The codevelopment of internalizing symptoms, externalizing symptoms, and cognitive ability across childhood and adolescence

Cognitive ability, externalizing symptoms, and internalizing symptoms are correlated in children. However, it is not known why they combine in the general child population over time. To address this, we used data on 17,318 children participating in the UK Millennium Cohort Study and followed-up five times between ages 3 and 14 years. We fitted three parallel-process latent growth curve models to identify the parallel unfolding of children's trajectories of internalizing symptoms, externalizing symptoms, and cognitive ability across this period. We also examined the effects of time-invariant (ethnicity, birth weight, maternal education and age at birth, and breastfeeding status) and time-varying covariates (maternal psychological distress and socioeconomic disadvantage) on the growth parameters of the trajectories. The results showed that the intercepts of the trajectories of cognitive ability and, particularly, externalizing symptoms were inversely correlated. Their linear slopes were also inversely correlated, suggesting parallel development. Internalizing symptoms were correlated positively with externalizing symptoms and inversely (and more modestly) with cognitive ability at baseline, but the slope of internalizing symptoms correlated (positively) only with the slope of externalizing symptoms. The covariates predicted 9% to 41% of the variance in the intercepts and slopes of all domains, suggesting they are important common risk factors. Overall, it appears that externalizing symptoms develop in parallel with both cognitive ability and internalizing symptoms from early childhood through to middle adolescence. Children on an increasing trajectory of externalizing symptoms are likely both increasing in internalizing symptoms and decreasing in cognitive skills as well, and are thus an important group to target for intervention

Nonperiodic delay mechanism in time-dependent chaotic scattering

We study the occurence of delay mechanisms other than periodic orbits in systems with time dependent potentials that exhibit chaotic scattering. By using as model system two harmonically oscillating disks on a plane, we have found the existence of a mechanism not related to the periodic orbits of the system, that delays trajectories in the scattering region. This mechanism creates a fractal-like structure in the scattering functions and can possibly occur in several time-dependent scattering systems.Comment: 12 pages, 9 figure

Distinct developmental trajectories of internalising and externalising symptoms in childhood: Links with mental health and risky behaviours in early adolescence

Background: High or increasing trajectories of internalising and externalising symptoms in childhood are mutually re-enforcing and associated with poor emotional and behavioural outcomes in adolescence. This study sought to identify classes of children with similar trajectories of internalising and externalising symptoms after adjusting one domain's symptoms for the other's at the classification stage, and to relate them to emotional and behavioural outcomes in mid-adolescence. Methods: We used growth mixture modelling to classify 16,844 members of the Millennium Cohort Study (baseline N=19,244) into distinct classes based on their trajectories, across ages 3,5,7 and 11 years, of internalising and externalising symptoms adjusted for one another. We examined the predictive ability of these classes for depression, self-harm, trouble with police and drug use among 11,134 children with available data at age 14. Results: We identified four classes of children following distinct trajectories of ‘pure’ internalising and externalising symptoms. After adjustments for confounding, those with increasing or initially high yet decreasing levels of internalising symptomatology, and those with persistently high or increasing levels of externalising problems were at increased risk of depression in early adolescence. Having initially low yet increasing levels of internalising symptomatology was additionally associated with an increased risk of self-harm and drug use in early adolescence. Limitations: We cannot ascertain whether our longitudinal typology of internalising and externalising symptoms holds for outcomes later in adolescence or adulthood. Conclusions: Interventions aiming to prevent depression, drug use or self-harm in mid-adolescence may be more successful if they target children showing increasing internalising symptoms in the primary school years

Flocking together and thinking apart: Gendered friendships and decision-making in adolescence

This study explored if adolescents’ style of decision-making is related to the sex composition of their friendship groups. Using data on 13,413 members of the Millennium Cohort Study at ages 11 and 14 years, we explored reciprocal associations between decision-making, measured with the Cambridge Gambling Task, and own-sex and other- or mixed-sex companionship. Cross-lagged models showed that girls whose friends at 11 were mainly girls showed better quality of decision-making, more risk adjustment, shorter deliberation time and less delay aversion at age 14, compared to girls in mixed-sex or other-sex friendship groups at 11. For boys, having predominantly male friends was associated only with more risk adjustment. Conversely, decision-making style at age 11 did little to predict keeping own-sex company at age 14. It appears that same-sex friendships may help develop better decision-making in adolescence, but only for girls

Quantum versus Classical Dynamics in a driven barrier: the role of kinematic effects

We study the dynamics of the classical and quantum mechanical scattering of a wave packet from an oscillating barrier. Our main focus is on the dependence of the transmission coefficient on the initial energy of the wave packet for a wide range of oscillation frequencies. The behavior of the quantum transmission coefficient is affected by tunneling phenomena, resonances and kinematic effects emanating from the time dependence of the potential. We show that when kinematic effects dominate (mainly in intermediate frequencies), classical mechanics provides very good approximation of quantum results. Moreover, in the frequency region of optimal agreement between classical and quantum transmission coefficient, the transmission threshold, i.e. the energy above which the transmission coefficient becomes larger than a specific small threshold value, is found to exhibit a minimum. We also consider the form of the transmitted wave packet and we find that for low values of the frequency the incoming classical and quantum wave packet can be split into a train of well separated coherent pulses, a phenomenon which can admit purely classical kinematic interpretation

Childhood Trajectories of Hyperactivity/Inattention Symptoms and Diurnal Cortisol in Middle Adolescence: Results from a UK Birth Cohort

Objective: Children with attention-deficit/hyperactivity disorder (ADHD) show hypoactivity of the hypothalamic-pituitary-adrenal (HPA) axis. Whether the association between hyperactivity/inattention symptoms with HPA axis dysfunction holds in the general child population too is not clear. // Method: We assessed associations between longitudinal trajectories of hyperactivity/inattention symptoms during ages 4 to 13 years and basal cortisol profiles at age 15 in a British general population cohort. // Results: Adolescents with persistently high levels of hyperactivity/inattention symptoms since childhood showed lower total morning cortisol and a smaller diurnal decline, even after adjusting for confounders. No associations were found between any of the symptom trajectories and cortisol awakening response, diurnal slope or daily output of cortisol. // Conclusion: This study provides evidence for hypocortisolism among adolescents with chronic hyperactivity/inattention symptoms in the general population

Prenatal and childhood adversity and inflammation in children: A population-based longitudinal study

BACKGROUND: Stressful life events experienced during childhood and early prenatal development have been associated with inflammation during childhood. However, no study has considered these two exposures jointly, or has investigated the effect of their interaction. METHODS: In the Avon Longitudinal Study of Parents and Children, a general-population birth cohort, we explored if inflammatory markers [serum C-reactive protein (CRP) and interleukin 6 (IL-6)] at age 9 years were related to early prenatal events (at 18 weeks pregnancy), childhood events (measured on seven occasions at ages 0-9 years) and their interaction (n=3,915). Latent growth curve modelling estimated trajectories of childhood events, and linear regression explored associations of prenatal and childhood events with inflammatory markers. Models controlled for ethnicity, socioeconomic status and body mass index, were stratified by gender and considered both unweighted and weighted (by impact) event exposures. RESULTS: Even after adjustment for confounders and prenatal events, both the intercept and the slope of number of childhood events were associated with IL-6, but only in females. The significant effect of the slope held for both weighted (by impact) and unweighted event specifications. Prenatal events were not associated with either inflammatory marker when childhood events were controlled. There was no evidence for synergistic effects of prenatal and childhood events. CONCLUSION: Independently of prenatal adverse life events, the number and increase in number of adverse life events experienced in childhood were associated positively with plasma levels of inflammatory markers, such as IL-6, in girls. This gender specificity warrants further research

Ability-grouping and problem behavior trajectories in childhood and adolescence: Results from a U.K. population-based sample

Ability-grouping has been studied extensively in relation to children's academic, but not emotional and behavioral outcomes. The sample comprised 7259 U.K. children (50% male) with data on between-class and within-class ability-grouping at age 7. Peer, emotional, hyperactivity, and conduct problems were measured at ages 7, 11, and 14 years. Children in low within-class ability groups showed more hyperactivity and emotional problems across the study period compared to non-grouped children, after adjustments for the different types of ability grouping and confounding. Additionally, children in the middle within-class ability groups showed more, and those in the top within-class groups less, hyperactivity compared to non-grouped children, after adjustment. Children in lower within-class groups should be monitored closely to ensure that their well-being is not compromised

The Role of Primary School Composition in the Trajectories of Internalising and Externalising Problems across Childhood and Adolescence

There is little research on the role of school and its composition in explaining individual children's psychological outcomes. This study examined for the first time the role of several primary-school compositional characteristics, and their interactions with individual level characteristics, in the development of two such outcomes, internalising and externalising problems, at ages 7, 11 and 14 years in 4794 children in England participating in the Millennium Cohort Study. Using hierarchical (multilevel) linear models, we found that, even after adjusting for individual and family characteristics, children in schools with higher proportions of pupils eligible for free school meals had more externalising problems. In general, children with special educational needs, lower academic performance, more distressed mothers, and those in non-intact families had more internalising and externalising problems. Our results underline the importance of targeting schools with less affluent overall intakes, but also highlight the key role of individual and family characteristics in the development of their pupils' psychological functioning

Early adolescent outcomes of joint developmental trajectories of problem behavior and IQ in childhood

General cognitive ability (IQ) and problem behavior (externalizing and internalizing problems) are variable and inter-related in children. However, it is unknown how they co-develop in the general child population and how their patterns of co-development may be related to later outcomes. We carried out this study to explore this. Using data from 16,844 Millennium Cohort Study children, we fitted three-parallel-process growth mixture models to identify joint developmental trajectories of internalizing, externalizing and IQ scores at ages 3-11 years. We then examined their associations with age 11 outcomes. We identified a typically developing group (83%) and three atypical groups, all with worse behavior and ability: children with improving behavior and low (but improving in males) ability (6%); children with persistently high levels of problems and low ability (5%); and children with worsening behavior and low ability (6%). Compared to typically developing children, the latter two groups were more likely to show poor decision-making, be bullies or bully victims, engage in antisocial behaviors, skip and dislike school, be unhappy and have low self-esteem. By contrast, children (especially males) in the improver group had outcomes that were similar to, or even better than, those of their typically developing peers. These findings encourage the development of interventions to target children with both cognitive and behavioral difficulties