Variation in neural development as a result of exposure to institutionalization early in childhood

Altered somatosensory processing in adult attention deficit hyperactivity disorder

BACKGROUND

Tactile sensitivity and sensory overload in ADHD are well-documented in clinical-, self-, and parent- reports, but empirical evidence is scarce and ambiguous and focuses primarily on children. Here, we compare both empirical and self-report tactile sensitivity and ADHD symptomatology in adults with ADHD and neurotypical controls. We evaluate whether tactile sensitivity and integration is more prevalent in ADHD and whether it is related to ADHD symptom severity.

METHODS

Somatosensory evoked potential (SEP) amplitudes were measured in 27 adults with ADHD and 24 controls during four conditions (rest, stroking of the own arm, stroking of the arm by a researcher, and stroking of an object). Participants also filled out questionnaires on tactile sensitivity and ADHD symptoms and performed a Qb-test as an objective measure of ADHD symptom severity.

RESULTS

Participants with ADHD self-reported greater tactile sensitivity and ADHD symptom severity than controls and received higher scores on the Qb-test. These values correlated with one another. ADHD participants showed lower tolerable threshold for electrical radial nerve stimulus, and greater reduction in cortical SEP amplitudes during additional tactile stimuli which was correlated with ADHD symptoms.

CONCLUSIONS

We find that ADHD symptomatology and touch sensitivity are directly linked, using both self-reports and experimental measures. We also find evidence of tactile sensory overload in ADHD, and an indication that this is linked to inattention specifically. Tactile sensitivity and sensory overload impact the functioning and life quality of many people with ADHD, and clinicians should consider this when treating their patients.

Impacts of early deprivation on behavioral and neural measures of executive function in early adolescence

Children reared in institutional settings experience early deprivation that has lasting implications for multiple aspects of neurocognitive functioning, including executive function (EF). Changes in brain development are thought to contribute to these persistent EF challenges, but little research has used fMRI to investigate EF-related brain activity in children with a history of early deprivation. This study examined behavioral and neural data from a response conflict task in 12-14-year-olds who spent varying lengths of time in institutional care prior to adoption (N = 84; age at adoption - mean: 15.85 months, median: 12 months, range: 4-60 months). In initial analyses, earlier- and later-adopted (EA, LA) youth were compared to a group of children raised in their biological families (non-adopted, NA). NA youth performed significantly more accurately than LA youth, with EA youth falling in between. Imaging data suggested that previously institutionalized (PI) youth activated additional frontoparietal regions, including dorsolateral prefrontal cortex, as compared to NA youth. In addition, EA youth uniquely activated medial prefrontal regions, and LA uniquely activated parietal regions during this task. A separate analysis in a larger group of PI youth examined whether behavioral or brain measures of EF varied with the duration of deprivation experienced. Duration of deprivation was negatively associated with activation of default mode network (DMN) regions. Overall, results suggest that there are lasting effects of deprivation on EF, but that those who are removed from institutional care earlier may be able to recruit additional neural resources as a compensatory mechanism.

Reconsidering the nature of threat in infancy: Integrating animal and human studies on neurobiological effects of infant stress

Early life stress has been associated with elevated risk for later psychopathology. One mechanism that may contribute to such long-term risk is alterations in amygdala development, a brain region critical to stress responsivity. Yet effects of stress on the amygdala during human infancy, a period of particularly rapid brain development, remain largely unstudied. In order to model how early stressors may affect infant amygdala development, several discrepancies across the existing literatures on early life stress among rodents and early threat versus deprivation among older human children and adults need to be reconciled. We briefly review the key findings of each of these literatures. We then consider them in light of emerging findings from studies of human infants regarding relations among maternal caregiving, infant cortisol response, and infant amygdala volume. Finally, we advance a developmental salience model of how early threat may impact the rapidly developing infant brain, a model with the potential to integrate across these divergent literatures. Future work to assess the value of this model is also proposed.

Dimensions of early life adversity are differentially associated with patterns of delayed and accelerated brain maturation

BACKGROUND

Different types of early-life adversity have been associated with children's brain structure and function. However, understanding the disparate influence of distinct adversity exposures on the developing brain remains a major challenge.

METHODS

This study investigates the neural correlates of 10 robust dimensions of early-life adversity identified through exploratory factor analysis in a large community sample of youth from the Adolescent Brain Cognitive Development (ABCD) Study. Brain age models were trained, validated, and tested separately on T1-weighted (T1; N = 9524), diffusion tensor (DTI; N = 8834), and resting-state functional (rs-fMRI; N = 8233) magnetic resonance imaging (MRI) data from two time points (mean age = 10.7 years, SD = 1.2, range = 8.9-13.8 years).

RESULTS

Bayesian multilevel modelling supported distinct associations between different types of early-life adversity exposures and younger- and older-looking brains. Dimensions generally related to emotional neglect, such as lack of primary and secondary caregiver support, and lack of caregiver supervision, were associated with lower brain age gaps (BAGs), i.e., younger-looking brains. In contrast, dimensions generally related to caregiver psychopathology, trauma exposure, family aggression, substance use and separation from biological parent, and socio-economic disadvantage and neighbourhood safety were associated with higher BAGs, i.e., older-looking brains.

CONCLUSIONS

The findings suggest that dimensions of early-life adversity are differentially associated with distinct neurodevelopmental patterns, indicative of dimension-specific delayed and accelerated brain maturation.

Faster pace of hippocampal growth mediates the association between perinatal adversity and childhood depression

Early life adversity has been posited to influence the pace of structural neurodevelopment. Most research, however, has relied on cross-sectional data, which do not reveal whether the pace of neurodevelopmental change is accelerated or slowed following early exposures. In a birth cohort study that included neuroimaging data obtained at 4.5, 6, and 7.5 years of age (N = 784), we examined associations among a cumulative measure of perinatal adversity relative to resources, nonlinear trajectories of hippocampal and amygdala volume, and children's subsequent depressive symptoms at 8.5 years of age. Greater adversity was associated with reduced bilateral hippocampal body volume in early childhood, but also to faster growth in the right hippocampal body across childhood. Further, the association between adversity and childhood depressive symptoms was mediated by faster hippocampal body growth. These findings suggest that perinatal adversity is biologically embedded in hippocampal structure development, including an accelerated pace of change in the right hippocampal body that is implicated in children's psychopathology risk. In addition, our findings suggest that reduced hippocampal volume is not inconsistent with accelerated hippocampal change; these aspects of structural development may typically co-occur, as smaller regional volumes in early childhood were associated with faster growth across childhood.

Cognitive Functioning of Children in Out-of-Home Care

PURPOSE

Most children who enter out-of-home care (OHC) have been subjected to prolonged maltreatment. Maltreatment potentially contributes to a cumulative deficit in neurocognitive maturation and development that is likely to proceed with the child's placement into OHC and persist throughout adulthood. From the theoretical perspective of how maltreatment may affect the developing brain, this study examines the IQ and executive function of children placed in OHC on standardized, norm-referenced measures. Furthermore, the study investigates the prevalence of serious cognitive delays, defined by scores in the clinical range on the administered instruments.

METHODS

The study included 153 children in foster care (66% female), aged 6-15 (M = 10.5, SD = 2.1). Independent two-sample t-tests were run to test for significant differences between the sample and the norm population on the applied neuropsychological measures.

RESULTS

The results showed that discrepancies in cognitive development were global in scope, with the children lagging significantly behind the norm population on all applied measures with discrepancies ranging from 0.61 to 2.10 SD (p < .001). Also, serious developmental delays in all cognitive domains were vastly overrepresented in the sample ranging from 11.3% (IQ) to 66.0% (executive function).

CONCLUSIONS

The results document a very high prevalence of cognitive deficits and delays among the children in the sample. The implications of identifying the neurocognitive effects of maltreatment in the practices of the child welfare system are discussed in terms of developing suitable assessment and intervention strategies.

Theta activity and cognitive functioning: Integrating evidence from resting-state and task-related developmental electroencephalography (EEG) research

The theta band is one of the most prominent frequency bands in the electroencephalography (EEG) power spectrum and presents an interesting paradox: while elevated theta power during resting state is linked to lower cognitive abilities in children and adolescents, increased theta power during cognitive tasks is associated with higher cognitive performance. Why does theta power, measured during resting state versus cognitive tasks, show differential correlations with cognitive functioning? This review provides an integrated account of the functional correlates of theta across different contexts. We first present evidence that higher theta power during resting state is correlated with lower executive functioning, attentional abilities, language skills, and IQ. Next, we review research showing that theta power increases during memory, attention, and cognitive control, and that higher theta power during these processes is correlated with better performance. Finally, we discuss potential explanations for the differential correlations between resting/task-related theta and cognitive functioning, and offer suggestions for future research in this area.

Annual Research Review: Early intervention viewed through the lens of developmental neuroscience

The overarching goal of this paper is to examine the efficacy of early intervention when viewed through the lens of developmental neuroscience. We begin by briefly summarizing neural development from conception through the first few postnatal years. We emphasize the role of experience during the postnatal period, and consistent with decades of research on critical periods, we argue that experience can represent both a period of opportunity and a period of vulnerability. Because plasticity is at the heart of early intervention, we next turn our attention to the efficacy of early intervention drawing from two distinct literatures: early intervention services for children growing up in disadvantaged environments, and children at elevated likelihood of developing a neurodevelopmental delay or disorder. In the case of the former, we single out interventions that target caregiving and in the case of the latter, we highlight recent work on autism. A consistent theme throughout our review is a discussion of how early intervention is embedded in the developing brain. We conclude our article by discussing the implications our review has for policy, and we then offer recommendations for future research.

Do housing-induced changes in brain activity cause stereotypic behaviours in laboratory mice?

Abnormal repetitive stereotypic behaviours (SBs) (e.g. pacing, body-rocking) are common in animals with poor welfare (e.g. socially isolated/in barren housing). But how (or even whether) poor housing alters animals' brains to induce SBs remains uncertain. To date, there is little evidence for environmental effects on the brain that also correlate with individual SB performance. Using female mice from two strains (SB-prone DBA/2s; SB-resistant C57/BL/6s), displaying two forms of SB (route-tracing; bar-mouthing), we investigated how housing (conventional laboratory conditions vs. well-resourced 'enriched' cages) affects long-term neuronal activity as assessed via cytochrome oxidase histochemistry in 13 regions of interest (across cortex, striatum, basal ganglia and thalamus). Conventional housing reduced activity in the cortex and striatum. However, DBA mice had no cortical or striatal differences from C57 mice (just greater basal ganglia output activity, independent of housing). Neural correlates for individual levels of bar-mouthing (positive correlations in the substantia nigra and thalamus) were also independent of housing; while route-tracing levels had no clear neural correlates at all. Thus conventional laboratory housing can suppress cortico-striatal activity, but such changes are unrelated to SB (since not mirrored by congruent individual and strain differences). Furthermore, the neural correlates of SB at individual and strain levels seem to reflect underlying predispositions, not housing-mediated changes. To aid further work, hypothesis-generating model fit analyses highlighted this unexplained housing effect, and also suggested several regions of interest across cortex, striatum, thalamus and substantia nigra for future investigation (ideally with improved power to reduce risks of Type II error).

The neurobiological effects of childhood maltreatment on brain structure, function, and attachment

Childhood maltreatment is a risk factor for psychopathologies, and influences brain development at specific periods, particularly during early childhood and adolescence. This narrative review addresses phenotypic alterations in sensory systems associated with specific types of childhood maltreatment exposure, periods of vulnerability to the neurobiological effects of maltreatment, and the relationships between childhood maltreatment and brain structure, function, connectivity, and network architecture; psychopathology; and resilience. It also addresses neurobiological alterations associated with maternal communication and attachment disturbances, and uses laboratory-based measures during infancy and case-control studies to elucidate neurobiological alterations in reactive attachment disorders in children with maltreatment histories. Moreover, we review studies on the acute effects of oxytocin on reactive attachment disorder and maltreatment and methylation of oxytocin regulatory genes. Epigenetic changes may play a critical role in initiating or producing the atypical structural and functional brain alterations associated with childhood maltreatment. However, these changes could be reversed through psychological and pharmacological interventions, and by anticipating or preventing the emergence of brain alterations and subsequent psychopathological risks.

The impact of out-of-home care on brain development: a brief review of the neuroscientific evidence informing our understanding of children's attachment outcomes

Researchers interested in the effects of early experiences of caregiving adversity have employed neuroscientific methods to illuminate whether and how such environmental input impacts on brain development, and whether and how such impacts underpin poor socioemotional outcomes in this population. Evidence is compelling in documenting negative effects on the individual's neurodevelopment following exposure to adverse or disadvantaged environments such as institutionalization or maltreatment. Neuroimaging research focused specifically on attachment-relevant processing of socioemotional stimuli and attachment outcomes among children looked-after is scarcer, but largely consistent. This review begins by summarizing the key general brain structural and functional alterations associated with caregiving deprivation. Then, neuroscientific evidence that is more directly relevant for understanding these children's attachment outcomes, both by employing social stimuli and by correlating children's neural markers with their attachment profiles, is reviewed. Brief interpretations of findings are suggested, and key limitations and gaps in the literature identified.

Examining the relationship between psychosocial adversity and inhibitory control: an fMRI study of children growing up in extreme poverty

Exposure to psychosocial adversity (PA) is associated with poor behavioral, physical, and mental health outcomes in adulthood. Growing evidence suggests that deficits in executive functions may in part moderate these outcomes, with inhibitory control as an example of such a putative moderator. However, much of the literature examining the development of inhibitory control has been based on children in higher resource environments, and little is known how growing up in a low resource setting might exacerbate the link between inhibitory control and health outcomes. In this context we collected fMRI data during a Go/No-Go inhibitory control task and PA variables for 68 children 5 to 7 years of age living in Dhaka, Bangladesh, an area with a high prevalence of PA. The children's mothers completed behavioral questionnaires to assess the child's PA and their own PA. Whole-brain activation underlying inhibitory control was examined using the No-Go versus Go contrast, and associations with PA variables were assessed using whole-brain regressions. Childhood neglect was associated with weaker activation in the right posterior cingulate, whereas greater family conflict, economic stress, and maternal PA factors were associated with greater activation in the left medial frontal gyrus, right superior and middle frontal gyrus, and left cingulate gyrus. These data suggest that neural networks supporting inhibitory control processes may vary as a function of exposure to different types of PA, particularly between those related to threat and deprivation. Furthermore, increased activation in children with greater PA may serve as a compensatory mechanism, allowing them to maintain similar behavioral task performance.

The effects of childhood maltreatment on social support, inflammation, and depressive symptoms in adulthood

RATIONALE

Social Safety Theory (SST) suggests that social threats increase inflammation, exacerbating health risks, but that social support may decrease inflammatory signaling. One of the key health problems affected by both social forces and inflammation is major depression.

OBJECTIVE

The present study sought to test aspects of the SST, to understand how social support and inflammation may mediate the effects of childhood maltreatment on depressive symptoms in adulthood.

METHODS

This study utilized data from the national Midlife Development in the United States study (n = 1969; mean age 53; 77.2% White; 53.6% female) to model the effects of childhood maltreatment on depressive symptoms in adulthood and the potential serial mediating effects of social support and inflammation. Analyses were conducted via structural equation modeling, using the four subscales of the Center for Epidemiologic Studies Depression Scale to indicate depressive symptoms, the five subscales of the Childhood Trauma Questionnaire to indicate childhood maltreatment, and the Positive Relations Scale and a network level measure of support as indicators of social support. Inflammation was indexed using C-reactive protein (CRP). The model was estimated via maximum likelihood with robust standard errors and significance of indirect effects were assessed via a Sobel test.

RESULTS

Childhood maltreatment was associated with increased depressive symptoms and CRP but decreased social support. Social support was associated with decreased depressive symptoms while CRP was associated with increased depressive symptoms. Assessing indirect effects yielded no serial mediation effect; however, a significant indirect effect from childhood maltreatment to depressive symptoms through social support was identified.

CONCLUSIONS

Analyses indicate mixed support for the SST with respect to depressive symptoms. Results highlight the role of social support in mitigating the effects depressive symptoms in adulthood; although, alternative strategies may be needed to decrease the effects of childhood maltreatment on inflammation as indexed by CRP.

Lessons from lonely flies: Molecular and neuronal mechanisms underlying social isolation

Animals respond to changes in the environment which affect their internal state by adapting their behaviors. Social isolation is a form of passive environmental stressor that alters behaviors across animal kingdom, including humans, rodents, and fruit flies. Social isolation is known to increase violence, disrupt sleep and increase depression leading to poor mental and physical health. Recent evidences from several model organisms suggest that social isolation leads to remodeling of the transcriptional and epigenetic landscape which alters behavioral outcomes. In this review, we explore how manipulating social experience of fruit fly Drosophila melanogaster can shed light on molecular and neuronal mechanisms underlying isolation driven behaviors. We discuss the recent advances made using the powerful genetic toolkit and behavioral assays in Drosophila to uncover role of neuromodulators, sensory modalities, pheromones, neuronal circuits and molecular mechanisms in mediating social isolation. The insights gained from these studies could be crucial for developing effective therapeutic interventions in future.

Leveraging the developmental neuroscience of caregiving to promote resilience among youth exposed to adversity

Early adversity is a major risk factor for the emergence of psychopathology across development. Identifying mechanisms that support resilience, or favorable mental health outcomes despite exposure to adversity, is critical for informing clinical intervention and guiding policy to promote youth mental health. Here we propose that caregivers play a central role in fostering resilience among children exposed to adversity via caregiving influences on children's corticolimbic circuitry and emotional functioning. We first delineate the numerous ways that caregivers support youth emotional learning and regulation and describe how early attachment lays the foundation for optimal caregiver support of youth emotional functioning in a developmental stage-specific manner. Second, we outline neural mechanisms by which caregivers foster resilience-namely, by modulating offspring corticolimbic circuitry to support emotion regulation and buffer stress reactivity. Next, we highlight the importance of developmental timing and sensitive periods in understanding caregiving-related mechanisms of resilience. Finally, we discuss clinical implications of this line of research and how findings can be translated to guide policy that promotes the well-being of youth and families.

Romania's Abandoned Children: The Effects of Early Profound Psychosocial Deprivation on the Course of Human Development

Understanding the impact that early psychosocial neglect has on the course of human development has implications for the millions of children around the world who are living in contexts of adversity. In the US, approximately 76% of cases reported to child protective services involve neglect; world-wide, there are more than 150 million orphaned or abandoned children, including 10.5 million orphaned because of COVID-19. In much of the world, children without primary caregivers are reared in institutional settings. We review two decades of research based on the only randomized controlled trial of foster care as an alternative to institutional care. We report that children randomly assigned to continued care as usual (institutional care) suffer from persistent deficits in social, cognitive, and emotional development, and show evidence of disruptions in brain development. By contrast, children randomly assigned to foster care show improvements in most domains of functioning, although the degree of recovery is in part a function of how old they were when placed into foster care and the stability of that placement. These findings have important implications for understanding critical periods in human development, as well as elucidating the power of the psychosocial environment in shaping multiple domains of human development.

Exploring the Role of Neuroplasticity in Development, Aging, and Neurodegeneration

Neuroplasticity refers to the ability of the brain to reorganize and modify its neural connections in response to environmental stimuli, experience, learning, injury, and disease processes. It encompasses a range of mechanisms, including changes in synaptic strength and connectivity, the formation of new synapses, alterations in the structure and function of neurons, and the generation of new neurons. Neuroplasticity plays a crucial role in developing and maintaining brain function, including learning and memory, as well as in recovery from brain injury and adaptation to environmental changes. In this review, we explore the vast potential of neuroplasticity in various aspects of brain function across the lifespan and in the context of disease. Changes in the aging brain and the significance of neuroplasticity in maintaining cognitive function later in life will also be reviewed. Finally, we will discuss common mechanisms associated with age-related neurodegenerative processes (including protein aggregation and accumulation, mitochondrial dysfunction, oxidative stress, and neuroinflammation) and how these processes can be mitigated, at least partially, by non-invasive and non-pharmacologic lifestyle interventions aimed at promoting and harnessing neuroplasticity.

A critical period plasticity framework for the sensorimotor-association axis of cortical neurodevelopment

To understand human brain development it is necessary to describe not only the spatiotemporal patterns of neurodevelopment but also the neurobiological mechanisms that underlie them. Human neuroimaging studies have provided evidence for a hierarchical sensorimotor-to-association (S-A) axis of cortical neurodevelopment. Understanding the biological mechanisms that underlie this program of development using traditional neuroimaging approaches has been challenging. Animal models have been used to identify periods of enhanced experience-dependent plasticity - 'critical periods' - that progress along cortical hierarchies and are governed by a conserved set of neurobiological mechanisms that promote and then restrict plasticity. In this review we hypothesize that the S-A axis of cortical development in humans is partly driven by the cascading maturation of critical period plasticity mechanisms. We then describe how recent advances in in vivo neuroimaging approaches provide a promising path toward testing this hypothesis by linking signals derived from non-invasive imaging to critical period mechanisms.

A systematic review of interventions to ameliorate the impact of adversity on brain development

Adversity, including abuse, neglect, and poverty, impacts child brain development. However, the developing brain is highly plastic, and some of the impacts of childhood adversity may be mitigated by psychosocial interventions. The purpose of this review is to synthesize literature on neural outcomes of childhood interventions among individuals exposed to adversity. A systematic literature search identified 36 reports of 13 interventions. Overall, these studies provide evidence for experience-dependent plasticity in the developing brain. We synthesize studies in light of three themes. First, there was mixed evidence for a benefit of a younger age at intervention. Second, interventions tended to accelerate functional brain development, but the impact of interventions on the pace of structural brain development was less clear. Third, individual differences in intervention response were difficult to predict, in part due to small samples. However, there was significant variability in intervention type and timing, neuroimaging outcomes, and follow-up timing. Together, the studies reviewed here hold promise for the role of psychosocial interventions in ameliorating the neurodevelopmental consequences of childhood adversity.

Early- and late-phase changes of brain activity and early-phase neuromodulation in the posttraumatic stress disorder rat model

Posttraumatic stress disorder (PTSD) is a complex syndrome that may occur after life-threatening events. Fear memory abnormalities may play vital roles in the pathogenesis of PTSD. Previous work has found that fear memories are not rigid; the retrieval of fear memories may change over time. Furthermore, prior studies suggest that theta wave (4 Hz) activity is highly correlated with fear expression in an animal model. However, the relationship between pathological fear memory and potential brain wave features in PTSD remains largely uncharacterized. Here, we hypothesized that after traumatic stress exposure, the longitudinal dynamics of abnormal fears in PTSD animal models could be reflected by the measurement of local field potentials (LFPs). Using a well-established modified single-prolonged stress and footshock (SPS & FS) PTSD rat model, animals were restrained for 2 h and subsequently subjected to 20 min of forced swimming, then exposed to diethyl ether until they lost consciousness and placed in a conditioning chamber for fear conditioning. To characterize the temporal changes, we characterized freezing behavior brain wave features during the conditioning chamber re-exposure in the early (10 and 30 min; 2, 4, and 6 h) and late (day 1, 3, 7, and 14) phases after traumatic stress exposure. Our results indicate that SPS & FS rats showed co-morbid PTSD phenotypes including significantly higher levels of anxiety-, depression-, and anhedonia-like behaviors, and impaired fear extinction. Delta wave (0.5-4 Hz) suppression in the medial prefrontal cortex, amygdala, and ventral hippocampus occurred 10 and 30 min after traumatic stress, followed by continuous delta wave activity from 2 h to day 14, correlating with fear levels. tDCS reduced delta activity and alleviated PTSD-like phenotypes in the SPS & FS group. In this study, profiling abnormal fears with brain wave correlates may improve our understanding of time-dependent pathological fear memory retrieval in PTSD and facilitate the development of effective intervention strategies.

Neuroanatomical and neurochemical effects of prolonged social isolation in adult mice

Introduction

As social animals, our health depends in part on interactions with other human beings. Yet millions suffer from chronic social isolation, including those in nursing/assisted living facilities, people experiencing chronic loneliness as well as those in enforced isolation within our criminal justice system. While many historical studies have examined the effects of early isolation on the brain, few have examined its effects when this condition begins in adulthood. Here, we developed a model of adult isolation using mice (C57BL/6J) born and raised in an enriched environment.

Methods

From birth until 4 months of age C57BL/6J mice were raised in an enriched environment and then maintained in that environment or moved to social isolation for 1 or 3 months. We then examined neuronal structure and catecholamine and brain derived neurotrophic factor (BDNF) levels from different regions of the brain, comparing animals from social isolation to enriched environment controls.

Results

We found significant changes in neuronal volume, dendritic length, neuronal complexity, and spine density that were dependent on brain region, sex, and duration of the isolation. Isolation also altered dopamine in the striatum and serotonin levels in the forebrain in a sex-dependent manner, and also reduced levels of BDNF in the motor cortex and hippocampus of male but not female mice.

Conclusion

These studies show that isolation that begins in adulthood imparts a significant change on the homeostasis of brain structure and chemistry.

Trajectories of cortical structures associated with stress across adolescence: a bivariate latent change score approach

BACKGROUND

Stress exposure in childhood and adolescence has been linked to reductions in cortical structures and cognitive functioning. However, to date, most of these studies have been cross-sectional, limiting the ability to make long-term inferences, given that most cortical structures continue to develop through adolescence.

METHODS

Here, we used a subset of the IMAGEN population cohort sample (N = 502; assessment ages: 14, 19, and 22 years; mean age: 21.945 years; SD = 0.610) to understand longitudinally the long-term interrelations between stress, cortical development, and cognitive functioning. To these ends, we first used a latent change score model to examine four bivariate relations - assessing individual differences in change in the relations between adolescent stress exposure and volume, surface area, and cortical thickness of cortical structures, as well as cognitive outcomes. Second, we probed for indirect neurocognitive effects linking stress to cortical brain structures and cognitive functions using rich longitudinal mediation modeling.

RESULTS

Latent change score modeling showed that greater baseline adolescence stress at age 14 predicted a small reduction in the right anterior cingulate volume (Std. β = -.327, p = .042, 95% CI [-0.643, -0.012]) and right anterior cingulate surface area (Std. β = -.274, p = .038, 95% CI [-0.533, -0.015]) across ages 14-22. These effects were very modest in nature and became nonsignificant after correcting for multiple comparisons. Our longitudinal analyses found no evidence of indirect effects in the two neurocognitive pathways linking adolescent stress to brain and cognitive outcomes.

CONCLUSION

Findings shed light on the impact of stress on brain reductions, particularly in the prefrontal cortex that have consistently been implicated in the previous cross-sectional studies. However, the magnitude of effects observed in our study is smaller than that has been reported in past cross-sectional work. This suggests that the potential impact of stress during adolescence on brain structures may likely be more modest than previously noted.

Maternal hair cortisol predicts periodic and aperiodic infant frontal EEG activity longitudinally across infancy

Maternal stress is known to be an important factor in shaping child development, yet the complex pattern of associations between stress and infant brain development remains understudied. To better understand the nuanced relations between maternal stress and infant neurodevelopment, research investigating longitudinal relations between maternal chronic physiological stress and infant brain function is warranted. In this study, we leveraged longitudinal data to disentangle between- from within-person associations of maternal hair cortisol and frontal electroencephalography (EEG) power at three time points across infancy at 3, 9, and 15 months. We analyzed both aperiodic power spectral density (PSD) slope and traditional periodic frequency band activity. On the within-person level, maternal hair cortisol was associated with a flattening of frontal PSD slope and an increase in relative frontal beta. However, on the between-person level, higher maternal hair cortisol was associated with steeper frontal PSD slope, increased relative frontal theta, and decreased relative frontal beta. The within-person findings may reflect an adaptive neural response to relative shifts in maternal stress levels, while the between-person results demonstrate the potentially detrimental effects of chronically elevated maternal stress. This analysis offers a novel, quantitative insight into the relations between maternal physiological stress and infant cortical function.

Introducing the Neuroplastic Narrative: a non-pathologizing biological foundation for trauma-informed and adverse childhood experience aware approaches

Most people accessing mental health services have adverse childhood experiences (ACEs) and/or histories of complex trauma. In recognition of this, there are calls to move away from medical model approaches and move toward trauma-informed approaches which privilege the impact of life experience over underlying pathology in the etiology of emotional and psychological suffering. Trauma-informed approaches lack a biological narrative linking trauma and adversity to later suffering. In its absence, this suffering is diagnosed and treated as a mental illness. This study articulates the Neuroplastic Narrative, a neuroecological theory that fills this gap, conceptualizing emotional and psychological suffering as the cost of surviving and adapting to the impinging environments of trauma and adversity. The Neuroplastic Narrative privileges lived experience and recognizes that our experiences become embedded in our biology through evolved mechanisms that ultimately act to preserve survival in the service of reproduction. Neuroplasticity refers to the capacity of neural systems to adapt and change. Our many evolved neuroplastic mechanisms including epigenetics, neurogenesis, synaptic plasticity, and white matter plasticity allow us to learn from, and adapt to, past experiences. This learning and adaption in turn allows us to better anticipate and physiologically prepare for future experiences that (nature assumes) are likely to occur, based on past experiences. However, neuroplastic mechanisms cannot discriminate between experiences; they function to embed experience regardless of the quality of that experience, generating vicious or virtuous cycles of psychobiological anticipation, to help us survive or thrive in futures that resemble our privileged or traumatic pasts. The etiology of suffering that arises from this process is not a pathology (a healthy brain is a brain that can adapt to experience) but is the evolutionary cost of surviving traumatizing environments. Misidentifying this suffering as a pathology and responding with diagnosis and medication is not trauma-informed and may cause iatrogenic harm, in part through perpetuating stigma and exacerbating the shame which attends complex trauma and ACEs. As an alternative, this study introduces the Neuroplastic Narrative, which is situated within an evolutionary framework. The Neuroplastic Narrative complements both Life History and Attachment Theory and provides a non-pathologizing, biological foundation for trauma-informed and Adverse Childhood Experience aware approaches.

Development and validation of the Dimensional Inventory of Stress and Trauma Across the Lifespan (DISTAL): A novel assessment tool to facilitate the dimensional study of psychobiological sequelae of exposure to adversity

Decades of research underscore the profound impact of adversity on brain and behavioral development. Recent theoretical models have highlighted the importance of considering specific features of adversity that may have dissociable effects at distinct developmental timepoints. However, existing measures do not query these dimensions in sufficient detail to support the proliferation of this approach. The Dimensional Inventory of Stress and Trauma Across the Lifespan (DISTAL) was developed with the aim to thoroughly and retrospectively assess the timing, severity (of exposure and reaction), type, persons involved, controllability, predictability, threat, deprivation, proximity, betrayal, and discrimination inherent in an individual's exposure to adversity. Here, we introduce this instrument, present descriptive statistics drawn from a sample of N = 187 adults who completed the DISTAL, and provide initial information about its psychometric properties. This novel measure facilitates the expansion of research focused on assessing the relative impact of exposure to key dimensions of adversity on the brain and behavior across development.

Effects of COVID-19 pandemic on structural brain development in early adolescence

The COVID-19 pandemic caused a global health crisis with large behavioral effects and serious stress and social consequences. Particularly, teenagers suffered pandemic-related social restrictions including school closures. This study examined whether and how structural brain development was influenced by the COVID-19 pandemic and whether pandemic length was associated with accumulating or resilience effects of brain development. We investigated structural changes in social brain regions (medial prefrontal cortex: mPFC; temporoparietal junction: TPJ) as well as the stress-related hippocampus and amygdala, using a longitudinal design of 2 MRI waves. We selected two age-matched subgroups (9-13 years old), one was tested before (n = 114) and the other during (peri-pandemic group, n = 204) the COVID-19 pandemic. Results indicated that teenagers in the peri-pandemic group showed accelerated development in the mPFC and hippocampus compared to the before-pandemic group. Furthermore, TPJ growth showed immediate effects followed by possibly subsequent recovery effects that returned to a typical developmental pattern. No effects were observed for the amygdala. The findings of this region-of-interest study suggest that experiencing the COVID-19 pandemic measures had accelerating effects on hippocampus and mPFC development but the TPJ showed resilience to negative effects. Follow-up MRI assessments are needed to test acceleration and recovery effects over longer periods.

Lasting impact of postnatal maternal separation on the developing BNST: Lifelong socioemotional consequences

Nearly one percent of children in the US experience childhood neglect or abuse, which can incite lifelong emotional and behavioral disorders. Many studies investigating the neural underpinnings of maleffects inflicted by early life stress have largely focused on dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. Newer veins of evidence suggest that exposure to early life stressors can interrupt neural development in extrahypothalamic areas as well, including the bed nucleus of the stria terminalis (BNST). One widely used approach in this area is rodent maternal separation (MS), which typically consists of separating pups from the dam for extended periods of time, over several days during the first weeks of postnatal life - a time when pups are highly dependent on maternal care for survival. MS has been shown to incite myriad lasting effects not limited to increased anxiety-like behavior, hyper-responsiveness to stressors, and social behavior deficits. The behavioral effects of MS are widespread and thus unlikely to be limited to hypothalamic mechanisms. Recent work has highlighted the BNST as a critical arbiter of some of the consequences of MS, especially socioemotional behavioral deficits. The BNST is a well-documented modulator of anxiety, reward, and social behavior by way of its connections with hypothalamic and extra-hypothalamic systems. Moreover, during the postnatal period when MS is typically administered, the BNST undergoes critical neural developmental events. This review highlights evidence that MS interferes with neural development to permanently alter BNST circuitry, which may account for a variety of behavioral deficits seen following early life stress. This article is part of the Special Issue on 'Fear, Anxiety and PTSD'.

The interaction of the oxytocin receptor gene and child abuse subtypes on social cognition in euthymic patients with bipolar disorder type I

Background

Most studies on cognitive impairment in bipolar disorder have neglected the role of early stress, despite the high frequency of childhood maltreatment in this clinical group. The aim of this study was to establish a connection between a history of emotional, physical, and sexual abuse in childhood and social cognition (SC) in patients with bipolar disorder type I (BD-I) in euthymia, and to test a possible moderating effect of the single nucleotide polymorphism rs53576 in the oxytocin receptor gene (OXTR).

Methods

One hundred and one participants were included in this study. History of child abuse was evaluated using the Childhood Trauma Questionnaire-Short Form. Cognitive functioning was appraised using The Awareness of Social Inference Test (social cognition). The interaction effect between the independent variables OXTR rs53576 (AA/AG and GG) and the absence or presence of any one type of child maltreatment or a combination of types was analyzed using a generalized linear model regression.

Results

BD-I patients who had been victims of physical and emotional abuse in childhood and were carriers of the GG genotype at OXTR rs53576 displayed greater SC alterations, specifically in emotion recognition.

Discussion

This gene-environment interaction finding suggests a differential susceptibility model of a genetic variants that can be plausibly associated with SC functioning and might help to identify at-risk clinical subgroups within a diagnostic category. Future research aimed at testing the interlevel impact of early stress constitutes an ethical-clinical duty given the high rates of childhood maltreatment reported in BD-I patients.

Family income buffers the relationship between childhood adverse experiences and putamen volume

Adverse experiences and family income in childhood have been associated with altered brain development. While there is a large body of research examining these associations, it has primarily used cross-sectional data sources and studied adverse experiences and family income in isolation. However, it is possible that low family income and adverse experiences represent dissociable and potentially interacting profiles of risk. To address this gap in the literature, we examined brain structure as a function of adverse experiences in childhood and family income in 158 youths with up to five waves of MRI data. Specifically, we assessed the interactive effect of these two risk factors on six regions of interest: hippocampus, putamen, amygdala, nucleus accumbens, caudate, and thalamus. Adverse experiences and family income interacted to predict putamen volume (B = 0.086, p = 0.011) but only in participants with family income one standard deviation below the mean (slope estimate = -0.11, p = 0.03). These results suggest that adverse experiences in childhood result in distinct patterns of brain development across the socioeconomic gradient. Given previous findings implicating the role of the putamen in psychopathology-related behaviors, these results emphasize the importance of considering life events and socioeconomic context when evaluating markers of risk. Future research should include interactive effects of environmental exposures and family income to better characterize risk for psychopathology in diverse samples.

Social isolation and the brain: effects and mechanisms

An obvious consequence of the coronavirus disease (COVID-19) pandemic is the worldwide reduction in social interaction, which is associated with many adverse effects on health in humans from babies to adults. Although social development under normal or isolated environments has been studied since the 1940s, the mechanism underlying social isolation (SI)-induced brain dysfunction remains poorly understood, possibly due to the complexity of SI in humans and translational gaps in findings from animal models. Herein, we present a systematic review that focused on brain changes at the molecular, cellular, structural and functional levels induced by SI at different ages and in different animal models. SI studies in humans and animal models revealed common socioemotional and cognitive deficits caused by SI in early life and an increased occurrence of depression and anxiety induced by SI during later stages of life. Altered neurotransmission and neural circuitry as well as abnormal development and function of glial cells in specific brain regions may contribute to the abnormal emotions and behaviors induced by SI. We highlight distinct alterations in oligodendrocyte progenitor cell differentiation and oligodendrocyte maturation caused by SI in early life and later stages of life, respectively, which may affect neural circuit formation and function and result in diverse brain dysfunctions. To further bridge animal and human SI studies, we propose alternative animal models with brain structures and complex social behaviors similar to those of humans.

Social interaction following prepubertal stress alters prefrontal gene expression associated with cell signalling and oligodendrocytes

Early-life adversity is associated with an increased risk of psychopathology, including mood disorders, later in life. Early-life stress affects several physiological systems, however, the exact mechanisms underlying pathological risk are not fully understood. This knowledge is crucial in developing appropriate therapeutic interventions. The prepubertal period is documented as a key developmental period for the maturation of the prefrontal cortex (PFC), a brain region involved in higher cognitive functions, including social function. In this study, we performed RNA sequencing on the PFC of adult rats who had experienced prepubertal stress (PPS) and controls to investigate the genome-wide consequences of this stress. PPS alters social behaviour in adulthood, therefore we also performed RNA sequencing on PPS and control rats following a social interaction test to determine social activity-dependent gene changes. At a baseline state (1 week following a social interaction test), no genes were differentially expressed in the PPS group. However, 1603 genes were differentially expressed in PPS rats compared to controls following a social interaction. These genes were enriched in biological pathways associated with cell signalling and axon myelination dynamics. Cell enrichment analysis showed these genes were associated with oligodendrocytes, and a comparison with an existing early-life stress sequencing dataset showed that pathways linked to oligodendrocyte morphology are impacted in a range of models of early-life stress in rodents. In conclusion, we identify pathways, including those involved in axon myelination, that are differentially activated in the adult in response to social stimulation following PPS. These differential responses may contribute to vulnerability to psychiatric pathology.

Roads Diverged: Developmental Trajectories of Irritability From Toddlerhood Through Adolescence

OBJECTIVE

Irritability is a dimensional trait that manifests from early life and is a robust transdiagnostic risk factor for psychopathology and impairment. A large, national dataset was leveraged to identify and broadly characterize trajectories from toddlerhood through adolescence, which is crucial for timely, targeted interventions.

METHOD

Data on irritability and a broad array of potential factors affecting irritability development from 4,462 children assessed longitudinally at ages 3, 5, 9, and 15 were included. Latent class growth models identified groups of children based on their nonlinear irritability trajectories from toddlerhood to adolescence. LASSO regression then identified key characteristics differentiating trajectory groups.

RESULTS

Five distinct irritability trajectories were identified, two of which were stable, maintaining medium or high irritability from age 3 to 15. Three trajectories showed undulating change over development, with an inflection point at the transition to adolescence (age 9): Most children had consistently low irritability. Two smaller groups started with high irritability at age 3 but diverged, sharply decreasing or increasing until a turning point at age 9. Developmental patterning of harsh/neglectful parenting and child internalizing symptoms most strongly differentiated trajectory groups. Sociodemographic characteristics, attachment style, neighborhood support, cognitive functioning, and genetic variation also differentiated trajectories.

CONCLUSION

The results demonstrated the importance of the transition to adolescence as a critical inflection point for youths with fluctuating irritability trajectories. Identifying these patterns and multiple malleable factors associated with stably high or rising trajectories is an important step toward targeted interventions for the most vulnerable subgroups.

DIVERSITY & INCLUSION STATEMENT

We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science. One or more of the authors of this paper self-identifies as living with a disability. One or more of the authors of this paper received support from a program designed to increase minority representation in science. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group.

A Prospective Study of the Impact of Severe Childhood Deprivation on Brain White Matter in Adult Adoptees: Widespread Localized Reductions in Volume But Unaffected Microstructural Organization

Early childhood neglect can impact brain development across the lifespan. Using voxel-based approaches we recently reported that severe and time-limited institutional deprivation in early childhood was linked to substantial reductions in total brain volume in adulthood, >20 years later. Here, we extend this analysis to explore deprivation-related regional white matter volume and microstructural organization using diffusion-based techniques. A combination of tensor-based morphometry (TBM) analysis and tractography was conducted on diffusion-weighted imaging (DWI) data from 59 young adults who spent between 3 and 41 months in the severely depriving Romanian institutions of the 1980s before being adopted into United Kingdom families, and 20 nondeprived age-matched United Kingdom controls. Independent of total volume, institutional deprivation was associated with smaller volumes in localized regions across a range of white matter tracts including (1) long-ranging association fibers such as bilateral inferior longitudinal fasciculus (ILF), bilateral inferior fronto-occipital fasciculus (IFOF), left superior longitudinal fasciculi (SLFs), and left arcuate fasciculus; (2) tracts of the limbic circuitry including fornix and cingulum; and (3) projection fibers with the corticospinal tract particularly affected. Tractographic analysis found no evidence of altered microstructural organization of any tract in terms of hindrance modulated orientational anisotropy (HMOA), fractional anisotropy (FA), or mean diffusivity (MD). We provide further evidence for the effects of early neglect on brain development and their persistence in adulthood despite many years of environmental enrichment associated with successful adoption. Localized white matter effects appear limited to volumetric changes with microstructural organization unaffected.

Early deprivation alters structural brain development from middle childhood to adolescence

Hypotheses concerning the biologic embedding of early adversity via developmental neuroplasticity mechanisms have been proposed on the basis of experimental studies in animals. However, no studies have demonstrated a causal link between early adversity and neural development in humans. Here, we present evidence from a randomized controlled trial linking psychosocial deprivation in early childhood to changes in cortical development from childhood to adolescence using longitudinal data from the Bucharest Early Intervention Project. Changes in cortical structure due to randomization to foster care were most pronounced in the lateral and medial prefrontal cortex and in white matter tracts connecting the prefrontal and parietal cortex. Demonstrating the causal impact of exposure to deprivation on the development of neural structure highlights the importance of early placement into family-based care to mitigate lasting neurodevelopmental consequences associated with early-life deprivation.

Linking Mild Childhood Adversity with Conflict and False Feedback Monitoring

It was proposed that dimensions of childhood adversity (i.e., deprivation and threat) have distinct effects on neural development and function. Present study examined the relationships between mild deprivation/threat and performance monitoring among undergraduate students without psychiatric diagnoses. By using event-related potentials (ERPs), 78 participants underwent a modified Flanker task in which false feedback on approximately 10% of the correct response trials was administered. The dynamic stages of performance monitoring in this task were differentiated into interference monitoring, feedback processing, and behavior adjustment. Childhood adversity was assessed by a Childhood Trauma Questionnaire (CTQ), which was further divided into subscales of neglect (as a proxy for deprivation dimension) and abuse (as a proxy for threat dimension). Our results showed that higher score of childhood neglect was associated with more interference cost indicated by longer RT to interference trials at the behavioral level, and altered interference monitoring indicated by smaller N2 amplitude to interference trials at the neural level. Meanwhile, higher score of childhood abuse was related to smaller P3 amplitude to unexpected negative feedback. These results suggested that mild childhood deprivation might be associated with altered processing of interference monitoring, while mild childhood threat might be linked to lower electrophysiological response to unexpected negative feedback among young adults without psychiatric disorders.

Association between child welfare reporting rates and the developmental vulnerability of kindergarten children at the neighborhood level

BACKGROUND

In Canada, more than one in four children are considered vulnerable in at least one domain of development when they enter kindergarten. Recent studies have suggested that this ratio is higher among those who were previously maltreated. However, little is known about this associations at the neighborhood level, although it may be an interesting way to identify risk areas and highlight child welfare system data to prevent public health issues.

OBJECTIVE

Using the census tract as the unit of measurement, this study examines the association between the proportions of vulnerable children in different domains of development upon entering kindergarten, and four indicators of child maltreatment (CM) among 0-5 year olds.

PARTICIPANTS, SETTING AND METHOD

This study is based on the secondary use of data from a survey on the development of kindergartners carried out in 2017, combined with data from child welfare records for that same year. The data have been aggregated on the basis of 759 census tracts located in four health regions of Quebec, Canada.

RESULTS

The results of spatial regression analyses show that all indicators of maltreatment are positively and significantly associated with each indicator of developmental vulnerability. The size of these associations varies according to the indicators used (β = 0.192, p < .05 to β = 1.587, p < .001).

CONCLUSION

The results highlight the link between CM and school readiness, including potential externalities on neighborhood children. Neighborhoods at high risk of maltreatment could help identify areas with high rate of vulnerable children in early childhood.

Adoption and trauma: Risks, recovery, and the lived experience of adoption

BACKGROUND

Although a very heterogeneous group, adopted persons may present developmental and mental health problems of varying severity. Pre-placement adversity and trauma have often been linked to these problems. It has been also suggested that adoption itself is a psychological trauma, predisposing the individual to emotional difficulties.

OBJECTIVES

This article examines the links between early adversity, trauma, and adoption. We begin by defining trauma and then describe the way in which pre-placement adversity can undermine neurobehavioral and interpersonal functioning, increasing the risk for long-term psychological difficulties. Next, we examine children's recovery when placed in a stable adoptive home. Finally, we explore adoption as a lived experience, highlighting contextual and developmental factors that facilitate the person's positive or negative attributions about being adopted, leading to varying patterns of emotional adjustment.

CONCLUSIONS

Although pre-placement adversity increases adopted individuals' risk for maladjustment, the human brain and behavior are malleable, and placement in a nurturing adoptive home often facilitates recovery from early adversity, with significant heterogeneity in the extent of recovery within and across domains of functioning. While there is no evidence that early adoption is a trauma for the individual, ongoing negative life circumstances, attachment difficulties, and developmentally-mediated attributions about adoption can undermine the person's self-esteem, identity, relationships, and sense of well-being. Conclusions and suggestions for future research are offered.

Neutrophil-to-lymphocyte ratio (NLR) variations in relationship with childhood maltreatment in patients with anorexia nervosa: a retrospective cohort study

PURPOSE

Anorexia nervosa (AN) is a serious mental illness. It is frequently accompanied by a history of childhood maltreatment (CM) that may constitute a specific ecophenotype in patients with eating disorders necessitating special assessment and management. This retrospective study tested whether in patients with AN, CM-related chronic stress may manifest through low-grade inflammation reflected by an increase in white blood cell ratios (neutrophil-to-lymphocyte ratio, NLR, platelet-to-lymphocyte ratio, and monocyte-to-lymphocyte ratio).

METHODS

Participants (N = 206) were enrolled at an eating disorder daycare unit in Montpellier, France, from March 2013 and January 2020. CM was assessed using the childhood trauma questionnaire (CTQ). The Eating Disorder Examination Questionnaire (EDE-Q) and the MINI were used to assess AN severity and the other clinical characteristics, respectively.

RESULTS

NLR was higher in patients with AN and history of CM (p = 0.029) and in patients with AN and history of emotional abuse (p = 0.021), compared with patients with AN without history of CM. In multivariate analysis, emotional abuse (β = 0.17; p = 0.027) contributed significantly to NLR variability.

CONCLUSION

In patients with AN, NLR is a low-grade inflammation marker that is influenced by various sociodemographic, clinical and biological factors. It is more directly affected by some CM types, especially emotional abuse, than by the presence/absence of CM history. Future studies should focus on mediators between CM and increased inflammation, such as interoceptive awareness, emotional dysregulation, food addiction, and stress sensitization.

LEVEL OF EVIDENCE

III. Evidence obtained from well-designed cohort or case-control analytic studies.

Examining the Role of Socioeconomic Status and Maternal Sensitivity in Predicting Functional Brain Network Connectivity in 5-Month-Old Infants

Infancy is a sensitive period of human brain development that is plastically shaped by environmental factors. Both proximal factors, such as sensitive parenting, and distal factors, such as socioeconomic status (SES), are known predictors of individual differences in structural and functional brain systems across the lifespan, yet it is unclear how these familial and contextual factors work together to shape functional brain development during infancy, particularly during the first months of life. In the current study, we examined pre-registered hypotheses regarding the interplay between these factors to assess how maternal sensitivity, within the broader context of socioeconomic variation, relates to the development of functional connectivity in long-range cortical brain networks. Specifically, we measured resting-state functional connectivity in three cortical brain networks (fronto-parietal network, default mode network, homologous-interhemispheric connectivity) using functional near-infrared spectroscopy (fNIRS), and examined the associations between maternal sensitivity, SES, and functional connectivity in a sample of 5-month-old infants and their mothers (N = 50 dyads). Results showed that all three networks were detectable during a passive viewing task, and that maternal sensitivity was positively associated with functional connectivity in the default mode network, such that infants with more sensitive mothers exhibited enhanced functional connectivity in this network. Contrary to hypotheses, we did not observe any associations of SES with functional connectivity in the brain networks assessed in this study. This suggests that at 5 months of age, maternal sensitivity is an important proximal environmental factor associated with individual differences in functional connectivity in a long-range cortical brain network implicated in a host of emotional and social-cognitive brain processes.

The effects of early life adversity on children's mental health and cognitive functioning

Emerging evidence suggests that partially distinct mechanisms may underlie the association between different dimensions of early life adversity (ELA) and psychopathology in children and adolescents. While there is minimal evidence that different types of ELA are associated with specific psychopathology outcomes, there are partially unique cognitive and socioemotional consequences of specific dimensions of ELA that increase transdiagnostic risk of mental health problems across the internalizing and externalizing spectra. The current review provides an overview of recent findings examining the cognitive (e.g., language, executive function), socioemotional (e.g., attention bias, emotion regulation), and mental health correlates of ELA along the dimensions of threat/harshness, deprivation, and unpredictability. We underscore similarities and differences in the mechanisms connecting different dimensions of ELA to particular mental health outcomes, and identify gaps and future directions that may help to clarify inconsistencies in the literature. This review focuses on childhood and adolescence, periods of exquisite neurobiological change and sensitivity to the environment. The utility of dimensional models of ELA in better understanding the mechanistic pathways towards the expression of psychopathology is discussed, with the review supporting the value of such models in better understanding the developmental sequelae associated with ELA. Integration of dimensional models of ELA with existing models focused on psychiatric classification and biobehavioral mechanisms may advance our understanding of the etiology, phenomenology, and treatment of mental health difficulties in children and youth.

Why and how does early adversity influence development? Toward an integrated model of dimensions of environmental experience

Two extant frameworks - the harshness-unpredictability model and the threat-deprivation model - attempt to explain which dimensions of adversity have distinct influences on development. These models address, respectively, why, based on a history of natural selection, development operates the way it does across a range of environmental contexts, and how the neural mechanisms that underlie plasticity and learning in response to environmental experiences influence brain development. Building on these frameworks, we advance an integrated model of dimensions of environmental experience, focusing on threat-based forms of harshness, deprivation-based forms of harshness, and environmental unpredictability. This integrated model makes clear that the why and the how of development are inextricable and, together, essential to understanding which dimensions of the environment matter. Core integrative concepts include the directedness of learning, multiple levels of developmental adaptation to the environment, and tradeoffs between adaptive and maladaptive developmental responses to adversity. The integrated model proposes that proximal and distal cues to threat-based and deprivation-based forms of harshness, as well as unpredictability in those cues, calibrate development to both immediate rearing environments and broader ecological contexts, current and future. We highlight actionable directions for research needed to investigate the integrated model and advance understanding of dimensions of environmental experience.

Timing of adoption is associated with electrophysiological brain activity and externalizing problems among children adopted internationally

This study investigated middle childhood resting electroencephalography (EEG) and behavioral adjustment in 35 internationally adopted children removed from early caregiving adversity between 6 and 29 months of age. Older age of adoption was associated with more immature or atypical profiles of middle childhood cortical function, based on higher relative theta power (4-6 Hz), lower relative alpha power (7-12 Hz), lower peak alpha frequency, and lower absolute beta (13-20 Hz) and gamma (21-50 Hz) power. More immature or atypical EEG spectral power indirectly linked older age of adoption with increased risk for externalizing problems in middle childhood. The findings add to existing evidence linking duration of early adverse exposures with lasting effects on brain function and behavioral regulation even years after living in a stable adoptive family setting. Findings underscore the need to minimize and prevent children's exposures to early caregiving adversity, especially in the first years of life. They call for innovative interventions to support neurotypical development in internationally adopted children at elevated risk.

A Review of Family Environment and Neurobehavioral Outcomes Following Pediatric Traumatic Brain Injury: Implications of Early Adverse Experiences, Family Stress, and Limbic Development

Pediatric traumatic brain injury (TBI) is a public health crisis, with neurobehavioral morbidity observed years after an injury associated with changes in related brain structures. A substantial literature base has established family environment as a significant predictor of neurobehavioral outcomes following pediatric TBI. The neural mechanisms linking family environment to neurobehavioral outcomes have, however, received less empiric study in this population. In contrast, limbic structural differences as well as challenges with emotional adjustment and behavioral regulation in non-TBI populations have been linked to a multitude of family environmental factors, including family stress, parenting style, and adverse childhood experiences. In this article, we systematically review the more comprehensive literature on family environment and neurobehavioral outcomes in pediatric TBI and leverage the work in both TBI and non-TBI populations to expand our understanding of the underlying neural mechanisms. Thus, we summarize the extant literature on the family environment's role in neurobehavioral sequelae in children with TBI and explore potential neural correlates by synthesizing the wealth of literature on family environment and limbic development, specifically related to the amygdala. This review underscores the critical role of environmental factors, especially those predating the injury, in modeling recovery outcomes post-TBI in childhood, and discusses clinical and research implications across pediatric populations. Given the public health crisis of pediatric TBI, along with the context of sparse available medical interventions, a broader understanding of factors contributing to outcomes is warranted to expand the range of intervention targets.

Consequences of Inadequate Caregiving for Children's Attachment, Neurobiological Development, and Adaptive Functioning

Given that human infants are almost fully reliant on caregivers for survival, the presence of parents who provide sensitive, responsive care support infants and young children in developing the foundation for optimal biological functioning. Conversely, when parents are unavailable or insensitive, there are consequences for infants' and children's attachment and neurobiological development. In this paper, we describe effects of inadequate parenting on children's neurobiological and behavioral development, with a focus on developing capacities for executive functioning, emotion regulation, and other important cognitive-affective processes. Most prior research has examined correlational associations among these constructs. Given that interventions tested through randomized clinical trials allow for causal inferences, we review longitudinal intervention effects on children's biobehavioral and cognitive-affective outcomes. In particular, we provide an overview of the Bucharest Early Intervention Project, a study in which children were randomized to continue in orphanage care (typically the most extreme condition of privation) or were placed into the homes of trained, supported foster parents. We also discuss findings regarding Attachment and Biobehavioral Catch-up, an intervention enhancing sensitivity among high-risk parents. We conclude by suggesting future directions for research in this area.

Early life stress and substance use disorders: The critical role of adolescent substance use

Early life stress (ELS) is a well-established risk factor for many psychiatric and medical disorders, including substance use disorders (SUDs). The relationship between ELS and SUDs is complex and there are likely multiple pathways from ELS to adverse substance use outcomes. The association between ELS and substance use emerges in adolescence. Adolescence is a critical period in development during which substance exposure markedly increases risk for SUDs. Therefore, this review focuses on the literature supporting the hypothesis that ELS increases risk for the development of SUDs through its influence on adolescent substance use. We discuss studies substantiating the role of ELS in adolescent substance use and explore how internalizing and externalizing psychopathology may be antecedents of substance use in adolescence. We examine clinical work suggesting ELS sculpts the Hypothalamic-Pituitary-Adrenal (HPA) Axis and developing brain-particularly subcortical brain regions that underlie stress response, mesocorticolimbic brain systems associated with reward sensitivity, and prefrontal regions that underlie executive control-in a way that increases risk for adolescent substance use and SUDs. We further explore how substance use during adolescence alters structure and function of these same systems, and how brain changes following ELS and adolescent substance use may independently, additively, or interactively contribute to risk for addiction. We conclude by discussing how the current literature can inform interventions aimed at reducing risk for SUDs in individuals with a history of ELS.

Early Life Stress and Neurodevelopment in Adolescence: Implications for Risk and Adaptation

An alarming high proportion of youth experience at least one kind of stressor in childhood and/or adolescence. Exposure to early life stress is associated with increased risk for psychopathology, accelerated biological aging, and poor physical health; however, it is important to recognize that not all youth who experience such stress go on to develop difficulties. In fact, resilience, or positive adaptation in the face of adversity, is relatively common. Individual differences in vulnerability or resilience to the effects of early stress may be represented in the brain as specific patterns, profiles, or signatures of neural activation, structure, and connectivity (i.e., neurophenotypes). Whereas neurophenotypes of risk that reflect the deleterious effects of early stress on the developing brain are likely to exacerbate negative outcomes in youth, neurophenotypes of resilience may reduce the risk of experiencing these negative outcomes and instead promote positive functioning. In this chapter we describe our perspective concerning the neurobiological mechanisms and moderators of risk and resilience in adolescence following early life stress and integrate our own work into this framework. We present findings suggesting that exposure to stress in childhood and adolescence is associated with functional and structural alterations in neurobiological systems that are important for social-affective processing and for cognitive control. While some of these neurobiological alterations increase risk for psychopathology, they may also help to limit adolescents' sensitivity to subsequent negative experiences. We also discuss person-centered strategies that we believe can advance our understanding of risk and resilience to early stress in adolescents. Finally, we describe ways in which the field can broaden its focus to include a consideration of other types of environmental factors, such as environmental pollutants, in affecting both risk and resilience to stress-related health difficulties in youth.

The role of sociodemographic and psychosocial variables in early childhood development: A secondary data analysis of the 2014 and 2019 Multiple Indicator Cluster Surveys in the Dominican Republic

The association between sociodemographic factors-poverty, lack of maternal schooling, being male at birth-, childhood developmental delay, and poor educational outcomes has been established in the Dominican Republic (DR). However, family moderating factors present or introduced to buffer sociodemographic factors effects on early childhood development (ECD) are still unknown. We conducted a secondary analysis of the DR's 2014 and 2019 Multiple Indicator Cluster Surveys. We had four study aims: 1) confirm the relationship between socioeconomic position (SP), parenting practices, and ECD; 2) determine if a sociodemographic model predicted ECD; 3) determine if a psychosocial model (family childrearing practices, discipline, and early childhood stimulation) predicted ECD above and beyond the sociodemographic model; 4) explore mothers' beliefs about physical punishment and its relationship with ECD and psychosocial variables. We found that both models predicted ECD significantly, but the psychosocial model explained more variance than the sociodemographic model (6.3% in 2014 and 4.4% in 2019). The most relevant sociodemographic predictors were SP (explaining 21.6% of ECD variance in 2014 and 18.6% in 2019) and mother's education (explaining 13.9% in 2014 and 14.1% in 2019). The most salient ECD psychosocial predictors were: negative discipline, number of children's books at home, stimulating activities at home, and attendance to an early childhood education program. The predicting weights of the independent variables were similar for both years. These results have multiple implications for social programs that aim to improve children's potential in contexts of poverty. Although the results show a protective effect of psychosocial factors, sustainable and large-scale interventions should not be limited to just buffering effects, but to solve the underlying problem, which is that poverty prevents children from reaching their developmental potential and exposes them to life-long greater risk for chronic disease. Addressing delays early in life can therefore contribute to achieving health equity.

Brain morphometry and diminished physical growth in Bangladeshi children growing up in extreme poverty: A longitudinal study

Diminished physical growth is a common marker of malnutrition and it affects approximately 200 million children worldwide. Despite its importance and prevalence, it is not clear whether diminished growth relates to brain development and general cognitive ability. Further, diminished growth is more common in areas of extreme poverty, raising the possibility that it may mediate previously shown links between socioeconomic status (SES) and brain structure. To address these gaps, 79 children growing up in an extremely poor, urban area of Bangladesh underwent MRI at age six years. Structural brain images were submitted to Mindboggle software, a Docker-compliant and high-reproducibility tool for tissue segmentation and regional estimations of volume, surface area, cortical thickness, sulcal depth, and mean curvature. Diminished growth predicted brain morphometry and mediated the link between SES and brain morphometry most consistently for subcortical and white matter subcortical volumes. Meanwhile, brain volume in left pallidum and right ventral diencephalon mediated the relationship between diminished growth and full-scale IQ. These findings offer malnutrition as one possible pathway through which SES affects brain development and general cognitive ability in areas of extreme poverty.