Subcortical structures and the neurobiology of infant attachment disorganization: A longitudinal ultrasound imaging study

Infant attachment does not depend on neonatal amygdala and hippocampal structure and connectivity

Infant attachment is an antecedent of later socioemotional abilities, which can be adversely affected by preterm birth. The structural integrity of amygdalae and hippocampi may subserve attachment in infancy. We aimed to investigate associations between neonatal amygdalae and hippocampi structure and their whole-brain connections and attachment behaviours at nine months of age in a sample of infants enriched for preterm birth. In 133 neonates (median gestational age 32 weeks, range 22.14-42.14), we calculated measures of amygdala and hippocampal structure (volume, fractional anisotropy, mean diffusivity, neurite dispersion index, orientation dispersion index) and structural connectivity, and coded attachment behaviours (distress, fretfulness, attentiveness to caregiver) from responses to the Still-Face Paradigm at nine months. After multiple comparisons correction, there were no significant associations between neonatal amygdala or hippocampal structure and structural connectivity and attachment behaviours: standardised β values - 0.23 to 0.18, adjusted p-values > 0.40. Findings indicate that the neural basis of infant attachment in term and preterm infants is not contingent on the structure or connectivity of the amygdalae and hippocampi in the neonatal period, which implies that it is more widely distributed in early life and or that network specialisation takes place in the months after hospital discharge.

Neurobiology of Disorganized Attachment: A Review of Primary Studies on Human Beings

This article describes and analyzes various aspects related to the neurobiology of disorganized attachment (DA), which is associated with personality, eating, affective, dissociative, and addictive disorders. We included primary studies in humans, published in PubMed from 2000 to 2022. Eight genetic and one epigenetic study were considered. Three molecular studies describe possible roles of oxytocin and cortisol, seven neurophysiological studies investigated functional correlates, and five morphological studies describe anatomical changes. Findings in candidate genes involved in dopaminergic, serotonergic, and oxytonergic systems have not been able to be replicated in large-scale human studies. Alterations in the functioning of cortisol and oxytocin are preliminary. Neurophysiological studies show changes in subcortical structures (mainly in the hippocampus) and occipital, temporal, parietal, and insular cortices. Since there is a lack of robust evidence on the neurobiology of DA in humans, the possible inferences of these studies are preliminary, which restricts their translation to clinical parameters.

Mothers’ Attachment Representations and Children’s Brain Structure

Ample research demonstrates that parents’ experience-based mental representations of attachment—cognitive models of close relationships—relate to their children’s social-emotional development. However, no research to date has examined how parents’ attachment representations relate to another crucial domain of children’s development: brain development. The present study is the first to integrate the separate literatures on attachment and developmental social cognitive neuroscience to examine the link between mothers’ attachment representations and 3- to 8-year-old children’s brain structure. We hypothesized that mothers’ attachment representations would relate to individual differences in children’s brain structures involved in stress regulation—specifically, amygdala and hippocampal volumes—in part via mothers’ responses to children’s distress. We assessed 52 mothers’ attachment representations (secure base script knowledge on the Attachment Script Assessment and self-reported attachment avoidance and anxiety on the Experiences in Close Relationships scale) and children’s brain structure. Mothers’ secure base script knowledge was significantly related to children’s smaller left amygdala volume but was unrelated to hippocampal volume; we found no indirect links via maternal responses to children’s distress. Exploratory analyses showed associations between mothers’ attachment representations and white matter and thalamus volumes. Together, these preliminary results suggest that mothers’ attachment representations may be linked to the development of children’s neural circuitry related to stress regulation.

Infant social interactions and brain development: A systematic review

•

Associations between caregiver-infant behaviours during social interactions and brain development outcomes were investigated.

•

Caregivers' and infants' behaviours in interactions related to children’s structural, functional and connectivity measures.

•

Concurrent associations between behavioural and brain measures were apparent as early as three months postnatally.

•

Long-term associations between behaviours in early interactions and brain development outcomes were observed decades later.

•

Individual differences in early interactions and associated brain development is an important avenue for further research.

From birth, interactions with others are an integral part of a person’s daily life. In infancy, social exchanges are thought to be critical for optimal brain development. This systematic review explores this association by drawing together infant studies that relate adult-infant behaviours – coded from their social interactions - to children’s brain measures collected during a neuroimaging session in infancy, childhood, adolescence or adulthood. In total, we identified 55 studies that explored associations between infants’ social interactions and neural measures. These studies show that several aspects of caregiver-infant behaviours are associated with, or predict, a variety of neural responses in infants, children and adolescents. The presence of both concurrent and long-term associations - some of which are first observed just a few months postnatally and extend into adulthood - open an important research avenue and motivate further longitudinal studies.

Social cognition following preterm birth: A systematic review

Social cognitive abilities are affected by preterm birth, but pathways to, and risk factors for this outcome are not well mapped. We examined direct assessment tasks including objective coding of parent-child play to chart social development in infancy and pre-school years. A systematic search and data-extraction procedure yielded seventy-nine studies (4930 preterm and 2109 term children, aged birth - five years), for inclusion. We detected a pattern of reduced social attention in the first 12 months of life with evidence of reduced performance in social cognitive tasks later in the preschool years. However, we did not identify a consistent, distinctive preterm social phenotype in early life. Instead, the interactive behaviour of preterm infants reflects factors from outside the social cognitive domain, such as attention, language, and socioeconomic status. By combining data across samples and measures we revealed the role of domain-general skills, which may in future prove fruitful intervention targets.

Promoting mother-infant relationships and underlying neural correlates: Results from a randomized controlled trial of a home-visiting program for adolescent mothers in Brazil

Poverty and teenage pregnancy are common in low-and-middle-income countries and can impede the development of healthy parent-child relationships. This study aimed to test whether a home-visiting intervention could improve early attachment relationships between adolescent mothers and their infants living in poverty in Brazil. Analyses were conducted on secondary outcomes from a randomized controlled trial (NCT0280718) testing the efficacy of a home-visiting program, Primeiros Laços, on adolescent mothers' health and parenting skills and their infants' development. Pregnant youth were randomized to intervention (n = 40) or care-as-usual (CAU, n = 40) from the first trimester of pregnancy until infants were aged 24 months. Mother-infant attachment was coded during a mother-infant interaction when the infants were aged 12 months. Electrophysiological correlates of social processing (mean amplitude of the Nc component) were measured while infants viewed facial images of the mother and a stranger at age 6 months. Infants in the intervention group were more securely attached and more involved with their mothers than those receiving CAU at 12 months. Smaller Nc amplitudes to the mother's face at 6 months were associated with better social behavior at 12 months. Our findings indicate that the Primeiros Laços Program is effective in enhancing the development of mother-infant attachment.

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.

Fetal brain ultrasound measures and maternal nutrition: A feasibility study in Ecuador

OBJECTIVE

Nutrition during pregnancy is an important modifiable determinant of fetal growth and development. This pilot study aimed to characterize the association between fetal anthropometry, fetal brain development, and maternal diet among women in Ecuador using portable ultrasound in resource-limited clinics, including measurements of brain structures not typically imaged in this setting.

METHODS

Pregnant women (n = 47) from four resource-limited health centers were surveyed on demographic, socioeconomic, morbidity, and dietary information. Maternal height, weight, and blood pressure were taken. A sonographer took 15 images per participant, including those standardly assessed during the fetal survey and additional brain structures identified as potentially responsive to maternal nutrition, but not part of the standard fetal survey.

RESULTS

Mean percentiles for all standard fetal survey measurements generated from WHO Fetal Growth Curves fell below 50%, and negative mean Z scores were found for biparietal diameter (-0.95 ± 1.11) and femur length (-0.22 ± 1.10). Generalized linear modeling adjusting for gestational age and other covariates showed frequency of seafood consumption was positively associated with fetal biparietal diameter Z score (P = 0.005), beans and legumes positively associated with femur length (P = 0.006), and a negative association was found for soda consumption and fetal head circumference (P = 0.013).

CONCLUSIONS

This pilot study demonstrated the feasibility of capturing images of nutrition-relevant fetal brain structures not part of the standard fetal survey in resource-limited settings using portable ultrasound. Our study revealed associations between anthropometry, brain structure size, and maternal diet demonstrating potential for prenatal nutrition research using ultrasound in the field.

Preconception and perinatal predictors of offspring attachment disorganization: Advancing the replicated evidence

Attachment disorganization in early childhood is an influential yet modifiable risk factor for later mental health problems. Beyond established transmission through parents' unresolved attachment representations and caregiving sensitivity, little replicated evidence exists for wider determinants of offspring attachment disorganization. This study examined the replicated evidence for psychosocial risk factors in the preconception, prenatal, and postnatal periods. We identified all relevant longitudinal studies, and examined all risk relationships for which evidence existed in two or more cohorts (48 effects, 17 studies, N = 6,099). Study-specific and pooled risk associations were estimated and a range of moderators evaluated. Mothers' low socioeconomic status (r = .28, k = 2), perinatal loss of a child (r = .26, k = 2), caregiving intrusiveness (r = .31, k = 2), and infant male sex (r = .26, k = 4) predicted offspring attachment disorganization. Maternal sensitivity (r = -.25, k = 6) and higher metacognition during pregnancy (r = -.23, k = 3) predicted lower risk of offspring attachment disorganization. Findings suggest the origins of offspring disorganized attachment include but extend beyond maternal unresolved attachment representations and caregiving. We discuss implications for theory and for identification of modifiable risk pathways in the perinatal window.

Observed infant-parent attachment and brain morphology in middle childhood- A population-based study

Poor quality of the early infant-parent bond predicts later child problems. Infant-parent attachment has been suggested to influence brain development, but this association has hardly been examined. In adults, larger amygdala volumes have been described in relation to early attachment disorganization; neuroimaging studies of attachment in children, however, are lacking. We examined the association between infant-parent attachment and brain morphology in 551 children from a population-based cohort in the Netherlands. Infant-parent attachment was observed with the Strange-Situation Procedure at age 14 months and different brain measures were collected with magnetic resonance imaging at mean age 10 years. Children with disorganized infant attachment had larger hippocampal volumes than those with organized attachment patterns. This finding was robust to the adjustment for confounders and consistent across hemispheres. The association was not explained by cognitive or emotional and behavioral problems. Disorganized attachment did not predict any other difference in brain morphology. Moreover, children with insecure organized infant attachment patterns did not differ from those who were securely attached in any brain outcome. Causality cannot be inferred, but our findings in this large population-based study provide novel evidence for a long-term association between the quality of infant-parent attachment and specific brain differences in childhood.

The influence of perceived parenting styles on socio-emotional development from pre-puberty into puberty

The relative impact of parenting on socio-emotional development of children has rarely been examined in a longitudinal context. This study examined the association between perceived parenting styles and socio-emotional functioning from childhood to adolescence. We hypothesized that optimal parenting associated with improvement in socio-emotional functioning from childhood into early adulthood, especially for those with more behavioral problems in childhood. Children between ages 7 and 9 years were recruited for the Singapore Cohort Study of Risk Factors for Myopia (SCORM). Nine years later, 700 out of 1052 subjects were followed up (67%). During childhood, parents completed the Child Behavior Checklist (CBCL), while young adults completed the Youth Self-Report (YSR) and Parental Bonding Instrument (PBI). Perceived optimal parental care resulted in less internalizing and externalizing problems in early adulthood in comparison to non-optimal parental care styles. Perceived optimal paternal parenting, but not maternal parenting, in interaction with childhood externalizing problems predicted externalizing symptoms in early adulthood. No significant interactions were found between perceived parenting styles and internalizing problems. In conclusion, perceived parental care associates with the quality of socio-emotional development, while optimal parenting by the father is especially important for children with more externalizing problems in childhood.

Paediatric population neuroimaging and the Generation R Study: the second wave

Paediatric population neuroimaging is an emerging field that falls at the intersection between developmental neuroscience and epidemiology. A key feature of population neuroimaging studies involves large-scale recruitment that is representative of the general population. One successful approach for population neuroimaging is to embed neuroimaging studies within large epidemiological cohorts. The Generation R Study is a large, prospective population-based birth-cohort in which nearly 10,000 pregnant mothers were recruited between 2002 and 2006 with repeated measurements in the children and their parents over time. Magnetic resonance imaging was included in 2009 with the scanning of 1070 6-to-9-year-old children. The second neuroimaging wave was initiated in April 2013 with a total of 4245 visiting the MRI suite and 4087 9-to-11-year-old children being scanned. The sequences included high-resolution structural MRI, 35-direction diffusion weighted imaging, and a 6 min and 2 s resting-state functional MRI scan. The goal of this paper is to provide an overview of the imaging protocol and the overlap between the neuroimaging data and metadata. We conclude by providing a brief overview of results from our first wave of neuroimaging, which highlights a diverse array of questions that can be addressed by merging the fields of developmental neuroscience and epidemiology.

Attention to Faces Expressing Negative Emotion at 7 Months Predicts Attachment Security at 14 Months

To investigate potential infant-related antecedents characterizing later attachment security, this study tested whether attention to facial expressions, assessed with an eye-tracking paradigm at 7 months of age (N = 73), predicted infant-mother attachment in the Strange Situation Procedure at 14 months. Attention to fearful faces at 7 months predicted attachment security, with a smaller attentional bias to fearful expressions associated with insecure attachment. Attachment disorganization in particular was linked to an absence of the age-typical attentional bias to fear. These data provide the first evidence linking infants' attentional bias to negative facial expressions with attachment formation and suggest reduced sensitivity to facial expressions of negative emotion as a testable trait that could link attachment disorganization with later behavioral outcomes.

Beyond the usual suspects: a multidimensional genetic exploration of infant attachment disorganization and security

Although the environmental influences on infant attachment disorganization and security are well-studied, little is known about their heritability. Candidate gene studies have shown small, often non-replicable effects. In this study, we gathered the largest sample (N = 657) of ethnically homogenous, 14-month-old children with both observed attachment and genome-wide data. First, we used a Genome-Wide Association Study (GWAS) approach to identify single nucleotide polymorphisms (SNPs) associated with attachment disorganization and security. Second, we annotated them into genes (Versatile Gene-based Association Study) and functional pathways. Our analyses provide evidence of novel genes (HDAC1, ZNF675, BSCD1) and pathways (synaptic transmission, cation transport) associated with attachment disorganization. Similar analyses identified a novel gene (BECN1) but no distinct pathways associated with attachment security. The results of this first extensive, exploratory study on the molecular-genetic basis of infant attachment await replication in large, independent samples.

Indiscriminate behaviors in previously institutionalized young children

OBJECTIVE

This study included 54-month-old children with a history of institutional care. Our goal was to: (1) examine differences in indiscriminate social behaviors in children with a history of institutional care compared with home-reared children; (2) test whether foster care reduces indiscriminate social behaviors in a randomized controlled trial; and (3) examine early predictors of indiscriminate behaviors.

METHODS

Participants were 58 children with a history of institutional care and 31 never-institutionalized control (NIG) subjects enrolled in a randomized controlled trial of foster care for institutional care, assessed from toddlerhood to 54 months. Indiscriminate social behaviors were measured naturalistically by using the Stranger at the Door procedure.

RESULTS

In the Stranger at the Door procedure, children with a history of institutional care left with a stranger at higher rates than NIG subjects (33% vs. 3.5%; P < .001). Children in the care as usual group left more than NIG subjects (41.9% vs. 3.6%; P ≤ .001). The differences between the foster care group (24.1%) and the care as usual group and between foster care group and NIG were not significant. In a logistic regression, early disorganized attachment behaviors, baseline developmental quotient, and caregiving quality after randomization contributed to variance at 54 months. In the same analysis using only children with a history of institutional care, only disorganized attachment contributed significantly to 54-month indiscriminate social behaviors (Exp[B] = 1.6 [95% confidence interval: 1.1-2.5]).

CONCLUSIONS

Observed socially indiscriminate behaviors at 54 months were associated with prolonged exposure to institutional care. Young children raised in conditions of deprivation who fail to develop organized attachments as toddlers are at increased risk for subsequent indiscriminate behaviors.

Attachment insecurity predicts child active resistance to parental requests in a compliance task

AIM

We studied the effects of early mother-child relationship quality and child temperament on the development of child compliance and active resistance in a large population-based cohort study (n = 534).

BACKGROUND

Parenting and the quality of the parent-child relationship can either hamper or support the development of child compliance directly or in interplay with child temperament.

METHODS

Mother-infant dyads were observed at 14 and 36 months and maternal and child behaviours were independently coded. The quality of compliance was assessed at 36 months in a clean-up task. Child behaviour was coded using a system differentiating between two dimensions: Compliance and Active Resistance.

RESULTS

Controlling for concurrent maternal sensitivity, child temperament, and gender children with a more insecure attachment relationship showed higher levels of active resistance during Clean-Up than more securely attached children. The effect was stronger for boys than for girls and mainly driven by attachment avoidance.

CONCLUSIONS

Early attachment is an important contributor to child socialization of moral behaviour.

Breastfeeding and early brain development: the Generation R study

Breastfeeding during infancy is associated with a range of short- and long-term health benefits. We examine whether breastfeeding in the first 2 months of life is associated with structural markers of brain development in infants from the general population. This study was embedded within the Generation R study. Cranial ultrasounds were obtained at approximately 7 weeks post-natal age. The diameter of the gangliothalamic ovoid, corpus callosum length, ventricular volume and head circumference were measured. Maternal reports of breastfeeding were obtained at 2 months of age. We examined associations in relation to current breastfeeding practices (exclusively breastfed, n = 318, breast- and bottle-fed, n = 119, and bottle-fed, n = 243). Analyses were adjusted for head size and relevant covariates. Secondary analyses were conducted for breastfeeding history (exclusively breastfed, n = 318, breast- and bottle-fed, n = 281, and never breastfed, n = 81). Exclusive breastfeeding was associated with more optimal brain development compared with babies who were bottle-fed or never breastfed. Results were most consistent for gangliothalamic ovoid diameter. Larger gangliothalamic ovoid diameters were evident in babies who were exclusively breastfed compared with bottle-fed babies [difference between means (95% confidence interval) = 0.21(0.02, 0.39), P = 0.02]. Smaller ventricular volume and larger head circumference were also found for exclusively breastfed babies. Breastfeeding was not significantly associated with corpus callosum length. Maternal reports of breastfeeding are associated with more mature brain development within the first 2 months of life. Results are most consistent for gangliothalamic ovoid diameter, a subcortical structure rich in docosahexaenoic acid. Findings also pointed to non-specific neural developmental advantage for exclusively breastfed babies.