Children, stress, and sensitization: an integration of basic and clinical research on emotion?

The Relationship Between Stressful Life Events and Axis I Diagnoses Among Adolescent Offspring of Probands With Bipolar and Non-Bipolar Psychiatric Disorders and Healthy Controls: The Pittsburgh Bipolar Offspring Study (BIOS)

BACKGROUND

Previous studies have explored the role of stressful life events in the development of mood disorders. We examined the frequency and nature of stressful life events as measured by the Stressful Life Events Schedule (SLES) among 3 groups of adolescent offspring of probands with bipolar (BD), with non-BD psychiatric disorders, and healthy controls. Furthermore, we examined the relationship between stressful life events and the presence of DSM-IV Axis I disorders in these offspring. Stressful life events were characterized as dependent, independent, or uncertain (neither dependent nor independent) and positive, negative, or neutral (neither positive nor negative).

METHODS

Offspring of probands with BD aged 13-18 years (n = 269), demographically matched offspring of probands with non-BD Axis I disorders (n = 88), and offspring of healthy controls (n = 81) from the Pittsburgh Bipolar Offspring Study were assessed from 2002 to 2007 with standardized instruments at intake. Probands completed the SLES for their offspring for life events within the prior year. Life events were evaluated with regard to current Axis I diagnoses in offspring after adjusting for confounds.

RESULTS

After adjusting for demographic and clinical between-group differences (in probands and offspring), offspring of probands with BD had greater independent (χ² = 11.96, P < .04) and neutral (χ² = 17.99, P < .003) life events compared with offspring of healthy controls and greater number of more severe stressful life events than offspring of healthy controls, but not offspring of probands with non-BD. Offspring of BD probands with comorbid substance use disorder reported more independent stressful life events compared to those without comorbid substance use disorder (P = .024). Greater frequency and severity of stressful life events were associated with current Axis I disorder in offspring of both probands with BD and probands with other Axis I disorders regardless of dependency or valence. Greater frequency and severity of stressful life events were associated with greater current Axis I disorder in all offspring.

CONCLUSIONS

Offspring of probands with BD have greater exposure to independent and neutral life events than offspring of healthy controls. Greater frequency and severity of stressful life events were associated with Axis I disorder in offspring of both BD and non-BD affected probands.

Drug withdrawal conceptualized as a stressor

Drug withdrawal is often conceptualized as an aversive state that motivates drug-seeking and drug-taking behaviors in humans. Stress is more difficult to define, but is also frequently associated with aversive states. Here we describe evidence for the simple theory that drug withdrawal is a stress-like state, on the basis of common effects on behavioral, neurochemical, and molecular endpoints. We also describe data suggesting a more complex relationship between drug withdrawal and stress. As one example, we will highlight evidence that, depending on drug class, components of withdrawal can produce effects that have characteristics consistent with mood elevation. In addition, some stressors can act as positive reinforcers, defined as having the ability to increase the probability of a behavior that produces it. As such, accumulating evidence supports the general principles of opponent process theory, whereby processes that have an affective valence are followed in time by an opponent process that has the opposite valence. Throughout, we identify gaps in knowledge and propose future directions for research. A better understanding of the similarities, differences, and overlaps between drug withdrawal and stress will lead to the development of improved treatments for addiction, as well as for a vast array of neuropsychiatric conditions that are triggered or exacerbated by stress.

Pathways and processes of risk in associations among maternal antisocial personality symptoms, interparental aggression, and preschooler's psychopathology

Two studies examined the nature and processes underlying the joint role of interparental aggression and maternal antisocial personality as predictors of children's disruptive behavior problems. Participants for both studies included a high-risk sample of 201 mothers and their 2-year-old children in a longitudinal, multimethod design. Addressing the form of the interplay between interparental aggression and maternal antisocial personality as risk factors for concurrent and prospective levels of child disruptive problems, the Study 1 findings indicated that maternal antisocial personality was a predictor of the initial levels of preschooler's disruptive problems independent of the effects of interparental violence, comorbid forms of maternal psychopathology, and socioeconomic factors. In attesting to the salience of interparental aggression in the lives of young children, latent difference score analyses further revealed that interparental aggression mediated the link between maternal antisocial personality and subsequent changes in child disruptive problems over a 1-year period. To identify the family mechanisms that account for the two forms of intergenerational transmission of disruptive problems identified in Study 1, Study 2 explored the role of children's difficult temperament, emotional reactivity to interparental conflict, adrenocortical reactivity in a challenging parent-child task, and experiences with maternal parenting as mediating processes. Analyses identified child emotional reactivity to conflict and maternal unresponsiveness as mediators in pathways between interparental aggression and preschooler's disruptive problems. The findings further supported the role of blunted adrenocortical reactivity as an allostatic mediator of the associations between parental unresponsiveness and child disruptive problems.

Copeptin: a marker for stress reaction in fetuses with intrauterine growth restriction

OBJECTIVE

To compare venous cord plasma concentrations of 4 vasoactive peptide precursors: carboxy-terminal proarginine vasopressin, CT-prondothelin (ET)-1, midregional proadrenomedullin, and MR-proatrial natriuretic peptide, between fetuses with intrauterine growth restriction and appropriate for gestational age controls.

STUDY DESIGN

Matched-pair analysis of 12 fetuses with significant intrauterine growth restriction and 42 healthy appropriate for gestational age control fetuses. All infants were singletons, delivered by elective section after 34 weeks and without chromosomal abnormalities.

RESULTS

Umbilical cord plasma copeptin levels (median [range]) were 4-fold higher in intrauterine growth restriction infants than in matched appropriate for gestational age controls: 23.2 (6.7-449) vs 5.1 (2.5-53) pmol/L (P < .001). Multivariate regression analysis revealed an association between copeptin and umbilical artery resistance index z-score (P = .034). The 3 other precursor peptides showed no changes.

CONCLUSION

High copeptin concentrations in the cord blood of intrauterine growth restriction newborns reflect a fetal stress response and support the fetal programming hypothesis.

Interparental aggression and children's adrenocortical reactivity: testing an evolutionary model of allostatic load

Guided by an evolutionary model of allostatic load, this study examined the hypothesis that the association between interparental aggression and subsequent changes in children's cortisol reactivity to interparental conflict is moderated by their temperamental dispositions. Participants of the multimethod, longitudinal study included 201 2-year-old toddlers and their mothers. These children experienced elevated levels of aggression between parents. Consistent with the theory, the results indicated that interparental aggression predicted greater cortisol reactivity over a 1-year period for children who exhibited high levels of temperamental inhibition and vigilance. Conversely, for children with bold, aggressive temperamental characteristics, interparental aggression was marginally associated with diminished cortisol reactivity. Further underscoring its implications for allostatic load, increasing cortisol reactivity over the one year span was related to concomitant increases in internalizing symptoms but decreases in attention and hyperactivity difficulties. In supporting the evolutionary conceptualization, these results further supported the relative developmental advantages and costs associated with escalating and dampened cortisol reactivity to interparental conflict.

Blunted stress response in small for gestational age neonates

There is evidence that adverse conditions during intrauterine development affect future health of the offspring. Hypothalamus-pituitary-adrenal (HPA) axis dysregulation is assumed to play an important role in the association of small for gestational age (SGA) and the pathogenesis of hypertension and the metabolic syndrome. Stress response patterns in SGA neonates may identify a link with intrauterine-induced permanent maladaptation of the HPA axis. Salivary cortisol and cortisone levels were therefore analyzed during resting conditions and in response to a pain-induced stress event in SGA (<5th percentile) and appropriate for gestational age (AGA) neonates born > or =34 wk of gestation. In AGA neonates, salivary cortisol and cortisone levels significantly increased after the stress event (p < 0.05). In contrast, SGA infants exhibited a blunted steroid release after stress induction (p = 0.76, p = 0.65, respectively). No influence of mode of delivery (p = 0.93), gender (p = 0.21), and gestational age (p = 0.57) on stress response patterns was observed in a multiple stepwise regression. SGA neonates show a blunted physiologic activation of the HPA axis in response to a stress stimulus. Thus, intrauterine-induced alteration of HPA axis regulation seems to persist into the postnatal period and represents a prerequisite for the hypothesis of HPA axis involvement in the fetal origin of adult diseases.

Childhood adversity and youth depression: influence of gender and pubertal status

This research examined three possible models to explain how childhood social adversity and recent stress interact to predict depression in youth: stress sensitization, stress amplification, and stress inoculation. Drawing from a stress-sensitization theory of depression, we hypothesized that exposure to childhood adversity, in the form of disruptions in critical interpersonal relationships, would lower youths' threshold for depressive reactions to recent interpersonal stress. We expected that this pattern of stress sensitization would be most salient for girls negotiating the pubertal transition. These hypotheses were examined in two studies: a longitudinal, questionnaire-based investigation of 399 youth (M = 11.66 years) and a concurrent, interview-based investigation of 147 youth (M = 12.39 years). Findings supported the role of stress-sensitization processes in pubertal girls and prepubertal boys, and stress-amplification processes in prepubertal girls. Childhood social adversity specifically predicted sensitization to recent interpersonal, but not noninterpersonal, stress. These findings build on prior theory and research by suggesting that early adversity exerts context-specific effects that vary across gender and development. Future research will need to identify the specific mechanisms underlying this stress-sensitization process.

The role of child adrenocortical functioning in pathways between interparental conflict and child maladjustment

This study examined the interplay between interparental conflict and child cortisol reactivity to interparental conflict in predicting child maladjustment in a sample of 178 families and their kindergarten children. Consistent with the allostatic load hypothesis (McEwen & Stellar, 1993), results indicated that interparental conflict was indirectly related to child maladjustment through its association with individual differences in child cortisol reactivity. Analyses indicated that the multimethod assessment of interparental conflict was associated with lower levels of child cortisol reactivity to a simulated phone conflict between parents. Diminished cortisol reactivity, in turn, predicted increases in parental reports of child externalizing symptoms over a 2-year period. Associations between interparental conflict, child cortisol reactivity, and child externalizing symptoms remained robust even after demographic factors and other family processes were taken into account.

Cerebral activation in patients with somatoform pain disorder exposed to pain and stress: An fMRI study

Patients with somatoform pain disorders are supposed to suffer from an early acquired defect in stress regulation. In order to look for common alterations of the pain- and stress-responsive cortical areas, we prospectively recorded cerebral activations induced by pin-prick pain, by cognitive stress and emotional stress using functional magnetic resonance imaging (fMRI) in a group of 17 patients and an age-matched control group. In addition, the hippocampal volumes of both groups were measured. Patients showed increased activations of the known pain-processing areas (thalamus, basal ganglia, operculo-insular cortex), but also of some prefrontal, temporal and parietal regions during first pain exposure and of temporal and parietal areas during cognitive stress, but reduced activations during emotional stress. In contrast to these functional differences, hippocampal volume was not significantly reduced in patients. Although the superior temporal gyrus was the only common area of an "overactivation" in patients in the pain and stress condition, findings of our study support the current concept of mechanisms involved in somatoform pain disorders: central processing of pain and of cognitive stress is increased in patients possibly due to exaggerated memory and/or anticipation of pain exposure and to a disturbance of stress-regulating systems which has to be worked out on a cortical level in more detail. Our finding of a reduced responsiveness to emotional stress is surprising, but not contradictive to these results because some sort of neglect or coping mechanisms may have developed over time as a response to early adversities.

Cognition- and anxiety-related behavior, synaptophysin and MAP2 immunoreactivity in the adult rat treated with a single course of antenatal betamethasone

We investigated the effects of a single course of antenatal betamethasone on cognition- and anxiety-related behavior and synaptophysin and microtubule-associated protein 2 (MAP2) immunoreactivity in the adult rat hippocampus. On d 20 of gestation, pregnant rats were injected with either 1) 170 microg/kg body weight of betamethasone ("clinically equivalent dose," equivalent to 12 mg twice, 24 h apart); 2) half this dose; or 3) vehicle. Cognition- and anxiety-related behavior of the offspring was analyzed at an age of 5 mo using the Morris water maze, object recognition task, and open field test. Subsequently, synaptophysin and MAP2 immunoreactivity were measured in the hippocampus. We report no detrimental effects of antenatal betamethasone on cognition- and anxiety-related behavior and synaptophysin immunoreactivity in the adult rat. On the other hand, MAP2 immunoreactivity was decreased by betamethasone in males, suggesting a permanent impairment in the hippocampus. Interestingly, the lower dose appears to have less influence in terms of growth restriction, known to be associated with an increased risk of disease in adulthood. Further research might elucidate whether the betamethasone effect on hippocampal neurons persists later in life and could affect the aging process increasing the risk for neuropathology of the adult.

A single course of antenatal betamethasone reduces neurotrophic factor S100B concentration in the hippocampus and serum in the neonatal rat

The effects of a single course of antenatal betamethasone on S100B protein concentration were investigated in Fisher 344 rats. On day 20 of gestation, pregnant rats were injected twice 8 h apart with either (1) 170 microg kg(-1) body weight betamethasone ("clinically-equivalent dose", equivalent to 12 mg twice, 24 h apart in humans), (2) half of this dose (equivalent to 6 mg) or (3) vehicle. We report reference values for S100B protein in the serum and different brain regions in both genders at 1, 2, and 21 days after birth. Interestingly, S100B concentration showed a time-dependent and brain region-specific pattern of expression. At P1, S100B was higher in the serum of males compared to females. In addition, we show that both doses of betamethasone decreased S100B concentration in the serum of males at P1, whereas in the hippocampus, it was reduced by the clinically-equivalent dose only. This suggests that lowering the dose of antenatal betamethasone may be less detrimental for brain maturation and therefore we reiterate the need for clinical trials with a low dose regimen.

Trauma, proximity, and developmental psychopathology: the effects of war and terrorism on children

This report summarizes recent literature relevant to the effects of terrorism on children's mental health. The paper addresses three aspects of this topic. In the first section of the paper, data are reviewed concerning the relationships among stress, trauma, and developmental psychopathology. A particular emphasis is placed on associations with indirect forms of trauma, given that terrorism involves high levels of indirect trauma. Second, the paper delineates a set of key principles to be considered when considering ways in which the effects of terrorism on children's mental health can be minimized. Third, data are reviewed from studies in developmental psychobiology. These data are designed to illustrate the mechanisms through which children exhibit unique effects in the wake of traumatic circumstances.

Effects of prenatal betamethasone exposure on regulation of stress physiology in healthy premature infants

The objective of this study was to examine the effects of prenatal exposure to betamethasone, a corticosteroid, on postnatal stress regulation, particularly activity of the hypothalamic-pituitary-adrenocortical (HPA) axis. Effects were assessed by measuring salivary cortisol production at baseline and in response to two potentially stressful events, a heel-stick blood draw and a physical exam, in infants born at 33-34 weeks gestation. Subjects included 9 infants with antenatal betamethasone treatment (2 doses of 12 mg of betamethasone administered intramuscularly to the mother twelve hours apart) and 9 infants without such treatment. Testing took place 3-6 days after delivery. Measures of behavioral distress confirmed that both events were stressful to these premature infants. Infants with betamethasone exposure, however, failed to exhibit increases in cortisol to either stressor. In contrast, infants without betamethasone exposure displayed elevated cortisol to the heel-stick blood draw but not the physical exam. These findings suggest that antenatal corticosteroids suppress infants' HPA response to a stressor typically encountered in a neonatal intensive care situation.

Children, stress, and context: integrating basic, clinical, and experimental prevention research

Findings from the Watamura, Donzella, Alwin, and Gunnar (this issue) study support the growing recognition of the importance of context on physiology and affective and behavioral regulation early in human development. This discussion focuses on the role of context and development on hypothalamic-pituitary-adrenal (HPA) axis regulation in young children. Discussed in this article are the Watamura et al. findings with regard to relevant animal studies, extension of these observations to samples of children at elevated risk for psychopathology, and experimental prevention studies with young children. It is contended that environmental factors operating at key points in development may shape affective and behavioral regulation as well as HPA axis function in children, much as environmental factors have been shown to shape HPA axis regulation in animals.