The gradual emergence of sex differences in aggression: alternative hypotheses

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.

Sex Differences in Social Cognition

In this review we explore the sex differences underlying various types of social cognition. Particular focus will be placed on the behaviors of social recognition, social learning, and aggression. Known similarities and differences between sexes in the expressions of these behaviors and the known brain regions where these behaviors are mediated are discussed. The role that the sex hormones (estrogens and androgens) have as well as possible interactions with other neurochemicals, such as oxytocin, vasopressin, and serotonin is reviewed as well. Finally, implications about these findings on the mediation of social cognition are mediated and the sex differences related to humans are considered.

Trajectories of dysregulation in preschool age

Dysregulation of emotions, behaviour and attention is involved in several areas of childhood psychopathology, but knowledge about early developmental trajectories remains scarce. This study aims to explore continuity and associations of dysregulation in preschool age. Dysregulation was measured at age 2½ years and again at 5 years in a community-based birth cohort of 1099 children using the Child Behavior Checklist, preschool version (CBCL1½-5), answered by mothers. Based on the Dysregulation Profile (CBCL-DP) score, we defined four trajectory groups, using the 75th percentile from the Danish norm material as a cut-off. Associations between the four CBCL-DP trajectory groups and potential covariates, including child, parental and family factors, were analysed using univariate and multiple multinomial logistic regression. Nearly half (54%) of the children showed persistent low scores of CBCL-DP, 17% displayed continuing dysregulation problems, 13% had problems that increased from 2½ years to 5 years, whereas 16% of the children showed reduced problems across preschool age. Persistent dysregulation was associated with maternal postpartum depressive symptoms RRR = 2.20 (95% CI 1.29-3.75), low maternal educational level RRR = 1.69 (95% CI 1.08-2.66), and mothers' smoking during pregnancy RRR = 2.87 (95% CI 1.09-7.55). Persistent problems of emotional, behavioural and attention regulation in children aged 2½ years to 5 years is influenced by maternal educational level and post-partum depression symptoms. The study draws clinical attention to early symptoms of dysregulation and to the importance of addressing the specific needs of mentally vulnerable parents in intervention planning.

The Moderating Role of Surgency, Behavioral Inhibition, Negative Emotionality and Effortful Control in the Relationship between Parenting Style and Children’s Reactive and Proactive Aggression

The principal aim of this study is to explore the moderating role of temperament in the relationship between parenting style and the reactive and proactive aggressive behavior of 8-year-old children. The participants are 279 children (154 boys and 125 girls). To measure reactive and proactive aggression, children completed the reactive and proactive questionnaire (RPQ). Child temperament and parenting styles were evaluated by both parents using the temperament in middle childhood questionnaire (TMCQ) and the parenting styles and dimensions questionnaire (PSDQ). The results revealed that boys with high surgency levels and authoritarian fathers displayed more reactive aggression, whereas behaviorally inhibited boys with mothers who scored low for authoritarian parenting displayed less reactive aggression. Finally, girls with high levels of effortful control and mothers who scored low for authoritative parenting displayed more proactive aggression. The results highlight the value of studying the moderating role of temperament in the relationship between children’s aggressive behavior and both mothers’ and fathers’ parenting styles, and underscores the importance of doing so separately for boys and girls.

Fathers' Mental Health and Children's Aggressive Behaviour A Study Based on Data from the Norwegian Mother, Father and Child Cohort Study (MoBa)

The aim of the study was to examine the association between fathers' prenatal psychological distress and children's aggressive behaviour in terms of hitting others, and how children's age, gender and temperament affect this association. The study is based on data from 20,155 fathers and mothers from the Norwegian Mother, Father and Child Cohort Study (MoBa). Fathers and mothers completed questionnaires at 17 or 18 weeks of gestation and mothers at children's age 18 months, and 3 and 5 years. Fathers' prenatal psychological distress was assessed by the 5-item Symptom Checklist (SCL-5), and children's temperament by 12 items from the Emotionality Activity Sociability (EAS) Temperament Survey. Increasing prenatal psychological distress in fathers was associated with an increase of hitting from 18 months to 3 years of age in boys. Children's temperament did not affect the association between fathers' prenatal psychological distress and children's aggressive behaviour.

Mean kids become mean adults: Trajectories of indirect aggression from age 10 to 22

Although much is known about the development of physical aggression across the lifespan, far less is known about the developmental pattern of indirect aggression from childhood to adulthood. Accordingly, we examined the self-reported use of indirect aggression from age 10 to 22 in a randomly drawn sample of 704 Canadians. A person-centered approach was used to capture intraindividual change and heterogeneity in development. Four childhood (age 10-18) indirect aggression trajectories were identified: (1) a very low decreasing group (64.8%), (2) a low decreasing group (26.0%), (3) a low-to-moderate increasing group (5.1%), and (4) a moderate increasing group (4.1%). There were more girls than boys in the moderate increasing group (75.9% vs. 24.1%). Two adulthood (age 19-22) indirect aggression trajectory groups were also identified: (1) a low decreasing group (82.6%), and (2) a moderate stable group (17.4%). No sex differences were found among adults' use across the two trajectories. When we examined the prediction of indirect aggression use in adulthood from indirect aggression use in childhood, we found that children who followed a moderate increasing trajectory from age 10 to 18 were nine times more likely to follow a moderate stable trajectory from age 19 to 22, while children who followed a low-to-moderate increasing trajectory across childhood were 14 times more likely to follow a moderate stable trajectory across adulthood (compared to the very low decreasing group). Given the negative impact indirect aggression has on others, intervening early to derail this pattern of abuse is justified.

Internalizing and externalizing problems in preschool children: The role of mothers' and fathers' observed parenting behavior in a well-resourced sample

Empirical evidence links sensitive parenting behavior to positive developmental trajectories in children, whereas parental intrusiveness, in contrast, has been found to increase the risk of socio-emotional problems in children of various ages. However, most studies investigating the effect of parenting behavior have been conducted with mothers. Thus, little is yet known about fathers' role in child development and if mothers' and fathers' parenting behaviors are linked to child socio-emotional outcomes in similar or different ways. To date, findings are ambiguous, and this is why more studies are needed. The present study examined associations between mothers' and fathers' observed sensitivity and intrusiveness and children's internalizing and externalizing problems as reported by parents and by children themselves. The sample compromised 52 mothers, 41 fathers and their preschool children. Results from hierarchical regression analyses showed a negative association between fathers' intrusiveness, at low levels, and children's internalizing problems. This result was unexpected. However, in line with this finding, a number of recent studies suggest that when fathers challenge and push their children's limits, it buffers against emotional problems such as anxiety. The present study highlights the importance of a continuous investigation into fathers' potentially unique contribution to children's socio-emotional development. No other associations were identified between mothers' and fathers' parenting behaviors and children's internalizing and externalizing problems. Most likely, because this study was conducted with a low-risk sample, where children were in general well-functioning.

Continuity and change in anger and aggressiveness from infancy to childhood: The protective effects of positive parenting

Early signs of anger and aggression can be identified in infancy. Our aim was to use person-centered methods to identify which infants were most at risk for clinically significant behavioral problems by age 3 and diagnoses of ODD/CD by 7 years, while considering the role of family risk factors and positive parenting. A representative British community sample of 304 infants was assessed by multiple informants at mean ages of 6, 21, and 36 months of age. Latent Transition Analysis (LTA) identified three ordered subgroups at each age, with one subgroup (18%) displaying high levels of physical force as well as anger. These angry aggressive infants were at elevated risk for behavioral problems in early childhood and diagnoses of conduct disorder (CD) and/or oppositional defiant disorder (ODD) at 7 years of age. After other risk factors were taken into account, parents' beliefs in warm parenting and their observed positive affect while interacting with their infants were protective factors. These findings indicate the significance of very early manifestations of angry aggressiveness and have relevance for developmental theories of aggression and prevention strategies.

The relation between behavioral problems and social competence: A correlational Meta-analysis

BACKGROUND

Previous studies have shown that children who display behavioral problems also tend to display low social competence. The relation does however vary according to type of behavior being measured, as well as demographic characteristics of the respondent. The present meta-analysis examined the correlation between different types of behavioral problems and social competence among children aged 3-13, and investigated possible moderators in this relation.

METHODS

A systematic literature search was conducted for English language studies from January 2008 to January 2018 that reported correlations between three types of behavioral problems (i.e., externalizing behaviors, conduct problems, or aggression) and two types of social competence (i.e., social competence or social skills). The studies included reports from parents and teachers, or both as a dyad. The review included data from 54 independent studies and a total of 46,828 participants. Effect sizes were estimated using a random effects approach and moderator analyses between subsets of categorical variables were tested by the significant Q test.

RESULTS

Results showed an overall correlation between behavioral problems and social competence of medium effect size (r = -.42, p < .01). Moderation analyses indicated no significant differences for different types of behavioral problems or social competence. However, a significant difference was found with regard to type of respondent; the correlation was significantly higher when both measures were reported by the same respondent (teacher or parent) compared to when measures were reported by parent-teacher as a dyad.

CONCLUSIONS

Findings summarized and quantified a robust negative correlation between behavioral problems and social competence. The results indicate that intervention programs targeting problem behaviors in children would benefit from reducing behavioral problems and in concert, increase social competence to help children with emerging or present problem behaviors.

Does playing violent video games cause aggression? A longitudinal intervention study

It is a widespread concern that violent video games promote aggression, reduce pro-social behaviour, increase impulsivity and interfere with cognition as well as mood in its players. Previous experimental studies have focussed on short-term effects of violent video gameplay on aggression, yet there are reasons to believe that these effects are mostly the result of priming. In contrast, the present study is the first to investigate the effects of long-term violent video gameplay using a large battery of tests spanning questionnaires, behavioural measures of aggression, sexist attitudes, empathy and interpersonal competencies, impulsivity-related constructs (such as sensation seeking, boredom proneness, risk taking, delay discounting), mental health (depressivity, anxiety) as well as executive control functions, before and after 2 months of gameplay. Our participants played the violent video game Grand Theft Auto V, the non-violent video game The Sims 3 or no game at all for 2 months on a daily basis. No significant changes were observed, neither when comparing the group playing a violent video game to a group playing a non-violent game, nor to a passive control group. Also, no effects were observed between baseline and posttest directly after the intervention, nor between baseline and a follow-up assessment 2 months after the intervention period had ended. The present results thus provide strong evidence against the frequently debated negative effects of playing violent video games in adults and will therefore help to communicate a more realistic scientific perspective on the effects of violent video gaming.

Sex differences in the neural correlates of aggression

Although sex differences in aggression have been investigated for decades, little is known about the underlying neurobiology of this phenomenon. To address this gap, the present study implemented a social reactive aggression paradigm in 20 women and 22 men, employing a modified Taylor Aggression Task (mTAT) to provoke aggressive behavior in an fMRI setting. Subjects were provoked by money subtraction from a fake opponent and given the opportunity to retaliate likewise. In the absence of behavioral differences, male and female subjects showed differential brain activation patterns in response to provocation. Men had higher left amygdala activation during high provocation. This amygdala activation correlated with trait anger scores in men, but not in women. Also, men showed a positive association between orbitofrontal cortex, rectal gyrus and anterior cingulate cortex (ACC) activity in the provocation contrast and their tendency to respond aggressively, whereas women displayed a negative association. As the rectal gyrus and OFC have been attributed a crucial role in automatic emotion regulation, this finding points toward the assumption that highly aggressive men use automatic emotion regulation to a greater extent in response to provocation compared to highly aggressive women.

The Stability of Problem Behavior Across the Preschool Years: An Empirical Approach in the General Population

This study examined the stability of internalizing and externalizing problems from age 1.5 to 6 years, while taking into account developmental changes in the presentation of problems. The study comprised a population-based cohort of 7,206 children (50.4 % boys). At ages 1.5, 3, and 6 years, mothers reported on problem behavior using the Child Behavior Checklist/1.5-5 (CBCL/1.5-5). At each age we performed latent profile analysis on the CBCL/1.5-5 scales. Latent transition analysis (LTA) was applied to study the stability of problem behavior. Profiles of problem behavior varied across ages. At each age, 82–87 % of the children did not have problems whereas approximately 2 % showed a profile of co-occurring internalizing and externalizing problems. This profile was more severe (with higher scores) at 6 years than at earlier ages. A predominantly internalizing profile only emerged at 6 years, while a profile with externalizing problems and emotional reactivity was present at each age. LTA showed that, based on profiles at 1.5 and 3 years, it was difficult to predict the type of profile at 6 years. Children with a profile of co-occurring internalizing and externalizing problems early in life were most likely to show problem behavior at 6 years. This study shows that the presentation of problem behavior changes across the preschool period and that heterotypic continuity of problems is very common among preschoolers. Children with co-occurring internalizing and externalizing problems were most likely to show persisting problems. The use of evidence-based treatment for these young children may prevent psychiatric problems across the life course.

Parental Perceptions of Aggressive Behavior in Preschoolers: Inhibitory Control Moderates the Association With Negative Emotionality

Inhibitory control (IC) and negative emotionality (NE) are both linked to aggressive behavior, but their interplay has not yet been clarified. This study examines different NE × IC interaction models in relation to aggressive behavior in 855 preschoolers (aged 2-5 years) using parental questionnaires. Hierarchical regression analyses revealed that NE and IC predict aggression both directly and interactively. The highest aggression levels were reported in children with high NE and low IC. Interestingly, the protective effect of IC for aggressive behavior increases with rising levels of NE. Analyses focusing on physical aggression revealed a significant NE × IC interaction in boys aged 4-5 years only. These findings shed new light on potential compensatory mechanisms for aggressive behavior in developing children.

Self-reported internalizing and externalizing behaviours among junior high school students at 2 and 4 years after the 921 earthquake in Taiwan

We examined the impact of the 921 Taiwan Earthquake on internalizing and externalizing behaviours among junior high school students 2 and 4 years after the earthquake. This study was a secondary analysis using data extracted from the Taiwan Education Panel Survey and included 12111 students. The impact of the earthquake was assessed by the length of time to restore the home environment and whether a family member died or was severely injured in the earthquake. Generalized estimating equations showed that living in an urban area and a longer duration after the earthquake were associated with increased internalizing and externalizing behaviours. Boys reported more externalizing but fewer internalizing behaviours than girls. After adjustment for those variables, having a family member who had died or was severely injured was not significantly associated with increased internalizing and externalizing behaviours. However, a longer duration of time to restore the home environment was significantly associated with these behaviours. Regardless of the impact level of the disaster, adolescents had increased internalizing and externalizing behaviours from the seventh to ninth grades. Post-disaster mental health services should continue monitoring and supporting children whose ordinary home living is affected by a natural disaster up to 4 years post-disaster.

[Female conduct disorders]

The last few years have seen much research on girls with conduct disorder (CD). This article summarizes the gender-specific data regarding prevalence, differences with respect to symptomatology (e.g., subtypes of aggression, callous-unemotional (cu)-traits), and it presents data on the autonomic and neuroendocrine stress system as well as genetic, neurocognitive, and neuroimaging data. Differences in the impact of environmental factors on boys and girls for the development of CD are discussed. Taken together, the data indicate that there is great overlap in symptomatology, personality traits, and neurobiological aberrations in girls and boys with CD. Since fewer girls than boys exhibit CD symptomatology, further investigations on CD in girls might help to identify resilience factors that could improve future therapeutic interventions.

Developmental trajectories and predictors of externalizing behavior: a comparison of girls and boys

Recent studies have shown that the development of externalizing behavior in childhood and adolescence can be described through different developmental pathways. However, knowledge about differences between the sexes regarding the trajectories is limited. This study focused on potential differences by examining the trajectories of self-reported externalizing symptoms for girls and boys separately. In addition, the relationships of several familiar and child-specific variables with those developmental courses were assessed. The study was conducted on a large community sample of German youths (N = 3,893; mean age 11.38 years; 50 % girls) over 4 years. Using growth mixture modeling, three different classes of trajectories were found for both sexes. The classes differed with regard to the level and the course of symptoms ("low", "moderate", "high-decreasing"). Girls were overrepresented in the "low" class, whereas boys were predominant in the "moderate" and "high-decreasing" classes. The multiple group analysis revealed that the girls and boys differed significantly in their level and linear course of symptoms with regard to the "high-decreasing" class. In contrast, no sex differences were found in the growth factors of the "low" and "moderate" classes. The regression analyses showed that the children's depressive symptoms, dysfunctional parenting style, and negative family climate were associated significantly with the level and course of symptoms as well as the class membership of girls and boys. Life events predicted class membership only for boys, whereas maternal depressive symptoms and family conflict did not demonstrate any significant relationship. The sizes of the predictive associations with the growth factors were similar for both sexes. The results are discussed with regard to existing developmental models and their possible implications for prevention and future research.

DEVELOPMENT OF DISRUPTIVE BEHAVIORS IN YOUNG CHILDREN: A PROSPECTIVE POPULATION-BASED COHORT STUDY

We know relatively little about the development of disruptive behaviors (DBs), and gender differences therein. The objective of this study was to describe the continuity and discontinuity in the degree to which young children in the general population are reported to exhibit specific DBs over time. Data came from the Québec Longitudinal Study of Child Development. First, the results show that relatively few children exhibit DBs on a frequent basis at 41 months of age. Second, the results show that a majority of children who exhibit a particular DB on a frequent basis at 41 months of age did not do so 1 year earlier. In addition, a majority of children who exhibited a particular DB on a frequent basis at 29 months of age no longer do so 1 year later. Third, gender differences in DBs (boys > girls) are either emerging or at least increasing in magnitude between 29 and 41 months of age. Consistent with the canalization of the behavioral development principle, children who exhibited DBs on a frequent basis at 29 months of age are less likely to stop doing so in the following year if they had exhibited the same behaviors at 17 months of age.

Aggression in children and adolescents with ASD: prevalence and risk factors

The prevalence of and risk factors for aggression were examined in 1,380 children and adolescents with autism spectrum disorders (ASD). Prevalence was high, with parents reporting that 68% had demonstrated aggression to a caregiver and 49% to non-caregivers. Overall, aggression was not associated with clinician observed severity of ASD symptoms, intellectual functioning, gender, marital status, parental educational level, or aspects of communication. Individuals who are younger, come from a higher income family, have more parent reported social/communication problems, or engage in repetitive behaviors were more likely to demonstrate aggression. Given the significant impact of aggression on individual and family outcomes, it is hoped that this knowledge will inform more targeted intervention efforts.

Relationships among individualism--collectivism, gender, and ingroup/outgroup status, and responses to conflict: a study in China and the United States

Responses to conflict were studied in samples of college students from a highly collectivistic society (China, n = 207) and a highly individualistic society (United States n = 209). As predicted, the collectivistic society reported more conflict-reducing behaviors and less verbal or physical aggression. However, the effect of individualism/collectivism was moderated by both the ingroup/outgroup status of the target and gender of the participant. Chinese and US women did not differ on any measure. However, of the four groups, Chinese men reported the most conflict-reducing behaviors and the least physical aggression, whereas US men reported the fewest conflict-reducing behaviors and the greatest physical aggression. As predicted, conflict-reducing behaviors were more common in the ingroup condition and both verbal and physical aggression was more common in the outgroup condition. However, the latter were moderated by gender of the participant. US men reported greater physical aggression than any other group. Neither gender nor society had any effect on the level of indirect aggression. There were no gender or individualism/collectivism effects on indirect aggression. Observed gender effects were attributed to differences in how collectivistic and individualistic societies conceptualize masculinity. The effect sizes associated with the ingroup/outgroup condition were consistently and substantially larger than effect sizes associated with individualism/collectivism or gender.

Parental familism and antisocial behaviors: development, gender, and potential mechanisms

OBJECTIVE

To examine the relation between parental familism (strong values of attachment to nuclear and extended family members) and youth antisocial behaviors over time.

METHOD

Puerto Rican children 5 to 13 years of age at baseline residing in the South Bronx in New York (n = 1,138) and in the Standard Metropolitan Area in San Juan and Caguas, Puerto Rico (n = 1,353) were followed over two waves 1 year apart from 2000 to 2004. Parental familism was assessed using an adaptation of the Sabogal Familism Scale. Level of youth past-year antisocial behaviors was measured by the Antisocial Behavior Index. The association between familism and Antisocial Behavior Index over three waves was examined through mixed models stratified by age and gender, adjusted by site (South Bronx or San Juan), propensity scores reflecting site differences in family income, maternal age and education, plus environmental and child risk factors. Specific family processes were examined as potential mediators.

RESULTS

Parental familism was protective against antisocial behaviors in girls (estimate = -0.11, standard error = 0.03, p < .001 for 5- to 9-year-olds; estimate = -0.15, standard error = 0.03, p < .0001 for those ≥ 10 years old). For boys, parental familism was only protective in 5- to 9-year-olds (estimate = -0.09, standard error = 0.03, p = .0008). The protective effect of parental familism on antisocial behaviors operated mostly through parent-child relationships for 5- to 9-year-old children and parental attitudes/behaviors toward youth high-risk behaviors for both age groups.

CONCLUSIONS

Familism may protect youth against increasing levels of antisocial behaviors (except for boys who are ≥ 10 years old). Incorporating familism as part of therapeutic approaches addressing antisocial behaviors for youth may be helpful.

Longitudinal relations between depressive symptoms and externalizing behavior in adolescence: moderating effects of maltreatment experience and gender

Among the explanations for the high rates of co-occurrence between depressive symptoms and externalizing behavior is the possibility of direct causal associations between the two symptom groups. However, the mechanisms by which co-occurrence arises may not be the same across etiologically significant variables. A gender-balanced sample of 303 adolescents (ages 9-12 at the first assessment) with carefully assessed histories of maltreatment experience and 151 demographically matched nonmaltreated adolescents were assessed over the period of 1 year. Multiple-group cross-lagged panel analyses assessed the equivalence of longitudinal relations between depressive symptoms and externalizing behavior for gender/maltreatment status groups. Consistent with previous findings, the results suggest that girls, particularly maltreated girls, who exhibit early externalizing behavior are at high risk for the development of subsequent depressive symptoms.

Predictors and sequelae of trajectories of physical aggression in school-age boys and girls

Teacher-rated trajectories of physical aggression in boys and girls from first through sixth grade were examined using data from the NICHD Study of Early Child Care and Youth Development. In separate analyses, four trajectories were identified in boys and three in girls. Higher levels of aggression in both boys and girls were related to greater sociodemographic risk and higher maternal harshness in the preschool years; lower levels of observed maternal sensitivity during early childhood also predicted higher trajectories of aggression among girls. Trajectory groups also differed on a range of social and academic adjustment outcomes in sixth grade, with the most aggressive children and even moderately aggressive children evidencing some difficulties in adjustment. Patterns and levels of aggression in boys and girls are discussed as are their predictors and consequences.

Childhood cruelty to animals: a tri-national study

Childhood cruelty to animals is a symptom of conduct disorder that has been linked to the perpetration of violence in later life. Research has identified several factors associated with its etiology, including social factors. However, no cross-cultural studies on this phenomenon have been reported. This study investigated childhood cruelty to animals in Japan, Australia and Malaysia. Parents of 1,358 children between the ages of 5 and 13 years completed the Children's Attitudes and Behaviours towards Animals questionnaire (CABTA) which assesses Typical and Malicious Cruelty to animals. Analyses revealed no overall differences between children from these countries on either scale. However, younger boys were more likely to be cruel than younger girls in each country, and younger children in Australia and Japan were more likely to be cruel that older children in those countries. The findings are discussed in relation to previous research, and recommendations for future studies are suggested.

Immediate and sustained effects of parenting on physical aggression in Canadian children aged 6 years and younger

OBJECTIVE

To determine whether the effects of factors associated with the development of childhood (aged 6 years or younger) physical aggression were immediate (cross-sectional), sustained (longitudinal), or both.

METHODS

A longitudinal subsample (n = 975) of children born between December 1994 and April 1995 was drawn from the Canadian National Longitudinal Survey of Children and Youth and followed from birth to 6 years of age. Using random- and fixed-effects logistic panel regression models, child (sex and preterm birth), maternal (education, employment, and positive or hostile/ineffective parenting), and family (lone-parent, older and younger siblings, and income) indicators were regressed on childhood physical aggression.

RESULTS

Hostile/ineffective parenting contributed significantly to explaining the variance in aggression. At each measurement time point (birth, 2, 4, and 6 years of age), a change in hostile/ineffective parenting had an effect on aggression, and this effect carried forward across time up to 6 years. Being a boy, having a mother with less education, and living in a lone-parent family with siblings also contributed significantly to aggression. Preterm birth, maternal employment, depressive symptoms, positive interaction, and income failed to contribute significantly to aggression.

CONCLUSIONS

These results support the hypothesis that hostile/ineffective parenting has an immediate effect on aggression. Contrary to predictions that it would have an immediate effect only at the time it was occurring, hostile/ineffective parenting had a sustained effect on aggression that carried forward in time up to 6 years of age. The results suggest that hostile/ineffective parenting has an effect on aggression prior to any evidence of aggressive behaviour in the child.

Antepartum and postpartum exposure to maternal depression: different effects on different adolescent outcomes

BACKGROUND

Postpartum depression (PPD) is considered a major public health problem that conveys risk to mothers and offspring. Yet PPD typically occurs in the context of a lifelong episodic illness, and its putative effects might derive from the child's exposure to other episodes, in pregnancy or later childhood. The aim of the study is to test two hypotheses: (1) that the effects of PPD on adolescent outcomes are partly explained by antepartum depression (APD) and (2) that the effects of APD and PPD are both explained by later exposure to the mother's depression.

METHOD

A random sample of 178 antenatal patients was drawn from two general medical practices in South London; 171 gave birth to live infants, and 150 (88%) were assessed at 3 months post partum, with 121 of their offspring (81%) assessed for emotional disorders (ED), disruptive behaviour disorders (DBD) and IQ, at 11 and 16 years of age.

RESULTS

When APD and subsequent episodes of depression were taken into account, PPD had a significant effect on adolescent IQ, especially for boys, but did not predict psychopathology. ED and DBD in adolescence were predicted by the extent of exposure to maternal depression after 3 months post partum; a significant effect of APD on ED in girls was accounted for by later exposure to the mother's illness. Mothers' symptoms of anxiety, smoking and alcohol use in pregnancy did not predict adolescent outcomes, once maternal depression was taken into account.

CONCLUSIONS

Some effects attributed to mothers' mental health problems in pregnancy or post partum may be mediated by cumulative exposure to maternal illness, probably reflecting genetic influence and gene-environment correlation. However, PPD has a direct effect on cognition. Clinicians should endeavour to identify women with depression in pregnancy (31% of this sample) and help them to manage their lifelong illness.