Examining stress reactivity in neonates: relations between cortisol and behavior

The association between cortisol and behavioral reactivity to a medical heel stick and a neurobehavioral exam was examined in 100 healthy African American neonates, who have been underrepresented in this area of research. Using continuous measures, behavioral distress was associated with cortisol reactivity to both stressors. High levels of behavioral distress, however, were associated with cortisol reactivity only in response to the neurobehavioral exam. In contrast, low levels of behavioral distress were associated with cortisol reactivity only in response to the heel stick. The results highlight potentially important parameters for exploring the relation between biological and behavioral reactivity to stress such as the operationalization of behavioral distress and the context in which a stress response is elicited.     

Neonatal Stress Reactivity: Predictions to Later Emotional Temperament

To investigate the relations among popular measures of neonatal stress and their link to subsequent temperament, 50 full-term newborns from a normal care nursery were examined responding to a heelstick blood draw. Baseline and heelstick measures of behavioral state, heart period, vagal tone, and salivary cortisol were obtained. Recovery measures of behavioral and cardiac activity were also analyzed. Mothers completed Rothbart's Infant Behavior Questionnaire when their infants reached 6 months of age. Baseline vagal tone predicted cortisol in response to the heelstick, suggesting that baseline vagal tone reflects the infants' ability to react to stressors. Greater reactivity to the heelstick (more crying, shorter heart periods, lower vagal tone, and higher cortisol) was associated with lower scores on "Distress-to-Limitations" temperament at 6 months. This finding was consistent with the expectation that the capacity to react strongly to an aversive stimulus would reflect better neurobehavioral organization in the newborn. Recovery measures of cardiac activity approximated and were correlated with baseline measures indicating the strong self-righting properties of the healthy newborn. Finally, vagal tone and salivary cortisol measures were not significantly related, suggesting the importance of assessing both systems in studies of the ontogeny of stress-temperament relations.     

Infant stress and parent responsiveness: regulation of physiology and behavior during still-face and reunion

This study examined infant response and recovery from a social challenge and parent responses. Behavioral and physiological responses were measured from forty-three 5- and 6-month-olds infants during a modified still-face procedure that used an additional still-face reunion sequence. Results confirm the hypothesis that infants of more responsive parents show more regulation than infants of less responsive parents. Infants of more responsive parents showed greater regulation of heart rate and negative affect during the final episode of the procedure than infants of less responsive parents. In addition, this procedure elicited a cortisol response (from .22 microg/dl to .31 microg/dl). Findings suggest important links between parent behavior and infant stress reactivity and regulation.     

Sex Differences in Neonatal Stress Reactivity

The question of whether a sexually dimorphic stress reaction exists prior to extensive socialization was addressed by examining sex differences in physiological and behavioral stress reactivity, in healthy, term neonates, after a mildly stressful behavioral assessment procedure. The Neonatal Behavior Assessment Scale (NBAS; Brazelton, 1973) was administered to 18 male and 18 female neonates. Heart rate (HR), salivary cortisol, and behavioral states were assessed before and after the exam. Sex differences included higher cortisol response in males and a greater change in HR and higher NBAS motor performance cluster score in females. Salivary cortisol, HR change, NBAS cluster scores, and behavioral states after NBAS provided 100% discrimination between male and female infants. These findings suggest that there are neonatal sex differences in behavioral and physiological stress reactivity prior to socialization.     

Adrenocortical Underpinnings of Children’s Psychological Reactivity to Interparental Conflict

This study examined interrelationships among children’s cortisol reactivity and their psychological reactivity to interparental conflict in a sample of 208 first graders (mean age = 6.6 years). Assessments of children’s psychological reactivity to conflict distinguished among their distress, hostile, and involvement responses across multiple methods (i.e., observation, questionnaire) and informants (i.e., observer, parent). Relative to other forms of conflict reactivity, children’s distress responses to interparental conflict were consistent, unique predictors of their elevated cortisol reactivity to interparental conflict even after inclusion of demographic factors as moderators and covariates. Moderator analyses further revealed that associations between distress and elevated cortisol levels in response to interparental conflict were particularly pronounced when children exhibited high levels of involvement in conflicts.     

Salivary cortisol as a predictor of socioemotional adjustment during kindergarten: a prospective study

This study, based on a sample of 172 children, examined the relation between average afternoon salivary cortisol levels measured at home at age 4.5 years and socioemotional adjustment a year and a half later, as reported by mothers, fathers, and teachers. Cortisol levels were hypothesized to be positively associated with withdrawal-type behaviors (e.g., internalizing, social wariness) and inversely related to approach-type behaviors, both negative and positive (e.g., externalizing, school engagement). Higher cortisol levels at age 4.5 predicted more internalizing behavior and social wariness as reported by teachers and mothers, although child gender moderated the relation between cortisol and mother report measures. An inverse relation was found between boys' cortisol levels and father report of externalizing behavior. A marginal inverse relation was found between child cortisol levels and teacher report of school engagement. Behavior assessed concurrently with cortisol collection did not account for the prospective relations observed,suggesting that cortisol adds uniquely to an understanding of behavioral development.     

Environmental control, social context, and individual differences in behavioral and cortisol responses to novelty in infant rhesus monkeys

The effects of appetitive controllability on behavioral and cortisol reactivity to novelty in 12 infant rhesus monkeys were studied. Surrogate-peer-reared infants had homecage access to food treats contingently via lever pressing ("master") or noncontingently ("yoked") for 12 weeks from postnatal month 2. Masters lever-pressed more, but did not differ in baseline cortisol. At month 5, infants were exposed to a novel environment in social groups and individually. Masters were significantly more active and exhibited significantly lower cortisol reactivity to the novel environment, but only in the individual context. Also, individual differences in operant behavior were positively correlated with behavioral activity and negatively correlated with cortisol reactivity to the novel environment. The results reveal context-specific benefits of contingent stimulation in infancy.     

Marital Conflict Predicts Mother-to-Infant Adrenocortical Transmission

Employing an experimental design, mother-to-infant transmission of stress was examined. Mothers (N = 117) were randomized to either have a positive or conflictual discussion with their marital partners, after which infants (age = 6 months) participated in a fear and frustration task. Saliva samples were collected to assess maternal cortisol responses to the discussion and infant cortisol responses to the challenge task. Results indicate maternal cortisol reactivity and recovery to the conflict (but not positive) discussion predicted infant cortisol reactivity to the infant challenge. Mothers’ positive affect during the discussion buffered, and intrusion during the free-play potentiated, mother-to-infant adrenocortical transmission. These findings advance our understanding of the social and contextual regulation of adrenocortical activity in early childhood.     

Infants' Responses to Frustrating Situations: Continuity and Change in Reactivity and Regulation

We examined continuity, stability, and change in behaviors reflecting infant reactivity and regulation. Healthy infants were observed in laboratory situations designed to elicit frustration when they were 5 ( N = 87) and 10 months of age ( N = 82) Behaviors indicative of reactivity included objective ratings of average intensity cry, peak intensity cry, and latency to cry. In addition, durations of orienting, avoidant, and nonnegative communicative behaviors were assessed as measures of regulation at each age. Results showed that several behaviors changed in level over time. In addition, Confirmatory Factor Analysis revealed both structural continuity and discontinuity: Behaviors were organized into 2 similar factors at 5 and 10 months (Reactivity and Regulation), but the relation between reactivity and regulation became increasingly independent over time, such that reactivity and regulation were negatively correlated at 5 months but not at 10 months. Finally, model-fitting revealed cross-dimension but not within-dimension stability (5-month reactivity predicted 10-month regulation).     

Does Dampened Physiological Reactivity Protect Youth in Aggressive Family Environments?

Is an attenuated physiological response to family conflict, seen in some youth exposed to early adversity, protective or problematic? A longitudinal study including 54 youth (average age 15.2 years) found that those with higher cumulative family aggression exposure showed lower cortisol output during a laboratory‐based conflict discussion with their parents, and were less likely to show the normative pattern of increased cortisol reactivity to a discussion they rated as more conflictual. Family aggression interacted with cortisol reactivity in predicting youth adjustment: Adolescents from more aggressive homes who were also more reactive to the discussion reported more posttraumatic stress symptoms and more antisocial behavior. These results suggest that attenuated reactivity may protect youth from the negative consequences associated with aggressive family environments.     

Effect of maternal soothing on infant stress response

The effect of maternal soothing to infant inoculation as well as everyday distress on infant cortisol and behavioral responses to stress was examined in two longitudinal samples of 55 and 74 infants, respectively, between 2 and 6 months of age. There was no evidence that maternal soothing was effective in reducing infants' cortisol or behavioral responses to stress. The absence of this relation occurred despite evidence for cross-time stability and cross-situation consistency in maternal soothing. That maternal soothing plays little role in lowering infant responses to stress leaves open the possibilities that other maternal behaviors may mediate children's distress or that infant temperament may be related to infant stress.     

Stress Reactivity and Self-Recognition

This study examined longitudinally whether early differences in reactivity to stress are related to self-recognition at 18 months of age. Adrenocortical and behavioral to Stress responses to routine inoculation at 2, and 4 months and at 6 and 18 months were obtained. Previous finding indicated a development shift in adrenocortical functioning by 6 months of age that included the emergence of stable individual differences in cortisol response from this point in development. Self-recognition was related to greater cortisol response and less rapid quieting at 6 to 18 months, whereas 2- to 4-month cortisol and quieting response did not differentiate self-recognizers and non-self-recognizators. These findings indicate a role for temperament differences in facilitating the emergence of self-recognition.     

The Relations among Infant Temperament, Security of Attachment, and Behavioral Inhibition at Twenty-Four Months

The purpose of this study was to examine the relations among infant temperament, attachment, and behavioral inhibition. 52 infants were seen at 2 days, 5, 14, and 24 months of age. Assessments were made of temperament at 2 days and 5 months of age, and attachment and behavioral inhibition were assessed at 14 and 24 months, respectively. EKG was recorded at each assessment, and measures of heart period and vagal tone were computed. Distress to pacifier withdrawal at 2 days of age was related to insecure attachment at 14 months. 2 types of distress reactivity at 5 months, reactivity to frustration and reactivity to novelty, were identified and related to high vagal tone. Attachment classification at 14 months was directly related to inhibited behavior at 24 months. Infants classified as insecure/resistant were more inhibited than those classified as insecure/avoidant. In addition, an interaction of infant reactivity to frustration and attachment classification was found to predict inhibition at 24 months. Infants classified as insecure/resistant and who had not cried to the arm restraint procedure at 5 months were the most inhibited at 24 months. These findings are discussed in terms of hypotheses regarding multiple modes of distress reactivity and regulation in early infancy and their different social and behavioral outcomes.     

Infant Temperament Profiles,Cultural Orientation,and Toddler Behavioral and Physiological Regulation in Mexican-American Families

This study sought to (a) replicate infant temperament profiles from predominantly White samples in a sample of low-income, predominantly first-generation Mexican-American families, (b) investigate associations between infant temperament profiles and toddler behavioral and physiological regulation, and (c) explore whether mothers’ cultural orientation would moderate those associations. Mothers and infants (n = 322; 46% male) were assessed during pregnancy and at infant ages 9, 12, and 24 months. Latent profile analysis yielded three temperament profiles that were consistent with those from extant research. Compared to the high positive affect, well-regulated profile, the negative reactive, low regulated profile was associated with poorer behavioral and parasympathetic (i.e., respiratory sinus arrhythmia) regulation, but associations depended on mothers’ Mexican and Anglo cultural orientation.     

Hypothalamic–Pituitary–Adrenal and Sympathetic Nervous System Activity and Children's Behavioral Regulation

Self-regulation ability is an important component of children's academic success. Physiological reactivity may relate to brain activity governing attention and behavioral regulation. Saliva samples collected from 186 preschool children (101 boys, mean age = 53 months, 34% minority) before and after a series of mildly challenging games and again 30 min following the challenges were used to assess hypothalamic–pituitary–adrenal (HPA) (cortisol) and sympathetic nervous system (SNS; alpha-amylase) activity. Behavioral regulation was measured in delay of gratification and slow-down motor activities included in the challenge task. Cortisol and alpha-amylase were related differentially to aspects of behavioral regulation. Low cortisol was related to classroom regulation difficulties. Children with greater cortisol elevations following the challenge task had poorer performance on the slow-down motor task. Children with greater increases in salivary alpha-amylase following challenge were less able to delay gratification. Results suggest that HPA axis and SNS arousal may contribute differentially to behavioral regulation ability.     

The Relations of Children's Emotion Regulation to Their Vicarious Emotional Responses and Comforting Behaviors

The purpose of the present study was to examine the relations of children's emotional and behavioral regulation (as indexed by heart rate variability and coping styles) to their emotional and prosocial responses to a crying infant. Kindergarten and second-grade children's vicarious emotional responses (e.g., facial reactions and heart rate slope) and comforting behaviors were recorded while children heard a crying infant. The mothers of these children completed a measure designed to assess their children's coping responses when exposed to others in distress. It was found that children who were able to regulate their arousal (as assessed with heart rate variance) and typically responded instrumentally when exposed to others' needy states and conditions were relatively unlikely to become distressed and relatively likely to talk to and comfort the crying infant. Compared to boys, girls were found to be more responsive to the crying infant and were reported to engage in more direct, active coping responses when exposed to others in distress. The results are discussed in relation to research on emotion regulation and coping in interpersonal contexts.     

A Structural Equation Modeling Approach for the Analysis of Cortisol Data Collected Using Pre–Post–Post Designs

Abstract

This study introduces a novel application of structural equation modeling (SEM) for the analysis of cortisol data that are collected using a pre–post–post design. By way of an extended example, an SEM model is developed that permits an examination of both the overall level of cortisol, as well as changes in cortisol (reactivity and regulation), as predictors of cognitive (executive) and behavioral functioning in 3- to 5-year-old children (N = 171) attending Head Start. The SEM model makes use of the parameterization of latent curve models. Throughout the extended example, the strengths of using an SEM approach for the analysis of cortisol data that are collected using pre–post–post designs is highlighted.     

Peer Problems Among Postinstitutionalized,Internationally Adopted Children: Relations to Hypocortisolism,Parenting Quality,and ADHD Symptoms

Seventy-eight postinstitutionalized (PI) children adopted at ages 17–36 months were assessed 2, 8, 16, and 24 months postadoption on measures of cortisol and parenting quality, and compared to same-aged children adopted from foster care (FC, n = 45) and nonadopted children (NA, n = 45). In kindergarten (M_age = 6.0 years), teachers, parents, and trained observers completed measures of peer relationships and attention deficit hyperactivity disorder (ADHD) symptoms. PI children had more peer problems and ADHD symptoms according to teachers and observers than NA children with FC children in between, whereas both PI and FC children were at significantly greater risk of hypocortisolism (i.e., blunted cortisol diurnal rhythm and reactivity). Hypocortisolism and ADHD symptoms mediated the association between preadoption adversity and peer difficulties. Higher postadoption parenting quality was protective.     

Analyzing change in school psychology research

We look at three common research scenarios, one in the behavioral domain (i.e., disruptive behaviors) one in the cognitive domain (i.e., academic achievement), and one in the affective domain (i.e., anxiety and stress) for which school psychologists are asked to address important questions related to change. We list measurement and statistical considerations across these scenarios, including whether variables are manifest or latent, the scales of measurement, the dimensionality of measures, the units of analysis, the sample size, and the frequency or duration of time, given the primary nature of the variables under study. We suggest that researchers carefully consider whether assumptions can be met employing classical general linear models, or whether contemporary alternatives, such as hierarchical linear modeling (HLM), should be recommended for the more appropriate handling of data. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 535–542, 2007.