Normative Trends in Physically Aggressive Behavior: Age-Aggression Curves from 6 to 24 Months

Modeling trajectories of physical aggression from infancy to pre-school age, their early predictors, and school-age outcomes

This study identified latent trajectories of physical aggression (TPA) from infancy to preschool age and evaluated (a) effects of early parent, parenting and child predictors on TPA as well as on social, behavioral, and academic functioning in Grade 2, and (b) TPA effects net of early predictor effects on Grade 2 functioning. We used data from the Behavior Outlook Norwegian Developmental Study (BONDS), which included 1,159 children (559 girls). Parents reported on risk and protective factors, and on physical aggression from 1 to 5 years of age; teachers reported on Grade 2 outcomes. We employed latent class growth curve analyses and identified nine TPA. In fully adjusted models simultaneously testing all associations among predictors, trajectories, and outcomes, maternal and paternal harsh parenting, child gender, and sibling presence predicted TPA, which significantly predicted externalizing and academic competence in Grade 2. Child gender had a pervasive influence on all outcomes as well as on TPA. To our knowledge, this is the first trajectory study to determine which predictors are most proximal, more distal, or just confounded, with their relative direct effect sizes, and to link early paternal as well as maternal harsh parenting practices with children's TPA. Our findings underscore the need to include fathers in developmental research and early prevention and intervention efforts.

When crying turns to hitting: Examining maternal responses to negative affect

Physical aggression in toddlerhood is empirically linked to anger and often conceptualized as a byproduct of frustration and related negative affect. Further, parenting is the major environmental construct implicated in the development of aggressive behaviors. Given parents' role as "external regulators," parents' responses to their toddlers' negative affect may serve to escalate or de-escalate their toddlers' affective experience, thereby impacting the likelihood of subsequent aggression. In the present study, we examined whether parents' negative affect, harsh, soothing, and distracting responses to their toddlers' negative affect mediated the relation between toddlers' negative affect and their aggressive behavior in brief conflict episodes. During a laboratory visit, a community sample of 69 mother-toddler dyads was observed in a structured interaction task. We found that child negative affect is associated with subsequent aggressive behavior by way of maternal harsh responses to negative affect. Negative emotional expression, soothing, and distraction neither facilitated or hindered children's escalation from negative affect to aggression. Our findings support a dyadic intervention in which patterns of coercive parent-child interactions are targets for prevention and intervention of toddler aggression.

Provoked and unprovoked aggression in toddlerhood: Evaluating measurement invariance and latent means across gender, age, and time

This paper re-examined the factor structure of a recently developed parent report of aggression, the Provoked and Unprovoked Aggression Questionnaire, and evaluated measurement invariance and latent mean differences across gender, age, and time. Participants were 333 mothers of toddlers (younger age group: n = 167, 53.9% boys, Mage Time 1  = 18.30 months, SD = 0.45; older age group: n = 166, 48.8% boys, Mage Time 1  = 24.29 months, SD = 0.38) who filled out provoked (eight items) and unprovoked (five items) aggression scales twice over a 3-month period. We found evidence for the configural, metric, and scalar measurement invariance-a requirement needed to make a meaningful comparison between aggression means across gender, age groups, and time. When comparing means for boys and girls, gender differences emerged earlier for unprovoked than provoked aggression. Also, the frequency of provoked aggression increased among younger, but not older, toddlers. By developing a brief parental report of aggression in toddlerhood, we hope to fill a void of early aggression measures that tap the contextual variability in aggressive behaviors, and thereby stimulate more research to further our understanding of different types of aggression and their correlates in toddlerhood.

Relational and physical aggression in preschool-age children: Associations with teacher, parent, sibling, and peer relationship quality

Early childhood relationships with teachers, parents, siblings, and peers are foundational factors for later social functioning. High rates of childhood aggression have been associated with negative developmental consequences, however, the associations between child aggression on the quality of these formative relationships have not been studied extensively. In a sample of young children attending preschool (N = 114, Mage = 46.27 months, SD = 9.94, 40% girls), this study investigated associations between early childhood relational and physical aggression and the quality of concurrent teacher-child and parent-child closeness and conflict, sibling relationship quality, and positive peer interactions and peer rejection. Early childhood relational and physical aggression was associated with negative teacher-child relationships, and this was true for boys and girls. Differential patterns of prediction were found for relational and physical aggression on the other relationship variables. Relational aggression strongly predicted more positive peer interactions, whereas physical aggression predicted fewer positive peer interactions and greater peer rejection. Early childhood relational aggression predicted higher levels of teacher-child closeness, whereas physical aggression predicted lower levels of teacher-child closeness and fewer positive sibling interactions. These findings challenge common perceptions that aggression is negatively associated with relationship quality. Notably, relational aggression relative to physical aggression may be associated with some favorable relationship outcomes. We did not find support for an additive model of aggression whereby children who were both relationally and physically aggressive (co-morbid) were at higher risk for negative relationship quality. Implications of these findings for future research and prevention and intervention are discussed.

Fetal Frontolimbic Connectivity Prospectively Associates With Aggression in Toddlers

Background

Aggression is a major public health concern that emerges early in development and lacks optimized treatment, highlighting need for improved mechanistic understanding regarding the etiology of aggression. The present study leveraged fetal resting-state functional magnetic resonance imaging to identify candidate neurocircuitry for the onset of aggressive behaviors before symptom emergence.

Methods

Pregnant mothers were recruited during the third trimester of pregnancy to complete a fetal resting-state functional magnetic resonance imaging scan. Mothers subsequently completed the Child Behavior Checklist to assess child aggression at 3 years postpartum (n = 79). Independent component analysis was used to define frontal and limbic regions of interest.

Results

Child aggression was not related to within-network connectivity of subcortical limbic regions or within-medial prefrontal network connectivity in fetuses. However, weaker functional coupling between the subcortical limbic network and medial prefrontal network in fetuses was prospectively associated with greater maternal-rated child aggression at 3 years of age even after controlling for maternal emotion dysregulation and toddler language ability. We observed similar, but weaker, associations between fetal frontolimbic functional connectivity and toddler internalizing symptoms.

Conclusions

Neural correlates of aggressive behavior may be detectable in utero, well before the onset of aggression symptoms. These preliminary results highlight frontolimbic connections as potential candidate neurocircuitry that should be further investigated in relation to the unfolding of child behavior and psychiatric risk.

Male and female mice display consistent lifelong ability to address potential life-threatening cues using different post-threat coping strategies

BACKGROUND

Sex differences ranging from physiological functions to pathological disorders are developmentally hard-wired in a broad range of animals, from invertebrates to humans. These differences ensure that animals can display appropriate behaviors under a variety of circumstances, such as aggression, hunting, sleep, mating, and parental care, which are often thought to be important in the acquisition of resources, including territory, food, and mates. Although there are reports of an absence of sexual dimorphism in the context of innate fear, the question of whether there is sexual dimorphism of innate defensive behavior is still an open question. Therefore, an in-depth investigation to determine whether there are sex differences in developmentally hard-wired innate defensive behaviors in life-threatening circumstances is warranted.

RESULTS

We found that innate defensive behavioral responses to potentially life-threatening stimuli between males and females were indistinguishable over their lifespan. However, by using 3 dimensional (3D)-motion learning framework analysis, we found that males and females showed different behavioral patterns after escaping to the refuge. Specifically, the defensive "freezing" occurred primarily in males, whereas females were more likely to return directly to exploration. Moreover, there were also no estrous phase differences in innate defensive behavioral responses after looming stimuli.

CONCLUSIONS

Our results demonstrate that visually-evoked innate fear behavior is highly conserved throughout the lifespan in both males and females, while specific post-threat coping strategies depend on sex. These findings indicate that innate fear behavior is essential to both sexes and as such, there are no evolutionary-driven sex differences in defensive ability.