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This study examined developmental patterns of co-occurrent alcohol, marijuana, and other illicit drugs use during adolescence and the associated preadolescent risk factors in a longitudinal sample of 926 boys from low-socioeconomic, urban neighborhoods. Latent growth mixture modeling revealed six developmental patterns: non-/low-alcohol and non-illicit drug users (61% sample) and five polysubstance user-groups varying in severity based on onset, frequency and type of substances used. In comparisons with non-/low-users, several preadolescent risk factors were associated with increasing severity of polysubstance use. Higher sensation-seeking and lower anxiety were associated with all user-groups. Low self-esteem and family-related risk factors differentiated all user-groups from later-onset users. Higher impulsivity and school problems characterized early-onset and frequent polysubstance users. Impulsive sensation-seekers with lower anxiety and self-esteem cumulated a larger number and higher severity of risk factors and were at risk of early-onset frequent polysubstance use, emphasising the importance of indicated prevention for these high-risk boys.

Classroom placement of twins is an ongoing issue for educational policy. Many educational jurisdictions have standard policy most commonly founded in the belief that separation supports individual identity, personal development and academic opportunity. This study examined the effects of classroom placement in a sample of 560 twin pairs whose behaviors were assessed from ages 5 to 12 years. We found no detrimental effect of classroom sharing on twins’ social development. In contrast, this study provides evidence that educating twins together is associated with modest positive twins’ behaviors and social functioning at school. Implications for educational policies are further discussed.

Compared to peer alcohol use, less is known on how parenting practices may modify genetic and environmental contributions to alcohol use longitudinally across adolescence. This study examined whether two maternal parenting behaviors, supervision and harsh parenting, may suppress or amplify genetic and environmental influences on three distinct developmental trajectories of adolescent alcohol use: normative increasing, early-onset, and low trajectories. Participants were drawn from a longitudinal study of a population-based twin sample (N = 842, 84% European descent, 52.7% female). Adolescents self-reported their past year alcohol use at ages 13, 14, 15, and 17 years, and their mothers reported their supervision and harsh parenting when twins were 13, 15, and 17 years old. Maternal supervision amplified non-shared environmental influence on the normative increasing and early-onset trajectories, whereas maternal harsh parenting amplified shared environmental influence on the early-onset trajectory and non-shared environmental influence on the low trajectory, respectively. The findings suggest maternal parenting practices as a potent developmental context that modulates the environmental influences of other proximal processes on adolescent alcohol use, and suggest that family-based parenting-focused intervention could be especially beneficial for adolescents following the early-onset trajectory.

Aggressive behavior is generally detrimental to children's friendships, both in terms of having friends and in terms of keeping friends. Despite this general tendency, many aggressive children have friends and some of these friendships are stable. We examined the moderating role of preference norms in the classroom and child's sex in the association between children's physical and relational aggression and their friendship experiences. A total of 1135 children (M = 10.24 years, SD = 1.01) in Grades 4 to 6 completed a peer nomination inventory in the Fall (T1) and Spring (T2) of the same school year. Norms were operationalized as the class- and sex-specific correlation between physical or relational aggression and social preference. Norms moderated associations between each form of aggression and number of friends. At T1, physical and relational aggression were concurrently associated with having more friends when norms favored this behavior and with fewer friends when norms were unfavorable. The latter effect was especially pronounced in girls. Over time, youth lost friends when norms favored physical aggression and gained friends when norms favored relational aggression. T1 friends' physical and relational aggression were strong predictors of new friends' aggressive behavior, suggesting that friends provide a type of norm more significant to new friend selection than norms of the peer group and individual aggressive behavior. Overall, our results suggest that physical and relational aggression are not necessarily detrimental to children's friendship experiences and may even be beneficial in specific social contexts.

This study used a longitudinal design from age six through age 19 (N = 1206 (603 girls)) to examine the associations between anxious-withdrawal and reactive aggression during childhood, distinct profiles of peer victimization from kindergarten to grade 11 and victimization in college or at work in emerging adulthood. In particular, it was tested whether the predictive effect of personal characteristics on victimization in emerging adulthood would be mediated via chronic peer victimization experiences during the school years. Teachers evaluated children's personal characteristics, whereas peer nominations and self-reports were used to assess victimization. Control variables included sex, parent-reported harsh parenting and SES. Longitudinal latent profile analysis revealed four distinct profiles of peer victimization during the school years: Consistently-Low (39.7%), Low-Moderate (42.8%), High-Decreasing (8.8%) and High-Increasing-Decreasing (8.7%). A subsequent 3-step regression-based path analysis supported the mediation hypothesis - albeit differently for different profiles of peer victimization. Specifically, compared to a Consistently-Low profile of peer victimization in school, a High-Decreasing profile was predicted by reactive aggression, but not anxious-withdrawal. In contrast, a High-Increasing-Decreasing profile was predicted by reactive aggression and anxious-withdrawal. In turn, elevated peer victimization profiles were associated with higher levels of later victimization in college or at work. The indirect effects linking the childhood behaviors to later victimization in college or at work - via elevated peer victimization profiles during childhood and adolescence - were significant. These results highlight the need for tailored interventions to optimize reactively aggressive or anxious-withdrawn children's response strategies to challenging and potentially threatening peer interactions.

Background Various combinations of childhood conduct problems, callous traits and anxiety may confer increased risk of offending, psychopathic traits and mental disorders. Knowledge of these outcomes in adulthood is limited. Aims To compare adult criminal convictions, psychopathy checklist scores and mental disorders between five groups of men, variously defined in childhood by: (1) callous traits, (2) conduct problems, (3) conduct problems and callous traits, (4) conduct problems and callous traits and anxiety or (5) developing typically. Method Teachers rated conduct problems, callous traits and anxiety at ages 6, 10 and 12 years. Criminal convictions from age 12 to 24 were extracted from official records. The Psychopathy Checklist-Revised (PCL-R) and diagnostic interviews were completed at age 33. Results Relative to the typically developing group, the groups with conduct problems, with and without callous traits and anxiety, showed 5-fold elevations in risks of violent convictions and 3 to 4-fold elevations in risk for antisocial personality disorder, while the groups with conduct problems only and with conduct problems plus callous traits plus anxiety were at increased risk for borderline personality disorder. All risk groups obtained higher PCL-R total scores than the typically developing childhood group. Conclusions and implications It is widely accepted that childhood conduct problems in boys are associated with increased risks of criminal convictions and poorer mental health, but our findings suggest that teachers can identify different subgroups and these have different trajectories. As some subgroups were small, replication is recommended, but our findings offer preliminary support for trialling specific interventions for at risk boys.

Background Peer victimization has been associated with long-lasting risks for mental health. Prior research suggests that stress-related systems underlying adaptation to changing environments may be at play. To date, inconsistent findings have been reported for the hypothalamic-pituitary-adrenal (HPA) axis, and its end product cortisol. This study tested whether peer victimization was associated with hair cortisol concentrations (HCC), and whether this association varied according to sex, timing, and changes in exposure. We also examined whether peer victimization differentially predicted depressive symptoms according to HCC. Methods The sample comprised 556 adolescents (42.0%; 231 males) who provided hair for cortisol measurement at 17 years of age. Peer victimization was reported at seven occasions between the ages of 6 and 15 years. Results Peer victimization was nonlinearly associated with HCC for boys only, whereas changes in peer victimization were related to HCC for boys and girls. Peer victimization predicted more depressive symptoms for all participants, except those with lower HCC. Conclusions Our findings provide further support for persistent dysregulation of the HPA axis following exposure to chronic adversity, of which the expression may change according to sex and the severity of victimization.

Student involvement in peer aggression is assumed to include the uninvolved, victims, aggressors, and victim-aggressor groups. Yet, evidence supporting this four-group configuration is equivocal. Although most studies report the four groups, several of the aggressor groups could have been labeled as moderate victim-aggressors. This study first reviews studies identifying subgroups of students involved in verbal, relational, and physical aggression. The study then assesses students’ perceived involvement in elementary ( n = 2,071; Grades 4–6) and secondary school ( n = 1,832; Grades 7–10), as well as the associations with outcomes (school belonging, depressive thoughts, and perceived school violence). Latent profile analysis identified three profiles (uninvolved, victim-only, and victim-aggressor) across all grades and genders. In primary school, the uninvolved, victim, and victim-aggressor respectively included 54.56%, 37.51%, and 7.83% of the girls, and 44.23%, 31.92%, and 23.85% of the boys. In secondary school, the uninvolved, victim, and victim-aggressor respectively included 80.16%, 14.93% and 4.91% of the girls, and 64.31%, 22.95% and 12.74% of the boys. Victims and victim-aggressors reported poorer adjustment than uninvolved students. Victims and victim-aggressors reported lower levels of school belonging and higher levels of depressive thoughts than uninvolved students. Also, victim-aggressors perceived more violence in their school than victims and uninvolved students, and victims perceived more violence than uninvolved students. These findings question the existence of an aggressor-only profile, at least, according to student perception, suggesting the need for a new perspective when intervening with students involved in peer aggression.

While converging evidence suggests that both environmental and genetic factors underlie variations in diurnal cortisol, the extent to which these sources of influence vary according to socioeconomic status (SES) has seldom been investigated, particularly in adolescence. To investigate whether a distinct genetic and environmental contribution to youth’s diurnal cortisol secretion emerges according to family SES and whether the timing of these experiences matters. Participants were 592 twin pairs, who mostly came from middle-income and intact families and for whom SES was measured in childhood and adolescence. Diurnal cortisol was assessed at age 14 at awakening, 30 min later, in the afternoon and evening over four nonconsecutive days. SES–cortisol phenotypic associations were specific to the adolescence period. Specifically, higher awakening cortisol levels were detected in wealthier backgrounds, whereas higher cortisol awakening response (CAR) and diurnal changes were present at both ends of the SES continuum. Moreover, smaller genetic contributions emerged for awakening cortisol in youth from poorer compared to wealthier backgrounds. The results suggest that the relative contribution of inherited factors to awakening cortisol secretion may be enhanced or suppressed depending on the socio-family context, which may help to decipher the mechanisms underlying later adjustment.

BackgroundPeer victimization is associated with a wide range of mental health problems in youth, yet few studies described its association with mental health comorbidities.MethodsTo 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.ResultsYouth 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.ConclusionsIrrespective 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.

This paper is a revised and updated edition of a previous description of the Quebec Newborn Twin Study (QNTS), an ongoing prospective longitudinal follow-up of a birth cohort of twins born between 1995 and 1998 in the greater Montreal area, Québec, Canada. The goal of QNTS is to document individual differences in the cognitive, behavioral, and social-emotional aspects of developmental health across childhood, their early genetic and environmental determinants, as well as their putative role in later social-emotional adjustment, school, health, and occupational outcomes. A total of 662 families of twins were initially assessed when the twins were aged 6 months. These twins and their family were then followed regularly. QNTS now has 16 waves of data collected or planned, including 5 in preschool. Over the last 24 years, a broad range of physiological, cognitive, behavioral, school, and health phenotypes were documented longitudinally through multi-informant and multimethod measurements. QNTS also entails extended and detailed multilevel assessments of proximal (e.g., parenting behaviors, peer relationships) and distal (e.g., family income) features of the child’s environment. QNTS children and a subset of their parents have been genotyped, allowing for the computation of a variety of polygenic scores. This detailed longitudinal information makes QNTS uniquely suited for the study of the role of the early years and gene–environment transactions in development.

This study aimed to identify joint trajectories of peer cyber and traditional victimization from ages 13 to 17 and individual, family, peer, and school risk factors associated with group membership. The sample was composed of 1,194 adolescents (54.2% girls). Cyber and traditional victimization were assessed at ages 13, 15, and 17. The results first revealed a low/increasing and a high/decreasing trajectories for cybervictimization and a low/decreasing and a moderate/chronic for traditional victimization. Conditional probabilities suggested that cybervictims had a high probability of being victims on school grounds, whereas traditional victims were not necessarily the target of cybervictimization. Four joint trajectory groups were also identified. With the low victimization group as the reference category, the results revealed that different sets of predictors were associated with membership in the three other joint trajectory groups. The results are discussed in relation to intervention and prevention strategies.

Among children exposed to elevated maternal depression symptoms (MDS), recent studies have demonstrated reduced internalizing and externalizing problems for those who have attended formal childcare (i.e., center-based, family-based childcare). However, these studies did not consider whether childcare attendance is associated with benefits for the child only or also with reduced MDS. Using a four-wave longitudinal cross-lagged model, we evaluated whether formal childcare attendance was associated with MDS or child behavior problems and whether it moderated longitudinal associations between MDS and child behavior problems and between child behavior problems and MDS. The sample was drawn from a population-based cohort study and consisted of 908 biologically related mother–child dyads, followed from 5 months to 5 years. Attending formal childcare was not associated with MDS or child behavior problems but moderated the association between MDS at 3.5 years and child internalizing and externalizing problems at 5 years as well as between girls’ externalizing problems at 3.5 years and MDS at 5 years. No other moderation of formal childcare was found. Findings suggest that attending formal childcare reduces the risks of behavior problems in the context of MDS but also the risk of MDS in the context of girls’ externalizing problems.

Substance use and gambling participation during adolescence are correlated, both concurrently and over time. It is unclear, however, whether this association can be explained by common underlying genetic vulnerabilities or environmental factors. The present study explored the concurrent and longitudinal associations between substance use and gambling participation and their genetic and environmental underpinnings by late adolescence. Participants were 373 pairs of monozygotic and dizygotic twins. Self-reports of substance use and gambling participation were collected at Ages 17 and 19 years. Results showed concurrent associations between substance use and gambling participation as well as a small, but significant unidirectional longitudinal association over time from substance use to gambling participation. Common genetic factors largely accounted for the concurrent associations at Ages 17 and 19, as well as for the unidirectional longitudinal association between substance use and gambling participation. Substance use and gambling participation share a common genetic component that account for most of their concurrent and longitudinal links during late adolescence. However, these behaviors are also influenced by specific environmental factors. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The present study used a genetically informed design of twins raised in the same family (375 monozygotic and 290 dizygotic twins; 50.2% girls) to examine the association between adolescents' genetic risk for depressive symptoms and the course of the parent-child relationship quality throughout adolescence. Depressive symptoms and the quality of the parent-adolescent relationships were measured through adolescents' self-reports from ages 13 to 17. Group-based trajectory modeling revealed that most adolescents experienced high-quality relationships with both of their parents, characterized by high levels of warmth and low levels of conflict, and marked by gradual changes over adolescence. However, 3% of adolescents showed a trajectory of high and increasing conflict with their mothers and 16% of adolescents showed a trajectory of low warmth with their fathers, which decreased until mid-adolescence before increasing thereafter. Moreover, in line with an evocative gene-environment correlation process, a higher genetic vulnerability to depressive symptoms increased the likelihood of following a more problematic relationship trajectory with parents. This rGE was mediated by adolescents' actual depressive behavior symptoms. Results also suggest that adolescents' depression symptoms may affect girls' and boys' relationship with their parents in a similar way, with specific sex-patterns revolving more around the sex of the parent. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Socialization among aggressive friends is believed to play a critical role in the development of aggressive behavior. This study examined the moderating effect of norm salience in the classroom on the association between reciprocal friends’ and children’s own physical, relational, and general aggression. A total of 713 children ( M = 10.32 years, SD = 0.99) in grades 4 to 6 completed a peer nomination inventory in the fall and spring of the same academic year. Norm salience was operationalized as the class- and sex-specific correlation between each form of aggression and social preference. Norm salience moderated relational aggression socialization among friends only for highly relationally aggressive girls. Specifically, socialization was exacerbated when norm salience was favorable and attenuated when norm salience was unfavorable, suggesting that highly relationally aggressive girls may possess skills allowing them to adapt to the social context in which they and their friends interact. In contrast, boys’ general aggression socialization was exacerbated when norm salience was neutral or unfavorable, suggesting that boys who affiliate with aggressive friends may be more susceptible to aggressive friends’ influence in general and especially in the context of potential peer rejection. No moderating effect of norm salience was found in regards to physical aggression socialization. Results suggest that interventions aimed at changing acceptability of aggression in the classroom may only be effective in specific subgroups of aggressive youth.

International audience; BACKGROUND: Most preschool children in Western industrialized countries attend child care during the day while parents work. Studies suggest that child care may be stressful to young children, perhaps because they still lack the social skills to interact daily in a group setting away from parents. This gap in social abilities may be greater for children in lower-income families, who may face more adversity at home, with fewer resources and more social isolation. METHODS: We conducted a cluster-randomized controlled trial in 2013-2014 to test whether a social skills intervention led by early childhood educators within the child care center could reduce diurnal cortisol levels to more typical patterns expected of children this age. We randomized 19 public child care centers (n = 361 children) in low-income neighborhoods of Montreal, Canada, to either: 1) the Minipally program - intervention group (n = 10 centers; 186 children), or 2) waiting list - control group (n = 9 centers; 175 children). Saliva samples for cortisol levels were collected 3 times/day, pre- and post-implementation. The Minipally puppet program consists of 2 workshops/month for 8 months for the development of social skills and self-regulation in 2-5-year-olds, with reinforcement activities between workshops. Educators received 2-days' training and 12 h' supervision in Minipally. RESULTS: Linear mixed models for repeated measures revealed a significant interaction between intervention status and time of day of cortisol sampling (beta = -0.18, p = 0.04). The intervention group showed patterns of decreasing diurnal cortisol secretion (beta = -0.32, p < 0.01), whereas the control group showed increasing slopes (beta = 0.20, p < 0.01). Moreover, family income was a moderator; children in lower-income families benefited most from the intervention. CONCLUSION: Results suggest that a social skills training program, when integrated into a preschool education curriculum, can foster an environment more conducive to typical childhood patterns of cortisol secretion.

Purpose To examine the cross-lagged associations between delinquency (nonviolent and violent), depression and anxiety symptoms in adolescence and to test the moderating effect of sex and family socioeconomic status (SES). Methods Participants (n=1,515) were from a birth cohort in the Canadian province of Quebec. Autoregressive cross-lagged panel analyses were used to examine the associations between delinquency (nonviolent and violent), depression and anxiety symptoms from ages 15 to 17 years, while taking into account conduct and emotional problems at ages 10-12 years. Results Findings suggest that delinquency (violent delinquency especially) and depression symptoms may develop according to a spiraling model, such that conduct problems in childhood give rise to depression symptoms in mid-adolescence, which in turn, contribute to more delinquent acts at the end of adolescence. Family SES, but not sex, had a moderating effect on the paths. We found that anxiety symptoms at age 15 years were associated with nonviolent delinquency at age 17 years when family SES was low, and that violent delinquency at age 15 years was associated with anxiety symptoms at age 17 years when family SES was high. Conclusions Delinquency and emotional problems do not develop independently from each other; both dimensions should be examined simultaneously.

This study investigates emotion recognition deficits as candidate neurocognitive endophenotypes for callous-unemotional (CU) behaviors. Using a twin design, we tested genetic correlations between child CU behaviors and poor processing of fearful and sad facial expressions. Participants were 504 twin pairs (209 MZ pairs; 295 DZ pairs) from the Quebec Newborn Twin Study, a longitudinal study of a population-based sample of twins. Teachers in kindergarten and first grade rated children's CU behaviors and other behavior problems (attention deficit and hyperactivity symptoms, physical aggression, and depressive symptoms). In first grade (mean age 7 years), the children completed the visual subtest of the Diagnostic Analysis of Nonverbal Accuracy Scale 2 (DANVA-II) to assess emotion recognition from facial stimuli. Using structural equation modeling, we examined the genetic-environmental etiology of the association between fear/sadness recognition and child CU behaviors, controlling for other behavior problems and recognition of other emotions. We found a significant genetic correlation between poor fear recognition and CU behaviors that was independent of other behavior problems. Poor recognition of sadness was not significantly associated with CU behaviors after taking into account other behavior problems. Our results suggest that CU behaviors and fear recognition have a partly shared genetic aetiology. This provides support for poor fear recognition as a key neurocognitive endophenotype for CU behaviors. Future research should test a hypothesized causal chain from specific genes, through amygdala functioning and fear recognition, to CU behaviors, and identify specific environmental factors (including intervention) that may disrupt this chain.

Although the development of psychopathy is not well understood, prior studies suggest that psychopathic traits begin to develop in childhood. Whereas research suggests consistency in the structure and correlates of psychopathic traits as assessed with clinical measures of psychopathic traits in adolescence and in adulthood, there is less agreement about the nature of psychopathic traits earlier in childhood. This study was designed to enhance understanding of the nature of psychopathic traits in youth by: 1) examining the fit of one, two, three, and four factor models of psychopathic traits during middle childhood, and 2) examining the stability of the factor structure of psychopathic traits over time through invariance testing. The participants were youth in the Quebec Longitudinal Study of Child Development (QLSCD) whose teachers provided ratings on 17 items associated with four validated dimensions of psychopathy at six (N = 605), seven (N = 747) and eight years of age (N = 686). Confirmatory factor analyses revealed that a hierarchical three-factor model of psychopathic traits, consisting of interpersonal, affective, and lifestyle/ antisocial components provided the best fit to the data at all three ages. Analyses also demonstrated strong invariance across these ages. These findings provide preliminary evidence that the internal structure for a syndrome of psychopathic traits in middle childhood is somewhat similar but slightly less differentiated than the factor structure identified during adolescence. Current findings also suggest that this internal structure is stable over a three-year period during middle childhood.

This study examines the link between behavior in kindergarten and adult-life welfare receipt. Teacher-rated behavioral assessments were obtained for inattention, hyperactivity, aggression–opposition, anxiety, and prosociality when children (n=2960) were aged 5–6 years and linked to their tax return records from age 18–35 years. We used group-based based trajectory modeling to identify distinct trajectories of welfare receipt and multinomial logistic regression models to examine the association between behaviors and trajectory group membership. The child's sex, IQ, and family background were adjusted for. Four trajectories of welfare receipt were identified: low (n = 2,390, 80.7%), declining (n = 260, 8.8%), rising (n = 150, 5.2%), and chronic (n = 160, 5.4%). Relative to the low trajectory, inattention and aggression–opposition at age 6 years were associated with increased risk of following a declining, rising, and chronic trajectory of welfare receipt, independent of hyperactivity and anxiety. Prosocial behaviors were independently associated with a lower risk of following a chronic trajectory. This study shows that kindergarten children exhibiting high inattention and aggression–opposition and low prosocial behaviors may be at increased risk of long-term welfare receipt in adulthood. The implications for early screening, monitoring, and prevention are discussed.

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.

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. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

This study examined bidirectional links between teachers’ disciplinary practices (punitive and educational), students’ peer status in class (acceptance and rejection), and students’ aggressive behaviors. A sample comprising 1,038 students (mean age = 5.43 years) was assessed with the same instruments in the fall and spring of one kindergarten year. Teachers reported the disciplinary practices they used with each student in their class. Aggression, peer rejection, and peer acceptance were measured by peer sociometric nomination. Autoregressive cross-lagged modeling was used to test bidirectional associations. The results showed reciprocal links between punitive disciplinary practices, peer rejection, and students’ aggressive behaviors. More specifically, punitive discipline at kindergarten start predicted greater peer rejection and higher levels of aggressive behaviors at year end. Students’ aggressive behaviors and peer rejection at year start predicted greater use of punitive practice at year end. Educational discipline did not contribute to a change in students’ peer status and students’ aggressive behaviors.

Cannabis use is linked to symptoms of depression and anxiety, particularly among sexual minorities. This study examines the relationships between cannabis, and depression and anxiety symptoms at 13, 15, and 17 years using cross-lagged models in a predominantly White (n = 1,430; 92%) subsample of 1,548 participants from the Quebec Longitudinal study of Child Development. Multigroup analyses were conducted to examine the models according to sexual orientation. Demographic covariates were included as control variables, as well as alcohol, cigarette, and other drug use to examine cannabis specificity. The full sample revealed small bidirectional associations, which remained significant once control variables were included in the model: cannabis at 13 and 15 years predicted anxiety symptoms at 15 and 17 years respectively, and depression symptoms at 15 years predicted cannabis at 17 years. The initial association between cannabis at 13 years and depression symptoms at 15 years was accounted for by other drug use at 13 years. Substantial differences were found between heterosexual participants and sexual minorities: LGB participants presented a substantially larger positive association between depression symptoms at 15 years and cannabis at 17 years, as well as a negative association between anxiety symptoms at 15 years and cannabis at 17 years. Both of these relationships remained significant when accounting for control variables. These results suggest that the relationships between cannabis, and depression and anxiety symptoms are bidirectional across adolescence, albeit small. Sexual minorities present particularly large associations that may represent self-medication efforts for depressive symptoms between 15 and 17 years. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

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.

Background Most people will partner at some point during their lives. Yet little is known about the association between childhood behavior and patterns of long-term romantic partnering in adulthood. Methods In this population-based cohort study, behavioral ratings were prospectively obtained from teachers when children (n = 2,960) were aged 10-12 years - for inattention, hyperactivity, aggression-opposition, anxiety, and prosociality - and linked to their tax return records from age 18 to 35 years (1998-2015). We used group-based based trajectory modeling to estimate the probability of partnership (marriage/cohabitation) over time and multinomial logistic regression models to examine the association between childhood behavior and trajectory group membership. The child's sex and family socioeconomic background were adjusted for. Results Five distinct trajectories of partnering were identified: early-partnered (n = 420, 14.4%), mid-partnered (n = 620, 21.3%), late-partnered (n = 570, 19.2%), early-partnered-separated (n = 460, 15.5%), and delayed-or-unpartnered (n = 890, 30.0%). Participants in the early-partnered-separated and delayed-or-unpartnered trajectories were more likely to have left high school without a diploma and to have lower earnings and higher welfare receipt from age 18 to 35 years. After adjustment for sex and family background, inattention and aggression-opposition were uniquely and additively associated with increased likelihood of following an early-partnered-separated trajectory, while inattention and anxiety were associated with an increased likelihood of following a delayed-or-unpartnered trajectory. Childhood prosocial behaviors were consistently associated with earlier and more sustained patterns of partnership. Conclusions Children with behavioral problems are more likely to separate or to be unpartnered across early adulthood. This may have consequences for their psychological health and wellbeing and that of their families.

Linked administrative data sets are an emerging tool for studying the health and well-being of the population. Previous papers have described methods for linking Canadian data, although few have specifically focused on children, nor have they described linkages between tax outcomes and a cohort of children who are particularly at risk for poor outcomes in adulthood. This paper describes a probabilistic linkage performed by Statistics Canada linking the Montreal Longitudinal Experimental Study (MLES) and the Quebec Longitudinal Study of Kindergarten Children (QLSKC) survey cohorts and administrative tax data from 1992 through 2012. The number of valid cases in the original cohort file with valid tax records was approximately 84%. Rates of false positives, false negatives, sensitivity, and specificity of the linkage were all acceptable. Using the linked file, the relationship of childhood behavioural indicators to adult outcomes including earnings, total household income, and use of social assistance can be investigated in future studies. Innovative methods for creating longitudinal datasets on children can enhance existing data by providing information on a variety of outcomes without an increase in response burden, additional costs, or additional data collection. These can increase the longevity of survey data by examining long-term outcomes associated with early childhood characteristics as well as interventions to enhance child outcomes.

Much research effort has been placed on understanding peer victimization. However, few studies have focused on victimization within friendships, which affects up to half of adolescents and bears similar consequences as victimization by the larger peer group. This study examined the temporal stability and the risk factors of victimization within friendships and victimization by other peers. In regard to the first objective, moderate to high levels of stability over a one-year period were expected for victimization by friends and by other peers. In regard to the second objective, two – not necessarily mutual exclusive – hypotheses were tested. The Common Risk Factors Hypothesis postulated that victimization by friends and by other peers share common personal and familial risk factors. Alternatively, the Mutual Influence Hypothesis proposed that victimization within one relationship context may increase the risk of being victimized in the other relationship context. These hypotheses were tested with a sample of 878 adolescents (Mage = 15.08 years, range 14.50–15.75; 52% female) assessed in Grades 8 and 9. Structural equation modeling revealed moderate and weak one-year stability for victimization by friends and by other peers, respectively. No common risk factors emerged, but victimization within one relationship context increased the risk of victimization in the other relationship context one year later. These results are in line with the mutual influence hypothesis and provide evidence of a cross-context transfer of victimization in adolescence.

This cross-sectional study examined the moderating role of support from three key figures (mothers, teachers, friends) in the association between peer victimization and parasomnias in childhood. The sample consisted of 1150 children aged 8 years who attended elementary school. Controlling for potential confounders, hierarchical multiple regressions revealed that peer victimization was associated with a higher level of parasomnias, equally for both girls and boys. However, for girls, the predictive association of peer victimization with parasomnias was moderated by the level of support in relationships with either their parents, their teachers, or their friends. The findings suggest that somatic symptoms such as sleep problems may be a first indicator that a child is being bullied. Because parents, teachers as well as friends can play a key role in preventing the development of parasomnias, it may be useful to help bullied children develop strong bonds within at least one of these relationships.

This study examined the moderating role of classroom injunctive norms salience regarding social withdrawal and regarding aggression in the longitudinal association between these behaviors and peer victimization. A total of 1,769 fourth through sixth graders (895 girls, M = 10.25 years, SD = 1.03) from 23 schools (67 classrooms) completed a peer nomination inventory in the fall (T1) and spring (T2) of the same academic year. Participants circled the name of each student who fit the description provided for social withdrawal, aggression, and peer victimization at T1 and T2. The salience of injunctive norms was sex-specific and operationalized by the extent to which children displaying the behavior were socially rewarded or sanctioned by their classmates. Generalized estimation equations (GEE) showed that the association between social withdrawal at T1 and peer victimization at T2 was moderated by injunctive norms. Social withdrawal at T1 was positively associated with peer victimization at T2 in classrooms where injunctive norms for this behavior were salient and unfavorable, as well as in classrooms where injunctive norms for aggression were salient and favorable, albeit for girls only. The association between aggression at T1 and peer victimization at T2 was also moderated by the injunctive norms regarding this behavior. Aggressive children were less likely to be victimized in classrooms where this behavior was rewarded. These results support bullying interventions that target factors related to the larger peer context, including social norms. (PsycINFO Database Record

Past studies have identified various risk and protective factors for problem gambling (PG). However, no study has examined the interplay between these factors using a combination of person-centered and variable-centered approaches embedded within a longitudinal design. The present study aimed to (a) identify distinct profiles in early adolescence based on a set of risk factors commonly associated with PG (impulsivity, depression, anxiety, drug-alcohol use, aggressiveness, and antisociality), (b) explore the difference in reported gambling problems between these profiles during midadolescence and early adulthood, and (c) identify family- and peer-related variables that could operate as protective or compensatory factors in this context. Two samples were used: (a) a population sample (N = 1,033) living in low socioeconomic-status neighborhoods and (b) a population sample (N = 3,017) representative of students attending Quebec schools. Latent profile analyses were conducted to identify at-risk profiles based on individual risk factors measured at age 12 years. Negative binomial regression models were estimated to compare profiles in terms of their reported gambling problems at ages 16 and 23. Finally, family- and peer-related variables measured at age 14 were included to test their protective or compensatory role with respect to the link between at-risk profiles and gambling problems. Four profiles were identified: well-adjusted, internalizing, externalizing, and comorbid. Compared to the well-adjusted profile, the externalizing and comorbid profiles reported more gambling problems at ages 16 and 23, but the internalizing profile did not differ significantly. Various protective and compensatory factors emerged for each profile at both time points. (PsycINFO Database Record

Cigarette use and binge drinking are risky behaviors emerging during adolescence. Although many beneficial factors are well documented, studies linking shyness to substance use are somehow conflicting, which may be due to the contribution of moderators. Therefore, the present study has 2 objectives: (a) to prospectively analyze the association between shyness and substance use during adolescence, and (b) to test the moderating role of peer group affiliation on the relationship between shyness and substance use. Participants are 1447 adolescents from the Quebec Longitudinal Study of Child Development, a representative cohort of single-birth children born between 1997 and 1998 in the province of Quebec, Canada. Shyness was assessed at age 12 years. Peer group affiliation, as well as past year cigarette use and binge drinking were assessed at age 15 years. Logistic regressions were used to analyze the data. All analyses were carried out using weighted data accounting for the complex multistage sample design. Results show that shyness negatively predicts the use of tobacco and the occurrence of binge drinking while controlling for confounding variables. However, shyness does not interact with peer group affiliation in predicting substance use. This is the first study that confirms the presence of a negative relationship between shyness and substance use during adolescence over a 3-year period. Results suggest that shyness could exert a beneficial effect against substance use notwithstanding the adolescent's social context. (PsycINFO Database Record

Purpose: Psychopathic traits are associated with multiple negative outcomes. The present prospective, longitudinal study identified associations of childhood factors with adult psychopathy scores. ...

This study examined the concurrent and long-term relations between the amount of time children attending daycare spend outdoors and their cognitive and behavioral development during preschool and first grade. We applied a multi-informant design using cognitive testing and ratings from parents and teachers to follow 562 Norwegian preschoolers (298 girls; mean age at first assessment = 52.45 months, SD = 15.96) over a period of four years. Children's attention skills were tested with the digit span test while teachers rated their behavior. Growth curve analyses showed a positive relation between outdoor hours and children's digit span scores, and an inverse relation between outdoor hours and inattention-hyperactivity symptoms, controlling for a host of possible confounds. Results indicate that outdoor time in preschool may support children's development of attention skills and protect against inattention-hyperactivity symptoms.

This study examined whether sports participation moderates the longitudinal link of depressive and aggressive symptoms with increased peer rejection. The sample consisted of 291 adolescents (50.5% girls), assessed at ages 12 and 13 years. Depressive and aggressive symptoms as well as peer rejection were assessed through peer nominations, whereas participation in team and individual sports was assessed via adolescents' self-reports. Regression analyses revealed that boys – but not girls – who displayed high levels of depressive symptoms experienced an increase in peer rejection. However, participation in team sports mitigated the association between depressive symptoms and increased peer rejection in boys, whereas participation in individual sports exacerbated that same association. Although aggressive symptoms were also associated with an increase in peer rejection for boys and girls, sports participation did not moderate this link. These results support the usefulness especially of team sports as part of prevention activities for vulnerable youth.

This study examined whether sports participation moderates the longitudinal link of depressive and aggressive symptoms with increased peer rejection. The sample consisted of 291 adolescents (50.5% girls), assessed at ages 12 and 13 years. Depressive and aggressive symptoms as well as peer rejection were assessed through peer nominations, whereas participation in team and individual sports was assessed via adolescents' self-reports. Regression analyses revealed that boys – but not girls – who displayed high levels of depressive symptoms experienced an increase in peer rejection. However, participation in team sports mitigated the association between depressive symptoms and increased peer rejection in boys, whereas participation in individual sports exacerbated that same association. Although aggressive symptoms were also associated with an increase in peer rejection for boys and girls, sports participation did not moderate this link. These results support the usefulness especially of team sports as part of prevention activities for vulnerable youth.

PURPOSE:Recent years have seen increased coverage of adolescent victimization and suicide. Both adolescent peer victimization and substance use have been associated with suicidal ideation, with evidence suggesting that all three factors are interrelated. There are at least four models which can explain the associations between these factors (i.e., self-medication, secondary mental disorder, bidirectional, and common factor). However, none of them is being empirically supported as the dominant model because few longitudinal studies have explored the association between these factors. METHODS:The present study compared longitudinal paths of all four models simultaneously using a cross-lagged model. This was done using self-reported measures of peer victimization, suicidal ideation, and alcohol use at age 13, 14, and 15 years in a longitudinal sample of 238 adolescents. RESULTS:All three variables were moderately stable across time. Significant cross-lagged associations were found, showing that frequent peer victimization at age 13 years was associated with higher odds of having suicidal ideation at age 14 years (odds ratio, 1.82; p < .05). In turn, presence of suicidal ideation at age 14 years was significantly associated with higher alcohol use frequency at age 15 years (β = .13; p < .05). CONCLUSIONS:Results support previous literature suggesting that peer victimization predates alcohol use and extends it by showing clear directionality between suicidal ideation and alcohol use over 1 year, supporting the self-medication model. Clarifying the empirical basis of these underlying models could allow for earlier prevention strategies, by targeting the risk factor that appears the earliest in the model.

Loos, Ruth J F/0000-0002-8532-5087; Huibregtse, Brooke M./0000-0003-0977-7249; Kandler, Christian/0000-0002-9175-235X; Hjelmborg, Jacob/0000-0001-9630-9149; mangino, massimo/0000-0002-2167-7470; Siribaddana, Sisira/0000-0001-5821-2557; Plomin, Robert/0000-0002-0756-3629; Latvala, Antti/0000-0001-5695-117X; Kaprio, Jaakko/0000-0002-3716-2455; Willemsen, Gonneke/0000-0003-3755-0236; Tan, Qihua/0000-0003-3194-0030; Pahlen, Shandell/0000-0003-0753-4155; Pedersen, Nancy/0000-0001-8057-3543; Haworth, Claire/0000-0002-8608-289X; Nistico, Lorenza/0000-0003-1805-6240; Skytthe, Axel/0000-0002-8629-4913; van Beijsterveldt, Toos/0000-0002-6617-4201; Rebato, Esther/0000-0003-1221-8501; Li, Lintao/0000-0002-0604-9660; Bartels, Meike/0000-0002-9667-7555; Silventoinen, Karri/0000-0003-1759-3079; Cunha Oliveira, Vinicius/0000-0002-8658-3774; Sund, Reijo/0000-0002-6268-8117; Sodemann, Morten/0000-0001-8992-2500; Rasmussen, Finn/0000-0001-7915-7809; Harden, Kathryn/0000-0002-1557-6737; Medda, Emanuela/0000-0003-4837-4549; Kyvik, Kirsten Ohm/0000-0003-2981-0245; Colodro Conde, Lucia/0000-0002-9004-364X WOS: 000517442200060 PubMed: 31364586 The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m(2)) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural-geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status. Academy of FinlandAcademy of Finland [266592, 100499, 205585, 118555, 141054, 265240, 263278, 264146]; Osaka University's International Joint Research Promotion Program; Centre of Research Excellence Grant from the National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [1079102]; National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01 HD068435, R01 MH062375, 1R01ESO15150-01, R21 AG039572]; National Medical Research Council Research Fellowship; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; National Institute on AgingUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Aging (NIA) [1RO1-AG13662-01A2]; Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) [340-2013-5867]; Swedish Heart-Lung FoundationSwedish Heart-Lung Foundation; Swedish Asthma and Allergy Association's Research Foundation; Special Fund for Health Scientific Research in the Public Welfare, China [201502006]; NIDAUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Drug Abuse (NIDA) [DA011015, HD10333]; National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation; Research Council for Health and Disease; Velux Foundation; US National Institute of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [P01 AG08761]; Fund of Scientific Research, FlandersFWO; ENGAGE - European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007 [201413]; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease GeneticsAcademy of Finland [213506, 129680]; Cancer Research UKCancer Research UK [C1418/A7974]; W T Grant Foundation; University of London Central Research fund; Medical Research CouncilMedical Research Council UK (MRC) [G81/343, G120/635]; Economic and Social Research CouncilEconomic & Social Research Council (ESRC) [RES-000-22-2206]; Institute of Social Psychiatry [06/07-11]; Leverhulme Research FellowshipLeverhulme Trust [RF/2/RFG/2008/0145]; Goldsmiths, University of London; UK Medical Research CouncilMedical Research Council UK (MRC) [MR/M021475/1, G0901245]; National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London; NIHUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01AG053217, RC2 HL103416]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [81125007]; Global Research Network Program of the National Research Foundation [NRF 2011-220-E00006]; European Research Council (ERC)European Research Council (ERC) [240994]; Michigan State University; National Institute of Mental Health (NIMH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01, 1R01-MH118848-01]; Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) [R01-HD066040]; MSU Foundation [11-SPG-2518]; Fundacion Seneca, Regional Agency for Science and Technology, Murcia, Spain [08633/PHCS/08, 15302/PHCS/10, 19479/PI/14]; Ministry of Science and Innovation, SpainSpanish Government [PSI2009-11560, PSI2014-56680-R]; MagW/ZonMW [904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192]; European Research CouncilEuropean Research Council (ERC) [ERC-230374]; JSPS KAKENHI JP [23593419, 24792601, 26671010, 24590695, 26293128, 16K15385, 16K15978, 16K15989, 16H03261]; Australian National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [437015, 607358]; Bonnie Babes Foundation [BBF20704]; Financial Markets Foundation for Children [032-2007]; Victorian Government; Portuguese agency for research (The Foundation for Science and Technology [FCT]) [POCI/DES/56834/2004]; Wellcome TrustWellcome Trust; Medical Research CouncilMedical Research Council UK (MRC); European UnionEuropean Union (EU); National Institute for Health Research (NIHR)National Institute for Health Research (NIHR); King's College London; Fonds Quebecois de la Recherche sur la Societe et la CultureFQRNT; Fonds de la Recherche en Sante du QuebecFonds de la Recherche en Sante du Quebec; Social Science and Humanities Research Council of Canada; National Health Research Development Program; Canadian Institutes for Health ResearchCanadian Institutes of Health Research (CIHR); Sainte-Justine Hospital's Research Center; Canada Research Chair ProgramCanada Research Chairs; National Research Foundation of KoreaNational Research Foundation of Korea [NRF-371-2011-1 B00047]; Swedish Research CouncilSwedish Research Council [2017-00641]; UK Biotechnology and Biological Sciences Research CouncilBiotechnology and Biological Sciences Research Council (BBSRC) [31/D19086]; MRCMedical Research Council UK (MRC) [MR/M021475/1]; Krkkale University [2009/43]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; National Institute of Mental HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01 MH58354]; National Institute of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [NIA R01 AG018384, R01 AG018386, R01 AG022381, R01 AG022982]; VA San Diego Center of Excellence for Stress and Mental Health; Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [15H05105]; Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust; Stockholm County Council (ALF-projects)Stockholm County Council; Twins, a nonprofit Association for Scientific Research in Multiple Births (Belgium); [5T32DA017637]; [5T32AG052371] This study was conducted within the CODATwins project (Academy of Finland #266592). K Silventoinen is supported by Osaka University's International Joint Research Promotion Program. This research was facilitated through access to Twins Research Australia, a national resource supported by a Centre of Research Excellence Grant (ID: 1079102), from the National Health and Medical Research Council. The Boston University Twin Project is funded by grants (#R01 HD068435 #R01 MH062375) from the National Institutes of Health to K. Saudino. Paulo Ferreira is funded by a National Medical Research Council Research Fellowship. California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01).; The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. The CATSS-Study is supported by the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF-projects), the Swedish Heart-Lung Foundation and the Swedish Asthma and Allergy Association's Research Foundation.; Chinese National Twin Registry is funded by Special Fund for Health Scientific Research in the Public Welfare (Project No: 201502006), China. Colorado Twin Registry is funded by NIDA-funded center grant DA011015, & Longitudinal Twin Study HD10333; Author Huibregtse is supported by 5T32DA017637 and 5T32AG052371. Danish Twin Registry is supported by the National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation, The Research Council for Health and Disease, the Velux Foundation and the US National Institute of Health (P01 AG08761). Since its origin, the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a nonprofit Association for Scientific Research in Multiple Births (Belgium). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE - European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145 and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278 and 264146 to J Kaprio). Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Waves 1-3 of Genesis 12-19 were funded by the W T Grant Foundation, the University of London Central Research fund and a Medical Research Council Training Fellowship (G81/343) and Career Development Award (G120/635) to Thalia C. Eley. Wave 4 was supported by grants from the Economic and Social Research Council (RES-000-22-2206) and the Institute of Social Psychiatry (06/07-11) to Alice M. Gregory, who was also supported at that time by a Leverhulme Research Fellowship (RF/2/RFG/2008/0145). Wave 5 was supported by funding to Alice M. Gregory from Goldsmiths, University of London. T. C. Eley is partly funded by a program grant from the UK Medical Research Council (MR/M021475/1).; This study presents independent research [partly] funded by the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. The Minnesota Twin Registry (MTR) acknowledges support from NIH grant R01AG053217. Guangzhou Twin Eye Study is supported by National Natural Science Foundation of China (grant #81125007). Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. Korean Twin-Family Register was supported by the Global Research Network Program of the National Research Foundation (NRF 2011-220-E00006). Longitudinal Israeli Study of Twins was funded by the Starting Grant no. 240994 from the European Research Council (ERC) to Ariel Knafo. The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01 and 1R01-MH118848-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) and 11-SPG-2518 from the MSU Foundation. The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the NIMH, the NICHD or the National Institutes of Health. The Murcia Twin Registry is supported by Fundacion Seneca, Regional Agency for Science and Technology, Murcia, Spain (08633/PHCS/08, 15302/PHCS/10 & 19479/PI/14) and Ministry of Science and Innovation, Spain (PSI2009-11560 & PSI2014-56680-R). The NAS-NRC Twin Registry acknowledges financial support from the National Institutes of Health grant number R21 AG039572. Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; VU University's Institute for Health and Care Research (EMGO+); the European Research Council (ERC-230374), the Avera Institute, Sioux Falls, South Dakota (USA). Osaka University Aged Twin Registry is supported by grants from JSPS KAKENHI JP (23593419, 24792601, 26671010, 24590695, 26293128, 16K15385, 16K15978, 16K15989, 16H03261). PETS was supported by grants from the Australian National Health and Medical Research Council (grant numbers 437015 and 607358 to JC, and RS), the Bonnie Babes Foundation (grant number BBF20704 to JMC), the Financial Markets Foundation for Children (grant no. 032-2007 to JMC), and by the Victorian Government's Operational Infrastructure Support Program.; Madeira data comes from the following project: Genetic and environmental influences on physical activity, fitness and health: the Madeira family study Project reference: POCI/DES/56834/2004 Founded by the Portuguese agency for research (The Foundation for Science and Technology [FCT]). TwinsUK receives funding from the Wellcome Trust, Medical Research Council and European Union.; TwinsUK and M. Mangino are supported by the National Institute for Health Research (NIHR)-funded BioResource, Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust in partnership with King's College London. The Quebec Newborn Twin Study acknowledges financial support from the Fonds Quebecois de la Recherche sur la Societe et la Culture, the Fonds de la Recherche en Sante du Quebec, the Social Science and Humanities Research Council of Canada, the National Health Research Development Program, the Canadian Institutes for Health Research, Sainte-Justine Hospital's Research Center, and the Canada Research Chair Program (Michel Boivin). South Korea Twin Registry is supported by National Research Foundation of Korea (NRF-371-2011-1 B00047). We acknowledge The Swedish Twin Registry for access to data. The Swedish Twin Registry is managed by Karolinska Institutet and receives funding through the Swedish Research Council under the grant no. 2017-00641.; The Twins Early Development Study (TEDS) is supported by a program grant (G0901245) from the UK Medical Research Council and the work on obesity in TEDS is supported in part by a grant from the UK Biotechnology and Biological Sciences Research Council (31/D19086). Currently TEDS is supported by MRC grant 'MR/M021475/1'. The Texas Twin Project is currently funded by grant R01HD083613 from the National Institutes of Health. S. Y. oncel and F. Aliev are supported by Krkkale University Research Grant: KKU, 2009/43 and TUBITAK grant 114C117. The University of Southern California Twin Study is funded by a grant from the National Institute of Mental Health (R01 MH58354). Washington State Twin Registry (formerly the University of Washington Twin Registry) was supported in part by grant NIH RC2 HL103416 (D. Buchwald, PI). Vietnam Era Twin Study of Aging was supported by National Institute of Health grants NIA R01 AG018384, R01 AG018386, R01 AG022381 and R01 AG022982, and, in part, with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs has provided financial support for the development and maintenance of the Vietnam Era Twin (VET) Registry. The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the NIA/NIH, or the VA. The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant number 15H05105) from the Japan Society for the Promotion of Science.

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.

The present study documented in two distinct population-based samples the contribution of preschool fluid and crystallized cognitive abilities to later school achievement in primary school and examined the mediating role of crystallized abilities in this sequence of predictive associations. In both samples, participants were assessed on the same fluid and crystallized abilities at 63 months (sample 1) and 73 months (sample 2), and then regarding their school achievement in grade 1 to grade 6. Both preschool fluid and crystallized abilities were found to significantly predict school achievement, but only in the early school years. Through path analyses controlling for sex, maternal education and family income, preschool crystallized abilities mediated the association between early fluid abilities and later school achievement in the early grades of school. Crystallized abilities predicted early school achievement beyond fluid abilities, but not in the later grades. These results support the importance of early interventions aimed at both preschool fluid and crystallized abilities to prevent children from developing future school difficulties.

Resource Control Theory (Hawley, 1999) posits a group of bistrategic popular youth who attain status through coercive strategies while mitigating fallout via prosociality. This study identifies and distinguishes this bistrategic popular group from other popularity types, tracing the adjustment correlates of each. Adolescent participants (288 girls, 280 boys; Mage = 12.50 years) completed peer nominations in the Fall and Spring of the seventh and eighth grades. Longitudinal latent profile analyses classified adolescents into groups based on physical and relational aggression, prosocial behavior, and popularity. Distinct bistrategic, aggressive, and prosocial popularity types emerged. Bistrategic popular adolescents had the highest popularity and above average aggression and prosocial behavior; they were viewed by peers as disruptive and angry but were otherwise well-adjusted.

Importance Specifying the association between childhood behaviors and adult earnings can inform the development of screening tools and preventive interventions to enhance social integration and economic participation. Objective To test the association between behaviors at age 6 years and employment earnings at age 33 to 35 years. Design, Setting, and Participants This study obtained data from the Quebec Longitudinal Study of Kindergarten Children, a population-based sample of boys and girls (n = 3020) born in 1980 or 1981 in Quebec, Canada, and followed up from January 1, 1985, to December 31, 2015. The data included behavioral ratings by kindergarten teachers when the children were aged 5 or 6 years and 2013 to 2015 government tax returns of those same participants at age 33 to 35 years. Data were analyzed from September 2017 to December 2018. Main Outcomes and Measures Mixed-effects linear regression models were used to test the associations between teacher-rated inattention, hyperactivity, aggression, opposition, anxiety, and prosociality at age 6 years and reported annual earnings on income tax returns at age 33 to 35 years. Participant IQ and family adversity were adjusted for in the analysis. Results The study included 2850 participants, with a mean (SD) age of 35.9 (0.29) years, of whom 1470 (51.6%) were male and 2740 (96.2%) were white. The mean (SD) personal earnings at follow-up were US $33 300 ($27 500) for men and $19 400 ($15 200) for women. A 1-unit increase in inattention score at age 6 years (males mean [SD], 2.47 [2.42] vs females mean [SD], 1.67 [2.07]) was associated with a decrease in annual earnings of $1271.49 (95% CI, −1908.67 to −634.30) for male participants and $924.25 (95% CI, −1424.44 to −425.46) for female participants. A combined aggression-opposition score (males mean [SD] 2.22 [2.52] vs females mean [SD], 1.05 [1.73]) was associated with a reduction in earnings of $699.83 (95% CI, −1262.49 to −137.17) for males only, albeit with an effect size roughly half that of inattention. A 1-unit increase in prosociality score (males mean [SD], 6.12 [4.30] vs females mean [SD], 7.90 [4.56]) was associated with an increase in earnings of $476.75 (95% CI, 181.53-771.96) for male participants only. A 1-SD reduction in inattention score at age 6 years would theoretically restore $3077 in annual earnings for male participants and $1915 for female participants. Conclusions and Relevance In this large population-based sample of kindergarten children, behavioral ratings at 5-6 years were associated with employment earnings 3 decades later, independent of a person’s IQ and family background. Inattention and aggression-opposition were associated with lower annual employment earnings, and prosociality with higher earnings but only among male participants; inattention was the only behavioral predictor of income among girls. Early monitoring and support for children demonstrating high inattention and for boys exhibiting high aggression-opposition and low prosocial behaviors could have long-term advantages for those individuals and society.

Purpose The purpose of the study was to investigate how peer alcohol use moderates genetic and environmental influences on three different developmental trajectories of alcohol use during adolescence: low (continuously low levels of use), early-onset fast-escalating (initiated use early, the level of use increased quickly), and normative increasing (started at a low level and increased steadily) using biometric modeling. Methods Data were from a longitudinal study on a sample of population-based adolescent twins (N = 842, 52.7% female, 84% European Caucasian). Adolescents self-reported past-year alcohol use at age 13, 14, 15, and 17 years. Adolescents' nominated friends reported their own past-year alcohol use at age 13, 15, and 17 years. Results Genetic and environmental influences on adolescents' alcohol use trajectories were differentially moderated by friends' alcohol use in different trajectories. Gene-environment interaction was implicated in the low and early-onset trajectories, such that genetic contributions were amplified when friends used more alcohol. Environment-environment interaction was involved in the normative increasing and early-onset trajectories, such that person-specific environmental contributions were amplified when friends' alcohol use increased. Conclusions Adolescent alcohol use remains a major public health issue, with peer alcohol use being a major risk factor. These findings suggest that close supervision to reduce deviant peer affiliation as well as preventions targeting peer group norms of alcohol use might be especially beneficial for adolescents following the normative increasing and early-onset trajectories.