A Multivariate Genetic Analysis of Specific Phobia, Separation Anxiety and Social Phobia in Early Childhood

BACKGROUND: Comorbidity amongst anxiety disorders is very common in children as in adults and leads to considerable distress and impairment, yet is poorly understood. Multivariate genetic analyses can shed light on the origins of this comorbidity by revealing whether genetic or environmental risks for one disorder also influence another. We examined the genetic and environmental influences on the comorbidity between three common childhood anxiety disorders: Specific Phobia, Separation Anxiety and Social Phobia. METHODS: Using a two-phase design 4,662 twin-pairs were screened in the first phase and 854 pairs were assessed in the second phase by maternal-informant diagnostic interview using DSM-IV criteria. RESULTS: Multivariate genetic analysis revealed significant shared environmental over-lap between Specific Phobia and Separation Anxiety and significant familial and non-shared environmental over-lap between Specific Phobia and Social Phobia. CONCLUSIONS: Familial influences, especially shared environment, are central to the comorbidity between Specific Phobia and both Separation Anxiety and Social Phobia.     

Sex differences in the genetic and environmental influences on childhood conduct disorder and adult antisocial behavior

Sex differences in the genetic and environmental influences on childhood conduct disorder and adult antisocial behavior were examined in a large community sample of 6,383 adult male, female, and opposite-sex twins. Retrospective reports of childhood conduct disorder (prior to 18 years of age) were obtained when participants were approximately 30 years old, and lifetime reports of adult antisocial behavior (antisocial behavior after 17 years of age) were obtained 8 years later. Results revealed that either the genetic or the shared environmental factors influencing childhood conduct disorder differed for males and females (i.e., a qualitative sex difference), but by adulthood, these sex-specific influences on antisocial behavior were no longer apparent. Further, genetic and environmental influences accounted for proportionally the same amount of variance in antisocial behavior for males and females in childhood and adulthood (i.e., there were no quantitative sex differences). Additionally, the stability of antisocial behavior from childhood to adulthood was slightly greater for males than females. Though familial factors accounted for more of the stability of antisocial behavior for males than females, genetic factors accounted for the majority of the covariation between childhood conduct disorder and adult antisocial behavior for both sexes. The genetic influences on adult antisocial behavior overlapped completely with the genetic influences on childhood conduct disorder for both males and females. Implications for future twin and molecular genetic studies are discussed.     

Genetic and environmental influences on interpersonal cognitions and associations with depressive symptoms in 8-year-old twins

Less is known about depression in children than in adults. This study integrates fields by combining cognitive and interpersonal research investigating childhood depression symptoms through the use of a genetic framework. Three research questions are addressed. First, what are the associations among interpersonal cognitions, anxiety, and depression? Second, what are the relative magnitudes of genetic and environmental influences on interpersonal cognitions? Third, to what extent do genetic and environmental influences explain associations between interpersonal cognitions and depression? Three hundred pairs of 8-year-old twins reported on symptoms of depression and anxiety by completing the Children's Depression Inventory and the Screen for Childhood Anxiety-Related Emotional Disorders. The authors examined interpersonal cognitions with the Children's Expectation of Social Behaviors and the Perceptions of Peers and Self Questionnaires. Interpersonal cognitions were more strongly correlated with depression (mean r = .35) than with anxiety (mean r = .13). Genetic influence on interpersonal cognitions was small (M = 3%), and associations between interpersonal cognitions and depression were mainly explained by environmental influences. These latter findings may result from interpersonal cognitions in young children, reflecting life experiences as opposed to trait-like cognitive biases.     

Internalizing Trajectories in Young Boys and Girls: The Whole is Not a Simple Sum of its Parts

There is support for a differentiated model of early internalizing emotions and behaviors, yet researchers have not examined the course of multiple components of an internalizing domain across early childhood. In this paper we present growth models for the Internalizing domain of the Infant-Toddler Social and Emotional Assessment and its component scales (General Anxiety, Separation Distress, Depression/Withdrawal, and Inhibition to Novelty) in a sample of 510 one- to three-year-old children. For all children, Internalizing domain scores decreased over the study, although girls had significantly higher initial levels and boys had steeper declines. General Anxiety increased over the study period and, when modeled individually, girls evidenced higher initial levels and greater increases. For all children, Separation Distress and Inhibition to Novelty decreased significantly over time, while Depression/Withdrawal remained low without change. Findings from our parallel process model, in which all components were modeled simultaneously, revealed that initial levels of internalizing scales were closely associated while rates of change were less closely related. Sex differences in variability around initial levels and rates of change emerged on some scales. Findings suggest that, for one- to three-year-olds, examining scales of the internalizing domain separately rather than as a unitary construct reveals more meaningful developmental and gender variation.     

Genetic and environmental influences on antisocial behavior: a meta-analysis of twin and adoption studies

A meta-analysis of 51 twin and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on antisocial behavior. The best fitting model included moderate proportions of variance due to additive genetic influences (.32), nonadditive genetic influences (.09), shared environmental influences (.16), and nonshared environmental influences (.43). The magnitude of familial influences (i.e., both genetic and shared environmental influences) was lower in parent-offspring adoption studies than in both twin studies and sibling adoption studies. Operationalization, assessment method, zygosity determination method, and age were significant moderators of the magnitude of genetic and environmental influences on antisocial behavior, but there were no significant differences in the magnitude of genetic and environmental influences for males and females.     

Maternal Life Stress and Subsequent Chinese Toddlers’ Social Adjustment: The Moderating Role of Inhibitory Control

The current study examined the links between maternal life stress and subsequent toddler behavior problems and social competence, as well as the potential moderating effects of cool and hot inhibitory control (IC) in mainland China. Participants included 89 mothers and their infants (42 boys, 47 girls). Mothers completed self-report measure of maternal life stress when their children were 1 year of age (M?=?1.18, SD?=?.07 at Time 1), and reported on their children’s social adjustment using the Chinese version of Infant-Toddler Social and Emotional Assessment (CITSEA) at Time 1 and again a year later (M?=?2.06, SD?=?.09 at Time 2). Toddler IC was assessed with laboratory tasks at Time 2. Structural equation modeling with a bootstrap resample of 1000 indicated that cool IC significantly moderated the longitudinal association between maternal life stress (T1) and latent construct of toddler behavior problems (T2), controlling for behavior problems at Time 1, child age and maternal age. Specifically, maternal life stress was associated with subsequent behavior problems only for toddlers who were low in cool IC. In comparison to the results of behavior problems, high levels of maternal life stress predicted subsequent low levels of social competence. Neither cool IC nor hot IC served as the moderator in the association between maternal life stress (T1) and toddler social competence (T2). These findings indicated that toddler cool IC may promote resilient adaptation and modify the links between maternal life stress and toddler behavior problems but not social competence.     

Early vocabulary development: Relationships with prelinguistic skills and early social-emotional/behavioral problems and competencies

The aim of this longitudinal study was to investigate early vocabulary development and its relationships with prelinguistic communication skills and social-emotional/behavioral (SEB¹) problems and competencies. The participants were 58 healthy Finnish-speaking children (30 girls, 28 boys). First, the concurrent relationships were investigated at the age of 18 months. Second, the relationships between prelinguistic communication skills and SEB problems and competencies at 18 months, and subsequent vocabulary scores at 24 and 30 months, were examined. Parental reports on early vocabulary (MacArthur Communicative Developmental Inventories; MCDI), prelinguistic communication skills (The Infant-Toddler Checklist of the Communication and Symbolic Behavior Scales Developmental Profile; ITC), SEB problems and competencies (Brief Infant-Toddler Social and Emotional Assessment; BITSEA) were gathered. Compared to boys, girls scored significantly higher on ITC Speech Composite at 18 months and expressive vocabulary measures at 18, 24, and 30 months. Vocabulary, as well as prelinguistic communication measures, correlated with SEB competencies at 18 months. Furthermore, vocabulary, as well as ITC Symbolic Composite and Total Score, correlated negatively with externalizing problem and SEB Total Problem scores. With regard to subsequent vocabulary development, all of the prelinguistic communication measures at 18 months correlated with vocabulary at 24 and 30 months. However, when accounted for gender and earlier vocabulary, only the associations with ITC Speech Composite and Total Score at 24 months remained significant. SEB Competencies at 18 months correlated positively, while externalizing problems at 18 months correlated negatively with vocabulary at 24 and 30 months, however, these associations did not remain significant, when accounted for gender and earlier vocabulary.     

Dramatic Increase in Heritability of Cognitive Development From Early to Middle Childhood: An 8-Year Longitudinal Study of 8,700 Pairs of Twins

ABSTRACT— The generalist genes hypothesis implies that general cognitive ability ( g ) is an essential target for understanding how genetic polymorphisms influence the development of the human brain. Using 8,791 twin pairs from the Twins Early Development Study, we examine genetic stability and change in the etiology of g assessed by diverse measures during the critical transition from early to middle childhood. The heritability of a latent g factor in early childhood is 23%, whereas shared environment accounts for 74% of the variance. In contrast, in middle childhood, heritability of a latent g factor is 62%, and shared environment accounts for 33%. Despite increasing importance of genetic influences and declining influence of shared environment, similar genetic and shared environmental factors affect g from early to middle childhood, as indicated by a cross-age genetic correlation of .57 and a shared environmental correlation of .65. These findings set constraints on how genetic and environmental variation affects the developing brain.     

The Etiology of Behavior Problems in 7-Year-Old Twins: Substantial Genetic Influence and Negligible Shared Environmental Influence for Parent Ratings and Ratings by Same and Different Teachers

Parent ratings of behavior problems in childhood show substantial genetic influence and modest shared environmental influence. However, few studies have compared these results to teacher ratings and no previous studies have compared same-teacher ratings to different-teacher ratings. 3,714 7-year-old twin pairs in the Twins Early Development Study were rated by parents and teachers on the Strengths and Difficulties Questionnaire. Substantial heritability and negligible shared environmental influence were found for data from all three raters for total behavior problems, hyperactivity, prosocial behavior, peer problems, conduct problems, and emotional symptoms. Sex-limitation models revealed similar results for males and females, although there was some evidence for greater heritability for boys, especially when twins were rated by the same teacher.     

Retrospective reports of parental physical affection and parenting style: a study of Finnish twins

Individual differences in parenting behaviors are due, in part, to genetic factors. In the present study, the authors sought to determine whether the degree of genetic influence varied according to the type of parental behavior under consideration. A population-based sample of 2,334 pairs of Finnish twins provided ratings on the physical affection, control, abusiveness, and indifference shown by their father and mother during childhood. Genetic influences, shared environmental influences, and nonshared environmental influences accounted for a small-to-medium proportion (17%-30%), a small-to-large proportion (22%-44%), and a medium-to-large proportion (37%-55%) of the variance in each parenting measure, respectively. There were no significant differences in effect sizes for mothers and fathers or across the 4 types of parental behavior. The genetic results may reflect characteristic styles with which parents respond to genetically influenced behaviors of individuals (gene-environment correlations) or individual perceptions of this relationship (gene-person correlation processes). The findings have implications for intervention and prevention work with families and for interpretation of evidence for interactions between genes and parenting behaviors.     

The etiology of variation in language skills changes with development: a longitudinal twin study of language from 2 to 12 years

The present study is the first long-term longitudinal examination of the etiology of individual differences in language from early childhood through to adolescence. We applied a multivariate latent factor genetic model to longitudinal data from the Twins Early Development Study in order to (a) compare the magnitude of genetic and environmental influences on language skills in early childhood (2, 3 and 4 years), middle childhood (7, 9 and 10 years), and early adolescence (12 years); and (b) determine to what extent the same genetic and environmental factors underlie variation in language skills at these three stages of language development. We found that while shared environmental influences appear to be dominant (latent factor c2 = .74) in early language, with a smaller though significant role for genetic factors (latent factor a2 = .24), the pattern is reversed by middle childhood such that genetic influences are substantially more important (latent factor a2 = .57-.63 at 7, 9 and 10 years and .47-.57 at 12 years) and shared environmental influences less so (latent factor c2 = .31-.37 at 7, 9 and 10 years and .31-.32 at 12 years). The increase in the heritability of language skills between early and middle childhood appears to be due to new genetic factors that come into play at that transition. In contrast, genetic factors remain stable from middle childhood through to early adolescence, and account for the phenotypic continuity in language skills across these two stages.     

A Genetically Informed Study of the Covariation Between Childhood Anxiety Dimensions and Social Competence

We investigated the nature of latent shared etiological elements in 398 Italian twin pairs aged 8–17, explaining covariation between high levels of anxiety symptoms and low social competence. We found significant negative correlations between Child Behaviour Checklist/6–18 Social Competence Scale and three (Panic Anxiety, Separation Anxiety, Social Anxiety) out of five Screen for Child Anxiety Related Disorders anxiety subscales. Results from causal analysis seem to exclude the hypothesis that co-occurrence between Anxiety Symptoms and Social Competence could be due to a direct phenotypic effect of one trait upon the other. Multivariate analysis suggested that both genetic and shared environmental components contribute to the phenotypic correlation between Social Competence and Anxiety Subscales, whereas unique environmental factors have a negligible influence. This means that both common genetic and shared environmental causal factors contribute simultaneously to increase risk of having low Social Competence and high Anxiety scores. In particular, covariation with Social Competence seems to be influenced by both genetic and shared environmental causal components in Separation Anxiety and Social Anxiety, whereas environmental factors have an irrelevant influence for covariation with Panic/Somatic Anxiety Subscale. Our results support the adoption of a broader view of the relationships between psychopathology and diminished social competences in childhood for both clinicians and educators.     

A Common Genetic Factor Explains the Covariation Among ADHD ODD and CD Symptoms in 9–10 Year Old Boys and Girls

Previous studies examining the covariation among Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD) and Conduct Disorder (CD) have yielded inconsistent results. Some studies have concluded that the covariation among these symptoms is due to common genetic influences, whereas others have found a common environmental overlap. The present study investigated the genetic and environmental correlations among these three childhood disorders, based on a sample of 1,219 twins, age 9–10 years. A latent externalizing behavior factor was found to explain the covariance among ADHD, ODD and CD symptoms. Genetic influences explained more than half of the variance in this externalizing factor in both boys and girls. There were also unique genetic and environmental influences in each set of symptoms, suggesting some etiological independence of the three disorders. Our findings have implications for molecular genetic studies trying to identify susceptibility genes for these disorders. This study was funded by NIMH (R01 MH58354). Catherine Tuvblad was supported by post-doctoral stipends from the Swedish Council for Working Life and Social Research (Project 2006-1501) and the Sweden-America Foundation. Adrian Raine was supported by NIMH (Independent Scientist Award K02 MH01114-08). We thank the Southern California Twin Project staff for their assistance in collecting data, and the twins and their families for their participation.     

Common Genetic but Specific Environmental Influences for Aggressive and Deceitful Behaviors in Preadolescent Males

Although both aggressive (AGG) and deceitful behaviors (DEC) are symptoms of childhood conduct problems, few studies have examined common vs. specific etiological influences. Early intervention is encouraged for conduct problems and findings from genetically informative studies can suggest whether interventions should focus on conduct problems in general or groupings of conduct problems more specifically. Twin model-fitting analyses were conducted on same and different teacher ratings of AGG and DEC for 872 9-year old male twin pairs. Common genetic influences were found to underlie the susceptibility for both AGG and DEC. The same teacher ratings resulted in somewhat higher heritability estimates than different teacher ratings. Results also indicated stronger environmental effects for DEC as compared with AGG, with a significant shared environmental component for same teachers and a substantial non-shared environmental component for different teachers. Our data suggest that AGG and DEC share risk genes and environmental factors may differentiate these two types of conduct problems. Characterizing these specific environmental factors may be useful when developing interventions.     

Can the home environment promote resilience for children born very preterm in the context of social and medical risk?

Relationships between the home environment and early developmental outcomes were examined in 166 children born very preterm in one tertiary maternity hospital to explore whether a more optimal home environment could promote resilience. In particular, we explored whether this effect was apparent over and above social risk and children's biological risk, as measured by cerebral white matter abnormality (WMA) evaluated using magnetic resonance imaging (MRI) at term-corrected age and length of hospital stay (LOS), and whether the effect of the home environment differed according to WMA. The home environment and social-emotional outcomes were assessed at 2years' corrected age using the Home Screening Questionnaire (HSQ) and the Infant-Toddler Social and Emotional Assessment (ITSEA). Children's cognitive and motor development was assessed using the Bayley Scales of Infant Development II. A more optimal home environment was associated with better cognitive and social-emotional development after adjusting for social risk, WMA, and LOS. Neonatal cerebral WMA moderated the relationship between the home environment and dysregulation problems only, such that the home environment had less effect on dysregulation for children with mild or moderate to severe WMA. The need to support parents to create an optimal home environment is discussed.     

Beyond the heritability of life satisfaction – The roles of personality and twin-specific influences

In a behavior genetic design, we investigated individual differences in life satisfaction and its relation to personality with respect to both internal and external influences. We questioned the absence of shared environment and examined the specific contribution of additive and non-additive genetic influences. We also tested for twin-specific environmental influences in a total sample of 1308 dyads including identical and fraternal twins, siblings, mother–child and grandparent–child pairs. The results showed substantial shared environmental influences on life satisfaction that varied between twins and non-twins, supporting twin-specific environmental influences. Additive and non-additive genetic influences on life satisfaction were completely shared with personality. The remaining variance could be explained by unique non-shared environmental influences for life satisfaction independent of personality.     

The Association Between Internalizing and Externalizing Behavior in Childhood and Early Adolescence: Genetic or Environmental Common Influences?

This study analyzed the genetic and environmental influences on internalizing and externalizing behavior problems and the nature of their cooccurrence in a national Norwegian twin sample. The sample comprised 526 identical and 389 fraternal same-sexed twin pairs from five birth cohorts, aged 5-6, 8-9, 12-13, 13-14, and 14-15 years. Behavior problems were assessed by parental ratings on the Child Behavior Checklist. A model of additive genetic, shared, and nonshared environmental influences was fitted to both internalizing and externalizing behavior in four sex and age groups. The considerable covariance,r = .51 to .58, between these traits is accounted for mainly by common environmental components; this effect was most marked in the 5 to 9-year olds. Concordance rates for children scoring above 1 standard deviation from the total sample mean on the internalizing scale only, externalizing scale only, or both indicated stronger genetic influences for internalizing or externalizing problems only than for combined problems.     

SOCIOEMOTIONAL AND BEHAVIORAL PROBLEMS IN TODDLERS WITH LANGUAGE DELAY

Toddlers with language delay are at risk for persistent developmental and behavioral difficulties; however, the association between socioemotional/behavior problems and language in young children is not well understood. This study explored socioemotional/behavior problems in a unique sample of toddlers with language delays using a measure developed explicitly for this age group. Toddlers identified by 18 months with receptive and expressive language delay (LD; n = 30) or typical development (TD; n = 61) were evaluated at 18 and 24 months of age using the Infant‐Toddler Social and Emotional Assessment (ITSEA) and the Mullen Scales of Early Learning. Compared to toddlers who had TD, toddlers with LD had significantly more concerning scores at 18 and 24 months on all ITSEA domains. The rate of “clinical concern” on most domains was not high in either group, except that >60% of LD toddlers were in the clinical concern range on the Competence domain. Socioemotional/behavioral problems were dimensionally related to receptive and expressive language, with greater language delay associated with more concerning ITSEA scores. Socioemotional and behavioral problems are related to receptive and expressive language abilities in 18‐ and 24‐month‐olds, indicating the need for screening of both types of concerns in toddlers identified with potential language delays.     

Human values: Genetic and environmental effects on five lexically derived domains and their facets

Whereas a substantial genetic component of Conservatism and Religiosity is well documented, there is little evidence with respect to the behavior genetics of other aspects of human values. A sample of 157 monozygotic and 74 dizygotic twins reared together received the Austrian Value Questionnaire (AVQ), which measures a broad variety of value domains and their facets, found by the lexical approach in the German language. Family resemblance of Intellectualism, Harmony, Materialism, and Conservatism was best explained by additive or dominance genetic and non-shared environmental effects, whereas the influence of the environment shared by twins was negligible. In contrast, Religiosity was transmitted by additive genetic, shared and non-shared environmental influences. At the level of facets, the Intellectualism and Harmony showed a homogenous etiology while Religiosity, Materialism, and Conservatism were etiologically heterogeneous.     

Preterm birth and maternal sensitivity: Findings from a non-western country

IntroductionAlthough there are several studies on maternal sensitivity of preterm-born children conducted in Western countries, the factors affecting the sensitivity of mothers of preterm infants have not been investigated outside the Western context.ObjectivesThis study aimed to compare maternal sensitivity of preterm children at 18 months of corrected age with their healthy term-born peers and explore the factors associated with maternal sensitivity in a middle-income non-Western country. Moreover, the associations of maternal sensitivity with socio-demographic factors, maternal depression, and social-emotional competency and behavior problems of infants were investigated.MethodsIn total, 70 (40 preterm-born and 30 term-born) mother-child dyads participated in this study. An observation-based measurement tool, Maternal Sensitivity Scale, was used to assess maternal sensitivity. Social-emotional competency and behavior problems of infants were evaluated via The Turkish version of the Brief Infant-Toddler Social Emotional Assessment. Maternal depressive symptoms were assessed via the Beck Depression Inventory. In addition, a demographic information form was filled out by the mothers.ResultsMaternal sensitivity scores of preterm infants were significantly lower compared to term infants. Depressive symptoms scores and employment status of mothers, socio-economic status (SES), gestational age, breastfeeding duration, and behavior problems of children were the factors related to maternal sensitivity scores. In hierarchical regression analysis, SES and gestational age were the strongest predictors of maternal sensitivity. After controlling SES and gestational age, maternal depressive symptoms scores negatively predicted maternal sensitivity scores.ConclusionThis study pointed out the factors associated with the maternal sensitivity of preterm infants outside the Western context. Interventions to improve sensitive parenting behaviors of preterm infants are needed, especially in socio-economically disadvantaged groups.