Amélie Petitclerc

The Developmental Trajectories of Peer Victimization in Middle to Late Childhood and the Changing Nature of Their Behavioral Correlates

This study investigated the evolving relations between peer victimization and social/emotional difficulties in middle to late childhood. Peer assessments of peer victimization and social/emotional difficulties (aggressive behavior, social withdrawal, and emotional vulnerability) were collected over 4 years for 1,035 children attending Grades 3–6 and were analyzed via cross-lagged panels and trajectory analyses. All dimensions were highly stable and significantly related initially. Peer victimization became progressively less related to aggression and increasingly associated with withdrawal. Bidirectional contributions over 1-year periods were found between withdrawal and emotional vulnerability and victimization. Trajectory analyses revealed heterogeneity in peer victimization patterns, with a small group of children (4.5%) being extremely victimized and with another group (10%), less severely, but increasingly victimized over time. Compared to nonvictimized children, these children were generally more emotional and became less aggressive but more socially withdrawn over time. These small behavioral changes were not associated with decreases in victimization.

Childhood Disruptive Behaviour Disorders: Review of Their Origin, Development, and Prevention

Objective: To review preventive studies of disruptive behaviour disorders (DBDs) in light of recent empirical knowledge on their development. Method: We draw on the results of longitudinal studies of children starting in infancy to examine the onset, development, and risk factors for DBD symptoms. We review randomized controlled trials of preventive interventions provided to families before the child is aged 3 years, with reported outcome measures of DBD symptoms at follow-up. Results: Children who present high levels of DBD symptoms start to do so in the first 2 years of life and have risk factors that can be identified in the mother during pregnancy or even earlier, and shortly after the childs birth. Most preventive experiments have started relatively late after birth and have targeted parenting, with weak effects on childrens DBDs. Preventive experiments that have provided intensive intervention to at-risk mothers starting during pregnancy have shown important effects in reducing key risk factors and some of the most severe consequences of DBDs. However, even those experiments have not succeeded in preventing childhood DBDs in the home and school contexts. Conclusions: We suggest adopting a sequential, multitarget, intergenerational, experimental approach both to increase our knowledge about causal mechanisms and to increase our effectiveness in curbing DBDs and their serious lifelong consequences.

Short- and Long-term Risk of Infections as a Function of Group Child Care Attendance: An 8-Year Population-Based Study

OBJECTIVE To determine whether the frequency of infections during the first 8 years of life varies according to age at initiation and type of group child care (GCC). DESIGN Eight-year (1998-2006) prospective cohort study. SETTING Families with a newborn living in Quebec in 1998. PARTICIPANTS A representative sample of families (n = 1238) selected through birth registries. MAIN EXPOSURE Home care compared with small or large GCC during the early (ie, before 2½ years old) or late (3½-4½ years old) preschool period. MAIN OUTCOME MEASURES Maternal reports of childrens respiratory tract, ear, and gastrointestinal tract infections during the early preschool, late preschool, and early elementary school (5-8 years old) periods. RESULTS Compared with children cared for at home, those who started large GCC in the early preschool period had higher rates of respiratory tract infections (incidence rate ratio [IRR], 1.61; 95% confidence interval [CI], 1.27-2.03) and ear infections (IRR, 1.62; 95% CI, 1.19-2.20) during that period but lower rates of respiratory tract infections (IRR, 0.79; 95% CI, 0.66-0.96) and ear infections (IRR, 0.57; 95% CI, 0.37-0.88) during the elementary school years. CONCLUSIONS Children contract infections around the time they initiate large structured group activities. Participation in large GCC before 2½ years old, although associated with increased infections at that time, seems to protect against infections during the elementary school years. Physicians may reassure parents that infections during the first child care years do not lead to a higher overall burden of infections.

A longitudinal twin study of physical aggression during early childhood: evidence for a developmentally dynamic genome.

BACKGROUND Physical aggression (PA) tends to have its onset in infancy and to increase rapidly in frequency. Very little is known about the genetic and environmental etiology of PA development during early childhood. We investigated the temporal pattern of genetic and environmental etiology of PA during this crucial developmental period. METHOD Participants were 667 twin pairs, including 254 monozygotic and 413 dizygotic pairs, from the ongoing longitudinal Quebec Newborn Twin Study. Maternal reports of PA were obtained from three waves of data at 20, 32 and 50 months. These reports were analysed using a biometric Cholesky decomposition and linear latent growth curve model. RESULTS The best-fitting Cholesky model revealed developmentally dynamic effects, mostly genetic attenuation and innovation. The contribution of genetic factors at 20 months substantially decreased over time, while new genetic effects appeared later on. The linear latent growth curve model revealed a significant moderate increase in PA from 20 to 50 months. Two separate sets of uncorrelated genetic factors accounted for the variation in initial level and growth rate. Non-shared and shared environments had no effect on the stability, initial status and growth rate in PA. CONCLUSIONS Genetic factors underlie PA frequency and stability during early childhood; they are also responsible for initial status and growth rate in PA. The contribution of shared environment is modest, and perhaps limited, as it appears only at 50 months. Future research should investigate the complex nature of these dynamic genetic factors through genetic-environment correlation (r GE) and interaction (G×E) analyses.

Genetic and environmental contributions to saliva testosterone levels in male and female infant twins

BACKGROUND Testosterone is the key hormone for the development of male reproductive organs and secondary sexual characteristics. In addition, testosterone is associated with behavioural traits, including sexual behaviour and social dominance. The level of circulating testosterone in the human body is determined by genetic and environmental factors. Twin studies have shown moderate to high heritability in adolescence and adulthood, but heritability in early childhood has not been investigated. This study aimed at disentangling the genetic and environmental contributions to testosterone levels soon after birth. METHODS Using a sample of 314 twin pairs, saliva testosterone levels were measured at 5 months after birth. Quantitative genetic modelling was used to assess genetic and environmental contributions to the variation in testosterone levels. RESULTS Variation in testosterone levels was explained by common (56.6%) and unique (43.4%) environmental factors. CONCLUSIONS Taken together, these data from the largest study of twin testosterone levels suggest that, in contrast to findings in adulthood, environmental factors determine the interindividual variability in testosterone levels in early infancy. This may have consequences for the development of sex-related behaviour during childhood and calls for studies designed to unravel specific genetic and environmental factors involved in this process.

Can the fear recognition deficits associated with callous-unemotional traits be identified in early childhood?

ABSTRACT Introduction: Callous-unemotional (CU) traits in the presence of conduct problems are associated with increased risk of severe antisocial behavior. Developmentally sensitive methods of assessing CU traits have recently been generated, but their construct validity in relation to neurocognitive underpinnings of CU has not been demonstrated. The current study sought to investigate whether the fear-specific emotion recognition deficits associated with CU traits in older individuals are developmentally expressed in young children as low concern for others and punishment insensitivity. Method: A subsample of 337 preschoolers (mean age 4.8 years, SD = 0.8) who completed neurocognitive tasks was taken from a larger project of preschool psychopathology. Children completed an emotional recognition task in which they were asked to identify the emotional face from the neutral faces in an array. CU traits were assessed using the Low Concern (LC) and Punishment Insensitivity (PI) subscales of the Multidimensional Assessment Profile of Disruptive Behavior (MAP-DB), which were specifically designed to differentiate the normative misbehavior of early childhood from atypical patterns. Results: High LC, but not PI, scores were associated with a fear-specific deficit in emotion recognition. Girls were more accurate than boys in identifying emotional expressions but no significant interaction between LC or PI and sex was observed. Conclusions: Fear recognition deficits associated with CU traits in older individuals were observed in preschoolers with developmentally defined patterns of low concern for others. Confirming that the link between CU-related impairments in empathy and distinct neurocognitive deficits is present in very young children suggests that developmentally specified measurement can detect the substrates of these severe behavioral patterns beginning much earlier than prior work. Exploring the development of CU traits and disruptive behavior disorders at very early ages may provide insights critical to early intervention and prevention of severe antisocial behavior.

Contextual variation in young children's observed disruptive behavior on the DB‐DOS: implications for early identification

BACKGROUND Contextual variation in child disruptive behavior is well documented but remains poorly understood. We first examine how variation in observed disruptive behavior across interactional contexts is associated with maternal reports of contextual variation in oppositional-defiant behavior and functional impairment. Second, we test whether child inhibitory control explains the magnitude of contextual variation in observed disruptive behavior. METHODS Participants are 497 young children (mean age = 4 years, 11 months) from a subsample of the MAPS, a sociodemographically diverse pediatric sample, enriched for risk of disruptive behavior. Observed anger modulation and behavioral regulation problems were coded on the Disruptive Behavior Diagnostic Observation Schedule (DB-DOS) during interactions with parent and examiner. Oppositional-defiant behavior, and impairment in relationships, with parents and nonparental adults, were measured with the Preschool Age Psychiatric Assessment (PAPA) interview with the mother. Functional impairment in the home and out-and-about was assessed with the Family Life Impairment Scale (FLIS), and expulsion from child care/school was measured with the baseline survey and FLIS. RESULTS Observed disruptive behavior on the DB-DOS Parent Context was associated with oppositional-defiant behavior with parents, and with impairment at home and out-and-about. Observed disruptive behavior with the Examiner was associated with oppositional-defiant behavior with both parents and nonparental adults, impairment in relationships with nonparental adults, and child care/school expulsion. Differences in observed disruptive behavior in the Parent versus Examiner Contexts was related to the differences in maternal reports of oppositional-defiant behavior with parents versus nonparental adults. Children with larger decreases in disruptive behavior from Parent to Examiner Context had better inhibitory control and fewer attention-deficit/hyperactivity disorder symptoms. CONCLUSIONS The DB-DOS showed clinical utility in a community sample for identifying contextual variation that maps onto reported oppositional-defiant behavior and functioning across contexts. Elucidating the implications of contextual variation for early identification and targeted prevention is an important area for future research.

Assessing the independent contribution of maternal educational expectations to children's educational attainment in early adulthood: A propensity score matching analysis

Background Parental educational expectations have been associated with children’s educational attainment in a number of long-term longitudinal studies, but whether this relationship is causal has long been debated. The aims of this prospective study were twofold: 1) test whether low maternal educational expectations contributed to failure to graduate from high school; and 2) compare the results obtained using different strategies for accounting for confounding variables (i.e. multivariate regression and propensity score matching). Methodology/Principal Findings The study sample included 1,279 participants from the Quebec Longitudinal Study of Kindergarten Children. Maternal educational expectations were assessed when the participants were aged 12 years. High school graduation – measuring educational attainment – was determined through the Quebec Ministry of Education when the participants were aged 22–23 years. Findings show that when using the most common statistical approach (i.e. multivariate regressions to adjust for a restricted set of potential confounders) the contribution of low maternal educational expectations to failure to graduate from high school was statistically significant. However, when using propensity score matching, the contribution of maternal expectations was reduced and remained statistically significant only for males. Conclusions/Significance The results of this study are consistent with the possibility that the contribution of parental expectations to educational attainment is overestimated in the available literature. This may be explained by the use of a restricted range of potential confounding variables as well as the dearth of studies using appropriate statistical techniques and study designs in order to minimize confounding. Each of these techniques and designs, including propensity score matching, has its strengths and limitations: A more comprehensive understanding of the causal role of parental expectations will stem from a convergence of findings from studies using different techniques and designs.

A longitudinal twin study of callous-unemotional traits during childhood.

Previous research indicates that genetic factors largely account for the stability of callous-unemotional (CU) traits in adolescence. However, the genetic-environmental etiology of the development of CU traits has not been extensively investigated in childhood, despite work showing the reliable measurement and stability of CU traits from a young age. The aim of this study was to investigate the temporal pattern of genetic and environmental etiology of CU traits across primary school, from school entry (7 years) to middle (9 and 10 years) and late childhood (12 years). Data were collected in a population sample of twins composed of 662 twin pairs (Quebec Newborn Twin Study). CU traits were reported by teachers and analyzed using a biometric latent growth curve model and a Cholesky decomposition model. Latent growth curve analyses revealed that genetic factors explain most of the variance in the intercept of CU traits. Individual differences in change over time were not significant. The Cholesky model revealed that genetic factors at 7 years had enduring contributions to CU traits at 9, 10, and 12 years. New, modest genetic contributions appeared at 9 and 10 years. Nonshared environmental contributions were generally age-specific. No shared environmental contributions were detected. In sum, both modeling approaches showed that genetic factors underlie CU traits during childhood. Initial and new genetic contributions arise during this period. Environments have substantial contributions, over and above genetic factors. Future research should investigate the source of genetic risk associated with CU traits.