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Given the importance of writing for academic achievement, this study aimed to understand how early oral language contributes to later writing skills. The first objective was to determine if preschool language skills were associated with high school writing, and if so, whether they contributed directly or indirectly through school age language. The second aim was to explore the extent to which genetic and environmental factors explained these potential associations. The sample was drawn from the Quebec Newborn Twin Study, a longitudinal follow-up of twins born in the greater Montreal area, Quebec, Canada. Language skills were assessed when children were 1.5, 2.5, 6, 7, 10, and 12 years old. Writing skills were measured at 15 years old. Participants who completed the writing task in French were included in the study (n = 316 twin pairs: 46% males). Mothers of these participants self-identified mostly as White. About 74% of them had a postsecondary diploma or certificate, and 27% further had a university degree. Most families had an income higher than 30,000 CND. Results indicate that preschool language was modestly associated with high school writing (r = 0.25) and that school age language fully mediated this association. Genes explained 53% of the association between preschool language and school age language and 64% of the association between school age language and high school writing. These results highlight the developmental continuity from oral to written language from preschool to high school and show that genetic factors largely account for this continuity.

The present study examined, within a longitudinal family-informed design and across middle childhood, the predictive associations between preference for solitude and social wariness, two forms of social withdrawal, and peer difficulties. Specifically, preference for solitude, rather than social wariness, was expected to predict peer victimization and rejection, two aspects of peer difficulties. A total of 1,014 children from the Quebec Newborn Twin Study were assessed by teachers and peers at ages 6, 7, and 10 years. Multilevel analyses conducted across three levels, between family, within family, and within person, revealed that preference for solitude, rather than social wariness, increased the risk for peer difficulties in terms of both peer victimization and peer rejection. Specifically, preference for solitude was systematically associated with peer rejection starting at age 6 years and became progressively associated with peer victimization over time. This pattern was found both between and within families. In addition, the predictive association with peer rejection was found within genetically identical, monozygotic twin pairs, suggesting that this predictive association existed after taking into account genetic vulnerabilities. Social wariness was systematically unrelated to peer difficulties. These findings suggest that preference for solitude, rather than social wariness, is a risk factor for peer difficulties. They underscore the relevance of distinguishing these dimensions of social withdrawal and illustrate the usefulness of a family-informed design to document the processes underlying childhood social adjustment.

Background: The number line task assesses the ability to estimate numerical magnitudes. People vary greatly in this ability, and this variability has been previously associated with mathematical skills. However, the sources of individual differences in number line estimation and its association with mathematics are not fully understood. Aims: This large-scale genetically sensitive study uses a twin design to estimate the magnitude of the effects of genes and environments on: (1) individual variation in number line estimation and (2) the covariation of number line estimation with mathematics. Samples: We used over 3,000 8- to 16-year-old twins from the United States, Canada, the United Kingdom, and Russia, and a sample of 1,456 8- to 18-year-old singleton Russian students. Methods: Twins were assessed on: (1) estimation of numerical magnitudes using a number line task and (2) two mathematics components: fluency and problem-solving. Results: Results suggest that environments largely drive individual differences in number line estimation. Both genes and environments contribute to different extents to the number line estimation and mathematics correlation, depending on the sample and mathematics component. Conclusions: Taken together, the results suggest that in more heterogeneous school settings, environments may be more important in driving variation in number line estimation and its association with mathematics, whereas in more homogeneous school settings, genetic effects drive the covariation between number line estimation and mathematics. These results are discussed in the light of development and educational settings.

There is little research to date on the academic implications of teaching twins in the same or different classroom. Consequently, it is not clear whether twin classroom separation is associated with positive or negative educational outcomes. As a result, parents and teachers have insufficient evidence to make a well-informed decision when twins start school. This study addresses two research questions: Are there average positive or negative effects of classroom separation? Are twins taught in different classes more different from each other than twins taught in the same class? Twin pairs from two large representative samples from Quebec (Canada) and the United Kingdom were evaluated across a large age range (7 to 16 years) on academic achievement, several cognitive abilities and motivational measures. Our results show almost no sizable positive or negative average effect of classroom separation on twins' achievement, cognitive ability and motivation. Twin pairs at age 12 (Quebec, Canada) and at age 16 (United Kingdom) were slightly more similar on achievement if placed in the same classroom, with slightly greater similarity among monozygotic twins than dizygotic twins. However, the few effects found were weak, and it remains unclear whether they result from classroom separation or other factors. These results suggest that in terms of educational outcomes, policymakers should not impose rigid guidelines to separate twin pairs during their education. The choice of whether to educate twin pairs together or separately should be up to parents, twins and teachers, in response to twins' individual needs.

This twin study examined the genetic and environmental etiology of vocabulary, syntax, and their association in first graders. French-speaking same-sex twins (n = 555) completed two vocabulary tests, and two scores of syntax were calculated from their spontaneous speech at 7 years of age. Multivariate latent factor genetic analyses showed that lexical skills were influenced mainly by the environment shared between the twins, whereas syntactic skills were influenced exclusively by genes and unique environment. Moreover, the moderate association between vocabulary and syntax was mostly due to common genetic factors. These novel findings may be attributable to the use of latent factors and the population studied. More research is needed to determine the specific factors involved in lexical and syntactic skills at this developmental period.

This study used a genetically controlled design to examine the direction and the magnitude of effects in the over-time associations between perceived relationship quality with mothers and adolescent maladjustment (i.e., depressive symptoms and delinquency). A total of 163 monozygotic (MZ) twins pairs (85 female pairs, 78 male pairs) completed questionnaires at ages 13 and 14. Non-genetically controlled path analyses models (in which one member of each twin dyad was randomly selected for analyses) were compared with genetically controlled path analyses models (in which MZ-twin difference scores were included in analyses). Results from the non-genetically controlled models revealed a) child-driven effects in the longitudinal associations between adolescent perceived maternal support and depressive symptoms, and b) parent-driven and child-driven effects in the longitudinal association between perceived maternal negativity and adolescent delinquent behaviors. However, results from the genetically controlled models revealed only child-driven effect, suggesting that, purported parent-driven effects were a product of error arising from potential gene-environment correlations (rGE).

Enriched environments may moderate the effect of genetic factors on prosocial leadership (gene-environment interaction, G × E). However, positive environmental experiences may also themselves be influenced by a genetic disposition for prosocial leadership (gene-environment correlation, rGE). Relating these processes to friendships, the present study examined (a) whether children with a genetic disposition for prosocial leadership possess a greater number of reciprocal friends (rGE) and (b) whether the number of reciprocal friends interacts with the effect of genetic factors on children's prosocial leadership (G × E). The sample comprised 275 twin pairs assessed in Grade 1 (mean age 84.7 months). Reciprocal friendship and prosocial leadership behavior were measured via peer nominations. Consistent with rGE, a genetic disposition for prosocial leadership was related to an increased likelihood of friendship. Moreover, consistent with a compensation process, environmental influences played a stronger role than genetic influences in prosocial leadership when children had many friends.

Objective: This study aimed to identify the pathways through which a preventive intervention targeting young low-SES disruptive boys could result in lower crime involvement during adulthood. Method: The preventive intervention was implemented when the children were between 7 and 9 years and included three components (i.e. social skills, parental practices, teacher support). Participants (N = 250) were randomly allocated to the intervention or to a control group. The tested pathways included antisocial behaviour, school engagement, parental supervision and friends' deviancy, both during early and middle adolescence. Crime involvement was assessed in early adulthood. Results: The intervention reduced adult criminal involvement via reduced early and middle adolescent antisocial behaviours. Conclusion: This study adds to the small group of studies that have examined the mechanisms through which early preventive interventions might impact distal outcomes.

The aim of this study was to investigate the unique and combined role of friendship quality and friends' aggression in regard to the persistence of young children's physical aggression from kindergarten to grade 2. The sample included 1555 children (808 girls) assessed annually using teacher ratings. Two theoretical perspectives (i.e., the social learning and the social bonding perspectives) served as frameworks to guide the analyses and interpret the results. In line with the social learning perspective, friends' aggression was related to a significant increase in children's physical aggression. However, in line with the social bonding perspective, good friendship quality played both a compensatory and a protective role, by, respectively, reducing children's initial level of physical aggression and by mitigating, albeit marginally, the associations between friends' and children's physical aggression. These results suggest that fostering a positive relationship between friends in the early school years may decrease physical aggression even if the friends are aggressive.

This study tested a transactional model of reciprocal influences regarding students' peer experiences (peer acceptance, peer rejection, and friends' academic achievement) and students' academic achievement from middle childhood to early adolescence. This longitudinal model was tested on 452 students (198 girls), mostly Caucasian and French speaking, who were assessed yearly from Grades 2 through 7. Structural equation models revealed that, for boys and for girls, higher academic achievement predicted (a) increases in peer acceptance from Grades 2 through 6, (b) decreases in peer rejection from Grades 2 through 4 (through Grade 5 for girls), and (c) increases in friends' achievement from Grades 4 through 7. Also, rejection predicted decreases in academic achievement from Grades 3 through 5. These results suggest that academic achievement is a good predictor of peer group status in middle childhood and that high-achieving students start selecting each other as friends as they enter early adolescence. These data also suggest that peer rejection in childhood may disrupt future academic achievement. Possible mediating mechanisms, as well as peer selection and influences in the context of social development, are discussed. (Contains 3 figures and 4 tables.)

Background: Genetic risk for depressive behavior may increase the likelihood of exposure to environmental stressors (gene-environment correlation, rGE). By the same token, exposure to environmental stressors may moderate the effect of genes on depressive behavior (gene-environment interaction, GxE). Relating these processes to a peer-related stressor in childhood, the present study examined (1) whether genetic risk for depressive behavior in children is related to higher levels of rejection by the peer group (rGE) and (2) whether peer rejection moderates the effect of genetic factors on children's depressive behavior (GxE). Methods: The sample comprised 336 twin pairs (MZ pairs = 196, same-sex DZ pairs = 140) assessed in kindergarten (mean age 72.7 months). Peer acceptance/rejection was measured via peer nominations. Depressive behavior was measured through teacher ratings. Results: Consistent with rGE, a moderate overlap of genetic effects was found between peer acceptance/rejection and depressive behavior. In line with GxE, genetic effects on depressive behavior varied across levels of peer acceptance/rejection. Conclusions: An increased genetic disposition for depressive behavior is related to a higher risk of peer rejection (rGE). However, genes play a lesser role in explaining individual differences in depressive behavior in rejected children than in accepted children (GxE).

Objectives: To longitudinally describe prosocial behaviour development from childhood to adolescence, using multiple informants within Canadian and Italian samples. Method: Participants in Study 1 were 1037 boys from low socioeconomic status (SES) areas in Montreal, Canada, for whom yearly teacher and mother reports were obtained between the ages of 10 and 15. Participants in Study 2 were 472 children (209 girls) from Genzano, Italy, for whom yearly self and teacher reports were obtained between the ages of 10 and 14. Developmental trajectories were estimated from ratings by each informant to identify subgroups of children following distinct courses of prosocial development. Results: In Study 1, three trajectory groups (low/declining 53%, high/declining 16%, high/steep declining 31%) were identified from teacher ratings, while five trajectories (low/stable 7%, low/declining 19%, moderate/stable 41%, high/declining 24%, high/stable 9%) were identified from mother ratings. Small but significant associations were observed between mother and teacher ratings. In Study 2, three trajectory groups (low/stable 9%, moderate/stable 50%, high/stable 42%) were identified from self-ratings, while four trajectory groups (low/stable 8%, moderate/declining 48%, high/declining 37%, increasing 7%) were identified from teacher ratings. Small but significant associations were observed between self- and teacher ratings. Conclusions: The present studies investigated levels of prosocial behaviours from childhood to adolescence, using a multi-informant, cross-cultural perspective. All but one of the developmental trajectories identified were characterised by stable or declining levels of prosocial behaviours. Further research longitudinally investigating prosociality across developmental periods is needed to clarify prosocial behaviour development over time.

Twin studies are well known for their value in quantifying the contribution of genes to population variation in behaviors and personality traits. Twin studies also provide a unique opportunity to untangle the contribution of environmental experiences to emotional and behavioral development. This is particularly true when examining monozygotic (MZ) twins since they represent a pair of individuals naturally matched on both their genetic background and their shared environment, thus allowing the identification of environmental experiences unique to each twin which may impact developmental outcome. This article presents two analytical strategies based on the discordant MZ-twin method. It stresses the power of this method to establish plausible causal pathways between environmental factors and developmental outcomes, and provides examples from the socio-developmental literature to illustrate its application. It also describes the limitations of this method and its requirements for optimal utilization.

This article reviews theoretical and empirical work on the relations between child and adolescent peer experiences and high school graduation. First, the different developmental models that guide research in this domain will be explained. Then, descriptions of peer experiences at the group level (peer acceptance/rejection, victimisation, and crowd affiliation) and at the dyadic level (friendship and clique membership) will be presented, together with their relation to graduation and other indicators of school adjustment. Finally, major theoretical issues and recommendations for future research will be discussed. Specifically, the necessity of including all relevant predictors and control variables in empirical studies and of dealing appropriately with time-related issues will be highlighted. Methodological challenges associated with these recommendations will be explored. (Contains 2 figures and 1 note.)

Using a prospective design spanning 17 years, the authors studied in a sample of 231 boys and girls the predictive links of verbal abuse by the teacher during childhood to high-school graduation and behavioral and emotional problems in young adulthood, as well as the putative mediating role of individuals' generalized and domain-specific self-concept in this context. Results show that verbal abuse by the teacher during childhood was positively related to behavior problems and (for girls) a low probability of having obtained a high school diploma by age 23 years, even when controlling for childhood levels of antisociality, anxiety, school performance, and social preference in the peer group. No conclusive evidence was found for a mediation effect of children's general or domain-specific self-concept, however. Theoretical and practical implications of these findings are discussed.

We examined the influence of income source within the context of persistent poverty on children's disruptive classroom behavior at age 12 and whether these associations were mediated by maternal supervision at ages 10 and 11. Using a subsample (N = 1,112) from the Quebec Longitudinal Study, we coded four economic circumstances indicating persistent poverty (income-to-needs ratio less than 1.5 times the poverty line) and income source (working poor, welfare dependent, work and welfare dependent, vs. never poor working) from ages 8 through 11. Children in welfare-dependent families showed an increase of 2.23 points on the disruptive scale compared with children in never-poor families, which could not be prospectively explained by maternal supervision. These results are above and beyond the influence of family structure, maternal characteristics, and early childhood disruptiveness. (Contains 3 figures and 1 table.)

This study used a sample of 551 children surveyed yearly from ages 6 to 13 to examine the longitudinal associations among early behavior, middle-childhood peer rejection and friendedness, and early-adolescent depressive symptoms, loneliness, and delinquency. The study tested a sequential mediation hypothesis in which (a) behavior problems in the early school years are associated with middle-childhood peer rejection and (b) rejection, in turn, leads to lower friendedness and subsequently higher adolescent internalizing--but not externalizing--problems. Results supported this sequential mediation model for internalizing outcomes and revealed an additional path from early disruptiveness to loneliness via peer rejection alone. No evidence of sequential mediation was observed for delinquency.

Aggressive behaviors in children and adolescents have undergone important conceptual and definitional modifications in the past two decades. In particular, subtypes of aggression have been proposed that separate the form and the function of the aggressive behaviors (i.e., social vs. physical aggression; reactive vs. proactive aggression). Moreover, new methodological tools have been developed to examine the developmental course of these subtypes, as well as their correlates. These conceptual and methodological innovations, in turn, have introduced new views of the development of aggressive behaviors. These "new views" contrast with more traditional perspectives about the evolution of aggressive behaviors from infancy to young adulthood, particularly with respect to the existence of individuals who begin to become aggressive by adolescence only. This article gives an overview of these definitional, conceptual, and methodological innovations. It also tries to reconcile different views about the development of aggressive behaviors from infancy through early adulthood. Theoretical and practical/clinical implications are also reviewed. The conclusion describes an integrative framework and identifies possible areas of research for the future.

Background: Three different explanations have been given for the observation that adolescent gang members report more delinquent behaviour than their counterparts who do not affiliate with gangs: a) adolescents who commit more crimes join gangs (selection hypothesis); b) gang membership facilitates deviant behaviour (facilitation hypothesis); c) selection and facilitation work interactively (enhancement hypothesis). The aim of this study was to test these hypotheses, while controlling for self-reported delinquency, friends' delinquency, and individual as well as family characteristics. Method: The sample included 756 boys first assessed when they attended kindergarten in disadvantaged areas of Montreal. Gang membership was assessed at the ages of 14, 15 and 16 years. Delinquency and drug use data were collected from self-reports and court files at the same ages. Results: Gang members displayed far higher rates of delinquent behaviour and drug use than non-gang members. The results support the facilitation model for transient gang members (i.e., youths in a gang during only one of the three periods considered) and the enhancement model for stable gang members (i.e., youths in a gang for at least two of the periods considered), for person and property offenses. The association between gang membership and delinquency persisted after introducing the control variables. Additional analyses showed that the effect associated with belonging to a gang was beyond that of simply having delinquent friends. Conclusion: Preventing the creation and participation in such gangs should reduce the frequency of antisocial behaviour during adolescence.

Eating disorders have early origins, and there could be a continuum between childhood eating behaviors, such as overeating, and long-term disordered eating, but this remains to be shown. BMI, desire for thinness and peer victimization could influence this continuum, but their interactions are unknown. To fill this gap, the study used data from the Quebec Longitudinal Study of Child Development (N = 1511; 52% girls), in which 30.9% of youth presented a trajectory associated with high disordered eating from 12 to 20 years. The results support an indirect association between overeating at age 5 and disordered eating trajectories, with different mediation processes observed between boys and girls. The findings underscore the importance of promoting healthy body images and eating behaviors among youths. [ABSTRACT FROM AUTHOR]

Background: Peer victimization is associated with a wide range of mental health problems in youth, yet few studies described its association with mental health comorbidities. Methods: To test the association between peer victimization timing and intensity and mental health comorbidities, we used data from 1216 participants drawn from the Quebec Longitudinal Study of Child Development, a population-based birth cohort. Peer victimization was self-reported at ages 6–17 years, and modeled as four trajectory groups: low, childhood-limited, moderate adolescence-emerging, and high-chronic. The outcomes were the number and the type of co-occurring self-reported mental health problems at age 20 years. Associations were estimated using negative binomial and multinomial logistic regression models and adjusted for parent, family, and child characteristics using propensity score inverse probability weights. Results: Youth in all peer victimization groups had higher rates of co-occurring mental health problems and higher likelihood of comorbid internalizing-externalizing problems [odds ratios ranged from 2.06, 95% confidence interval (CI) 1.52–2.79 for childhood-limited to 4.34, 95% CI 3.15–5.98 for high-chronic victimization] compared to those in the low victimization group. The strength of these associations was highest for the high-chronic group, followed by moderate adolescence-emerging and childhood-limited groups. All groups also presented higher likelihood of internalizing-only problems relative to the low peer victimization group. Conclusions: Irrespective of timing and intensity, self-reported peer victimization was associated with mental health comorbidities in young adulthood, with the strongest associations observed for high-chronic peer victimization. Tackling peer victimization, especially when persistent over time, could play a role in reducing severe and complex mental health problems in youth. [ABSTRACT FROM AUTHOR]

Background: Children's academic achievement is considerably influenced by genetic factors, which rarely operate independently of environmental influences such as teachers' behaviour. Praise and punitive discipline are commonly used management strategies by teachers. However, their effects on the genetic expression of children's academic achievement are still unclear. Aims: This study examined potential gene–environment interactions in the associations between children's estimated genetic disposition for academic achievement and teachers' use of praise and punitive discipline in predicting academic achievement. Sample: The participants were 165 twin pairs in sixth grade (M = 12.1 years). Methods: Teachers reported on children's academic achievement, as well as on their own behaviour. Results: Multilevel regression analyses showed significant interactions between children's estimated genetic disposition for academic achievement and teachers' use of praise and punitive discipline, respectively, in predicting academic achievement. These interactions indicated an enhancement process, suggesting that genetically advantaged children are those most likely to benefit from regular praise and infrequent punishments from their teacher. Moreover, genetically advantaged children were not more (nor less) likely to receive praise or punishments than other students. However, students from underprivileged backgrounds were less likely to receive praise from their teachers. Conclusions: The results emphasize the importance of teachers' regular use of praise and infrequent punitive discipline to help genetically advantaged children reach their full potential. Future studies should investigate other protective factors of the school environment that might reduce the role of genetic influences that undermine disadvantaged youth's academic achievement. [ABSTRACT FROM AUTHOR]

The present study investigated prenatal and early postnatal risk factors associated with developmental patterns of disruptive behaviors (DBs; e.g., hyperactivity-impulsivity, noncompliance, physical aggression) from ages 1.5 to 5 years in a population birth cohort {N = 2,057; 50.7% boys). Six high-trajectory classes obtained by latent growth modeling were used as longitudinal indicators of single-DB and co-occurrent DBs. Children following low or moderate trajectories for all DBs served as the reference class. Results showed low commonality of risk factors among single-DB trajectory classes, suggesting that "pure" forms of DBs have specific etiologies. In contrast, the trajectory classes with a high DB in common shared 20.0% to 46.7% of their risk factors. Overall, 40.0% of significant risk factors across trajectory classes were common to between two and four classes, whereas 60.0% of the significant risk factors were specific to one class or another. However, risk factors common among classes accounted for the greater part (63.2%) of the associations, especially in co-occurrent DBs trajectory classes. These risk factors included male sex, a higher number of siblings, maternal symptoms of depression and conduct problems, young motherhood, lack of positive parenting, family dysfunction, and lower socioeconomic status. Children thus develop early distinct patterns of DBs associated with both common and specific prenatal and early postnatal risk factors. Longitudinal assessments of early manifestations of DB, including a range of behaviors and a variety of potential risk factors to reflect the distinctiveness of children and their families, could help guide etiological research, tailor early interventions, and prevent a cascade of deleterious influences and outcomes. [ABSTRACT FROM AUTHOR]

Background: Children who consistently withdraw from social situations face increased risk for later socioemotional difficulties. Twin studies indicate that genetic factors substantially account for the persistence of social withdrawal over time. However, the molecular genetic etiology of chronic courses of social wariness and preference for solitude, two dimensions of social withdrawal, remains undocumented. The objectives of the present study were (a) to identify high‐risk trajectories for social wariness and preference for solitude in childhood and (b) to examine whether falling on these high‐risk trajectories can be predicted by specific polygenic scores for mental health traits and disorders and by a general polygenic predisposition to these traits. Methods: Teachers evaluated 971 genotyped children at five occasions (age 6 to 12 years) from two prospective longitudinal studies, the Quebec Newborn Twin Study and the Quebec Longitudinal Study of Child Development. Developmental trajectories for social wariness and preference for solitude were identified. We tested whether polygenic scores for attention deficit hyperactivity disorder, autism spectrum disorder, depression, loneliness, and subjective well‐being, as well as a general mental health genetic risk score derived across these traits, were associated with the developmental trajectories. Results: Polygenic scores differentially predicted social wariness and preference for solitude. Only the loneliness polygenic score significantly predicted the high trajectory for social wariness. By contrast, the general mental health genetic risk score factor was associated with the trajectory depicting high‐chronic preference for solitude. Conclusions: Distinct associations were uncovered between the polygenic scores, social wariness, and preference for solitude. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to compare children with persistent versus transient preschool language delay on language, academic, and psychosocial outcomes in elementary school. Method: Children with persistent language delay (n = 30), transient language delay (n = 29), and no language delay (controls; n = 163) were identified from a population-based sample of twins. They were compared on language skills, academic achievement, and psychosocial adjustment in kindergarten and Grades 1, 3, 4, and 6. Results: Children with persistent language delay continued to show language difficulties throughout elementary school. Furthermore, they had academic difficulties, in numeracy, and psychosocial difficulties (attention-deficit/hyperactivity disorder behaviors, externalizing behaviors, peer difficulties) from Grade 1 to Grade 6. Children with transient language delay did not differ from controls on language and academic performance. However, they showed more externalizing behaviors in kindergarten and peer difficulties in Grade 1 than controls. Conclusion: Difficulties at school age are widespread and enduring in those with persistent early language delay but appear specific to psychosocial adjustment in those with transient language delay. [ABSTRACT FROM AUTHOR]

Background: Childhood disruptive behaviors are highly prevalent and associated with adverse long-term social and economic outcomes. Trajectories of welfare receipt in early adulthood and the association of childhood behaviors with high welfare receipt trajectories have not been examined. Methods: Boys (n = 1000) from low socioeconomic backgrounds were assessed by kindergarten teachers for inattention, hyperactivity, aggression, opposition, and prosociality, and prospectively followed up for 30 years. We used group-base trajectory modeling to estimate trajectories of welfare receipt from age 19–36 years using government tax return records, then examined the association between teacher-rated behaviors and trajectory group membership using mixed effects multinomial regression models. Results: Three trajectories of welfare receipt were identified: low (70.8%), declining (19.9%), and chronic (9.3%). The mean annual personal employment earnings (US$) for the three groups at age 35/36 years was $36 500 (s.d. = $24 000), $15 600 (s.d. = $16 275), and $1700 (s.d. = $4800), respectively. Relative to the low welfare receipt group, a unit increase in inattention (mean = 2.64; s.d. = 2.32, range = 0–8) at age 6 was associated with an increased risk of being in the chronic group (relative risk ratio; RRR = 1.16, 95% CI 1.03–1.31) and in the declining group (RRR = 1.13, 95% CI 1.03–1.23), after adjustment for child IQ and family adversity, and independent of other behaviors. Family adversity was more strongly associated with trajectories of welfare receipt than any behavior. Conclusions: Boys from disadvantaged backgrounds exhibiting high inattention in kindergarten are at elevated risk of chronic welfare receipt during adulthood. Screening and support for inattentive behaviors beginning in kindergarten could have long-term social and economic benefits for individuals and society. [ABSTRACT FROM AUTHOR]

Background: Population‐based and family studies showed that impulsive‐aggression predicts suicidality; however, the underlying etiological nature of this association is poorly understood. The objective was to determine the contribution of genes and environment to the association between childhood impulsive‐aggression and serious suicidal ideation/attempt in young adulthood. Methods: N = 862 twins (435 families) from the Quebec Newborn Twin Study were followed up from birth to 20 years. Repeated measures of teacher‐assessed impulsive‐aggression were modeled using a genetically informed latent growth model including intercept and slope parameters reflecting individual differences in the baseline level (age 6 years) and in the change (increase/decrease) of impulsive‐aggression during childhood (6 to 12 years), respectively. Lifetime suicidality (serious suicidal ideation/attempt) was self‐reported at 20 years. Associations of impulsive‐aggression intercept and slope with suicidality were decomposed into additive genetic (A) and unique environmental (E) components. Results: Additive genetic factors accounted for an important part of individual differences in impulsive‐aggression intercept (A = 90%, E = 10%) and slope (A = 65%, E = 35%). Genetic (50%) and unique environmental (50%) factors equally contributed to suicidality. We found that 38% of the genetic factors accounting for suicidality were shared with those underlying impulsive‐aggression slope, whereas 40% of the environmental factors accounting for suicidality were shared with those associated with impulsive‐aggression intercept. The genetic correlation between impulsive‐aggression slope and suicidality was 0.60, p =.027. Conclusions: Genetic and unique environmental factors underlying suicidality significantly overlap with those underlying childhood impulsive‐aggression. Future studies should identify putative genetic and environmental factors to inform prevention. [ABSTRACT FROM AUTHOR]

Recent studies have shown that the association between maternal depression and child outcome can be moderated by children's experience of childcare (e.g., daycare) during early childhood (0–5 years). We also know that maternal depression in the child's early years has long-term associations with child development. However, the moderating role of childcare quality on long-term associations between maternal depression and child outcome has not been thoroughly investigated. This article examined longitudinal associations between probable maternal depression (PMD) during early childhood (0–5 years) and childcare quality on children's emotional and behavioral development at the age of 7–8 years (N = 207). Childcare quality was evaluated through observations within the settings. PMD during early childhood was assessed using complementary information from interviews conducted with the mother and current maternal symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. Internalizing and externalizing behaviors were reported by the mother, father and the child at age 7–8 years. Results indicate that when mothers reported clinically relevant depression in early childhood, 7-8-year-old children demonstrate fewer behavioral problems if they attended a higher quality childcare setting. The moderating role of childcare quality remained after considering current maternal depression symptoms. Therefore, it is important to ensure high-quality childcare during early childhood to optimize child development. [ABSTRACT FROM AUTHOR]

Background: Few studies are grounded in a developmental framework to study proactive and reactive aggression. Furthermore, although distinctive correlates, predictors and outcomes have been highlighted, proactive and reactive aggression are substantially correlated. To our knowledge, no empirical study has examined the communality of genetic and environmental underpinning of the development of both subtypes of aggression. The current study investigated the communality and specificity of genetic-environmental factors related to heterogeneity in proactive and reactive aggression’s development throughout childhood. Methods: Participants were 223 monozygotic and 332 dizygotic pairs. Teacher reports of aggression were obtained at 6, 7, 9, 10 and 12 years of age. Joint development of both phenotypes were analyzed through a multivariate latent growth curve model. Set point, differentiation, and genetic maturation/environmental modulation hypotheses were tested using a biometric decomposition of intercepts and slopes. Results: Common genetic factors accounted for 64% of the total variation of proactive and reactive aggression’s intercepts. Two other sets of uncorrelated genetic factors accounted for reactive aggression’s intercept (17%) on the one hand, and for proactive (43%) and reactive (13%) aggression’s slopes on the other. Common shared environmental factors were associated with proactive aggression’s intercept (21%) and slope (26%) and uncorrelated shared environmental factors were also associated with reactive aggression’s slope (14%). Common nonshared environmental factors explained most of the remaining variability of proactive and reactive aggression slopes. Conclusions: A genetic differentiation hypothesis common to both phenotypes was supported by common genetic factors associated with the developmental heterogeneity of proactive and reactive aggression in childhood. A genetic maturation hypothesis common to both phenotypes, albeit stronger for proactive aggression, was supported by common genetic factors associated with proactive and reactive aggression slopes. A shared environment set point hypothesis for proactive aggression was supported by shared environmental factors associated with proactive aggression baseline and slope. Although there are many common features to proactive and reactive aggression, the current research underscores the advantages of differentiating them when studying aggression. [ABSTRACT FROM AUTHOR]

Background: Difficult temperament in infancy is a risk factor for forms of later internalizing and externalizing psychopathology, including depression and anxiety. A better understanding of the roots of difficult temperament requires assessment of its early development with a genetically informative design. The goal of this study was to estimate genetic and environmental contributions to individual differences in infant negative emotionality, their persistence over time and their influences on stability between 5 and 18 months of age. Method: Participants were 244 monozygotic and 394 dizygotic twin pairs (49.7% male) recruited from birth. Mothers rated their twins for negative emotionality at 5 and 18 months. Longitudinal analysis of stability and innovation between the two time points was performed in Mplus. Results: There were substantial and similar heritability (approximately 31%) and shared environmental (57.3%) contributions to negative emotionality at both 5 and 18 months. The trait’s interindividual stability across time was both genetically- and environmentally- mediated. Evidence of innovative effects (i.e., variance at 18 months independent from variance at 5 months) indicated that negative emotionality is developmentally dynamic and affected by persistent and new genetic and environmental factors at 18 months. Conclusions: In the first two years of life, ongoing genetic and environmental influences support temperamental negative emotionality but new genetic and environmental factors also indicate dynamic change of those factors across time. A better understanding of the source and timing of factors on temperament in early development, and role of sex, could improve efforts to prevent related psychopathology. [ABSTRACT FROM AUTHOR]

Background Little is known about how children differ in the onset and evolution of separation anxiety ( SA) symptoms during the preschool years, and how SA develops into separation anxiety disorder. In a large, representative population-based sample, we investigated the developmental trajectories of SA symptoms from infancy to school entry, their early associated risk factors, and their associations with teachers' ratings of SA in kindergarten. Methods Longitudinal assessment of SA trajectories and risk factors in a cohort of 1,933 families between the ages of 1.5 and 6 years. Results Analyses revealed a best-fitting, 4-trajectory solution, including a prevailing, unaffected Low-Persistent group (60.2%), and three smaller groups of distinct developmental course: a High-Increasing (6.9%), a High-Decreasing (10.8%), and a Low-Increasing group (22.1%). The High-Increasing group remained high throughout the preschool years and was the only trajectory to predict teacher-assessed SA at age 6 years. Except for the High-Increasing, all trajectories showed substantial reduction in symptoms by age 6 years. The High-Increasing and High-Decreasing groups shared several early risk factors, but the former was uniquely associated with higher maternal depression, maternal smoking during pregnancy, and parental unemployment. Conclusions Most children with high SA profile at age 1.5 years are expected to progressively recover by age 4-5. High SA at age 1.5 that persists over time deserves special attention, and may predict separation anxiety disorder. A host of child perinatal, parental and family-contextual risk factors were associated with the onset and developmental course of SA across the preschool years. [ABSTRACT FROM AUTHOR]

Numerous studies have shown that aggressive and non-aggressive antisocial behaviors are important precursors of later adjustment problems. There is also strong empirical evidence that both types of antisocial behavior are partially influenced by genetic factors. However, despite its important theoretical and practical implications, no study has examined the question whether environmental factors differentially moderate the expression of genetic influences on the two types of antisocial behavior. Using a genetically informed design based on 266 monozygotic and dizygotic twin pairs, this study examined whether the expression of genetic risk for aggressive and non-aggressive antisocial behavior varies depending on the peer group's injunctive norms (i.e., the degree of acceptability) of each type of antisocial behavior. Self-reported aggressive and non-aggressive antisocial behavior and classroom-based sociometric nominations were collected when participants were 10 years old. Multivariate genetic analyses revealed some common genetic factors influencing both types of antisocial behavior (i.e., general antisocial behavior) as well as genetic influences specific to non-aggressive antisocial behavior. However, genetic influences on general antisocial behavior, as well as specific genetic influences on non-aggressive antisocial behavior, vary depending on the injunctive classroom norms regarding these behaviors. These findings speak to the power of peer group norms in shaping aggressive and non-aggressive antisocial behavior. They also contribute further to understanding the distinctive development of both types of antisocial behavior. Finally, they may have important implications for prevention purposes. [ABSTRACT FROM AUTHOR]

The article offers a study on the role of personal dispositions, low inhibition and disinhibition, in predicting early gambling in children. It says that disinhibition, such as teacher-rate impulsivity, can predict early gambling for both genders, but low inhibition, such as low anxiety, can predict above and beyond disinhibition. It adds that impulsivity and anxiety neither interact with each other nor with parent gambling, which predicted early gambling above and beyond personal dispositions.

This study pursued three goals. The first goal was to explore children's trajectories of anxiety from age 6 to 12 using a representative community sample. The second goal was to assess the link between certain behavioral characteristics assessed in kindergarten (i.e., inattention, hyperactivity, aggressiveness, and low prosociality) and these trajectories. The third goal was to determine whether certain aspects of maternal parenting (i.e., warmth and discipline) could moderate the association between these characteristics and the trajectories of anxiety. A population sample of 2,000 children (1,001 boys, 999 girls) participated in this longitudinal study. Developmental trajectory analyses allowed us to identify four trajectory groups: low, low-increasing, highdeclining, and high anxiety groups. Moreover, multinomial logistic regressions revealed a profile of children at risk of developing high anxiety symptoms (i.e., high group), characterized by sociofamily adversity, inattention, and low prosociality in the classroom. Hyperactivity was also found in this profile, but only for children exposed to a mother who showed little affective warmth. Finally, mothers' high level of discipline increased the odds of belonging to the high anxiety group. The results are discussed in relation to studies examining the association among anxiety, behavioral characteristics, and parenting during childhood. [ABSTRACT FROM AUTHOR]

This study addressed gender differences in the developmental links among antisocial behavior, friends' antisocial behavior, and peer rejection. High and increasing, moderate, and low antisocial developmental trajectories were identified among 289 Dutch children, ages 7 to 10, and 445 French-Canadian children, ages 9 to 12. Only boys followed the high trajectory. These boys had more deviant friends and were more often rejected than other children. A minority of girls followed the moderate antisocial behavior trajectory. These girls had fewer deviant friends than moderate antisocial boys, but moderate antisocial boys and girls were equally likely to be rejected. The influence of friends and poor peer relations plays a crucial but different role in the development of antisocial behavior among boys and girls. [ABSTRACT FROM AUTHOR]

This study examined longitudinal patterns of affiliation with delinquent friends during late childhood and early adolescence, i.e., from ages 10 through 13, in a sample of 376 participants of both genders. Four groups with distinct affiliation profiles were found: an early affiliative group, a late affiliative group, a declining group (i.e., a group that affiliates with delinquent friends early on but much less so thereafter), and a group of children who did not affiliate with delinquent friends throughout the period covered in this study. There was also a fifth group of children who had no mutual friends throughout. The proportion of boys and girls varied in some groups but not in others. Participants’ own delinquency and depression trajectories as well as other behavior- , peer- , school- , and family-related correlates were examined in association with group membership through the use of growth curves analysis. The results are discussed in light of prevalent theories about the role of delinquent friends with respect to externalizing and internalizing problems. [ABSTRACT FROM AUTHOR]