Individual differences in the activity of the hypothalamic pituitary adrenal axis: Relations to age and cumulative risk in early childhood.

This study examined individual differences in the function of the hypothalamic-pituitary-adrenal (HPA) axis with regard to age and cumulative risk during challenging laboratory tasks administered at 6, 12, 24, and 36 months. Saliva samples were collected from a majority-minority sample of N=185 children (57% African American, 50% female) prior to and following these tasks and later assayed for cortisol. Cumulative distal risk was indexed via a composite of maternal marital status, maternal education, income-to-needs ratio, the number of children in the household, and maternal age at childbirth.

Patterns of joint parasympathetic, sympathetic, and adrenocortical activity and their associations with temperament in early childhood.

Evidence has accrued to show that autonomic and adrenocortical systems act in coordination to facilitate responses to environmental opportunities and threats. In the current study, we used cluster analysis to examine whether individual differences in patterns of joint baseline activity among the parasympathetic and sympathetic branches of the autonomic nervous system with the hypothalamic-pituitary-adrenal axis are associated with parent-reported temperamental positive and negative affectivity in 36-month old children. The resulting clusters corresponded to the sensitive, buffered, and vigilant patterns as predicted by the adaptive calibration model of stress responsivity (Del Giudice et al.

The developmental course of salivary alpha-amylase and cortisol from 12 to 36 months: Relations with early poverty and later behavior problems.

This study examined the development of baseline autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) physiological activity from 12 to 36 months as well as antecedents (poverty) and consequents (behavior problems) of individual differences in physiological development. Children (N=179; 50% poor; 56% African American; 52% male) provided saliva samples at 12, 18, 24, 30, and 36 months of age. Latent growth curve models indicated that nonlinear change was evident for both sAA and cortisol, with sAA increasing and cortisol decreasing with age.

Parenting behaviors and vagal tone at six months predict attachment disorganization at twelve months.

The authors investigated the relationships among parenting behaviors, infant vagal tone, and subsequent attachment classification. Vagal tone was assessed among 6-month olds (n = 95) during the still-face paradigm (SFP) via respiratory sinus arrhythmia (RSA), while attachment security and disorganization were measured at 12 months during the strange situation procedure (SSP). Infants demonstrating higher levels of RSA during the normal interaction and reunion episodes of the SFP whose mothers were also rated as negative-intrusive exhibited higher levels of attachment disorganization at 12 months, while infants with lower RSA and mothers who were negative-intrusive did not exhibit higher levels of disorganization.

Systems theory and cascades in developmental psychopathology.

In the wake of prominent theoreticians in developmental science, whose contributions we review in this article, many developmental psychologists came to endorse a systems approach to understanding how the individual, as it develops, establishes functional relationships to social ecological contexts that from birth to school entry rapidly increase in complexity. The concept of developmental cascade has been introduced in this context to describe lawful processes by which antecedent conditions may be related with varying probabilities to specified outcomes. These are understood as processes by which function at one level or in one domain of behavior affect the organization of competency in later developing domains of general adaptation.

Psychophysiological correlates of parenting behavior in mothers of young children.

This study investigated HPA and vagal functioning as correlates of parenting in mothers of 175 six-month-old children. Salivary cortisol indexed HPA functioning and respiratory sinus arrhythmia (RSA) reduction indexed vagal regulation. Positive engagement and negative intrusiveness were observed during the Face-to-Face Still Face Paradigm (FFSFP) reunion and a semi-structured free play episode.

An anxiety-like phenotype in mice selectively bred for aggression.

Using selective bi-directional breeding procedures, two different lines of mice were developed. The NC900 line is highly reactive and attacks their social partners without provocation, whereas aggression in NC100 animals is uncommon in social environments. The enhanced reactivity of NC900 mice suggests that emotionality may have been selected with aggression.

Changes in maternal sensitivity across the first three years: are mothers from different attachment dyads differentially influenced by depressive symptomatology?

Hierarchical linear modeling was used to describe longitudinal relations between maternal sensitivity and depressive symptomatology for mothers of children with differing attachment classifications at 36 months of child age using data from the NICHD Study of Early Child Care. Attachment during toddlerhood was assessed using a modified Strange Situation Paradigm developed by the MacArthur Working Group on Attachment. On average, maternal sensitivity increased longitudinally from 6 to 36 months for groups with children classified as secure or resistant, but not for groups classified as avoidant or disorganized.

Parasympathetic and sympathetic responses to the strange situation in infants and mothers from avoidant and securely attached dyads.

Vagal reactivity and salivary alpha-amylase (sAA) were assessed in infants (M age = 13.55 months) and their mothers during the Strange Situation Paradigm (SSP) to investigate differences in physiological responses in a sample of insecure-avoidant and securely-attached dyads (N = 132). Infants classified as insecure-avoidant had significantly higher vagal withdrawal during the SSP and higher sAA overall, suggesting that the avoidant attachment pattern is associated with a greater allostatic load.

A biological window on psychological development.

The articles in this special issue of Developmental Psychobiology were presented in May 2005 at an international institute on developmental science hosted by the University of North Carolina at Chapel Hill. Conducted annually at one of the participating universities, these meetings are intended to foster collaboration and build consensus on specific theoretical, methodological, and analytical issues faced by developmentally oriented researchers. The overall goal of the 2005 meeting, titled "Integrating Biology and Developmental Science," was to identify different ways by which a developmental study of psychological phenomena in their joint biological and behavioral aspects may shed new light on their organization in the individual.

Bidirectional genetic and environmental influences on mother and child behavior: the family system as the unit of analyses.

Family systems theory proposes that an individual's functioning depends on interactive processes within the self and within the context of dyadic family subsystems. Previous research on these processes has focused largely on behavioral, cognitive, and psychophysiological properties of the individual and the dyad. The goals of this study were to explore genetic and environmental interactions within the family system by examining how the dopamine receptor D2 gene (DRD2) A1+ polymorphism in mothers and children relates to maternal sensitivity, how maternal and child characteristics might mediate those effects, and whether maternal sensitivity moderates the association between DRD2 A1+ and child affective problems.

Infant and parent factors associated with early maternal sensitivity: a caregiver-attachment systems approach.

We examined variations in maternal sensitivity at 6 months of child age as a function of child negativity and maternal physiology. We expected maternal vagal withdrawal in response to infant negative affect to facilitate the maintenance of sensitivity, but only for mothers of securely attached children. One hundred and forty-eight infant-mother dyads were observed in multiple contexts at 6 months of child age, and associations among maternal and child variables were examined with respect to 12-month attachment quality.

Handling, genetic and housing effects on the mouse stress system, dopamine function, and behavior.

This research was designed to examine how early stimulation (i.e., handling), subsequent housing conditions and genetic factors interact to produce adult differences in stress regulation.