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The Thought-Problem scale (TP) of the CBCL assesses symptoms such as hallucinations and strange thoughts/behaviors and has been associated with other behavioral disorders. This study uses parental reports to examine the etiology of variation in TP, about which relatively little is known, in 7-year-old twins. Parental ratings on TP were collected in 8,962 7-year-old twin pairs. Because the distribution of TP scores was highly skewed scores were categorized into 3 classes. The data were analyzed under a threshold liability model with genetic structural equation modeling. Ratings from both parents were simultaneously analyzed to determine the rater agreement phenotype (or common phenotype [TPc]) and the rater specific phenotype [TPs] that represents rater disagreement caused by rater bias, measurement error and/or a unique view of the parents on the child's behavior. Scores on the TP-scale varied as a function of rater (fathers rated fewer problems), sex (boys scored higher) and zygosity (DZ twins scored higher). The TPc explained 67% of the total variance in the parental ratings. Variation in TPc was influenced mainly by the children's genotype (76%). Variance in TPs also showed a contribution of genetic factors (maternal reports: 61%, paternal reports: 65%), indicating that TPs does not only represent rater bias. Shared environmental influences were only found in the TPs. No sex differences in genetic architecture were observed. These results indicate an important contribution of genetic factors to thought problems in children as young as 7 years. [ABSTRACT FROM AUTHOR]

Our objective was to examine the overlap between autistic traits and other behavioral problems in a general population sample, and explore the extent to which this overlap is due to genetic or environmental factors. Youth Self Report (YSR) data were collected in a general population sample of 424 twin pairs at 18 years of age, and their nontwin siblings. In 197 of these twin families, self-report ratings on the Autism-spectrum Quotient (AQ) were collected. Stepwise backward regression analyses revealed that of all 8 YSR syndrome scales, the Withdrawn Behavior (WB) and Social Problems (SOC) scale were the most important predictors of AQ scores, and together with sex, explained 23% of the variance in AQ scores. Genetic structural equation modeling showed that the overlap between AQ and WB and SOC was mainly due to genetic effects. About half of the genetic variance in AQ scores was specific to the AQ, with the remaining half shared with genetic variance in WB and SOC. Endorsement of autistic traits in a general population sample is associated with social and withdrawn behavioral problems and these problems partly share a common genetic etiology with autistic traits. However, most of the variance in AQ scores remains unexplained by YSR scores, and half of the genetic variance in AQ is unshared with WB and SOC. These results indicate that autistic traits have specific characteristics that are substantially genetically independent from other common but related behavioral domains such as social problems and withdrawn behavior. [ABSTRACT FROM AUTHOR]

Background: A high rate of bullying episodes has been reported in Italian schools, as well as its association with psychopathology in adolescents. However, information regarding moderators of this interaction are still lacking. This study explored whether gender, exercise frequency, and sport participation exerted a protective effect on the association between bullying and depressive symptoms in Italian students.Methods: Researchers obtained data from 4,829 Italian youth ages 13 to 21 using the self-report Epidemiologia dell'Infortunistica Stradale survey (EDIT) developed by the Regional Health Agency of Tuscany, Italy. Three structural equation models were run to assess moderators of the association between bullying and depressive symptoms. Moderators examined in the models included gender, exercise frequency, and sport participation.Results: The association between bullying and depressive symptoms was stronger for females (B=0.95, SE=0.04, p< .001) than for males (B=0.45, SE=0.00, p< .001) and for students who did not play sports (B=0.74, SE=0.09, p< .001) than for those who played sports (B=0.61, SE=0.06, p< .001). Females may be more affected by the depressive effects of bullying than males.Conclusions: Participation in sports buffers against the effects of bullying and may prove a helpful strategy for increasing exercise, positive peer interactions, and mood in adolescents.Limitations: The cross-sectional nature of the study, the possible role of BMI as a confounding factor and the use of a not widely used measure of depression. [ABSTRACT FROM AUTHOR]

This study examined the stability of internalizing and externalizing problems from age 1.5 to 6 years, while taking into account developmental changes in the presentation of problems. The study comprised a population-based cohort of 7,206 children (50.4 % boys). At ages 1.5, 3, and 6 years, mothers reported on problem behavior using the Child Behavior Checklist/1.5-5 (CBCL/1.5-5). At each age we performed latent profile analysis on the CBCL/1.5-5 scales. Latent transition analysis (LTA) was applied to study the stability of problem behavior. Profiles of problem behavior varied across ages. At each age, 82-87 % of the children did not have problems whereas approximately 2 % showed a profile of co-occurring internalizing and externalizing problems. This profile was more severe (with higher scores) at 6 years than at earlier ages. A predominantly internalizing profile only emerged at 6 years, while a profile with externalizing problems and emotional reactivity was present at each age. LTA showed that, based on profiles at 1.5 and 3 years, it was difficult to predict the type of profile at 6 years. Children with a profile of co-occurring internalizing and externalizing problems early in life were most likely to show problem behavior at 6 years. This study shows that the presentation of problem behavior changes across the preschool period and that heterotypic continuity of problems is very common among preschoolers. Children with co-occurring internalizing and externalizing problems were most likely to show persisting problems. The use of evidence-based treatment for these young children may prevent psychiatric problems across the life course. [ABSTRACT FROM AUTHOR]

Background Oppositional defiant disorder ( ODD) has components of both irritability and defiance. It remains unclear whether children with variation in these domains have different adult outcomes. This study examined the concurrent and predictive validity of classes of oppositional defiant behavior. Methods Latent class analysis was performed on the oppositional defiant problems scale of the Child Behavior Checklist in two samples, one in the US (the Achenbach Normative Sample, N = 2029) and one in the Netherlands (the Zuid-Holland Study, N = 2076). A third sample of American children (The Vermont Family Study, N = 399) was examined to determine concurrent validity with DSM diagnoses. Predictive validity over 14 years was assessed using the Zuid-Holland Study. Results Four classes of oppositional defiant problems were consistent in the two latent class analyses: No Symptoms, All Symptoms, Irritable, and Defiant. Individuals in the No Symptoms Class were rarely diagnosed concurrently with ODD or any future disorder. Individuals in the All Symptoms Class had an increased frequency of concurrent childhood diagnosis of ODD and of violence in adulthood. Subjects in the Irritable Class had low concurrent diagnosis of ODD, but increased odds of adult mood disorders. Individuals in the Defiant Class had low concurrent diagnosis of ODD, but had increased odds of violence as adults. Conclusions Only children in the All Symptoms class were likely to have a concurrent diagnosis of ODD. Although not diagnosed with ODD, children in the Irritable Class were more likely to have adult mood disorders and children in the Defiant Class were more likely to engage in violent behavior. [ABSTRACT FROM AUTHOR]

This study examined hostility and harsh discipline of both mothers and fathers as potential mechanisms explaining the association between a maternal maltreatment history and her offspring's internalizing and externalizing problems. Prospective data from fetal life to age 6 were collected from a total of 4,438 families participating in the Generation R Study. Maternal maltreatment was assessed during pregnancy using a self-administered questionnaire. Mothers and fathers each reported on their psychological distress and harsh discipline when the child was 3 years. Children's internalizing and externalizing problems were assessed by parental reports and child interview at age 6. Findings from structural equation modeling showed that the association between a maternal maltreatment history and her offspring's externalizing problems was explained by maternal hostility and harsh discipline and, at least partially, also by paternal hostility and harsh discipline. Child interview data provided support for both these indirect paths, with associations largely similar to those observed for parent reports. [ABSTRACT FROM AUTHOR]

Background Social withdrawal is a core neuropsychiatric phenomenon in developmental psychopathology. Its presence predicts psychopathology across many domains, including depression, psychosis, autism, anxiety, and suicide. Withdrawn behavior is highly heritable, persistent, and characteristically worsens without intervention. To date, few studies have successfully identified genetic associations with withdrawn behavior, despite the abundance of evidence of its heritability. This may be due to reliance of categorical over dimensional measures of the behaviorally inhibited phenotype. The aim of this study is to identify associations between known psychiatric candidate genes and a dimensionally derived measure of withdrawn behavior. Methods Genetic information was collected on 20 single-nucleotide polymorphisms ( SNPs) from a custom-designed SNP chip and TAQMAN arrays of 4 variable number of tandem repeat ( VNTR) genes for 551 individuals from 187 families. Linear mixed modeling was employed to examine the relationship between genotypes of interest and Child Behavior Checklist ( CBCL) Withdrawn Behavior Subscale Score ( WBS) while controlling for gender and age through multiple linear regressions. Results Withdrawn behavior was highly associated with polymorphism of the serotonin receptor 2A ( HTR2A) [ p = .009, estimate = 0.310 (bootstrap 95% CI 0.155-0.448), bootstrap p = .001] and of the alpha 2-adrenergic ( ADRA2A) [ p = .001, estimate = −0.310 (bootstrap 95% CI −0.479 to −0.126), bootstrap p = .001] genes after correction for gender and age. The association between withdrawn behavior and ADRA2A was stronger for younger children. Conclusions HTR2A and ADRA2A genes are associated with withdrawn behavior. This reinforces the role of catecholaminergic genes in the heritability of withdrawn behavior. [ABSTRACT FROM AUTHOR]

The article discusses research which was conducted to investigate the relative influence genetic and environmental factors had on children's leisure time exercise behavior through the classic twin design. Researchers evaluated data taken from The Netherlands Twin Register which included information on seven, 10 and 12 year old twins and information on their leisure activity which was supplied by parents. They found that while the shared environmental influencing exercise was partially different between girls and boys, shared environmental factors did influence exercise behavior in both girls and boys.

Background: Previous research highlights the significance of a functional polymorphism located in the promoter region (5-HTTLPR) of the serotonin transporter gene in emotional behaviour. This study examined the effect of the 5-HTTLPR polymorphism on emotion processing in a large number of healthy preschoolers. Methods: The 5-HTTLPR genotype was classified in 605 children as homozygous for the short allele (SS), homozygous for the long allele (LL), or heterozygous (LS). Emotion-processing was assessed using age-appropriate computer tasks where children matched happy, sad, angry, and fearful facial expressions preceded by a shape-matching task to assess basic matching ability. Results: We found that young children could differentiate between emotion categories ( F = 12.1, p < .001). The effect of 5-HTTLPR genotype depended on the emotion category presented ( F = 2.3, p = .031). This effect was explained by the finding that SS children were less accurate at recognising fearful faces than LL or LS children ( F = 5.3, p = .005). We did not find any significant differences as a result of 5-HTTLPR genotype for happy, sad or angry expressions ( p > .05). Conclusions: Results indicate that 5-HTTLPR allele status selectively impacts the processing of fearful but not other facial expressions. This pattern is already apparent in very young typically developing children. Results may signal an early vulnerability for affective problems before disorders emerge. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the reliability of obtaining through mailed surveys maternal reports of specific major motor milestones achievement. To accomplish this aim we compared and contrasted mailed survey data and telephone interview data on a series of questions about age at which motor milestones were achieved. We used monthly telephone interviews with mothers of 238 twin pairs, beginning at age 6 months, which ascertained the age at which each specific milestone was met. The contrasting 'through the mail' survey was sent after the second birthday of an independent group of children, and included 463 twin pairs. All twins were born between March 2003 and March 2004. Comparisons were made for the following 5 milestones: sitting without support, hands and knees crawling, turning from back to belly, standing without support, and walking without support. There was no difference between the concurrent telephone interviews and the retrospective through the mail survey on any of the landmarks, except 'standing without support'. From this work we conclude that data on achieving milestones can be reliably obtained through the mail using retrospective surveys when the children are 2 years of age. [ABSTRACT FROM AUTHOR]

The Netherlands Twin Register (NTR) was established around 1987 at the Vrije Universiteit in Amsterdam, the Netherlands. The current article summarizes the longitudinal genetic analyses of maternal and paternal ratings of twins' behavior as a function of the sex of the children for the traits of aggression (AGG), attention problems (AP), anxious/depression (ANX), internalizing behavior (INT) and externalizing behavior (EXT). We found that genetic influences are the most important factor in explaining individual differences in these traits. For most phenotypes, influences of genetic factors fluctuate throughout development, with the exception of AP, for which genetic influences remain of similar magnitude. Changes in genetic influences parallel those in shared environmental influences, while nonshared environmental influences remain relatively constant. Around 10% to 20% of the variance is accounted for by parent-specific shared environment, which includes rater bias. For all phenotypes, stability throughout childhood is accounted for by genetic and shared environmental factors, while nonshared environmental influences are mainly age/measurement specific. About 15% of the phenotypic stability is accounted for by rater-specific shared environmental influences, which include rater bias. In conclusion, between ages 3 and 12 genetic factors are the most important cause of individual differences in emotional and behavioral problems. [ABSTRACT FROM AUTHOR]

In the late 1980s The Netherlands Twin Register (NTR) was established by recruiting young twins and multiples at birth and by approaching adolescent and young adult twins through city councils. The Adult NTR (ANTR) includes twins, their parents, siblings, spouses and their adult offspring. The number of participants in the ANTR who take part in survey and / or laboratory studies is over 22,000 subjects. A special group of participants consists of sisters who are mothers of twins. In the Young NTR (YNTR), data on more than 50,000 young twins have been collected. Currently we are extending the YNTR by including siblings of twins. Participants in YNTR and ANTR have been phenotyped every 2 to 3 years in longitudinal survey studies, since 1986 and 1991 for the YNTR and ANTR, respectively. The resulting large population-based datasets are used for genetic epidemiological studies and also, for example, to advance phenotyping through the development of new syndrome scales based on existing items from other inventories. New research developments further include brain imaging studies in selected and unselected groups, clinical assessment of psychopathology through interviews, and cross-referencing the NTR database to other national databases. A large biobank enterprise is ongoing in the ANTR in which blood and urine samples are collected for genotyping, expression analysis, and metabolomics studies. In this paper we give an update on the YNTR and ANTR phenotyping and on the ongoing ANTR biobank studies. [ABSTRACT FROM AUTHOR]