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

The authors examined preschoolers' aggressive and cooperative behaviors and their associations with social dominance. First and as predicted, directly observed aggressive interactions decreased across the school year, and same-sex aggression occurred more frequently than cross-sex aggression. Next, the authors examined the relation between aggression and reconciliation, cooperation, and social display variables. Teacher ratings of children's aggression related to observed aggression but not to observed "wins" of aggressive bouts. Instead, wins were related to cooperation and display variables. Finally, they examined the relative power of wins and cooperation in predicting 2 measures of social dominance. After age was controlled, wins alone predicted teacher-rated social dominance. Results are discussed in terms of different forms of competition and how school ethos affects these forms.

Associations between behavioral inhibition and activity of the hypothalamic-pituitary-adrenocortical (HPA) system, a stress-sensitive neuroendocrine system indexed by salivary cortisol, have varied widely across studies. The current study examined the role of peer social experiences in moderating patterns of association between inhibition/risk-aversion and cortisol reactivity. As expected based on previous research, preschool children (N= 165, 78 boys, 3.0–5.0 years) had significantly different social experiences in their preschool classrooms depending on temperament. Highly inhibited/risk-averse children were less socially integrated, less dominant, and less involved in aggressive encounters than both average and highly exuberant/risk-seeking children, but they were no more likely to be peer rejected. Highly exuberant children were more dominant, exhibited anger more often, and had friendships characterized by higher conflict. Cortisol levels fell from fall to spring for the average and highly exuberant children, but not for the highly inhibited children. Unexpectedly, for highly inhibited children, having friends and being more dominant and popular than other highly inhibited children was associated with increasing cortisol levels over the school year. In contrast, highly exuberant children who were less socially integrated than other highly exuberant children maintained higher cortisol levels. Results indicate that the types of social experiences that affect stress-responsive biological systems may differ markedly for highly inhibited and highly exuberant children.

This study examined the formation and quality of attachment of 65 post-institutionalized (PI) toddlers with their parents at 1-3 and 7-9 months post adoption compared to 52 non-adopted (NA) children. The formation of attachment relationships of PI children with adoptive parents occurred relatively quickly. Children exposed to greater pre-adoption adversity took longer to form an attachment to their adoptive parents, although by 7-9 months post adoption, nearly all (90%) of the children achieved the highest level on an attachment formation rating scale. PI children did not differ from NA children in attachment security, based either on the Attachment Q-Sort or Strange Situation categorical scoring. However, the PI children were more likely to be disorganized in their attachment pattern. Pre-adoption adversity was related to lower Q-sort security scores especially at the initial assessment 1-3 months post adoption. The results indicated that attachment formation and attachment quality in PI children are differentiable constructs with different precursors.

The most commonly reported socially aberrant behavior in postinstitutionalized (PI) children is disinhibited social engagement (DSE; also known as indiscriminate friendliness). There is no gold standard for measurement of this phenomenon or agreement on how to differentiate it from normative behavior. We adopted a developmental psychopathology approach (Cicchetti, 1984) to study this phenomenon by comparing it to normative social development and by studying its patterns over time in 50 newly adopted PI children (16–36 months at adoption) compared with 41 children adopted early from foster care overseas and 47 nonadopted (NA) controls. Using coded behavioral observations of the child’s interaction with an unfamiliar adult, atypical behaviors were differentiated from normative behaviors. Principal components analysis identified two dimensions of social disinhibition. The nonphysical social dimension (e.g., initiations, proximity) showed wide variation in NA children and is therefore considered a typical form of sociability. Displays of physical contact and intimacy were rare in NA children, suggesting that they represent an atypical pattern of behavior. Both adopted groups demonstrated more physical DSE behavior than NA children. There were no group differences on the nonphysical factor, and it increased over time in all groups. Implications for understanding the etiology of DSE and future directions are discussed.