The genetic and environmental contributions to attention deficit hyperactivity disorder as measured by the Conners' Rating Scales-revised

Objective: The majority of published reports on twin studies of attention deficit hyperactivity disorder (ADHD) have indicated robust additive genetic influences and unique environmental influences. These studies typically used DSM ADHD symptoms collected by telephone or interviews with mothers. The purpose of this study was to test the genetic architecture of ADHD by using the ADHD index from Conners' Rating Scales - Revised. Method: From the Conners' scale forms, data for the ADHD index were collected from the mothers of 1,595 7-year-old twin pairs from the Netherlands Twin Registry. Rates of ADHD diagnoses were computed by using Conners' gender- and age-specific cutoff points. Contributions from additive, dominant, unique environmental, interaction, and gender effects were computed by using gender-genetic models. Results: The prevalence of ADHD across the sample of 7-year-old twin pairs was about 4% according to the mothers' reports, consistent with other reported rates of ADHD. However, using the gender norms provided with the ADHD index, the authors found slightly higher rates of ADHD in girls than previously reported. Genetic analyses yielded a model that includes genetic dominance (48%), additive genetic factors (30%), and unique environmental factors (22%). Conclusions: The ADHD index from Conners' Rating Scales - Revised identified an appropriate percentage of children across this epidemiologic twin sample as being at risk for ADHD. The results of the genetic analyses are consistent with prior reports that ADHD is predominantly influenced by genetic factors that are both dominant and additive

Non-additive and Additive Genetic Effects on Extraversion in 3314 Dutch Adolescent Twins and Their Parents.

The influence of non-additive genetic influences on personality traits has been increasingly reported in adult populations. Less is known, however, with respect to younger samples. In this study, we examine additive and non-additive genetic contributions to the personality trait of extraversion in 1,689 Dutch twin pairs, 1,505 mothers and 1,637 fathers of the twins. The twins were on average 15.5 years (range 12-18 years). To increase statistical power to detect non-additive genetic influences, data on extraversion were also collected in parents and simultaneously analyzed. Genetic modeling procedures incorporating age as a potential modifier of heritability showed significant influences of additive (20-23%) and non-additive genetic factors (31-33%) in addition to unshared environment (46-48%) for adolescents and for their parents. The additive genetic component was slightly and positively related to age. No significant sex differences were found for either extraversion means or for the magnitude of the genetic and environmental influences. There was no evidence of non-random mating for extraversion in the parental generation. Results show that in addition to additive genetic influences, extraversion in adolescents is influenced by non-additive genetic factors. © 2008 Springer Science+Business Media, LLC

Individual Differences in Aggression: Genetic Analyses by age, gender, and informant in 3-, 7-, and 10-year-old Dutch Twins

Aggression in humans is associated with substantial morbidity and mortality. In this study we report on the aggressive behavior syndrome (AGG) in young children as defined by the Child Behavior Checklist (CBCL) and the Teacher Report Form (TRF). We assessed aggression in a large sample of Dutch twins at ages 3, 7, and 10 years. The purpose of this study was three-fold. First, we determined the number of children who are "clinically deviant" on the AGG scale. Second, we assessed the genetic and environmental contributions to AGG for the maternal, paternal, and teacher ratings at each age, for boys and girls. Third, we explored issues of rater bias by analyzing parental and teacher data simultaneously. CBCL data were available from mothers on 6436 three-year-old, 5451 seven-year-old, and 2972 ten-year-old twin pairs and CBCL data from fathers on 4207 three-year-old, 4269 seven-year-old, and 2295 ten-year-old twin pairs. Teacher report data from the TRF were collected for 1036 seven-year-old and 903 ten-year-old twin pairs from the Netherlands Twin Registry. Structural equation modeling was employed to obtain genetic and environmental estimates at each age. Analyses were conducted separately by age and informant, as well as simultaneously, for all informants. Differences in raw scores across gender were found, with boys being rated as more aggressive than girls by all informants. Mothers reported more symptoms than fathers, who reported more symptoms than teachers. Evidence for moderate to high genetic influence (51%-72%) was seen for AGG by all three informants at all ages with only small sex differences in heritability estimates. Best fitting models for AGG by parent reports also included a small contribution of common environment. The largest sex differences in heritabilities were seen at age 10. Contributions of common (13%-27%) and unique (16%-31%) environment were small to moderate. There was some evidence of genetic dominance by teacher report for 10-year-old girls

Exploring Links between Neuroticism and Psychoticism Personality Traits, Attentional Biases to Threat and Friendship Quality in 9-11-year-olds

The current study used an eye-movement Remote Distractor Paradigm (RDP) to explore attention to threat and considered associations with personality traits (neuroticism and psychoticism) and self-reported friendship quality in children aged 9–11 years. The RDP asked children to look at and identify a target presented on a computer display in the presence or absence of a central, parafoveal or peripheral visual distractor (an angry, happy or neutral face). The results showed that symptoms of neuroticism were associated with hypervigilance for threat (i.e., slower latencies to initiate eye movements to the target in the presence of angry versus happy or neutral faces). In addition, when distractors were presented centrally, this relationship was most evident in children who reported lower levels of attentional control. Psychoticism traits were associated with increased selective attention to all distractors (as measured by directional errors to face stimuli) and to child reported lower friendship quality. Moreover, the negative relationship between psychoticism and friendship characteristics associated with companionship was mediated via attentional capture of threat (i.e., a greater proportion of directional errors to angry distractors). The findings have potential to inform the development of translational research, to reduce symptoms of psychopathology and address attentional biases to threat with an aim to improve peer relationships in late childhood

Latent class analysis shows strong heritability of the Child Behavior Checklist-Juvenile Bipolar Phenotype.

Background: The Child Behavior Checklist (CBCL) has been used to provide a quantitative description of childhood bipolar disorder (BPAD). Many have reported that children in the clinical range on the Attention Problems (AP), Aggressive Behavior (AGG), and Anxious-Depressed (A/D) syndromes simultaneously are more likely to meet the criteria for childhood BPAD. The purpose of this study was to determine if Latent Class Analysis (LCA) could identify heritable phenotypes representing the CBCL-Juvenile Bipolar (CBCL-JBD) profile and whether this phenotype demonstrates increased frequency of suicidal endorsement. Methods: The CBCL data were received by survey of mothers of twins in two large twin samples, the Netherlands Twin Registry. The setting for the study was the general community twin sample. Participants included 6246 10-year-old Dutch twins from the Netherlands Twin Registry. The main outcome measure consisted of the LCA on the items comprising the AP, AGG, and A/D subscales and means from the suicidal items #18 and #91 within classes. Results: A 7 class model fit best for girls and an 8 class fit best for boys. The most common class for boys or girls was one with no symptoms. The CBCL-JBD phenotype was the least common-about 4%-5% of the boys and girls. This class was the only one that had significant elevations on the suicidal items of the CBCL. Gender differences were present across latent classes with girls showing no aggression without the CBCL-JBD phenotype and rarely showing attention problems in isolation. Evidence of high heritability of these latent classes was found with odds ratios. Conclusions: In a general population sample, LCA identifies a CBCL-JBD phenotype latent class that is associated with high rates of suicidality, is highly heritable, and speaks to the comorbidity between attention problems, aggressive behavior, and anxious/depression in children. © 2006 Society of Biological Psychiatry

Latent class analysis shows strong heritability of the Child Behavior Checklist-Juvenile Bipolar Phenotype.

Background: The Child Behavior Checklist (CBCL) has been used to provide a quantitative description of childhood bipolar disorder (BPAD). Many have reported that children in the clinical range on the Attention Problems (AP), Aggressive Behavior (AGG), and Anxious-Depressed (A/D) syndromes simultaneously are more likely to meet the criteria for childhood BPAD. The purpose of this study was to determine if Latent Class Analysis (LCA) could identify heritable phenotypes representing the CBCL-Juvenile Bipolar (CBCL-JBD) profile and whether this phenotype demonstrates increased frequency of suicidal endorsement. Methods: The CBCL data were received by survey of mothers of twins in two large twin samples, the Netherlands Twin Registry. The setting for the study was the general community twin sample. Participants included 6246 10-year-old Dutch twins from the Netherlands Twin Registry. The main outcome measure consisted of the LCA on the items comprising the AP, AGG, and A/D subscales and means from the suicidal items #18 and #91 within classes. Results: A 7 class model fit best for girls and an 8 class fit best for boys. The most common class for boys or girls was one with no symptoms. The CBCL-JBD phenotype was the least common-about 4%-5% of the boys and girls. This class was the only one that had significant elevations on the suicidal items of the CBCL. Gender differences were present across latent classes with girls showing no aggression without the CBCL-JBD phenotype and rarely showing attention problems in isolation. Evidence of high heritability of these latent classes was found with odds ratios. Conclusions: In a general population sample, LCA identifies a CBCL-JBD phenotype latent class that is associated with high rates of suicidality, is highly heritable, and speaks to the comorbidity between attention problems, aggressive behavior, and anxious/depression in children. © 2006 Society of Biological Psychiatry

When parent and teacher ratings don't agree: the Tracking Adolescents' Individual Lives Survey (TRAILS)

Abstract Objectives: A commonly encountered situation for evaluating clinicians is a history of significant problems in one setting with little or no difficulties in another. This study aims to describe this phenomenon and to examine its relations with other child and family characteristics. Method: A total of 1,730 children (mean age 11.05 years) was studied from the first wave of the Tracking Adolescents' Individual Lives Survey (TRAILS), a large population-based study of Dutch youth. Parent and teacher ratings of aggression, rule breaking, inattention, and hyperactivity were obtained. Children were assigned to groups according to the presence of clinically relevant problems at home only, at school only, or in both settings. The rate of setting specific problems was calculated and comparisons between groups were made. Results: Setting specific, especially home-specific, problems were quite common. Among children whom parents rated as having at least borderline-clinical problems, teachers reported clear or very clear behaviors at school at the following rates: aggression (22%), rule breaking (12.5%), inattention (55%), and hyperactivity/impulsivity (33%). Compared with the school-specific group, the home-specific group contained a significantly higher percentage of girls with regard to inattention or hyperactivity and a significantly lower percentage of girls with regards to rule breaking. Logistic regression analyses revealed that home- versus school-specific problems were related to sex, child effortful control, and parental stress. Conclusion: Externalizing problems are frequently encountered only in one setting between home and school and are related to sex, child effortful control, and parental stress

Genetic and environmental contributions to childhood obsessive behavior: A cross-cultural twin study.

Context: We have reported elsewhere on the development of an 8-item Obsessive-Compulsive Scale (OCS) contained in the Child Behavior Checklist (CBCL) to identify children who meet criteria for DSM-IV obsessive-compulsive disorder. Twin studies of obsessive-compulsive disorder have indicated a significant genetic component to its expression. Objective: To determine the relative contributions of genetic and environmental influences on childhood obsessive-compulsive behavior using the CBCL OCS in twin samples. Design: The CBCL data were received by survey of twins in the Netherlands Twin Registry (NTR) and the Missouri Twin Study (USA/MOTWIN). Setting: General community twin samples. Participants: Participants were 4246 twin pairs aged 7 years, 2841 aged 10 years, and 1562 aged 12 years (who also participated in the study at 7 and 10 years of age) from the NTR and 1461 mixed-age twin pairs (average age, approximately 9 years) from the USA/MOTWIN. Main Outcome Measures: Model fitting to test for genetic and environmental influences, sex differences, and sibling interaction/rater contrast effects on the CBCL OCS. Results: In each case, the best-fitting model was one that indicated significant additive genetic influences (range, 45%-58%; 95% confidence interval [CI], 45%-61%), and unique environmental influences (range, 42%-55%; 95% CI, 39%-55%), with shared environmental influences in the NTR sample aged 12 years (16%). Sex differences were seen in the mixed-age USA/MOTWIN model, but not in the NTR samples. No evidence of dominance, sibling interaction, or rater-contrast effects was seen. These data were relatively consistent across age and cultures. Conclusions: The CBCL OCS is influenced by genetic factors (approximately 55%) and unique environmental factors (approximately 45%) in the younger sample, with common environmental influences only at 12 years of age. These effects do not vary with differences in sex or sibling interaction/rater contrast effects. Our data reveal higher genetic influences for obsessive-compulsive behavior and do not demonstrate genetic differences across sex

COMT Val158Met genotype as a risk factor for problem behaviors in youth

Objective: To test the association between the catechol-O-methyltransferase (COMT) Val158Met polymorphism and both aggressive behavior and attention problems in youth. We hypothesized that youth carrying a Met allele would have greater average aggressive behavior scores, and that youth exhibiting Val-homozygosity would have greater average attention problems scores. Method: Complete data on maternally rated Child Behavior Checklist (CBCL) measures of aggressive behavior (AGG) and attention problems (AP), COMT polymorphism data, demographics, and maternal parenting quality were available for 149 youth (6 to 18 years old). Multivariable linear regression models were used to test the degree to which youth COMT Val158Met genotype was associated with AGG and AP while statistically controlling for age, gender, parental socioeconomic status (SES), and maternal parenting quality from the Alabama Parenting Questionnaire. Results: Mothers of Met-carriers rated their children higher on average AGG scores when compared with mothers of Val-homozygotes (p = .016). Further analyses revealed that this association was even more robust for maternal ratings of direct aggression (p = .007). The hypothesized association between Val-homozygosity and higher average AP scores relative to average AP scores of Met-carriers did not quite reach statistical significance (p = .062). Conclusions: After controlling for demographics, SES, and maternal parenting quality as confounders, there remains a strong association between youth carrying a Met allele and higher average AGG scores relative to Val-homozygotes