Development of symptoms of oppositional defiant disorder from preschool to adolescence: the role of bullying victimization and emotion regulation.

BACKGROUND: Childhood oppositional defiant disorder (ODD) is associated with adverse outcomes which can continue to impair life well into adulthood. Identifying modifiable etiological factors of ODD is therefore essential. Although bullying victimization and poor emotion regulation are assumed to be risk factors for the development of ODD symptoms, little research has been conducted to test this possibility. METHODS: A sample (n = 1,042) from two birth cohorts of children in the city of Trondheim, Norway, was assessed biennially from age 4 to 14 years. Parents and children (from age 8) were assessed with clinical interviews to determine symptoms of ODD, children reported on their victimization from bullying, and teachers reported on children's emotion regulation. RESULTS: Oppositional defiant disorder symptoms increased from age 4 to 6, from age 8 to 10, and then started to wane as children entered adolescence. A Random Intercept Cross-Lagged Panel Model revealed that increased emotion regulation predicted a reduced number of ODD symptoms across development (ß = -.15 to -.13, p < .001). This prediction was equally strong for the angry/irritable and argumentative/defiant dimensions of ODD. No longitudinal links were observed between bullying victimization and ODD symptoms. CONCLUSIONS: Improving emotion regulation skills may protect against ODD symptoms throughout childhood and adolescence.

From vision to cognition: potential contributions of cerebral visual impairment to neurodevelopmental disorders.

Vision has a crucial role to play in human development and functioning. It is, therefore, not surprising that vision plays a fundamental role in the development of the child. As a consequence, an alteration in visual function is, therefore, likely to hinder the child's development. Although ocular disorders are well known, diagnosed and taken into account, cerebral visual impairments (CVI) resulting from post-chiasmatic damage are largely underdiagnosed. However, among the disorders resulting from an episode of perinatal asphyxia and/or associated with prematurity, or neonatal hypoglycaemia, CVIs are prominent. In this article, we focus on the role of the possible effects of CVI on a child's learning abilities, leading to major difficulty in disentangling the consequences of CVI from other neurodevelopmental disorders (NDD) such as dyslexia, dyscalculia, dysgraphia, attention-deficit/hyperactivity disorder (ADHD), developmental coordination disorder (DCD) and autism spectrum disorders (ASD). Although we focus here on the possible overlap between children with CVI and children with other NDD, De Witt et al. (Wit et al. Ear Hear 39:1-19, 2018) have raised exactly the same question regarding children with auditory processing disorders (the equivalent of CVI in the auditory modality). We underline how motor, social and cognitive development as well as academic success can be impaired by CVI and raise the question of the need for systematic evaluation for disorders of vision, visual perception and cognition in all children presenting with a NDD and/or previously born under adverse neurological conditions.

Novel Oppositional Defiant Disorder 12 Months After Traumatic Brain Injury in Children and Adolescents.

OBJECTIVE: The investigators examined the factors predictive of novel oppositional defiant disorder in the 6-12 months following traumatic brain injury (TBI). METHODS: Children ages 5-14 years old who experienced a TBI were recruited from consecutive admissions to five hospitals. Participants were evaluated soon after injury (baseline) for preinjury characteristics, including psychiatric disorders, adaptive function, family function, psychosocial adversity, family psychiatric history, socioeconomic status, and injury severity, to develop a biopsychosocial predictive model for development of novel oppositional defiant disorder. MRI analyses were conducted to examine potential brain lesions. Psychiatric outcome, including that of novel oppositional defiant disorder, was assessed 12 months after injury. RESULTS: Although 177 children were recruited for the study, 120 children without preinjury oppositional defiant disorder, conduct disorder, or disruptive behavior disorder not otherwise specified (DBD NOS) returned for the 12-month assessment. Of these 120 children, seven (5.8%) exhibited novel oppositional defiant disorder, and none developed conduct disorder or DBD NOS in the 6-12 months postinjury. Novel oppositional defiant disorder was significantly associated with lower socioeconomic status, higher psychosocial adversity, and lower preinjury adaptive functioning. CONCLUSIONS: These results demonstrate that novel oppositional defiant disorder following TBI selectively and negatively affects an identifiable group of children. Both proximal (preinjury adaptive function) and distal (socioeconomic status and psychosocial adversity) psychosocial variables significantly increase risk for this outcome.

Maternal postpartum depressive symptoms partially mediate the association between preterm birth and mental and behavioral disorders in children.

Preterm birth has been linked with postpartum depressive (PPD) disorders and high symptom levels, but evidence remains conflicting and limited in quality. It remains unclear whether PPD symptoms of mothers with preterm babies were already elevated before childbirth, and whether PPD symptoms mediate/aggravate the effect of preterm birth on child mental disorders. We examined whether preterm birth associated with maternal PPD symptoms, depressive symptoms trajectories from antenatal to postpartum stage, and whether PPD symptoms mediated/aggravated associations between preterm birth and child mental disorders. Mothers of preterm (n = 125) and term-born (n = 3033) children of the Prediction and Prevention of Preeclampsia and Intrauterine Growth Restriction study reported depressive symptoms four times within 8 weeks before and twice within 12 months after childbirth. Child mental and behavioral disorder diagnoses until age 8.4-12.8 years came from medical register. Preterm birth associated with higher PPD symptoms (mean difference = 0.19 SD, 95% CI 0.01, 0.37, p = 0.04), and higher odds (odds ratio = 2.23, 95% CI 1.22, 4.09, p = 0.009) of the mother to belong to a group that had consistently high depressive symptoms levels trajectory from antenatal to postpartum stage. PPD symptoms partially mediated and aggravated the association between preterm birth and child mental disorders. Preterm birth, maternal PPD symptoms and child mental disorders are associated, calling for timely prevention interventions.

Novel Oppositional Defiant Disorder 6 Months After Traumatic Brain Injury in Children and Adolescents.

OBJECTIVE: The investigators aimed to assess predictive factors of novel oppositional defiant disorder (ODD) among children and adolescents in the first 6 months following traumatic brain injury (TBI). METHODS: Children ages 5-14 years who experienced a TBI were recruited from consecutive admissions to five hospitals. Testing of a biopsychosocial model that may elucidate the development of novel ODD included assessment soon after injury (baseline) of preinjury characteristics, including psychiatric disorders, adaptive function, family function, psychosocial adversity, family psychiatric history, socioeconomic status, injury severity, and postinjury processing speed (which may be a proxy for brain injury). MRI analyses were also conducted to examine potential brain lesions. Psychiatric outcome, including that of novel ODD, was assessed 6 months after the injury. RESULTS: A total of 177 children and adolescents were recruited for the study, and 134 who were without preinjury ODD, conduct disorder, or disruptive behavior disorder not otherwise specified (DBD NOS) returned for the 6-month assessment. Of those who returned 6 months postinjury, 11 (8.2%) developed novel ODD, and none developed novel conduct disorder or DBD NOS. Novel ODD was significantly associated with socioeconomic status, preinjury family functioning, psychosocial adversity, and processing speed. CONCLUSIONS: These findings show that an important minority of children with TBI developed ODD. Psychosocial and injury-related variables, including socioeconomic status, lower family function, psychosocial adversity, and processing speed, significantly increase risk for this outcome.

Oxytocin: at birth and beyond. A systematic review of the long-term effects of peripartum oxytocin.

Oxytocin is one of the most commonly used medications during labour and delivery. Recent insights from basic neuroscience research suggest that the uterotonic effects of oxytocin may arguably be trivial when compared with its profound effects on higher-order human behaviour. The purpose of this review is to highlight the potential consequences of manipulating oxytocinergic signalling during the peripartum period and its long-term impact on the maternal-infant dyad. We identified four domains where modulation of oxytocinergic signalling might be consequential: postpartum depression; breastfeeding; neurodevelopment; and chronic pain, and performed a literature search to address the impact of peripartum oxytocin administration. We have shown modest, but inconsistent, evidence linking peripartum oxytocin administration with postpartum depression. Breastfeeding success appeared to be negatively correlated with peripartum oxytocin exposure, perhaps secondary to impaired primitive neonatal reflexes and maternal-infant bonding. The association between perinatal oxytocin exposure and subsequent development of neurodevelopmental disorders such as autism in the offspring was weak, but these studies were limited by the lack of information on the cumulative dose. Finally, we identified substantial evidence for analgesic and anti-hypersensitivity effects of oxytocin which might partly explain the low incidence of chronic pain after caesarean birth. Although most data presented here are observational, our review points to a compelling need for robust clinical studies to better dissect the impact of peripartum oxytocin administration, and as stewards of its use, increase the precision with which we administer oxytocin to prevent overuse of the drug.

The relationship between allergic diseases and internalising and externalising behaviours in Spanish children: A cross-sectional study.

INTRODUCTION AND OBJECTIVES: The relationship between allergic diseases and behavioural disorders is still unclear. The objective of this study was to describe and compare children's behaviour (internalising and externalising) across a sample of children aged 6-11 years with and without allergic diseases. MATERIALS AND METHODS: This was a cross-sectional observational case-control study. A survey to 366 families (194 allergic cases and 172 controls), including a child behaviour checklist (CBCL) and a socio-demographic questionnaire with questions related to family, school education, health conditions and allergy symptoms, was administered. RESULTS: Children with a diagnosis of allergy showed higher scores in the overall CBCL score (standardised mean differences [SMD] = 0.47; confidence intervals [CI]: 0.26-0.68) and in the internalising and externalising factors (SMD = 0.52 and SMD = 0.36, respectively) than non-allergic children. Odds ratio (OR) analyses showed a higher risk (OR = 2.76; 95% CI [1.61 to 4.72]) of developing a behavioural difficulty in children diagnosed with allergies. Age and level of asthma appear as modulatory variables. CONCLUSIONS: Children aged 6-11 years diagnosed with allergies showed larger behavioural problems than non-allergic children, especially in the case of internalising behaviours. These findings suggest the importance of attending to them and treating them in the early stages of diagnosis to avoid future psychological disorders.

Disruptive Behavior Disorders: The Challenge of Delineating Mechanisms in the Face of Heterogeneity.

Causal pathways to disruptive behavior disorders, even within the same diagnostic category, are varied. Both equifinality and multifinality pose considerable challenges to uncovering underlying mechanisms and understanding varied developmental trajectories associated with disruptive behavior disorders. Uncovering genetic causes requires improved granularity in how we operationalize presentation and developmental trajectories associated with disruptive behavior disorders. If we want to integrate the study of genetic, environmental, and neurocognitive factors within a longitudinal framework, we need to improve measurement. Furthermore, brain changes associated with disruptive behavior disorders should not simply be understood as outcomes of genetic and environmental influences, but also as factors that reciprocally influence future social environments over time in ways that are important in contributing to risk and resilience. Advancing the field with regard to these challenges will result in more truly integrated investigation of disruptive behavior disorders, which holds the promise of improving our ability to develop more effective preventive and intervention approaches.

[Hemicerebellitis due to chikungunya associated with refractory status epilepticus in the paediatric age]. / Hemicerebelitis por chikungunya asociado a estado epiléptico refractario en edad pediátrica.

TITLE: Hemicerebelitis por chikungunya asociado a estado epiléptico refractario en edad pediátrica.

Increased attention deficit/hyperactivity and oppositional defiance symptoms of 6-12 years old Chinese children with atopic dermatitis.

Atopic dermatitis (AD), a prevalent chronic skin disease in children, has been associated with psychosocial illness and reduced quality of life because of severe itching and sleep deprivation. Previous studies have found a consistent association between AD and attention deficit hyperactivity disorder (ADHD). However, little is known about this relationship in Chinese children with AD.To investigate co-occurrence of ADHD symptoms, oppositional defiant disorder (ODD) symptoms, and the relevant risk factors of AD, as well as its impact on the quality of life in Chinese school-aged children with AD.Outpatients aged 6 to 12 years with confirmed AD and healthy controls matched for age were randomly included in this study from October 2018 to October 2019. AD severity was evaluated using the Severity Scoring of Atopic Dermatitis scale (SCORAD). Inattention, hyperactivity, and oppositional defiant symptoms were evaluated by using the Swanson, Nolan and Pelham IV Teacher and Parent 26-Item Rating Scale (SNAP-IV) questionnaires and quality of life was evaluated using the Children's Dermatology Life Quality Index (CDLQI).The study included 89 AD patients and 184 healthy controls. AD patients were more likely to have ADHD symptoms (10.1% vs. 3.8%; P = .04) and ODD symptoms (5.6% vs 0%; P < .001) than controls, especially hyperactive/impulsive (P = .03). The severity of itching and sleep loss in AD patients were positively correlated with inattention (P = .03; P < .001), hyperactivity/impulsiveness (P = .01; P = .03), and oppositional defiance scores (P < .01; P = .04). Sleep loss in AD patients was independently associated with an increased risk of ADHD symptoms (OR, 1.78; 95% CI, 1.07-2.98; P = .03). The mean CDLQI scores of AD patients were 6.98 ±â€Š5.02, and CDLQI scores were significantly higher in AD patients with ADHD symptoms than in those without ADHD symptoms (11.44 vs. 6.48; P = .01).AD is a prevalent chronic condition associated with an increased likelihood of ADHD symptoms and ODD symptoms in school-aged children. Sleep deprivation caused by AD may be a risk factor for ADHD. AD affects quality of life, especially in patients with ADHD symptoms. AD patients with symptoms of inattention and hyperactivity should be evaluated for ADHD.

Psychiatric Disorders in the Adolescent Offspring of Mothers with Thyroid Problems During Pregnancy.

Maternal thyroid problems during pregnancy have been linked to neurocognitive impairments in children. While studies suggest that disorders of maternal thyroid function during pregnancy are associated with symptoms of mental health problems in children, little is known about the risk of clinically significant psychiatric disorders in adolescence. A sample of 2451 Canadian adolescents enrolled in the Ontario Child Health Study completed the Mini International Neuropsychiatric Interview for Children and Adolescents at 12-17 years of age. Their mothers self-reported thyroid problems during pregnancy. Gestational thyroid problems were associated with offspring oppositional defiant disorder (ODD; OR 3.73; 95% CI 1.69-8.24), conduct disorder (CD; OR 12.95; 95% CI 5.12-32.75), and social anxiety disorder (SAD; OR 6.25; 95% CI 2.53-15.47). Neither sex nor gestational age moderated associations between prenatal thyroid dysfunction and the majority of outcomes. School performance mediated 8% of the association between thyroid problems and SAD, 21% for CD and 53% for ODD.

Six-Month Follow-up of the Families on Track Intervention Pilot Trial for Children With Fetal Alcohol Spectrum Disorders and Their Families.

BACKGROUND: When the primary disabilities associated with fetal alcohol spectrum disorders (FASD) are not well supported, individuals are at higher risk for mental health problems and other secondary conditions. The Families on Track (FOT) intervention was designed to prevent secondary conditions and improve family functioning in children with FASD. Promising results from a pilot study demonstrated positive effects on child and caregiver outcomes immediately following the intervention. The objective of this study was to examine the sustainability of these effects 6 months postintervention. METHODS: Thirty children (ages 4 to 8) with prenatal alcohol exposure and their caregivers were enrolled in the original study. Families were randomized to the FOT intervention or an active comparison group that provided comprehensive assessment and individualized feedback. The intervention integrated a positive parenting curriculum and a child skills group. Families were assessed at baseline, postintervention, and 6-month follow-up visits. Follow-up data were available for 24 families on child and caregiver outcomes. Data were analyzed using effect size calculations and analysis-of-variance techniques. RESULTS: Relative to the comparison group, intervention families showed continued gains in parenting efficacy and maintained prior improvements in FASD knowledge over the follow-up period. Although intervention families reported a decrease in their needs being met over the follow-up period, they continued to report their needs being met to greater extent than those in the comparison group. Consistent with postintervention outcomes, children in both groups exhibited similar decreases in child disruptive behavior 6 months following the intervention. Unfortunately, positive gains seen at postintervention for child self-esteem and emotion regulation were attenuated at follow-up. CONCLUSIONS: This pilot study yielded promising effects on important areas of caregiver functioning. However, the intervention's impact on child functioning waned over time, suggesting the need for sustained or alternate child intervention.

Attachment and reflective functioning in children with somatic symptom disorders and disruptive behavior disorders.

Our goal in conducting this study was to examine whether children with somatic symptom disorders (SSD) and disruptive behavior disorders (DBD) have higher rates of insecure or disorganized attachment and difficulties in mentalizing (operationalized as reflective functioning) as compared to a control group. Participants were 131 children (8-15 years) spanning two groups-a clinical group (n = 85), comprised of children fitting the criteria of our target diagnostic classifications (SSD: N = 45; DBD: N = 40), as well as a comparison group of healthy control children (n = 46). Children completed the Child Attachment Interview, which was later coded by reliable raters for attachment security and reflective functioning (RF). Consistent with our predictions, children in the clinical group had significantly lower RF and were significantly more likely to have insecure (over 80%) and disorganized attachment (over 40%) than children in the comparison group. In addition, RF was significantly lower in children with DBD than children with SSD. Furthermore, in the SSD group, children's RF regarding self was significantly lower than RF regarding others. Finally, consistent with prior studies, RF and attachment were associated. The findings indicate that school-aged children with SSD and DBD have higher rates of insecure and disorganized attachment. Consistent with theory, RF and attachment were loosely coupled, but RF alone differentiated among the diagnostic subgroups. Implications for treatment and prevention are discussed.

The Longitudinal Relation between Observed Maternal Parenting in the Preschool Period and the Occurrence of Child ADHD Symptoms in Middle Childhood.

In this longitudinal population-based cohort (N = 547) we examined the relation between maternal discipline and sensitivity in the preschool period and the occurrence of attention-deficit hyperactivity disorder (ADHD) symptoms in middle childhood, taking into account pre-existing child attention and executive function (EF) problems, and oppositional defiant disorder (ODD) symptom comorbidity. Maternal parenting was observed during a 'do not touch task' (positive and negative discipline) and a teaching task (sensitivity) at age 3. Parents reported on the occurrence of ADHD and ODD symptoms at age 8 using the Conners' Parent Rating Scale. Attention and executive function problems were assessed using parent questionnaires at age 4. Important covariates such as harsh discipline and maternal depression were also taken into account. Maternal sensitivity significantly predicted later ADHD symptoms beyond pre-existing child attention and EF problems, and comorbid ODD symptoms. However, maternal negative and positive discipline did not significantly predict later ADHD symptoms over and above these covariates. This study demonstrates the importance of maternal sensitivity in the etiology of core ADHD symptoms above and beyond pre-existing child attention and EF problems, and comorbid ODD symptoms.

Pregnancy risk factors in relation to oppositional-defiant and conduct disorder symptoms in the Avon Longitudinal Study of Parents and Children.

BACKGROUND: Pregnancy factors have been implicated in offspring oppositional-defiant disorder (ODD) and conduct disorder (CD) symptoms. Literature still holds notable limitations, such as studying only a restricted set of pregnancy factors, use of screening questionnaires which assess broadly defined outcome measures, and lack of control for disruptive behavior comorbidity and genetic confounds. We aimed to address these gaps by prospectively studying a broad range of pregnancy factors in relation to both offspring ODD and CD symptomatology in the Avon Longitudinal Study of Parent and Children. METHODS: Outcomes were ODD and CD symptom scores at age 7;9 years using the Development and Well-Being Assessment interview. We analyzed maternal (N ≈ 6300) and teacher ratings (N ≈ 4400) of ODD and CD scores separately using negative binomial regression in multivariable models. Control variables included comorbid attention-deficit/hyperactivity disorder symptoms, ODD or CD symptoms as appropriate, and genetic risk scores based on an independent CD genome-wide association study. RESULTS: Higher ODD symptom scores were linked to paracetamol use (IRR = 1.24 [98.3% confidence interval 1.05-1.47], P = 0.002, teacher ratings) and life events stress (IRR = 1.22 [1.07-1.39], P = 0.002, maternal ratings) during pregnancy. Higher CD symptom scores were linked to maternal smoking (IRR = 1.33 [1.18-1.51], P < 0.001, maternal ratings), life events stress (IRR = 1.24 [1.11-1.38], P < 0.001, maternal ratings) and depressive symptoms (IRR = 1.14 [1.01-1.30], P = 0.006, maternal ratings) during pregnancy. CONCLUSIONS: Common and potentially preventable pregnancy risk factors were independently related to both offspring ODD and CD symptomatology in children from the general population. Future studies should further address genetic confounds and confounding by environmental factors later in life.

Dimensions of deprivation and threat, psychopathology, and potential mediators: A multi-year longitudinal analysis.

Prior research demonstrates a link between exposure to childhood adversity and psychopathology later in development. However, work on mechanisms linking adversity to psychopathology fails to account for specificity in these pathways across different types of adversity. Here, we test a conceptual model that distinguishes deprivation and threat as distinct forms of childhood adversity with different pathways to psychopathology. Deprivation involves an absence of inputs from the environment, such as cognitive and social stimulation, that influence psychopathology by altering cognitive development, such as verbal abilities. Threat includes experiences involving harm or threat of harm that increase risk for psychopathology through disruptions in social-emotional processing. We test the prediction that deprivation, but not threat, increases risk for psychopathology through altered verbal abilities. Data were drawn from the Child Development Project (N = 585), which followed children for over a decade. We analyze data from assessment points at age 5, 6, 14, and 17 years. Mothers completed interviews at age 5 and 6 on exposure to threat and deprivation experiences. Youth verbal abilities were assessed at age 14. At age 17, mothers reported on child psychopathology. A path analysis model tested longitudinal paths to internalizing and externalizing problems from experiences of deprivation and threat. Consistent with predictions, deprivation was associated with risk for externalizing problems via effects on verbal abilities at age 14. Threat was associated longitudinally with both internalizing and externalizing problems, but these effects were not mediated by verbal abilities. Results suggest that unique developmental mechanisms link different forms of adversity with psychopathology. (PsycINFO Database Record

Chronic Stressors and Adolescents' Externalizing Problems: Genetic Moderation by Dopamine Receptor D4. The TRAILS Study.

The existing literature does not provide consistent evidence that carriers of the Dopamine D4 Receptor 7-repeat allele are more sensitive to adverse environmental influences, resulting in enhanced externalizing problems, compared to noncarriers. One explanation is that the adverse influences examined in prior studies were not severe, chronic, or distressing enough to reveal individual differences in sensitivity reflected by DRD4-7R. This study examined whether the 7-repeat allele moderated the association between chronic stressors capturing multiple stressful aspects of individuals' lives and externalizing problems in adolescence. We expected that chronic stressor levels would be associated with externalizing levels only in 7-repeat carriers. Using Linear Mixed Models, we analyzed data from 1621 Dutch adolescents (52.2% boys), obtained in three measurement waves (mean age approximately 11, 13.5, and 16 years) from the TRacking Adolescents' Individual Lives Survey (TRAILS) population-based birth cohort and the parallel clinic-referred cohort. Across informants, we found that higher levels of chronic stressors were related to higher externalizing levels in 7-repeat carriers but not in noncarriers, as hypothesized. Although previous studies on the 7-repeat allele as a moderator of environmental influences on adolescents' externalizing problems have not convincingly demonstrated individual differences in sensitivity to adverse environmental influences, our findings suggest that adolescent carriers of the Dopamine D4 Receptor 7-repeat allele are more sensitive to chronic, multi-context stressors than noncarriers.

Conduct problems in youth and the RDoC approach: A developmental, evolutionary-based view.

Problems related to aggression in young people are traditionally subsumed under the header of conduct problems, which include conduct disorder and oppositional defiant disorder. Such problems in children and adolescents are an important societal and mental health problem. In this paper we present an evolutionarily informed developmental psychopathology view of conduct problems inspired by the NIMH Research Domain Criteria (RDoC) initiative. We assume that while there are many pathways to conduct problems, chronic or temporary impairments in the domain of social cognition or mentalizing are a common denominator. Specifically, we conceptualize conduct problems as reflecting temporary or chronic difficulties with mentalizing, that is, the capacity to understand the self and others in terms of intentional mental states, leading to a failure to inhibit interpersonal violence through a process of perspective-taking and empathy. These difficulties, in turn, stem from impairments in making use of a normally evolutionarily protected social learning system that functions to facilitate intergenerational knowledge transmission and protect social collaborative processes from impulsive and aggressive action. Temperamental, biological, and social risk factors in different combinations may all contribute to this outcome. This adaptation then interacts with impairments in other domains of functioning, such as in negative and positive valence systems and cognitive systems. This view highlights the importance of a complex interplay among biological, psychological, and environmental factors in understanding the origins of conduct problems. We outline the implications of these views for future research and intervention.

Do Genetic Factors Explain the Links Between Callous-Unemotional, Attention Hyperactivity and Oppositional Defiant Problems in Toddlers?

Research demonstrates that callous-unemotional (CU) behaviors, Attention Deficit Hyperactivity Disorder (ADHD) and Oppositional Defiant Problems (ODD) are related, but little is known about the sources of covariation among the three externalizing behaviors. The present study looked at genetic and environmental links between all three behavioral domains in twins at ages 2 and 3 years (MZ = 145, DZ = 169), a time when CU behaviors are beginning to emerge. CU, ADHD, and ODD behaviors as assessed using the Child Behavior Checklist 1.5-5 (Achenbach and Rescorla 2000) were strongly interrelated at both ages. Genetic factors primarily explained the covariation among the three behavioral domains via a common externalizing factor; however, there were also genetic factors unique to each behavior. Furthermore, the majority of nonshared environmental influences on each externalizing behavior were behavior-specific. The heritable externalizing factor was highly stable across age, largely due to genetic factors shared across ages 2 and 3 years. Despite their extensive phenotypic and genetic overlap, CU, ADHD, and ODD behaviors have unique genetic and nonshared environmental influences as early as toddlerhood. This supports phenotypic research showing that the three are related but distinct constructs in very young children.

Evidence for the Trait-Impulsivity Etiological Model in a Clinical Sample: Bifactor Structure and Its Relation to Impairment and Environmental Risk.

The trait-impulsivity etiological model assumes that a general factor (trait-impulsivity) underlies attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and other externalizing disorders. We investigated the plausibility of this assumption by testing the factor structure of ADHD and ODD in a bifactor framework for a clinical sample of 1420 children between 6 and 18 years of age (M = 9.99, SD = 3.34; 85% male). Further, the trait-impulsivity etiological model assumes that ODD emerges only if environmental risk factors are present. Our results support the validity of the trait-impulsivity etiological model, as they confirm that ADHD and ODD share a strong general factor of disruptive behavior (DB) in this clinical sample. Furthermore, unlike the subdimensions of ADHD, we found that the specific ODD factor explained as much true score variance as the general DB factor. This suggests that a common scale of ADHD and ODD may prove to be as important as a separate ODD subscale to assess externalizing problems in school-age children. However, all other subscales of ADHD may not explain sufficient true score variance once the impact of the general DB factor has been taken into consideration. In accordance with the trait-impulsivity model, we also showed that all factors, but predominantly the general factor and specific inattention factor, predicted parent-rated impairment, and that predominantly ODD and impulsivity are predicted by environmental risk factors.