Phenotypic and genetic differentiation of anxiety-related behaviors in middle childhood

Fluctuations in Maternal Depressive Symptoms, Anxiety, and Anger and Children's Depression Risks in Middle Childhood

Research suggests a robust link between the severity of maternal depression and children's depression risks in middle childhood. Variations among depressed mothers in terms of affective dysregulation and frequent mood changes are also observed. However, the understanding of how fluctuations in maternal depressive symptoms and negative affect influence children is limited. Guided by life history theory, the current study tested whether the degree of fluctuations in maternal depressive symptoms, anxiety, and anger contributed to depression risks among school-aged children. The sample included 1,364 families where maternal depressive symptoms, anxiety, and anger were longitudinally assessed when children were in Grades 1, 3, 5, and 6. Children's anxious depression and withdrawn depression behaviors were rated in Grades 1, 3, 4, 5, and 6 by two caregivers. Parallel latent growth curve analyses revealed that, first, fluctuations in maternal anxiety from Grade 1 to 6 were related to an increase in children's withdrawn depression over the same period. Second, mean maternal anger over time was related to higher mean levels of child anxious and withdrawn depression, yet fluctuations in maternal anger were not linked to child outcomes. Findings support life history theory by highlighting the degree of fluctuations in maternal anxiety as a source of environmental unpredictability and reveal different effects of maternal anxiety and anger in the intergenerational transmission of depression, with important theoretical and clinical implications.

The Influence of Genetic and Environmental Factors on Anxiety among Chinese Adolescents: A Twin Study

This study explored the influence of genetic and environmental factors on adolescent anxiety. Ninety-eight monozygotic and dizygotic twins from Chongqing, China (aged 15-18 years) were assessed for anxiety with the Self-Rating Anxiety Scale (SAS). The Parenting Styles and Dimensions Questionnaire (PSDQ) and Strengths and Difficulties Questionnaire (SDQ) were applied to assess environmental factors. Venous blood was drawn from the twins for zygosity determination. Structural equation modeling was performed to evaluate the effects of additive genetic factors (A), common environmental factors (C), and individual-specific environmental factors (E) on adolescent anxiety. The estimates of A and E on adolescent anxiety were 0.34 (95% CI = 0.12-0.53) and 0.66 (95% CI:0.47-0.89), respectively. The environment played an important role in adolescent anxiety. Adolescent anxiety was significantly positively correlated with peer relations (r = 0.606, p < 0.05) and negatively correlated with prosocial behavior (r = 0.207, p < 0. 05). No sex differences were observed. Adolescent anxiety was influenced by both genetic and environmental factors. The individual-specific environmental factors played an important role. Consideration of these variables will facilitate the targeted and individualized implementation of specific interventions for adolescent anxiety.

Prospective associations between internalising symptoms and educational achievement in youth: A monozygotic twin differences study

BACKGROUND

Educational achievement is an independent predictor of many life outcomes and so it is important to understand its causes and correlates. Internalising symptoms, encompassing anxiety and depression symptoms, are one candidate influence.

METHODS

Using a prospective and genetically-informative design, the present study investigated the associations between internalising symptoms and educational achievement, controlling for IQ at age 7 years and socioeconomic status, among participants of the Twin and Early Development Study (up to N = 10,791). Internalising symptoms were measured by the parent-rated Anxiety Related Behaviours Questionnaire (ages 7, 9, 16 years), and educational attainment were indexed by UK-wide standardized examination results at ages 16 and 18 years, and self-reported transition to university education.

RESULTS

Negative affect was the only internalising symptom subtype that was uniquely associated with academic underachievement at all timepoints, from mid-adolescence to early adulthood. The association between negative affect and achievement became non-significant when using MZ twin difference scores, suggesting that the majority of the relationship is accounted for by genetic and shared environmental effects.

LIMITATIONS

Limitations include the reliance on parent-reported internalising symptoms.

CONCLUSIONS

Negative affect in youth may be an important marker of later academic underachievement. Findings suggest that academic underachievement is not simply a consequence of the disruption caused by negative affect symptoms and therefore educational interventions may be required to optimise outcomes.

Extracting stability increases the SNP heritability of emotional problems in young people

Twin studies have shown that emotional problems (anxiety and depression) in childhood and adolescence are moderately heritable (~20-50%). In contrast, DNA-based 'SNP heritability' estimates are generally <15% and non-significant. One notable feature of emotional problems is that they can be somewhat transient, but the moderate stability seen across time and across raters is predominantly influenced by stable genetic influences. This suggests that by capturing what is in common across time and across raters, we might be more likely to tap into any underlying genetic vulnerability. We therefore hypothesised that a phenotype capturing the pervasive stability of emotional problems would show higher heritability. We fitted single-factor latent trait models using 12 emotional problems measures across ages 7, 12 and 16, rated by parents, teachers and children themselves in the Twins Early Development Study sample. Twin and SNP heritability estimates for stable emotional problems (N = 6110 pairs and 6110 unrelated individuals, respectively) were compared to those for individual measures. Twin heritability increased from 45% on average for individual measures to 76% (se = 0.023) by focusing on stable trait variance. SNP heritability rose from 5% on average (n.s.) to 14% (se = 0.049; p = 0.002). Heritability was also higher for stable within-rater composites. Polygenic scores for both adult anxiety and depression significantly explained variance in stable emotional problems (0.4%; p = 0.0001). The variance explained was more than in most individual measures. Stable emotional problems also showed significant genetic correlation with adult depression and anxiety (average = 52%). These results demonstrate the value of examining stable emotional problems in gene-finding and prediction studies.

The Shared Etiology of Attentional Control and Anxiety: An Adolescent Twin Study

We investigated the etiology of attentional control (AC) and four different anxiety symptom types (generalized, obsessive-compulsive, separation, and social) in an adolescent sample of over 400 twin pairs. Genetic factors contributed to 55% of the variance in AC and between 43 and 58% of the variance in anxiety. Negative phenotypic associations between AC and anxiety indicated that lower attentional ability is related to increased risk for all 4 anxiety categories. Genetic correlations between AC and anxiety phenotypes ranged from -.36 to -.47, with evidence of nonshared environmental covariance between AC and generalized and separation anxiety. Results suggest that AC is a phenotypic and genetic risk factor for anxiety in early adolescence, with somewhat differing levels of risk depending on symptomatology.

Aetiological influences on stability and change in emotional and behavioural problems across development: a systematic review

Emotional and behavioural problems in childhood and adolescence can be chronic and are predictive of future psychiatric problems. Understanding what factors drive the development and maintenance of these problems is therefore crucial. Longitudinal behavioural genetic studies using twin, sibling or adoption data can be used to explore the developmental aetiology of stability and change in childhood and adolescent psychopathology. We present a systematic review of longitudinal, behavioural genetic analyses of emotional and behavioural problems between ages 0 to 18 years. We identified 58 studies, of which 19 examined emotional problems, 30 examined behavioural problems, and 9 examined both. In the majority of studies, stability in emotional and behavioural problems was primarily genetically influenced. Stable environmental factors were also widely found, although these typically played a smaller role. Both genetic and environmental factors were involved in change across development. We discuss the findings in the context of the wider developmental literature and make recommendations for future research.

Genetic and environmental influences on obsessive-compulsive behaviour across development: a longitudinal twin study

BACKGROUND

Little is known about the factors influencing the stability of obsessive-compulsive behaviour (OCB) from childhood to adolescence. The current study aimed to investigate: (1) the stability of paediatric OCB over a 12-year period; (2) the extent to which genetic and environmental factors influence stability; and (3) the extent to which these influences are stable or dynamic across development.

METHOD

The sample included 14 743 twins from a population-based study. Parental ratings of severity of OCB were collected at ages 4, 7, 9 and 16 years.

RESULTS

OCB was found to be moderately stable over time. The genetic influence on OCB at each age was moderate, with significant effects also of non-shared environment. Genetic factors exerted a substantial influence on OCB persistence, explaining 59-80% of the stability over time. The results indicated genetic continuity, whereby genetic influences at each age continue to affect the expression of OCB at subsequent ages. However, we also found evidence for genetic attenuation in that genetic influences at one age decline in their influence over time, and genetic innovation whereby new genes 'come on line' at each age. Non-shared environment influenced stability of OCB to a lesser extent and effects were largely unique to each age and displayed negligible influences on OCB at later time points.

CONCLUSIONS

OCB appears to be moderately stable across development, and stability is largely driven by genetic factors. However, the genetic effects are not entirely constant, but rather the genetic influence on OCB appears to be a developmentally dynamic process.

Genetic and environmental contributions to social anxiety across different ages: a meta-analytic approach to twin data

Social anxiety disorder (SAD) and social anxiety symptoms (SAS) have been largely studied both epidemiologically and genetically, however, estimates of genetic and environmental influences for these phenotypes widely vary across reports. Based upon available literature, 13 cohorts (42,585 subjects) were included in 3 meta-analytic estimates of the standardized variance components of aetiological influences on SAD/SAS, on the effect of age and of phenotype (symptoms vs. diagnosis). The proportions of variance accounted for by genetic and environmental factors were calculated by averaging estimates among studies, and pondered by the number of individuals in each sample. Meta-analytic estimations showed that genetic and non-shared environmental factors explain most of individual differences for SAD/SAS. In adults, the genetic contribution was half than that in younger patients, with higher contribution of non-shared environmental influences. In contrast, the shared environmental factors seem to be less relevant.

Characterization of psychotic experiences in adolescence using the specific psychotic experiences questionnaire: findings from a study of 5000 16-year-old twins

We aimed to characterize multiple psychotic experiences, each assessed on a spectrum of severity (ie, quantitatively), in a general population sample of adolescents. Over five thousand 16-year-old twins and their parents completed the newly devised Specific Psychotic Experiences Questionnaire (SPEQ); a subsample repeated it approximately 9 months later. SPEQ was investigated in terms of factor structure, intersubscale correlations, frequency of endorsement and reported distress, reliability and validity, associations with traits of anxiety, depression and personality, and sex differences. Principal component analysis revealed a 6-component solution: paranoia, hallucinations, cognitive disorganization, grandiosity, anhedonia, and parent-rated negative symptoms. These components formed the basis of 6 subscales. Correlations between different experiences were low to moderate. All SPEQ subscales, except Grandiosity, correlated significantly with traits of anxiety, depression, and neuroticism. Scales showed good internal consistency, test-retest reliability, and convergent validity. Girls endorsed more paranoia, hallucinations, and cognitive disorganization; boys reported more grandiosity and anhedonia and had more parent-rated negative symptoms. As in adults at high risk for psychosis and with psychotic disorders, psychotic experiences in adolescents are characterized by multiple components. The study of psychotic experiences as distinct dimensional quantitative traits is likely to prove an important strategy for future research, and the SPEQ is a self- and parent-report questionnaire battery that embodies this approach.

Measuring anxiety as a treatment endpoint in youth with autism spectrum disorder

Despite the high rate of anxiety in individuals with autism spectrum disorder (ASD), measuring anxiety in ASD is fraught with uncertainty. This is due, in part, to incomplete consensus on the manifestations of anxiety in this population. Autism Speaks assembled a panel of experts to conduct a systematic review of available measures for anxiety in youth with ASD. To complete the review, the panel held monthly conference calls and two face-to-face meetings over a fourteen-month period. Thirty eight published studies were reviewed and ten assessment measures were examined: four were deemed appropriate for use in clinical trials, although with conditions; three were judged to be potentially appropriate, while three were considered not useful for clinical trials assessing anxiety. Despite recent advances, additional relevant, reliable and valid outcome measures are needed to evaluate treatments for anxiety in ASD.

First genome-wide association study on anxiety-related behaviours in childhood

BACKGROUND

Twin studies have shown that anxiety in a general population sample of children involves both domain-general and trait-specific genetic effects. For this reason, in an attempt to identify genes responsible for these effects, we investigated domain-general and trait-specific genetic associations in the first genome-wide association (GWA) study on anxiety-related behaviours (ARBs) in childhood.

METHODS

The sample included 2810 7-year-olds drawn from the Twins Early Development Study (TEDS) with data available for parent-rated anxiety and genome-wide DNA markers. The measure was the Anxiety-Related Behaviours Questionnaire (ARBQ), which assesses four anxiety traits and also yields a general anxiety composite. Affymetrix GeneChip 6.0 DNA arrays were used to genotype nearly 700,000 single-nucleotide polymorphisms (SNPs), and IMPUTE v2 was used to impute more than 1 million SNPs. Several GWA associations from this discovery sample were followed up in another TEDS sample of 4804 children. In addition, Genome-wide Complex Trait Analysis (GCTA) was used on the discovery sample, to estimate the total amount of variance in ARBs that can be accounted for by SNPs on the array.

RESULTS

No SNP associations met the demanding criterion of genome-wide significance that corrects for multiple testing across the genome (p<5×10(-8)). Attempts to replicate the top associations did not yield significant results. In contrast to the substantial twin study estimates of heritability which ranged from 0.50 (0.03) to 0.61 (0.01), the GCTA estimates of phenotypic variance accounted for by the SNPs were much lower 0.01 (0.11) to 0.19 (0.12).

CONCLUSIONS

Taken together, these GWAS and GCTA results suggest that anxiety--similar to height, weight and intelligence--is affected by many genetic variants of small effect, but unlike these other prototypical polygenic traits, genetic influence on anxiety is not well tagged by common SNPs.

Bringing a developmental perspective to anxiety genetics

Despite substantial recent advancements in psychiatric genetic research, progress in identifying the genetic basis of anxiety disorders has been limited. We review the candidate gene and genome-wide literatures in anxiety, which have made limited progress to date. We discuss several reasons for this hindered progress, including small samples sizes, heterogeneity, complicated comorbidity profiles, and blurred lines between normative and pathological anxiety. To address many of these challenges, we suggest a developmental, multivariate framework that can inform and enhance anxiety phenotypes for genetic research. We review the psychiatric and genetic epidemiological evidence that supports such a framework, including the early onset and chronic course of anxiety disorders, shared genetic risk factors among disorders both within and across time, and developmentally dynamic genetic influences. We propose three strategies for developmentally sensitive phenotyping: examination of early temperamental risk factors, use of latent factors to model underlying anxiety liability, and use of developmental trajectories as phenotypes. Expanding the range of phenotypic approaches will be important for advancing studies of the genetic architecture of anxiety disorders.

Disentangling the associations between autistic-like and internalizing traits: a community based twin study

Internalizing difficulties are prevalent in children with autism spectrum disorders (ASD), yet little is known about the underlying cause of this comorbidity. It is also unclear which types of autistic-like and internalizing difficulties are most strongly associated. The current study investigated the phenotypic and etiological associations between specific autistic-like traits and internalizing traits within a population-based sample. Parent-reported data were analyzed from 7,311 twin pairs at age 7 to 8 years. Structural equation modeling revealed distinguishable patterns of overlap between the three autistic-like traits (social difficulties, communication problems and repetitive/restricted behaviors) and four subtypes of internalizing traits (social anxiety, fears, generalized anxiety, negative affect). Although all phenotypic associations were modest (rph = 0.00-0.36), autistic-like communication impairments and repetitive/restricted behaviors correlated most strongly with generalized anxiety and negative affect both phenotypically and genetically. Conversely, autistic-like social difficulties showed little overlap with internalizing behaviors. Disentangling these associations and their etiological underpinnings may help contribute to the conceptualization and diagnosis of 'comorbidity' within ASD and internalizing disorders.

Stable genetic influence on anxiety-related behaviours across middle childhood

We examined the aetiology of anxiety symptoms in an unselected population at ages 7 and 9, a period during which anxiety disorders first begin to develop (mean age at onset is 11 years). Specifically, the aim of the study was to investigate genetic and environmental continuity and change in components of anxiety in middle childhood. Parents of over 3,500 twin pairs completed the Anxiety-Related Behaviours Questionnaire (ARBQ) when twins were 7 and 9 years old. Multivariate-longitudinal analyses were conducted to examine genetic and environmental influences on stability and change in four anxiety scales: Negative Cognition, Negative Affect, Fear and Social Anxiety. We found moderate temporal stability in all four scales from 7 to 9 years (correlations ranging from 0.45 to 0.54) and moderate heritability (average 54%). Both shared and non-shared environmental influences were modest (average 18%–28% respectively). Genetic factors (68%) explained most of the homotypic continuity in anxiety. We show that homotypic continuity of Anxiety-Related Behaviours (i.e. the continuation of one specific type of anxiety over time) was largely driven by genetic factors. In contrast, though more varied, heterotypic continuity between some traits (i.e. the change from one type of anxiety-related behaviour into another over time) was mainly due to shared-environmental factors.

Integrating etiological models of social anxiety and depression in youth: evidence for a cumulative interpersonal risk model

Models of social anxiety and depression in youth have been developed separately, and they contain similar etiological influences. Given the high comorbidity of social anxiety and depression, we examine whether the posited etiological constructs are a correlate of, or a risk factor for, social anxiety and/or depression at the symptom level and the diagnostic level. We find core risk factors of temperament, genetics, and parent psychopathology (i.e., depression and anxiety) are neither necessary nor sufficient for the development of social anxiety and/or depression. Instead, aspects of children's relationships with parents and/or peers either mediates (i.e., explains) or moderates (i.e., interacts with) these core risks being related to social anxiety and/or depression. We then examine various parent- and peer-related constructs contained in the separate models of social anxiety and depression (i.e., parent-child attachment, parenting, social skill deficits, peer acceptance and rejection, peer victimization, friendships, and loneliness). Throughout our review, we report evidence for a Cumulative Interpersonal Risk model that incorporates both core risk factors and specific interpersonal risk factors. Most studies fail to consider comorbidity, thus little is known about the specificity of these various constructs to depression and/or social anxiety. However, we identify shared, differential, and cumulative risks, correlates, consequences, and protective factors. We then put forth demonstrated pathways for the development of depression, social anxiety, and their comorbidity. Implications for understanding comorbidity are highlighted throughout, as are theoretical and research directions for developing and refining models of social anxiety, depression, and their comorbidity. Prevention and treatment implications are also noted.

A twin study of computer anxiety in Turkish adolescents

The present study investigated computer anxiety within a sample of Turkish twins aged 10-18. A total of 185 twin-pairs participated in the study. Of the twins, 64 pairs (34.6 percent) were monozygotic (MZ) and 121 pairs (65.4 percent) were dizygotic (DZ). Of the 121 DZ twins, 54 pairs (44.63 percent) were same-sex twins and 67 pairs (55.37 percent) were opposite-sex twins. Computer anxiety was assessed using Computer Anxiety Rating Scale-Turkish Version (CARS-TV), one of the three main scales of "Measuring Technophobia Instruments" developed by Rosen and Weil. The results of paired t test comparisons showed no significant differences in MZ and same-sex DZ twin-pairs' levels of computer anxiety. On the other hand, a significant difference was found in opposite-sex DZ twin-pairs' level of computer anxiety. Interesting enough, males appeared to be more computer anxious than their female co-twins. In the present study, using Falconer's formula, heritability estimate for computer anxiety was derived from correlations based on MZ and DZ twins' mean scores on CARS-TV. The results showed that 57 percent of the variance in computer anxiety was from genetics and 41.5 percent was from nonshared environmental factors. Shared environmental influence, on the other hand, was very small and negligible. Interpretations of results and potential directions for future research are presented.

Patterns of anxiety symptoms in toddlers and preschool-age children: evidence of early differentiation

The degree to which young children's anxiety symptoms differentiate according to diagnostic groupings is under-studied, especially in children below the age of 4 years. Theoretical (confirmatory factor analysis, CFA) and statistical (exploratory factor analysis, EFA) analytical methods were employed to test the hypothesis that anxiety symptoms among 2-3-year-old children from a non-clinical, representative sample would differentiate in a manner consistent with current diagnostic nosology. Anxiety symptom items were selected from two norm-referenced parent-report scales of child behavior. CFA and EFA results suggested that anxiety symptoms aggregate in a manner consistent with generalized anxiety, obsessive-compulsive symptoms, separation anxiety, and social phobia. Multi-dimensional models achieved good model fit and fit the data significantly better than undifferentiated models. Results from EFA and CFA methods were predominantly consistent and supported the grouping of early childhood anxiety symptoms into differentiated, diagnostic-specific categories.

The neurobiology of anxiety disorders: brain imaging, genetics, and psychoneuroendocrinology

Anxiety disorders are highly comorbid with each other and with major depressive disorder. As syndromes, anxiety and mood disorders share many symptoms, and several treatments are effective for both. Despite this overlap, there exist many distinguishing features that support the continued classification of individual anxiety disorders that are distinct from each other and from major depression. The goal of this article is to describe the key biological similarities and differences between anxiety disorders.

The role of genes and environment in shaping co-occurrence of DSM-IV defined anxiety dimensions among Italian twins aged 8-17

This study investigated the ultimate causes of co-variation between symptoms of four common DSM-IV anxiety dimensions - Generalized Anxiety, Panic, Social Phobia and Separation Anxiety disorder - assessed with the Italian version of the Screen for Child Anxiety-Related Emotional Disorders questionnaire in a sample of 378 twin pairs aged 8-17 from the population-based Italian Twin Register. Genetic and environmental proportions of covariance between the targeted anxiety dimensions were estimated by multivariate twin analyses. Genetic influences (explaining from 58% to 99% of covariance) and unique environmental factors were the sole sources of co-variation for all phenotypes under study. Genetic influences associated with different anxiety dimensions coincide remarkably, as indicated by genetic correlations ranging from 0.40 to 0.61, while unique environmental overlap is less substantial. Thus, while additive genetic effects are important in explaining why children report symptoms from multiple anxiety disorders, environmental idiosyncratic factors seem to play a marginal role in shaping the co-occurrence of different anxiety dimensions in childhood.

Temperament and the environment in the etiology of childhood anxiety

Anxiety disorders are prevalent throughout childhood and adolescence. As such, identifying the factors and mechanisms that precede, maintain, or exacerbate anxiety disorders is essential for the development of empirically based prevention and intervention programs. The current review focuses on child temperament (i.e., behavioral inhibition) and the child's environment, including parenting, childcare, and peer relationships, as these factors have been linked to internalizing problems and anxiety diagnoses. Research programs are needed that examine the associations between the environment and anxiety in temperamentally at-risk populations. In order to be successful, early intervention and prevention programs require a more detailed analysis of the interplay between various environmental contexts, both distal and proximal to the child, and the child's temperamental reactivity to novelty and threat. Furthermore, conducting these investigations across multiple levels of analysis in large-scale, longitudinal samples would be an important addition to the literature on the developmental psychopathology of anxiety.

The neurobiology of anxiety disorders: brain imaging, genetics, and psychoneuroendocrinology

Anxiety disorders are highly comorbid with each other and with major depressive disorder. As syndromes, anxiety and mood disorders share many symptoms, and several treatments are effective for both. Despite this overlap, there exist many distinguishing features that support the continued classification of individual anxiety disorders that are distinct from each other and from major depression. The goal of this article is to describe the key biological similarities and differences between anxiety disorders.

Investigating the association between autistic-like and internalizing traits in a community-based twin sample

OBJECTIVES

Recent research has suggested that children with autistic spectrum disorders often experience comorbid symptoms of anxiety and depression. However, despite this overlap, no quantitative genetic studies have addressed the phenotypic overlap and the etiologic association between internalizing and autistic-like traits within the general population. This study aimed to investigate the phenotypic and etiologic relation between internalizing and autistic-like traits using a community-based twin sample.

METHOD

We investigated the co-occurrence of these traits in a population-based sample of 3,233 twin pairs aged 8 to 9 years, using both parent- and teacher-report questionnaires. Bivariate structural equation modeling techniques were used to determine the extent to which internalizing and autistic-like traits shared common genetic and environmental influences.

RESULTS

Our results showed that there was a modest phenotypic correlation (r = 0.26-0.29) between autistic-like and internalizing traits. The traits were both substantially heritable but were largely independent with regard to their genetic influences (r(G) = 0.12-0.19). Shared environmental influences were modest but were largely common to both traits. Similar results were found using both parent- and teacher-reported data.

CONCLUSIONS

Internalizing and autistic-like traits showed moderate phenotypic overlap within the general population. This association was explained in small part by shared genetic factors, but the results suggested that most genetic influences were specific to either internalizing traits or autistic traits. Given these findings, we discuss the potential mechanisms that may underlie the relation between these traits.