Acute Maternal Stress Disrupts Infant Regulation of the Autonomic Nervous System and Behavior: A CASP Study.

Exposure to maternal stress is assumed to influence infant health and development across the lifespan. The autonomic nervous system (ANS) is especially sensitive to the effects of the early caregiving environment and linked to predictors of later mental health. Understanding how exposure to maternal stress adversely affects the developing ANS could inform prevention. However, there is no agreed upon definition of maternal stress making its study difficult. Here we use the Caretaker Acute Stress Paradigm (CASP) to study the effects of maternal stress in an experimentally controlled laboratory setting. The CASP has 5 episodes, a natural play, followed by a caretaker stressor (or control) condition, another play, a classic still face episode, followed by another play. A total of 104 4-months-old infants and their mothers were randomly assigned to either the caretaker-stress or caretaker-control condition. Changes in behavior, heart rate (HR), and respiratory sinus arrhythmia (RSA) before and after the introduction of the stressor (or control condition) were recorded and compared. Infants in the maternal stress condition showed significantly more behavioral distress [X 2 = (1, N = 104) = 4.662, p = 0.031]. Moreover, infants whose mothers were in the stress condition showed an significant increase in heart rate after the caretaker condition [F (1, 102) = 9.81, p = 0.002]. Finally we observed a trend to faster RSA recovery in infants of the control condition [F (1, 75) = 3.539, p = 0.064]. Results indicate that exposure to acute maternal stress affects infant regulation of the autonomic nervous system and behavior.

A Caretaker Acute Stress Paradigm: Effects on behavior and physiology of caretaker and infant.

While experimental stress paradigms of infants (arm restraint; the Still-Face) are powerful tools for infant research, no study has experimentally stressed mothers to observe its independent effects on infant stress regulation. Extant caretaker/maternal stress studies essentially are correlational and confounded by other conditions (e.g., depression). Here, we present a standard procedure, the Caregiver Acute Stress Paradigm (CASP), for stressing mothers during en face interactions with their infants. We hypothesized that infants of the stressed mothers would be more distressed than infants of non-stressed mothers. A total of 106 four-month-old infants and their mothers were randomly assigned to the experimental stress or non-stress manipulation. Confirming our hypothesis, infants of the stressed mothers were significantly more likely to become distressed and require terminating the procedure. While objective ratings of maternal behavior showed no difference between groups, mother in the stress condition self-rated the episode following the caretaker stress significantly lower than mothers in the non-stress group. The self-ratings in the maternal stress-group were reflected in infant cortisol. The findings indicate that CASP is an effective experimental paradigm for exploring the independent effects of an acute stress on caretakers, including effects of conditions, such as poverty or mental illness.

Infant affect response in the face-to-face still face among Chinese- and European American mother-infant dyads.

Early face-to-face interactions with caregivers allow infants to learn how to express and exchange emotions with others. Within the field, however, the research regarding infant regulatory processes across cultures remains limited. The Double Face-to-Face Still Face (FFSF) paradigm provided an opportunity to examine infant affect in dyadic interactions with European American (EA, n = 54) and Chinese American (CA, n = 48) infants and caregivers. Consistent with our hypothesis that CA infants are less reactive than EA infants, CA infants in our study showed less negative and more neutral affect compared to EA infants. We also examined the number of infants who were unable to complete the full FFSF paradigm due to high levels of distress (e.g., 30-sec of sustained hard cries). Compared to EA infants, more CA infants were unable to complete the paradigm due to negative affect (e.g., sustained cries). Analyses showed an association between mothers' negative affect from the start of the paradigm with infant incompletion of the paradigm. These findings point to cultural differences in infant affect within the FFSF. As well, researchers should consider the characteristics of infants who do not complete the FFSF paradigm as they can provide meaningful data in understanding infant affect and regulation. Taken together, our findings suggest that the Double FFSF paradigm provides a reasonable threshold for distinguishing infants on their ability to regulate during a repeated social stressor.

Effect of Maternal Distress on Perceptions of Infant Behavior May Differ in Chinese-American and European-American Mothers and Infants.

OBJECTIVE: This study examined the associations between maternal distress (symptoms of depression and anxiety) and observer and maternal ratings of infant temperament in Chinese-American (CA) and European-American (EA) 4-month-old infants (N = 114 dyads). METHODS: Maternal distress was obtained through self-reported symptoms of depression and anxiety. Mothers reported infant temperament (distress at limitations, soothability, and fear) through the short form of the Infant Behavior Questionnaire-Revised. To obtain observer-rated infant reactivity, infants were administered a battery of visual and auditory stimuli in the laboratory, in which infant behaviors (fret/cry, limb activity, and arching of the back) were coded. RESULTS: Maternal distress accounted more for the maternal perception of her infant among EA mothers than among CA mothers, but the relation was only observed for soothability. Higher maternal distress was associated with maternal report of lower soothability for EA mothers. Observer-rated infant reactivity, but not maternal distress, was positively associated with EA and CA maternal report of distress at limitations. Observer-rated infant negativity was associated with somewhat higher ratings of infant fear for EA mothers, although this association for EA mothers was not significantly different from CA mothers. CONCLUSIONS: Potential biases in maternal report of infant behavior due to effects from maternal distress may not be generalizable across cultures but may vary because of cultural norms for emotional experience and expectations for infant behavior. EA mothers' ratings of infant distress and soothability, but not fear, may be influenced by maternal distress.

Here Today, Gone Tomorrow? Changes in 4-Month-Olds' Physiologic and Behavioral Responses Do Not Indicate Memory for a Social Stressor.

Although much is known about early memory development, only a few studies have explored infants' memory of social stress. While these few studies suggest that infants can remember stressful interactions, limitations seen in both methodology and statistical analyses give pause. In the current study, 4-month-olds and their mothers participated in both stressful and non-stressful interactions over 2 days. On Day 1, memory group infants participated in the double Face-to-Face Still-Face (FFSF) paradigm and control group infants participated in typical play. Both groups experienced the double FFSF paradigm on Day 2. Memory group infants exhibited the standard SF response but no differences in infant cortisol on Day 1. Both infant groups exhibited the standard SF response on Day 2. However, infants in the memory group, who saw the FFSF paradigm for the second time, did not demonstrate changes in cortisol or behavior indicative of memory across the 2 days. There was also no relationship between changes in cortisol and behavior for both days. The findings question the use of salivary cortisol as a measure of social stress and suggest that, although 4-month-olds reacted to the Still-Face social stressor immediately, they did not remember the following day.

Posttraumatic Stress Disorder Diagnosis in Young Children With Burns.

The primary aim of this study was to assess the prevalence of posttraumatic stress disorder (PTSD) in young children hospitalized for burns. A secondary aim was to assess partial PTSD in this population. PTSD diagnosis and symptoms were evaluated utilizing both the diagnostic interview for children and adolescents (DICA-P) module and the PTSD semistructured interview and observational report (PTSDSSI). PTSD symptomatology was assessed from parent interviews at 1 month after discharge from a major pediatric burn center. Four of the 42 participants who completed the DICA-P met full criteria for a diagnosis of PTSD (10%).Of the 39 who also completed the PTSDSSI, 1 (3%) met full criteria for PTSD diagnosis on that measure. Twenty-seven percentage of subjects met partial criteria on the DICA-P vs 16% on the PTSDSSI, without impairment. Furthermore, 67% of subjects met DICA-P criteria for the re-experiencing cluster and 54% met the PTSDSSI re-experiencing criteria. Although only a small percentage met full PTSD diagnostic criteria by either measure, a high percentage of young children with burns manifested some posttraumatic symptoms 1 month after discharge. Because PTSDSSI diagnosis is strongly linked to the diagnostic and statistical manual-5 (DSM-5) criteria for "PTSD in children 6 years and younger," these results may offer clues to current diagnoses of PTSD in young children. Future research is needed to improve care by determining the risk factors and course of PTSD to further refine the diagnostic criteria for identifying children most in need of intervention, such as those hospitalized for burn injuries.

Intra-individual stability and developmental change in hair cortisol among postpartum mothers and infants: Implications for understanding chronic stress.

The study goal was to determine the intra-individual stability, developmental change, and maternal-reported correlates (socio-demographic, stress experiences, hair characteristics, and care) of hair cortisol in mothers and their infants. To assess cortisol deposition in hair during the periods of 6-to-9 months and 9-to-12 months of age, 3 cm segments of hair samples deemed to represent approximately 3 months of retrospective hair cortisol were sampled longitudinally at 9- and 12-months in 41 mothers and infants. Bivariate correlations and mean level comparisons of log-transformed hair cortisol levels at 9- (T1) and 12-months (T2) in mothers and infants were examined. Hair cortisol values were positively correlated from T1 to T2 for mothers (r = .41, p < .05) and infants (r = .39, p < .05). Hair cortisol values did not significantly differ from T1 to T2 in infants but decreased for mothers (F(1,34) = 9.2, p < .01). Maternal and infant hair cortisol was not associated with each other at either time point. Self-reported measures of stress, and hair characteristics and care were not associated with hair cortisol. This is the first study to obtain hair cortisol from more than one time point within the first year after birth in mothers and infants. The intra-individual stability of hair cortisol suggests that it may be a possible biomarker for detecting change in chronic stress experiences within the first year of life and in the postpartum period.

The relation between reactivity at 4 months and Behavioral Inhibition in the second year: Replication Across Three Independent Samples.

This paper examines the predictive relations between two infant temperamental biases assessed at 4 months and inhibited behavior during the first two years of life in three independent samples from two research laboratories. Although each sample used slightly different criteria for classifying infants, the results across samples were consistent. Infants of both genders who displayed high levels of motor activity and distress to unfamiliar events were more inhibited at 14 months of age. By 24 months there were significant sex differences: boys identified as high reactive were more inhibited than high reactive girls.

Structural differences in adult orbital and ventromedial prefrontal cortex predicted by infant temperament at 4 months of age.

CONTEXT: The term temperament refers to a biologically based predilection for a distinctive pattern of emotions, cognitions, and behaviors first observed in infancy or early childhood. High-reactive infants are characterized at age 4 months by vigorous motor activity and crying in response to unfamiliar visual, auditory, and olfactory stimuli, whereas low-reactive infants show low motor activity and low vocal distress to the same stimuli. High-reactive infants are biased to become behaviorally inhibited in the second year of life, defined by timidity with unfamiliar people, objects, and situations. In contrast, low-reactive infants are biased to develop into uninhibited children who spontaneously approach novel situations. OBJECTIVE: To examine whether differences in the structure of the ventromedial or orbitofrontal cerebral cortex at age 18 years are associated with high or low reactivity at 4 months of age. DESIGN: Structural magnetic resonance imaging in a cohort of 18-year-olds enrolled in a longitudinal study. Temperament was determined at 4 months of age by direct observation in the laboratory. SETTING: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital. PARTICIPANTS: Seventy-six subjects who were high-reactive or low-reactive infants at 4 months of age. MAIN OUTCOME MEASURE: Cortical thickness. RESULTS: Adults with a low-reactive infant temperament, compared with those categorized as high reactive, showed greater thickness in the left orbitofrontal cortex. Subjects categorized as high reactive in infancy, compared with those previously categorized as low reactive, showed greater thickness in the right ventromedial prefrontal cortex. CONCLUSIONS: To our knowledge, this is the first demonstration that temperamental differences measured at 4 months of age have implications for the architecture of human cerebral cortex lasting into adulthood. Understanding the developmental mechanisms that shape these differences may offer new ways to understand mood and anxiety disorders as well as the formation of adult personality.

Preliminary evidence for the effects of morphine on posttraumatic stress disorder symptoms in one- to four-year-olds with burns.

This study tested the hypothesis that very young children who received more morphine for acute burns would have larger decreases in posttraumatic symptoms 3 to 6 months later. This has never before been studied in very young children, despite the high frequency of burns and trauma in this age group. Seventy 12- to 48-month-old nonvented children with acute burns admitted to a major pediatric burn center and their parents participated. Parents were interviewed at three time points: during their child's hospitalization, 1 month, and 3 to 6 months after discharge. Measures included the Child Stress Disorders Checklist - Burn Version (CSDC-B). Chart reviews were conducted to obtain children's morphine dosages during hospitalization. Mean equivalency dosages of morphine (mg/kg/d) were calculated to combine oral and intravenous administrations. Eleven participants had complete 3 to 6-month data on the CSDC. The correlation between average morphine dose and amount of decrease in posttraumatic stress disorder symptoms on the CSDC (r = -0.32) was similar to that found in studies with older children. The correlation between morphine dose and amount of decrease in symptoms on the arousal cluster of the CSDC was significant (r = -0.63, P < .05). Findings from the current study suggest that, for young children, management of pain with higher doses of morphine may be associated with a decreasing number of posttraumatic stress disorder symptoms, especially those of arousal, in the months after major trauma. This extends, with very young children, the previous findings with 6- to 16-year olds.

Young burned children: the course of acute stress and physiological and behavioral responses.

OBJECTIVE: Symptoms of posttraumatic stress disorder (PTSD) are a focus of much research with older children, but little research has been conducted with young children, who account for about 40% of all pediatric burn injuries. This is a longitudinal study of 72 acutely burned children (12-48 months old) that assessed the course of acute posttraumatic symptoms and physiological reactivity. METHOD: Parents were interviewed shortly after their child was admitted to the hospital and 1 month after discharge. PTSD symptoms were measured with the Diagnostic Interview for Children and Adolescents (DICA) module. Nurses recorded the child's physiological data throughout the hospital stay. The child's physical and behavioral responses were assessed in a laboratory at about 1 month after discharge. RESULTS: Reduced social smiling in the children was related to PTSD symptoms, as measured by the DICA, and heart rate at 24 hours and 7 days. Reduced vocalization was related to the child's rating of pain at 24 hours. Smiling and vocalizations were also related to some DICA cluster scores but not avoidance. CONCLUSIONS: Preschool children admitted to a burn unit demonstrated PTSD symptoms and physiological reactivity. There was a relation to the frequency of smiles and vocalizations.

Trauma severity influences acute stress in young burned children.

The purpose of this study was to assess the role of trauma severity on subsequent symptoms of posttraumatic stress disorder (PTSD) and physiological reactivity in a total of 70 children, ranging from 12 to 48 months of age, who were acutely burned. Parents were interviewed shortly after the child was admitted to the hospital. PTSD symptoms were measured using the Posttraumatic Stress Disorder Semi-Structured Interview and Observational Record for Infants and Young Children and the Diagnostic Interview for Children and Adolescents. Nurses completed a questionnaire about the child's symptoms and recorded the child's physiological data throughout the hospital stay. Significant relationships were found between severity of childhood trauma and the total number of PTSD symptoms and physiological reactivity. This study supports the hypothesis that severity of trauma experienced by young children influences psychological and physiological stress indicators after burn injuries. These findings provide new directions for the assessment and prevention of PTSD in this age group.

The corticotropin-releasing hormone gene and behavioral inhibition in children at risk for panic disorder.

BACKGROUND: Behavioral inhibition to the unfamiliar (BI) is a heritable temperamental phenotype involving the tendency to display fearful, avoidant, or shy behavior in novel situations. BI is a familial and developmental risk factor for panic and phobic anxiety disorders. We previously observed an association between BI and a microsatellite marker linked to the corticotropin releasing hormone (CRH) gene in children at risk for panic disorder. To evaluate this further, we genotyped additional families for this marker and a panel of markers encompassing the CRH locus. METHODS: Sixty-two families that included parents with panic disorder and children who underwent laboratory-based behavioral observations were studied. Family-based association tests and haplotype analysis were used to evaluate the association between BI and polymorphisms spanning the CRH locus. RESULTS: We examined a set of markers which we found to reside in a block of strong linkage disequilibrium encompassing the CRH locus. The BI phenotype was associated with the microsatellite marker (p=.0016) and three single nucleotide polymorphisms (SNPs), including a SNP in the coding sequence of the gene (p=.023). Haplotype-specific tests revealed association with a haplotype comprising all of the markers (p=.015). CONCLUSIONS: These results suggest that the CRH gene influences inhibited temperament, a risk factor for panic and phobic anxiety disorders. Genetic studies of anxiety-related temperament represent an important strategy for identifying the genetic basis of anxiety disorders.

Association of a genetic marker at the corticotropin-releasing hormone locus with behavioral inhibition.

BACKGROUND: Behavioral inhibition to the unfamiliar (BI), a heritable temperamental profile involving an avoidant response to novel situations, may be an intermediate phenotype in the development of anxiety disorders. Corticotropin-releasing hormone (CRH) is a key mediator of the stress response through its effects on the hypothalamic-pituitary-adrenal axis and limbic brain systems. Transgenic mice overexpressing CRH exhibit BI-like behaviors, implicating this gene in the development of the phenotype. METHODS: We genotyped a marker tightly linked to the CRH locus in 85 families of children who underwent laboratory-based behavioral assessments of BI and performed family-based association analyses. RESULTS: We observed an association between an allele of the CRH-linked locus and BI (p =.015). Among offspring of parents with panic disorder, this association was particularly marked (p =.0009). We further demonstrate linkage disequilibrium between this marker and single nucleotide polymorphisms encompassing the CRH gene. CONCLUSIONS: These results are consistent with the possibility that variants in the CRH gene are associated with anxiety proneness.

EEG asymmetry, power, and temperament in children.

Measures of EEG spectral power, lateral asymmetry in the frontal and parietal areas, and social behavior with an examiner were analyzed on 166 children, 10 to 12 years old, who were participating in a longitudinal study of the temperamental contributions to social behavior. Loss of 8- to 13-Hz power (alpha band) on the right, compared with the left, frontal area (right frontal active) was most prevalent among children who were classified as high reactive at 4 months and were highly fearful at 14 and 21 months. Second, greater frontal power in the 14- to 30-Hz band (beta) at rest was correlated with the tendency to be right frontal active. Finally, spontaneous talkativeness with an unfamiliar examiner was associated with right frontal activation and high alpha power for boys, but with right frontal activation and high beta power for girls. Right frontal activation is most characteristic of children who begin life with a temperamental bias favoring high reactivity and who develop a fearful reaction to unfamiliar events in the second year of life.

One measure, one meaning: multiple measures, clearer meaning.

This paper tries to make three points. First, current constructs in personality and psychopathology are based on the restrictive evidence contained in self-reports. As a result, heterogeneous categories of individuals are assigned to the same category. Second, it is suggested that when different sources of evidence are included, theoretically distinct groups will be detected within the prior heterogeneous category. Third, the authors argue that physiological information has the potential to parse individuals with similar phenotypes on self-report data into distinct groups that reveal the temperamental origins of their phenotype.