Association between developmental patterns of single and concurrent externalizing behaviors and internalizing problems over the preschool years.

The present study investigated whether distinct developmental patterns of externalizing behaviors (EBs: hyperactivity-impulsivity, noncompliance, physical aggression) based on parent reports were repeatedly and differentially associated with separate dimensions of internalizing problems such as general anxiety, separation anxiety, and depressive symptoms across the early, middle, and late preschool 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 EB and co-occurrent EBs. Children following low or moderate trajectories for all EBs served as the reference class. Results revealed that children in trajectory classes reflecting high levels of co-occurring EBs showed higher levels of general anxiety, separation anxiety, and depressive symptoms across the preschool years. In contrast, children in trajectory classes reflecting single EB manifested higher levels of some, but not all, dimensions of internalizing problems. In addition, their scores varied from one period to another. No sex differences were observed in the above associations. These results underline the need for comprehensive assessments across distinct types of EBs and internalizing problems to better reflect the characteristics that distinguish individual children. Finally, results suggest that children showing early co-occurrent EBs and internalizing symptoms may be an important group to target for in-depth assessment and possibly preventive intervention. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Intergenerational transmission of genetic risk for hyperactivity and inattention. Direct genetic transmission or genetic nurture?

Background: Hyperactivity and inattention, the symptoms of ADHD, are marked by high levels of heritability and intergenerational transmission. Two distinct pathways of genetic intergenerational transmission are distinguished: direct genetic transmission when parental genetic variants are passed to the child's genome and genetic nurture when the parental genetic background contributes to the child's outcomes through rearing environment. This study assessed genetic contributions to hyperactivity and inattention in childhood through these transmission pathways. Methods: The sample included 415 families from the Quebec Newborn Twin Study. Twins' hyperactivity and inattention were assessed in early childhood by parents and in primary school by teachers. The polygenic scores for ADHD (ADHD-PGS) and educational attainment (EA-PGS) were computed from twins' and parents' genotypes. A model of intergenerational transmission was developed to estimate (1) the contributions of parents' and children's PGS to the twins' ADHD symptoms and (2) whether these variances were explained by genetic transmission and/or genetic nurture. Results: ADHD-PGS explained up to 1.6% of the variance of hyperactivity and inattention in early childhood and primary school. EA-PGS predicted ADHD symptoms at both ages, explaining up to 1.6% of the variance in early childhood and up to 5.5% in primary school. Genetic transmission was the only significant transmission pathway of both PGS. The genetic nurture channeled through EA-PGS explained up to 3.2% of the variance of inattention in primary school but this association was non-significant. Conclusions: Genetic propensities to ADHD and education predicted ADHD symptoms in childhood, especially in primary school. Its intergenerational transmission was driven primarily by genetic variants passed to the child, rather than by environmentally mediated parental genetic effects. The model developed in this study can be leveraged in future research to investigate genetic transmission and genetic nurture while accounting for parental assortative mating.

Hair steroid before and after COVID-19 in preschoolers: the moderation of family characteristics.

BACKGROUND: Frequent or prolonged exposure to stressors may jeopardize young children's health. The onset of the COVID-19 pandemic, coupled with disruptions in daily routines and social isolation resulting from public health preventive measures, have raised concerns about its potential impact on children' experienced stress, particularly for young children and vulnerable families. However, whether the pandemic was accompanied by changes in physiological stress remains unknown as perceived stress is not a good proxy of physiological stress. This study examined if preschoolers showed increasing hair steroid concentrations following the onset of the COVID-19 pandemic and whether family characteristics may have exacerbated or buffered these changes. METHODS: 136 preschoolers (2-4 years) provided hair for steroid measurement (cortisol, dehydroepiandrosterone (DHEA), cortisone, cortisol-to-DHEA ratio, cortisol-to-cortisone ratio) in October-November 2019 (T0) and in July-August 2020 (T1). A 2-centimeter hair segment was analyzed, reflecting steroid production over the two months leading up to collection. Family income, conflict resolution and lack of cohesion, as well as parents' COVID-19 stress were reported by parents. Linear mixed models for repeated measures and Bayes factors were used. RESULTS: No significant changes were noted from before to after the onset of the COVID-19 pandemic for most hair steroids. However, a moderating role of family conflict resolution was noted. Children living with parents with a better ability to resolve conflicts had lower levels of DHEA compared to those who had more difficulty managing conflicts. Additionally, lower levels of family cohesion and income were linked to some steroids, especially DHEA, suggesting that these factors may relate to children's physiological stress. Finally, boys had higher DHEA levels than girls. CONCLUSION: Our findings suggest that stress biomarkers were comparable from before to during the COVID-19 pandemic. This observation holds true despite the pandemic being perceived by many as a novel, unpredictable, and potentially threatening event. Findings further suggest that family characteristics are associated with hair steroid, especially DHEA, which deserves further investigation.

Childhood behavior problems and adverse economic outcomes: a 30-year population-based study of intergenerational income mobility.

BACKGROUND: The objectives of this study were to (a) assess the associations between early behavioral problems and intergenerational income mobility (i.e., the degree to which income status is transmitted from one generation to the next), (b) verify whether these associations are moderated by child sex, and (c) explore indirect effects of early behavioral problems on income mobility via high school graduation. METHODS: Data were drawn from the Quebec Longitudinal Study of Kindergarten Children (n = 3,020; 49.17% girls). Participants were followed from age 6 to 37 years. Measures included parents' and teachers' ratings of behavioral problems at age 6 years as well as participants' (ages 30-35 years) and their parents' (when participants were aged 10-19 years) income data obtained from tax return records. Regression models were used to predict upward and downward mobility (i.e., increased or decreased income status from one generation to the next) from attention-deficit/hyperactivity problems, conduct/opposition problems, depression/anxiety problems, prosociality, and the quality of children's relationship with their caregiver. Two-way interaction effects between behavioral problems and child sex were examined and indirect effect models including high school graduation as a mediator of these associations were conducted. RESULTS: Despite their higher educational attainment, females had lower incomes and experienced lower upward (but higher downward) income mobility than males. For both females and males, higher levels of attention-deficit/hyperactivity and conduct/opposition problems were associated with decreased odds of upward mobility, whereas higher levels of attention-deficit/hyperactivity were associated with increased odds of downward mobility. Attention-deficit/hyperactivity problems, conduct/opposition problems as well as low prosociality were associated with lower educational attainment (no high school diploma), which in turn was associated with increased odds of downward mobility. CONCLUSIONS: Results highlight the importance of providing intensive support to children with early behavioral problems as a means of improving educational attainment and intergenerational income mobility.

Genetic and phenotypic evidence of the predictive validity of preschool parent reports of hyperactivity/impulsivity and inattention.

To determine the validity of parent reports (PRs) of ADHD in preschoolers, we assessed hyperactivity/impulsivity (HI) and inattention (IN) in 1114 twins with PRs at 1.5, 2.5, 4, 5, 14, 15, and 17 years, and teacher-reports at 6, 7, 9, 10, and 12. We examined if preschool PRs (1) predict high HI/IN trajectories, and (2) capture genetic contributions to HI/IN into adolescence. Group-based trajectory analyses identified three 6-17 years trajectories for both HI and IN, including small groups with high HI (N = 88, 10.4%, 77% boys) and IN (N = 158, 17.3%, 75% boys). Controlling for sex, each unit of HI PRs starting at 1.5 years and at 4 years for IN, increased more than 2-fold the risk of belonging to the high trajectory, with incremental contributions (Odds Ratios = 2.5-4.5) at subsequent ages. Quantitative genetic analyses showed that genetic contributions underlying preschool PRs accounted for up to a quarter and a third of the heritability of later HI and IN, respectively. Genes underlying 1.5-year HI and 4-year IN contributed to 6 of 8 later HI and IN time-points and largely explained the corresponding phenotypic correlations. Results provide phenotypic and genetic evidence that preschool parent reports of HI and IN are valid means to predict developmental risk of ADHD.

Association of childhood externalizing, internalizing, comorbid problems with criminal convictions by early adulthood.

Childhood externalizing problems have been linked with adult criminality. However, little is known about criminal outcomes among children with comorbid externalizing and internalizing problems. We examined the associations between profiles of behavioral problems during childhood (i.e., externalizing, internalizing, and comorbid) and criminality by early adulthood. Participants were N = 3017 children from the population-based Quebec Longitudinal Study of Kindergarten Children followed up from age 6-25. Multitrajectory modeling of teacher-rated externalizing and internalizing problems from age 6-12 years identified four distinct profiles: no/low, externalizing, internalizing, and comorbid problems. Juvenile (age 13-17) and adult (age 18-25) criminal convictions were extracted from official records. Compared to children in the no/low profile, those in the externalizing and comorbid profiles were at higher risk of having a criminal conviction, while no association was found for children in the internalizing profile. Children with comorbid externalizing and internalizing problems were most at risk of having a criminal conviction by adulthood, with a significantly higher risk when compared to children with externalizing or internalizing problems only. Similar results were found when violent and non-violent crimes were investigated separately. Specific interventions targeting early comorbid behavioral problems could reduce long-term criminality.

Mechanisms and pathways linking kindergarten behavior problems with mid-life employment earnings for males from low-income neighborhoods.

Childhood behavior problems are associated with reduced labor market participation and lower earnings in adulthood, but little is known about the pathways and mechanisms that explain these associations. Drawing on a 33-year prospective birth cohort of White males from low-income backgrounds (n = 1040), we conducted a path analysis linking participants' teacher-rated behavior problems at age 6 years-that is, inattention, hyperactivity, aggression-opposition, and low prosociality-to employment earnings at age 35-39 years obtained from tax records. We examined three psychosocial mediators at age 11-12 years (academic, behavioral, social) and two mediators at age 25 years (non-high school graduation, criminal convictions). Our findings support the notion that multiple psychosocial pathways-especially low education attainment-link kindergarten behavior problems to lower employment earnings decades later.

Reconsidering the failure model: Using a genetically controlled design to assess the spread of problems from reactive aggression to internalizing symptoms through peer rejection across the primary school years.

According to the failure model (Patterson & Capaldi, 1990), peer rejection is the intermediary link between problem behaviors and internalizing symptoms. The present study tested the model with 464 monozygotic and same-sex dizygotic twin pairs (234 female, 230 male dyads). Teacher-reported reactive aggression and internalizing symptoms, and peer-reported peer rejection were collected at ages 6, 7, and 10 (from 2001 to 2008). Support for the failure model emerged in conventional non-genetically controlled analyses, but not twin-difference score analyses (which remove shared environmental and genetic contributions). Univariate biometric models attributed minimal variance in failure model variables to shared environmental factors, suggesting that genetic factors play an important unacknowledged role in developmental pathways historically ascribed to nonshared experiences in the failure model.

Childhood behavioral problems are associated with the intergenerational transmission of low education: a 16-year population-based study.

The intergenerational transmission of low educational attainment is well-documented, but little is known about how behavioral problems in childhood explain this association. Drawing upon a population-based cohort study (n = 3020) linked to administrative records, we investigated the extent to which inattentive, internalizing, externalizing, and prosocial behaviors at child ages 6-8 years accounted for associations between parental education and child's risk of failing to graduate from high school. We adjusted for economic, demographic, cognitive, and perinatal factors, as well as parental mental health. Using logistic regressions and the Karlson-Holm-Breen decomposition method, we found that childhood behaviors together explained 19.5% of the association between mother's education and child's high school graduation status at age 22/23, and 13.7% of the association between father's education and this same outcome. Inattentive behaviors were most strongly associated with failure to graduate from high school, while the role of other behaviors was modest or negligible. Inattentive behaviors may represent a mediational pathway between parental education and child education. Early interventions targeting inattentive behaviors could potentially enhance the prospects of intergenerational educational mobility.

Concurrent and prospective associations between family socioeconomic status, social support and salivary diurnal and hair cortisol in adolescence.

BACKGROUND: Exposure to socioeconomic adversity is hypothesized to impact hypothalamic-pituitary-adrenal (HPA) axis activity and cortisol secretion, but existing evidence is inconsistent. Yet, few studies have investigated this association using a developmental approach that considers potential protective contextual factors. This study examined the role of stability and changes in family socioeconomic status (SES) in the prediction of multiple cortisol indicators and tested whether social support moderated these associations. METHODS: Participants were part of a population-based sample of twin pairs recruited at birth. Family SES was assessed in early childhood (ages 0-5) and mid-adolescence (age 14). Social support was assessed at ages 14 and 19. Diurnal cortisol (n = 569) was measured at age 14 at awakening, 30 min later, in the afternoon and evening over four non-consecutive days. Hair cortisol concentration (HCC, n = 704) was measured at age 19. All data were collected before the pandemic and multilevel regression models were conducted to account for the nested data structure. RESULTS: Youth exposed to lower family SES levels in childhood and mid-adolescence had a flatter diurnal slope and higher HCC compared with those who experienced upward socioeconomic mobility in mid-adolescence. Contrastingly, mid-adolescence SES showed no association with the diurnal slope or HCC for youth from higher-SES households in early childhood. Moreover, youth raised in higher-SES families in early childhood had a higher CAR in mid-adolescence if they reported greater social support in mid-adolescence. Social support also moderated the SES-cortisol association in mid-adolescence, with higher-SES youth showing higher awakening cortisol secretion when reporting more social support. CONCLUSIONS: Our findings support the hypothesis that early socioeconomic adversity sensitizes HPA axis activity to later socioeconomic disadvantage, which may bear consequences for socioemotional and behavioral functioning.

Childhood hyperactivity, eating behaviours, and executive functions: Their association with the development of eating-disorder symptoms in adolescence.

BACKGROUND: Cross-sectional studies have shown that hyperactivity and impaired executive functioning are associated with symptoms of eating disorders in adolescence and adulthood. Whether hyperactivity and executive functions in early life can prospectively predict the emergence of eating disorder symptoms in adolescence remains unknown. The present study relies on a longitudinal design to investigate how hyperactivity at age 3, eating behaviours at age 3.5 and cognition at ages 3-6 were associated with the development of eating-disorder symptoms from 12 to 20 years old. METHODS: Using archival data collected since 1997 from the Quebec Longitudinal Study of Child Development cohort (N = 2, 223), we used Latent Curve Models to analyse predictors of youth's trajectories of eating-disorder symptoms at four timepoints. RESULTS: A quadratic (curvilinear) trajectory of eating-disorder symptoms was found to be most representative of the data. Higher hyperactivity at age 3 was associated with higher levels of eating-disorder symptoms at age 12, and this association was partially mediated by higher levels of overeating and cognitive inflexibility in childhood. Cognitive inflexibility in childhood also mediated the association between hyperactivity at age 3 and increases in eating-disorder symptoms during adolescence. Furthermore, working memory was indirectly related to eating-disorder symptoms via the mediational role of cognitive flexibility. CONCLUSIONS: Hyperactivity, overeating, cognitive inflexibility, and working memory early in life might precede the onset of eating-disorder symptoms in adolescence. Early behavioural and cognitive screening may help to identify children who are most at risk for eating disorders. This, in turn, could guide preventive interventions.

Eating-disorder symptoms, such as body image issues, maladaptive behaviors, and preoccupation with weight, tend to develop in adolescence. However, it is unclear whether early childhood characteristics or behaviours could be indicators of a risk of developing eating-disorder symptoms later. The current study examined the possible link between certain early behaviours (e.g., hyperactivity, childhood eating), early cognitive processes, and eating-disorder symptoms development in a community cohort followed from birth. Results showed that being hyperactive in early childhood predicts higher levels of eating-disorder symptoms at the beginning of adolescence (age 15), and that this is partially explained by a link between being hyperactive, being more rigid in our ways of thinking, and engaging in overeating behaviours. Additionally, more early rigid ways of thinking predicted the increase in symptoms over time. Our results demonstrate possible behaviours and characteristics that could be used to identify children at risk of eating disorders, which in future research could potentially help improve our preventive interventions.

Childhood Overeating and Disordered Eating From Early Adolescence to Young Adulthood: A Longitudinal Study on the Mediating Role of BMI, Victimization and Desire for Thinness.

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.

Adolescent anxiety and pain problems: A joint, genome-wide investigation and pathway-based analysis.

Both common pain and anxiety problems are widespread, debilitating and often begin in childhood-adolescence. Twin studies indicate that this co-occurrence is likely due to shared elements of risk, rather than reciprocal causation. A joint genome-wide investigation and pathway/network-based analysis of adolescent anxiety and pain problems can identify genetic pathways that subserve shared etiopathogenetic mechanisms. Pathway-based analyses were performed in the independent samples of: The Quebec Newborn Twin Study (QNTS; 246 twin pairs and 321 parents), the Longitudinal Study of Child Development in Quebec (QLSCD; n = 754), and in the combined QNTS and QLSCD sample. Multiple suggestive associations (p<1×10-5), and several enriched pathways were found after FDR correction for both phenotypes in the QNTS; many nominally-significant enriched pathways overlapped between pain problems and anxiety symptoms (uncorrected p<0.05) and yielded results consistent with previous studies of pain or anxiety. The QLSCD and the combined QNTS and QLSCD sample yielded similar findings. We replicated an association between the pathway involved in the regulation of myotube differentiation (GO:0010830) and both pain and anxiety problems in the QLSDC and the combined QNTS and QLSCD sample. Although limited by sample size and thus power, these data provide an initial support to conjoint molecular investigations of adolescent pain and anxiety problems. Understanding the etiology underlying pain and anxiety co-occurrence in this age range is relevant to address the nature of comorbidity and its developmental pathways, and shape intervention. The replication across samples implies that these effects are reliable and possess external validity.

Longitudinal patterns of polysubstance use throughout adolescence: association with adult substance use and psychosocial outcomes controlling for preadolescent risk factors in a male cohort.

PURPOSE: Inconsistent reports raise the question of the extent to which poor adult outcomes are associated with adolescent polysubstance use (PSU: alcohol, marijuana, other illicit drugs) above and beyond earlier risk factors. METHODS: Early adulthood substance-related and psychosocial outcomes were examined in association with age 13 to 17 developmental patterns of PSU in boys from urban, low SES neighborhoods (N = 926). Three classes obtained by latent growth modeling described low/non-users (N = 565, 61.0%), lower risk PSU (later onset, occasional use, 2 ≤ substances; N = 223, 24.1%), and higher risk PSU (earlier onset, frequent use, 3 ≥ substances; N = 138, 14.9%). Preadolescent individual, familial and social predictors of adolescent PSU patterns were used as covariates. RESULTS: Adolescent PSU contributed to both age-24 substance-related outcomes (frequency of alcohol, drug use, and getting drunk, risky behaviors under influence, and use-related problems) and psychosocial outcomes (no high school diploma, professional or financial strain, ASP symptoms, criminal record) over and above preadolescent risk factors. Controlling for preadolescent risk factors, adolescent PSU made a more important contribution to adult substance use outcomes (increasing the risk by about 110%) than to psychosocial outcomes (16.8% risk increase). PSU classes showed poorer adjustment for all age-24 substance use, and for various psychosocial outcomes than low/non-users. Higher risk polysubstance users also reported poorer outcomes than their lower risk peers for most substance use outcomes, and for professional or financial strain and criminal record. CONCLUSION: Findings highlight the contribution of adolescent PSU in a dose-response fashion, over and above preadolescent risk factors, on both homotypic and heterotypic outcomes in early adulthood.

The social and economic impact of the Montreal Longitudinal and Experimental Study.

BACKGROUND: The effectiveness of early prevention programmes and their viability as a public policy option have increasingly caught the attention of scholars and policymakers. Given the implementation costs of such programmes, it is important to assess whether they achieved anticipated objectives and whether they made efficient use of taxpayer money. AIM: To discuss the social and economic impact of a 2-year randomised intervention aimed to improve social skills and self-control (i.e., non-cognitive skills) among disruptive boys from low-income neighbourhoods in Montreal. METHOD: We review findings from published studies documenting the impact of the intervention at different stages of the life course, as well as its cost-effectiveness and cost-benefit. RESULTS: The intervention improved behavioural indicators throughout adolescence and eventually led to greater high school graduation rates, reduced crime, and better labour market outcomes in adulthood. Importantly, the prevention programme generated considerable returns to taxpayer investments. CONCLUSION: Findings from the Montreal Longitudinal Experimental Study have been well-received and have contributed to an early prevention 'awakening' in Quebec and elsewhere.

Childhood Abuse, Intimate Partner Violence in Young Adulthood, and Welfare Receipt by Midlife.

OBJECTIVE: To investigate prospective associations between type of child abuse (physical, sexual, both), timing (childhood, young adulthood, both), and welfare receipt into middle-age. METHODS: Database linkage study using the Quebec Longitudinal Study of Kindergarten Children cohort born in 1980 and government administrative databases (N = 3020). We assessed parental tax returns, family and personal background characteristics (1982-1987). At age 22 years, participants answered retrospective questionnaires on experienced childhood abuse (physical, sexual abuse < age 18 years) and intimate partner violence (IPV) (ages 18-22). Main outcome was years on social assistance, on the basis of participant tax returns (ages 23-37 years). Analysis included weights for population representativeness. RESULTS: Of 1690 participants (54.4% females) with available data, 22.4% reported childhood abuse only, 14.5% IPV only, and 18.5% both. Prevalence of childhood physical, sexual, and both was 20.4%, 12.2%, and 8.3%, respectively. Adjusting for socioeconomic background and individual characteristics, we found that childhood physical abuse alone and physical or sexual abuse combined were associated with a two-fold risk of welfare receipt, as compared to never-abused (adjusted incidence risk ratio 2.43, 95% confidence interval [CI], 1.65-3.58; and adjusted incidence risk ratio 2.04, 95% CI, 1.29-3.23, respectively). Repeated abuse (childhood abuse combined with adult IPV) had a three-fold risk (adjusted incidence ratio 3.59, 95% CI, 2.39-5.37). CONCLUSIONS: Abuse across several developmental periods (childhood and young adulthood) is associated with increased risks of long-term welfare receipt, independently of socioeconomic background. Results indicate a dose-response association. Early prevention and targeted identification are crucial to preventing economic adversity that may potentially lead to intergenerational poverty.

Child Sexual Abuse and Employment Earnings in Adulthood: A Prospective Canadian Cohort Study.

INTRODUCTION: Child sexual abuse remains a worldwide concern with devastating consequences on an individual's life. This longitudinal study investigates the associations between child sexual abuse (official reports versus retrospective self-reports) and subgroups by perpetrator identity (intrafamilial and extrafamilial), severity (penetration/attempted penetration, fondling/touching, noncontact), and chronicity (single, multiple episodes) and employment earnings in adulthood in a cohort followed for over 30 years. METHODS: The Quebec Longitudinal Study of Kindergarten Children database was linked to child protection services (official reports of sexual abuse) and to Canadian government tax returns (earned income). The sample included 3,020 individuals in Quebec French-language school kindergartens in 1986/1988, followed until 2017, and assessed with retrospective self-reports at age 22 years. Tobit regressions were used for associations with earnings (ages 33-37 years), adjusting for sex and family socioeconomic characteristics in 2021-2022. RESULTS: Individuals who experienced child sexual abuse had lower annual earnings. Those with retrospective self-reported sexual abuse (n=340) earned $4,031 (95% CI= -7,134, -931) less annually at ages 33-37 years than nonabused individuals (n=1,320), with pronounced differences for those with official reports (n=20), earning $16,042 (95% CI= -27,465, -4,618) less. Individuals self-reporting intrafamilial sexual abuse earned $4,696 (95% CI= -9,316, -75) less than those who experienced extrafamilial sexual abuse, whereas those self-reporting penetration/attempted penetration earned $6,188 (95% CI= -12,248, -129) less than those who experienced noncontact sexual abuse. CONCLUSIONS: Earnings gaps were highest for severest child sexual abuse (official reports, intrafamilial, penetrative). Future studies should investigate the underlying mechanisms. Improving support for victims of child sexual abuse could yield socioeconomic returns.

Association of Childhood Externalizing, Internalizing, and Comorbid Symptoms With Long-term Economic and Social Outcomes.

Importance: Little is known about the long-term economic and social outcomes for children with longitudinally assessed comorbid externalizing and internalizing symptoms, especially compared with children with externalizing symptoms or internalizing symptoms only. Objective: To examine the association between childhood trajectories of externalizing, internalizing, and comorbid symptoms and long-term economic and social outcomes. Design, Setting, and Participants: A 32-year prospective cohort study linked with administrative data was conducted in school-aged participants aged 6 to 12 years in the Québec Longitudinal Study of Kindergarten Children (N = 3017) followed up from 1985 to 2017. Data analysis was conducted between August 1, 2021, and March 31, 2022. Exposures: Teacher-rated behavioral symptoms were used to categorize children from age 6 to 12 years into developmental profiles using group-based trajectory modeling. Main Outcomes and Measures: Multivariable regression models were used to test the association between childhood symptom profile group and adult employment earnings, welfare receipt, intimate partnership status, and having children living in the household. Participant sex, IQ, and socioeconomic background were adjusted for. Results: Of 3017 participants in this sample, 1594 (52.8%) were male and 1423 (47.2%) were female. Per confidentiality rules established by Statistics Canada, income variables were rounded to base 100 and count variables were rounded to base 10; the mean (SD) age was 37 (0.29) years at follow-up. Four symptom profiles were identified: no/low (n = 1369 [45.4%]), high externalizing (882 [29.2%]), high internalizing (354 [11.7%]), and comorbid (412 [13.7%]) symptoms. Compared with the no/low symptom profile, participants in the high externalizing-only profile earned $5904 (95% CI, -$7988 to -$3821) less per year and had 2.0 (95% CI, 1.58-2.53) times higher incidence of welfare receipt, while participants in the high internalizing group earned $8473 (95% CI, -$11 228 to -$5717) less per year, had a 2.07 (95% CI, 1.51-2.83) higher incidence of welfare receipt, and had a lower incidence of intimate partnership (incident rate ratio [IRR], 0.89; 95% CI, 0.80-0.99). Participants in the comorbid profile fared especially poorly: they earned $15 031 (95% CI, -$18 030 to -$12 031) less per year, had a 3.79 (95% CI, 2.75-5.23) times higher incidence of annual welfare receipt, and were less likely to have an intimate partner (IRR, 0.71; 95% CI, 0.63-0.79) and children living in the household (IRR, 0.86; 95% CI, 0.80-0.92). Estimated lost earnings over a 40-year working career were $140 515 for the high externalizing, $201 657 for the high internalizing, and $357 737 for the comorbid profiles. Conclusions and Relevance: In this cohort study, children exhibiting sustained childhood high externalizing, high internalizing, or comorbid symptoms were at increased risk of poor economic and social outcomes into middle age. These findings suggest that children exhibiting comorbid problems were especially vulnerable and that early detection and support are indicated.

Mental health comorbidities following peer victimization across childhood and adolescence: a 20-year longitudinal study.

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.

The phenotypic associations and gene-environment underpinnings of socioeconomic status and diurnal cortisol secretion in adolescence.

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.