However, advances in our understanding of these processes have been constrained by conceptualizations that rely on categories of adversity that are overlapping, have vague boundaries, and lack consistent biological evidence. Here, we discuss central problems in understanding the link between early-life adversity and children’s brain development. We conclude by suggesting alternative formulations that hold promise for advancing knowledge about the neurobiological mechanisms through which adversity affects human development.

Is there evidence for sensitive periods in emotional development?

During sensitive periods an individual's development is especially receptive to information from the environment in ways that it is not at earlier and later developmental stages. Here, we describe challenges in applying the concept of sensitive periods to the domain of socio-emotional development, review what applications of this approach have accomplished, and point to promising future directions. We also argue that since emotional development consists of higher-order cognitive processes, it likely involves multiple and overlapping sensitive periods tied to different mechanisms (e.g., facial recognition, reward processing, fear conditioning). Moreover, we note a distinction between the construct of a sensitive period versus the identification of an effect of early experience-two ideas that are often confused in the literature. Progress in the study of emotion will require understanding the mechanisms involved in developmental change and models that predict children's behavior based on their prior experience.

The Role of Inhibitory Control, Attention and Vocabulary in Physical Aggression Trajectories From Infancy to Toddlerhood

Physical aggression has its origin very early in development, but no studies to date have examined physical aggression trajectories starting before the age of 1.5 years. This study examined whether cognition plays a role in the development of physical aggression from infancy onward. In a sample of 182 mother-child dyads (94 boys; 88 girls), child physical aggression was assessed by maternal report using the Physical Aggression Scale for Early Childhood at 12, 20, and 30 months. Children performed cognitive tasks measuring inhibitory control and attention, and mothers rated children's vocabulary at 12 and 30 months. Results showed that differential development of physical aggression already starts at 12 months of age: low-stable, low-increasing, moderate-decreasing and high-stable trajectory groups were identified. Inhibitory control, attention and vocabulary at 12 months and development of these abilities from 12 to 30 months were selectively related to the likelihood of following the low-increasing and moderate-decreasing trajectories compared to the low-stable physical aggression trajectory. This study is the first to show that specific aspects of cognition and cognitive development are related to differential physical aggression development from infancy onward.

Editorial: The primacy of parenting

The contention that supportive and sensitive parenting is important to healthy emotional and behavioral development of children is a widely accepted maxim. There is also increasing consensus among developmentalists about the nature of optimal parenting practices. However, what remains under appreciated is just how powerful an influence these positive elements of caregiving have in shaping, driving, and fortifying a healthy developmental trajectory across multiple domains of function. The notion that positive caregiving is an 'essential ingredient' necessary for healthy human development has become increasingly evident. Importantly, both animal and human data have established that there are early sensitive periods, representing windows of opportunity, during which optimal caregiving has its most powerful effects (Curley & Champagne, Frontiers in neuroendocrinology, 40, 52, 2016; Nelson et al., Science, 318, 1937, 2007). These points are underscored by papers in this volume showing the sustained effects of early parenting interventions focused on enhancing attachment relationship (Zajac, Raby, & Dozier, Journal of Child Psychology and Psychiatry, 57, 1099, 2019). Using another parenting program, Brody, Yu, Miller, and Chen (Journal of Child Psychology and Psychiatry, 2019) report longitudinal data showing mechanistic pathways by which the effects of enhanced caregiving impact later adaptive functioning in a high risk sample. These findings suggest that early parenting interventions may have uniquely positive and enduring effects highlighting their unique importance as a focus for developmental enhancement.

Influences of early-life stress on frontolimbic circuitry: Harnessing a dimensional approach to elucidate the effects of heterogeneity in stress exposure

Early-life stress confers profound and lasting risk for developing cognitive, social, emotional, and physical health problems. The effects of stress on the developing brain contribute to this risk, with frontolimbic circuitry particularly susceptible to early experiences, possibly due to its innervation with glucocorticoid receptors and the timing of frontolimbic circuit maturation. To date, the majority of studies on stress and frontolimbic circuitry have employed a categorical approach, comparing stress-exposed versus non-stress-exposed youth. However, there is vast heterogeneity in the nature of stress exposure and in outcomes. Recent forays into understanding the psychobiological effects of stress have employed a dimensional approach focused on experiential, environmental, and temporal factors that influence the association between stress and subsequent vulnerability. This review highlights empirical findings that inform a dimensional approach to understanding the effects of stress on frontolimbic circuitry. We identify the timing, type, severity, controllability, and predictability of stress, and the degree to which a caregiver is involved, as specific features of stress that may play a substantial role in differential outcomes. We propose a framework for the effects of these features of stress on frontolimbic development that may partially determine how heterogeneity in stress exposure influences this circuitry and, ultimately, mental health.

The neural and computational systems of social learning

Learning the value of stimuli and actions from others - social learning - adaptively contributes to individual survival and plays a key role in cultural evolution. We review research across species targeting the neural and computational systems of social learning in both the aversive and appetitive domains. Social learning generally follows the same principles as self-experienced value-based learning, including computations of prediction errors and is implemented in brain circuits activated across task domains together with regions processing social information. We integrate neural and computational perspectives of social learning with an understanding of behaviour of varying complexity, from basic threat avoidance to complex social learning strategies and cultural phenomena.

Early Adversity and the Neotenous Human Brain

Human brain development is optimized to learn from environmental cues. The protracted development of the cortex and its connections with subcortical targets has been argued to permit more opportunity for acquiring complex behaviors. This review uses the example of amygdala-medial prefrontal cortex circuitry development to illustrate a principle of human development-namely, that the extension of the brain's developmental timeline allows for the (species-expected) collaboration between child and parent in co-construction of the human brain. The neurobiology underlying affective learning capitalizes on this protracted timeline to develop a rich affective repertoire in adulthood. Humans are afforded this luxuriously slow development in part by the extended period of caregiving provided by parents, and parents aid in scaffolding the process of maturation during childhood. Just as adequate caregiving is a potent effector of brain development, so is adverse caregiving, which is the largest environmental risk factor for adult mental illness. There are large individual differences in neurobiological outcomes following caregiving adversity, indicating that these pathways are probabilistic, rather than deterministic, and prolonged plasticity in human brain development may also allow for subsequent amelioration by positive experiences. The extant research indicates that the development of mental health cannot be considered without consideration of children in the context of their families.

Early Childhood Parenting Predicts Late Childhood Brain Functional Connectivity During Emotion Perception and Reward Processing

Seventy-nine 3-year olds and their mothers participated in a laboratory-based task to assess maternal hostility. Mothers also reported their behavioral regulation of their child. Seven years later, functional magnetic resonance imaging data were acquired while viewing emotional faces and completing a reward processing task. Maternal hostility predicted more negative amygdala connectivity during exposure to sad relative to neutral faces with frontal and parietal regions as well as more negative left ventral striatal connectivity during monetary gain relative to loss feedback with the right posterior orbital frontal cortex and right inferior frontal gyrus. In contrast, maternal regulation predicted enhanced cingulo-frontal connectivity during monetary gain relative to loss feedback. Results suggest parenting is associated with alterations in emotion and reward processing circuitry 7-8 years later.

Childhood Adversity and Neural Development: A Systematic Review

An extensive literature on childhood adversity and neurodevelopment has emerged over the past decade. We evaluate two conceptual models of adversity and neurodevelopment-the dimensional model of adversity and stress acceleration model-in a systematic review of 109 studies using MRI-based measures of neural structure and function in children and adolescents. Consistent with the dimensional model, children exposed to threat had reduced amygdala, medial prefrontal cortex (mPFC), and hippocampal volume and heightened amygdala activation to threat in a majority of studies; these patterns were not observed consistently in children exposed to deprivation. In contrast, reduced volume and altered function in frontoparietal regions were observed consistently in children exposed to deprivation but not children exposed to threat. Evidence for accelerated development in amygdala-mPFC circuits was limited but emerged in other metrics of neurodevelopment. Progress in charting neurodevelopmental consequences of adversity requires larger samples, longitudinal designs, and more precise assessments of adversity.

Neurocognitive Adaptation and Mental Health Vulnerability Following Maltreatment: The Role of Social Functioning

Childhood maltreatment is associated with a lifetime increase in risk of mental health disorder. We propose that such vulnerability may stem in large part from altered patterns of social functioning. Here, we highlight key findings from the psychological and epidemiological literature indicating that early maltreatment experience compromises social functioning and attenuates social support in ways that increase mental health vulnerability. We then review the extant neuroimaging studies of children and adolescents, focusing on three domains implicated in social functioning: threat processing, reward processing, and emotion regulation. We discuss how adaptations in these domains may increase latent vulnerability to mental health problems by impacting on social functioning via increased stress susceptibility as well as increased stress generation. Finally, we explore how computational psychiatry approaches, alongside systematically reported measures of social functioning, can complement studies of neural function in the creation of a mechanistic framework aimed at informing approaches to prevention and intervention.

Early-life adversity and neurological disease: age-old questions and novel answers

Neurological illnesses, including cognitive impairment, memory decline and dementia, affect over 50 million people worldwide, imposing a substantial burden on individuals and society. These disorders arise from a combination of genetic, environmental and experiential factors, with the latter two factors having the greatest impact during sensitive periods in development. In this Review, we focus on the contribution of adverse early-life experiences to aberrant brain maturation, which might underlie vulnerability to cognitive brain disorders. Specifically, we draw on recent robust discoveries from diverse disciplines, encompassing human studies and experimental models. These discoveries suggest that early-life adversity, especially in the perinatal period, influences the maturation of brain circuits involved in cognition. Importantly, new findings suggest that fragmented and unpredictable environmental and parental signals comprise a novel potent type of adversity, which contributes to subsequent vulnerabilities to cognitive illnesses via mechanisms involving disordered maturation of brain 'wiring'.

During infant maltreatment, stress targets hippocampus, but stress with mother present targets amygdala and social behavior

Infant maltreatment increases vulnerability to physical and mental disorders, yet specific mechanisms embedded within this complex infant experience that induce this vulnerability remain elusive. To define critical features of maltreatment-induced vulnerability, rat pups were reared from postnatal day 8 (PN8) with a maltreating mother, which produced amygdala and hippocampal deficits and decreased social behavior at PN13. Next, we deconstructed the maltreatment experience to reveal sufficient and necessary conditions to induce this phenotype. Social behavior and amygdala deficits (volume, neurogenesis, c-Fos, local field potential) required combined chronic high corticosterone and maternal presence (not maternal behavior). Hippocampal deficits were induced by chronic high corticosterone regardless of social context. Causation was shown by blocking corticosterone during maltreatment and suppressing amygdala activity during social behavior testing. These results highlight (1) that early life maltreatment initiates multiple pathways to pathology, each with distinct causal mechanisms and outcomes, and (2) the importance of social presence on brain development.

Epigenetic dynamics in infancy and the impact of maternal engagement

The contribution of nature versus nurture to the development of human behavior has been debated for centuries. Here, we offer a piece to this complex puzzle by identifying the human endogenous oxytocin system-known for its critical role in mammalian sociality-as a system sensitive to its early environment and subject to epigenetic change. Recent animal work suggests that early parental care is associated with changes in DNA methylation of conserved regulatory sites within the oxytocin receptor gene (OXTRm). Through dyadic modeling of behavior and OXTRm status across the first year and a half of life, we translated these findings to 101 human mother-infant dyads. We show that OXTRm is dynamic in infancy and its change is predicted by maternal engagement and reflective of behavioral temperament. We provide evidence for an early window of environmental epigenetic regulation of the oxytocin system, facilitating the emergence of individual differences in human behavior.

Friendship and social functioning following early institutional rearing: The role of ADHD symptoms

Early institutional rearing is associated with increased risk for subsequent peer relationship difficulties, but the underlying mechanisms have not been identified. Friendship characteristics, social behaviors with peers, normed assessments of social problems, and social cue use were assessed in 142 children (mean age = 10.06, SD = 2.02; range 7-13 years), of whom 67 were previously institutionalized (PI), and 75 were raised by their biological families. Anxiety and attention-deficit/hyperactivity disorder (ADHD) symptoms, often elevated among PI children, were examined as potential mediators of PI status and baseline social functioning and longitudinal follow-ups (2 and 4 years later). Twenty-seven percent of PI children fell above the Child Behavior Checklist Social Problems cutoff. An examination of specific social behaviors with peers indicated that PI and comparison children did not differ in empathic concern or peer social approach, though parents were more likely to endorse aggression/overarousal as a reason that PI children might struggle with friendships. Comparison children outperformed PI children in computerized testing of social cue use learning. Finally, across these measures, social difficulties exhibited in the PI group were mediated by ADHD symptoms with predicted social problems assessed 4 years later. These findings show that, when PI children struggle with friendships, mechanisms involving attention and behavior regulation are likely contributors.

Maternal overprotection in childhood is associated with amygdala reactivity and structural connectivity in adulthood

Recently, we reported that variability in early-life caregiving experiences maps onto individual differences in threat-related brain function. Here, we extend this work to provide further evidence that subtle variability in specific features of early caregiving shapes structural and functional connectivity between the amygdala and medial prefrontal cortex (mPFC) in a cohort of 312 young adult volunteers. Multiple regression analyses revealed that participants who reported higher maternal overprotection exhibited increased amygdala reactivity to explicit signals of interpersonal threat but not implicit signals of broad environmental threat. While amygdala functional connectivity with regulatory regions of the mPFC was not significantly associated with maternal overprotection, participants who reported higher maternal overprotection exhibited relatively decreased structural integrity of the uncinate fasciculus (UF), a white matter tract connecting these same brain regions. There were no significant associations between structural or functional brain measures and either maternal or paternal care ratings. These findings suggest that an overprotective maternal parenting style during childhood is associated with later functional and structural alterations of brain regions involved in generating and regulating responses to threat.

Cross-species convergence in pupillary response: understanding human anxiety via non-human primate amygdala lesion

Few studies have used matched affective paradigms to compare humans and non-human primates. In monkeys with amygdala lesions and youth with anxiety disorders, we examined cross-species pupillary responses during a saccade-based, affective attentional capture task. Given evidence of enhanced amygdala function in anxiety, we hypothesized that opposite patterns would emerge in lesioned monkeys and anxious participants. A total of 53 unmedicated youths (27 anxious, 26 healthy) and 8 adult male rhesus monkeys (Macaca mulatta) completed matched behavioral paradigms. Four monkeys received bilateral excitotoxic amygdala lesions and four served as unoperated controls. Compared to healthy youth, anxious youth exhibited increased pupillary constriction in response to emotional and non-emotional distractors (F(1,48) = 6.28, P = 0.02, η2p = 0.12). Pupillary response was associated significantly with anxiety symptoms severity (F(1,48) = 5.59, P = 0.02, η2p = 0.10). As hypothesized, lesioned monkeys exhibited the opposite pattern i.e. decreased pupillary constriction in response to distractors, compared to unoperated control monkeys (F(1,32) = 24.22, P < 0.001, η2 = 0.33). Amygdala lesioned monkeys and youth with anxiety disorders show opposite patterns of pupil constriction in the context of an affective distractor task. Such findings suggest the presence of altered amygdala circuitry functioning in anxiety. Future lesion and human neuroimaging work might examine the way in which specific amygdala sub-nuclei and downstream circuits mediate these effects.