Assessing gene-environment interactions on anxiety symptom subtypes across childhood and adolescence

A Twin Study of the Relationships between Cognitive Disengagement Syndrome and Anxiety Phenotypes in Childhood and Adolescence

Data on the etiological factors underlying the co-occurrence of Cognitive Disengagement Syndrome (CDS) with anxiety symptoms are very limited. The present study investigated the nature of latent shared etiological elements in 400 Italian twin pairs aged 8-18, explaining the covariation between CDS and anxiety symptoms. Preliminary analysis demonstrated significant correlations between Child Behaviour Checklist/6-18 Sluggish Cognitive Tempo Scale and two (Somatic Anxiety, Generalized 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 CDS and Anxiety Symptoms could be due to a direct phenotypic effect of one trait upon the other. Model fitting-analysis indicated that the aforementioned associations were partially explained by shared genetic and environmental factors influencing a common liability factor. A latent variable capturing the covariation between CDS and anxiety problems can be considered as a unifying (patho)physiological mechanism/system common to these constructs. Our results support the adoption of a broader view of the relationships between CDS and anxiety phenotypes in childhood and adolescence for both clinicians and educators.

The clinical characterization of the adult patient with an anxiety or related disorder aimed at personalization of management

The clinical construct of "anxiety neurosis" was broad and poorly defined, so that the delineation of specific anxiety disorders in the DSM-III was an important advance. However, anxiety and related disorders are not only frequently comorbid, but each is also quite heterogeneous; thus diagnostic manuals provide only a first step towards formulating a management plan, and the development of additional decision support tools for the treatment of anxiety conditions is needed. This paper aims to describe systematically important domains that are relevant to the personalization of management of anxiety and related disorders in adults. For each domain, we summarize the available research evidence and review the relevant assessment instruments, paying special attention to their suitability for use in routine clinical practice. We emphasize areas where the available evidence allows the clinician to personalize the management of anxiety conditions, and we point out key unmet needs. Overall, the evidence suggests that we are becoming able to move from simply recommending that anxiety and related disorders be treated with selective serotonin reuptake inhibitors, cognitive-behavioral therapy, or their combination, to a more complex approach which emphasizes that the clinician has a broadening array of management modalities available, and that the treatment of anxiety and related disorders can already be personalized in a number of important respects.

Family socioeconomic status amplifies unique environmental influences on the dynamics of adolescent daily positive affective process

BACKGROUND AND OBJECTIVE

Affective processes as complex dynamical systems happen in people's daily lives. Affective dynamics characterizing unique features of individual affective systems are linked with long-term developmental outcomes. This study investigated genetic and environmental contributions, and the moderation by family socioeconomic status (SES), to two affective dynamics characterizing affective system sensitivity to the relative levels and change in affect, respectively.

METHODS

Using a sample of 490 17-year-old twins (41.1% males, 93.9% White) in a 40-day-long daily diary design, dynamical systems modeling estimated individual affective dynamics of positive and negative affect. Twin modeling examined genetic and environmental contributions to affective dynamics as well as the moderation of SES.

RESULTS

For both positive and negative affect, system sensitivity to the relative levels of affect was predominantly under unique environmental influences with negligible genetic influences; system sensitivity to the change in affect was affected by both genetic and unique environmental influences. SES amplifies unique environmental influences on sensitivity to the change in positive affect.

CONCLUSIONS

These findings highlight different genetic and environmental origins of different adolescent affective dynamics in their daily lives, and suggest that macro contexts could influence micro timescale affective dynamics.

A Population-Based Twin Study of Childhood Irritability and Internalizing Syndromes

Childhood irritability exhibits significant theoretical and empirical associations with depression and anxiety syndromes. The current study used the twin design to parse genetic and environmental contributions to these relationships. Children ages 9-14 from 374 twin pairs were assessed for irritability and symptoms of depression, generalized anxiety, panic, social phobia, and separation anxiety using dimensional self-report instruments. Multivariate structural equation modeling decomposed the correlations between these syndromes into genetic and environmental components to examine shared and specific risk domains. Irritability had significant associations with each internalizing symptom domain. Genetic contributions to irritability are moderately correlated with genetic risk for symptoms of depression, generalized anxiety, and separation anxiety with weaker overlap with the other anxiety syndromes. Familial and specific environmental risk factors explained covariation among syndromes and indicated potential syndrome-specific risk. There is substantial overlap among the genetic and environmental factors that influence individual differences in irritability and those that increase liability for depression and anxiety symptoms in children. These findings deepen the current understanding of childhood internalizing risk factors and provide important implications for syndrome prediction and susceptibility gene discovery efforts.

Childhood socioeconomic status and longitudinal patterns of alcohol problems: Variation across etiological pathways in genetic risk

Childhood socioeconomic status (SES) is an important aspect of early life environment associated with later life health/health behaviors, including alcohol misuse. However, alcohol misuse is modestly heritable and involves differing etiological pathways. Externalizing disorders show significant genetic overlap with substance use, suggesting an impulsivity pathway to alcohol misuse. Alcohol misuse also overlaps with internalizing disorders, suggesting alcohol is used to cope. These differing pathways could lead to different patterns over time and/or differential susceptibility to environmental conditions, such as childhood SES. We examine whether: 1) genetic risk for externalizing and internalizing disorders influence trajectories of alcohol problems across adolescence to adulthood, 2) childhood SES alters genetic risk these disorders on trajectories of alcohol problems, and 3) these patterns are consistent across sex. We find modest evidence of gene-environment interaction. Higher childhood SES increases the risk of alcohol problems in late adolescence/early adulthood, while lower childhood SES increases the risk of alcohol problems in later adulthood, but only among males at greater genetic risk of externalizing disorders. Females from lower SES families with higher genetic risk of internalizing or externalizing disorders have greater risk of developing alcohol problems.

No gene-by-environment interaction of BDNF Val66Met polymorphism and childhood maltreatment on anxiety sensitivity in a mixed race adolescent sample

Background: Anxiety disorders in youth are attributable to multiple causal mechanisms, comprising biological vulnerabilities, such as genetics and temperament, and unfavourable environmental influences, such as childhood maltreatment (CM). Objective: A gene-environment (G x E) interaction study was conducted to determine the interactive effect of the BDNF Val66Met polymorphism and CM to increase susceptibility to anxiety sensitivity (AS) in a sample of mixed race adolescents. Method: Participants (n = 308, mean age = 15.8 years) who were all secondary school students and who completed measures for AS and CM were genotyped for the BDNF Val66Met polymorphism. Hierarchical multiple regression analysis was conducted to assess G x E influences on AS. Age and gender were included in the models as covariates as age was significantly associated with AS total score (p < .05), and females had significantly higher AS scores than males (p < .05). Results: A main effect of CM on AS was evident (p < .05), however, no main effect of BDNF genotype on AS was observed (p > .05). A non-significant G x E effect on AS was revealed (p < .05). Conclusions: Our results suggest that CM does not have a moderating role in the relationship between the BDNF Val66Met genotype and the increased risk of anxiety-related phenotypes, such as AS. Given the exploratory nature of this study, findings require replication in larger samples and adjustment for population stratification to further explore the role of BDNF Val66Met and CM on AS in mixed race adolescents.

Anxiety disorders

Anxiety disorders constitute the largest group of mental disorders in most western societies and are a leading cause of disability. The essential features of anxiety disorders are excessive and enduring fear, anxiety or avoidance of perceived threats, and can also include panic attacks. Although the neurobiology of individual anxiety disorders is largely unknown, some generalizations have been identified for most disorders, such as alterations in the limbic system, dysfunction of the hypothalamic-pituitary-adrenal axis and genetic factors. In addition, general risk factors for anxiety disorders include female sex and a family history of anxiety, although disorder-specific risk factors have also been identified. The diagnostic criteria for anxiety disorders varies for the individual disorders, but are generally similar across the two most common classification systems: the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and the International Classification of Diseases, Tenth Edition (ICD-10). Despite their public health significance, the vast majority of anxiety disorders remain undetected and untreated by health care systems, even in economically advanced countries. If untreated, these disorders are usually chronic with waxing and waning symptoms. Impairments associated with anxiety disorders range from limitations in role functioning to severe disabilities, such as the patient being unable to leave their home.

Developmental changes in genetic and environmental influences on Chinese child and adolescent anxiety and depression

BACKGROUND

Twin and family studies using Western samples have established that child and adolescent anxiety and depression are under substantial genetic, modest shared environmental, and substantial non-shared environmental influences. Generalizability of these findings to non-Western societies remains largely unknown, particularly regarding the changes of genetic and environmental influences with age. The current study examined changes in genetic and environmental influences on self-reported anxiety and depression from late childhood to mid-adolescence among a Chinese twin sample. Sex differences were also examined.

METHOD

Self-reported anxiety and depression were collected from 712 10- to 12-year-old Chinese twins (mean = 10.88 years, 49% males) and again 3 years later. Quantitative genetic modeling was used to examine developmental changes in genetic and environmental influences on anxiety and depression, and sex differences.

RESULTS

Heritability of anxiety and depression in late childhood (23 and 20%) decreased to negligible in mid-adolescence, while shared environmental influences increased (20 and 27% to 57 and 60%). Shared environmental factors explained most of the continuity of anxiety and depression (75 and 77%). Non-shared environmental factors were largely time-specific. No sex differences were observed.

CONCLUSIONS

Shared environmental influences might be more pronounced during the transition period of adolescence in non-Western societies such as China. Future research should examine similarities and differences in the genetic and environmental etiologies of child and adolescent internalizing and other psychopathology in development between Western and non-Western societies.

Peer Victimization and Anxiety in Genetically Vulnerable Youth: The Protective Roles of Teachers' Self-Efficacy and Anti-Bullying Classroom Rules

Many victimized youngsters are at risk of developing internalizing problems, and this risk seems to be especially pronounced when they are genetically vulnerable for these problems. It is unclear, however, whether protective features of the school environment such as anti-bullying classroom policies and teacher's perceived self-efficacy in handling bullying situations can mitigate these negative outcomes. Using a genetically informed design based on twins, this study examined the potential moderating role of classroom anti-bullying policies and teachers' perceived self-efficacy in handling bullying situations in regard to the additive and interactive effects of peer victimization and genetic vulnerability on anxiety symptoms. To this end, 208 monozygotic and same-sex dizygotic twins (120 girls) rated their level of anxiety and peer victimization in grade 6 (mean age = 12.1 years, SD = 2.8). Teachers rated their self-efficacy in handling bullying situations and the extent of anti-bullying classroom policies. Multilevel regressions revealed triple interactions showing that genetic disposition for anxiety predicted actual anxiety for twins who were highly victimized by their peers, but only when their teachers had low perceived self-efficacy in handling bullying situations or when anti-bullying classroom rules were absent or rarely enforced. In contrast, for victimized youth with teachers who perceive themselves as effective or in classrooms where anti-bullying classroom policies were strongly enforced, genetic disposition for anxiety was not associated with actual anxiety symptoms. Anti-bullying programs should continue to promote teachers' involvement, as well as the enforcement of anti-bullying classroom policies, in order to diminish peer victimization and its related consequences.

The stability and change of etiological influences on depression, anxiety symptoms and their co-occurrence across adolescence and young adulthood

BACKGROUND

Depression and anxiety persist within and across diagnostic boundaries. The manner in which common v. disorder-specific genetic and environmental influences operate across development to maintain internalizing disorders and their co-morbidity is unclear. This paper investigates the stability and change of etiological influences on depression, panic, generalized, separation and social anxiety symptoms, and their co-occurrence, across adolescence and young adulthood.

METHOD

A total of 2619 twins/siblings prospectively reported symptoms of depression and anxiety at mean ages 15, 17 and 20 years.

RESULTS

Each symptom scale showed a similar pattern of moderate continuity across development, largely underpinned by genetic stability. New genetic influences contributing to change in the developmental course of the symptoms emerged at each time point. All symptom scales correlated moderately with one another over time. Genetic influences, both stable and time-specific, overlapped considerably between the scales. Non-shared environmental influences were largely time- and symptom-specific, but some contributed moderately to the stability of depression and anxiety symptom scales. These stable, longitudinal environmental influences were highly correlated between the symptoms.

CONCLUSIONS

The results highlight both stable and dynamic etiology of depression and anxiety symptom scales. They provide preliminary evidence that stable as well as newly emerging genes contribute to the co-morbidity between depression and anxiety across adolescence and young adulthood. Conversely, environmental influences are largely time-specific and contribute to change in symptoms over time. The results inform molecular genetics research and transdiagnostic treatment and prevention approaches.

BDNF Val66Met, stress, and positive mothering: Differential susceptibility model of adolescent trait anxiety

Etiological research has indicated the gene-environment interaction (G × E) on adolescent anxiety. This study aimed to examine how the BDNF Val66Met polymorphism interacted with stressful life events and positive mothering to influence youth trait anxiety. The study sample included 780 community adolescents of Chinese Han ethnicity (M = 13.6, 51.3% females). Participants' trait anxiety, exposure to stressful life events, and mother's warmth-reasoning were assessed by self-reported questionnaires. We found that BDNF Val66Met polymorphism significantly moderated the influences of stressful life events and mother's warmth-reasoning on adolescent anxiety. The influences were significantly greater in adolescents carrying one or two Val allele than those with Met/Met genotype. Moreover, the G × E interactions were more consistent with the differential susceptibility than the diathesis-stress model. Adolescents carrying Val allele who were more susceptible to adversity were also more likely to benefit from supportive experiences. These findings provide novel evidence for the role of BDNF Val66Met as a genetic susceptibility modulating the influences of stressful life events and mother's warmth-reasoning on adolescent anxiety. We speculate that BDNF Val66Met may moderate anxious youths' responses to mindfulness-based stress reduction program and family-based treatment targeting the enhancement of positive parenting.

Genetic and environmental contributions to anxiety among Chinese children and adolescents--a multi-informant twin study

BACKGROUND

Child and adolescent anxiety has become a major public health concern in China, but little was known about the etiology of anxiety in Chinese children and adolescents. The present study aimed to investigate genetic and environmental influences on trait anxiety among Chinese children and adolescents. Rater, sex, and age differences on these estimates were also examined.

METHODS

Self-reported and parent-reported child's trait anxiety was collected from 1,104 pairs of same-sex twins aged 9-18 years. Genetic models were fitted to data from each informant to determine the genetic (A), shared (C), and non-shared environmental (E) influences on trait anxiety.

RESULTS

The parameter estimates and 95% confidence intervals (CI) of A, C, E on self-reported trait anxiety were 50% [30%, 60%], 5% [0%, 24%], 45% [40%, 49%]. For parent-reported data, the corresponding parameter estimates were 63% [47%, 78%], 13% [1%, 28%], and 24% [22%, 27%], respectively. The heritability of anxiety was higher in girls for self-reported data, but higher in boys for parent-reported data. There was no significant age difference in genetic and environmental contributions for self-reported data, but a significant increase of heritability with age for parent-reported data.

CONCLUSIONS

The trait anxiety in Chinese children and adolescents was highly heritable. Non-shared environmental factors also played an important role. The estimates of genetic and environmental effects differed by rater, sex and age. Our findings largely suggest the cross-cultural generalizability of the etiological model of child and adolescent anxiety.

Aetiological overlap between anxiety and attention deficit hyperactivity symptom dimensions in adolescence

BACKGROUND

Anxiety and attention-deficit/hyperactivity (ADH) problems are common in adolescence, often co-occur, and are characterised by high heterogeneity in their phenotypic expressions. Although it is known that anxiety and ADH problems correlate, the relationships between subtypes of anxiety and ADH problems have been scarcely investigated.

METHODS

Using a large population sample of adolescent twins and siblings we explored the phenotypic and aetiological association between anxiety subtypes (panic/agoraphobia, separation anxiety, social anxiety, physical injury fears, obsessive-compulsive symptoms and generalised anxiety) and the two ADH dimensions (attention problems and hyperactivity/impulsivity). Both phenotypes were assessed using self-report questionnaires.

RESULTS

The association between ADH problems and anxiety could be entirely attributed to attention problems, not hyperactivity/impulsivity. Most of the correlations between anxiety subtypes and attention problems showed an approximately equal role of genetic and nonshared environmental factors.

CONCLUSIONS

The high heterogeneity within anxiety and ADH problems should be taken into account in order to better understand comorbidity between them.

RORA and posttraumatic stress trajectories: main effects and interactions with childhood physical abuse history

BACKGROUND

Longitudinal studies of posttraumatic stress (PTS) have documented environmental factors as predictors of trajectories of higher, versus lower, symptoms, among them experiences of childhood physical abuse. Although it is now well-accepted that genes and environments jointly shape the risk of PTS, no published studies have investigated genes, or gene-by-environment interactions (GxEs), as predictors of PTS trajectories. The purpose of this study was to fill this gap.

METHODS AND MATERIALS

We examined associations between variants of the retinoid-related orphan receptor alpha (RORA) gene and trajectory membership among a sample of predominantly non-Hispanic Black urban adults (N = 473). The RORA gene was selected based on its association with posttraumatic stress disorder (PTSD) in the first PTSD genome wide association study. Additionally, we explored GxEs between RORA variants and childhood physical abuse history.

RESULTS

We found that the minor allele of the RORA SNP rs893290 was a significant predictor of membership in a trajectory of consistently high PTS, relatively to a trajectory of consistently low PTS. Additionally, the GxE of rs893290 with childhood physical abuse was significant. Decomposition of the interaction showed that minor allele frequency was more strongly associated with membership in consistently high or decreasing PTS trajectories, relative to a consistently low PTS trajectory, among participants with higher levels of childhood physical abuse.

CONCLUSION

The results of the study provide preliminary evidence that variation in the RORA gene is associated with membership in trajectories of higher PTS and that these associations are stronger among persons exposed to childhood physical abuse. Replication and analysis of functional data are needed to further our understanding of how RORA relates to PTS trajectories.

Friendship Experiences and Anxiety Among Children: A Genetically Informed Study

This study examined (a) whether, in line with a gene-environment correlation (rGE), a genetic disposition for anxiety puts children at risk of having anxious friends or having no reciprocal friends; (b) to what extent these friendship experiences are related to anxiety symptoms, when controlling for sex and genetic disposition for this trait; and (c) the additive and interactive predictive links of the reciprocal best friend's anxiety symptoms and of friendship quality with children's anxiety symptoms. Using a genetically informed design based on 521 monozygotic and ic twins (264 girls; 87% of European descent) assessed in Grade 4 (M age = 10.04 years, SD = .26), anxiety symptoms and perceived friendship quality were measured with self-report questionnaires. Results indicated that, in line with rGE, children with a strong genetic disposition for anxiety were more likely to have anxious friends than nonanxious friends. Moreover, controlling for their genetic risk for anxiety, children with anxious friends showed higher levels of anxiety symptoms than children with nonanxious friends but did not differ from those without reciprocal friends. Additional analyses suggested a possible contagion of anxiety symptoms between reciprocal best friends when perceived negative features of friendship were high. These results underline the importance of teaching strategies such as problem solving that enhance friendship quality to limit the potential social contagion of anxiety symptoms.

Cognitive content specificity in anxiety and depressive disorder symptoms: a twin study of cross-sectional associations with anxiety sensitivity dimensions across development

BACKGROUND

The classification of anxiety and depressive disorders has long been debated and has important clinical implications. The present study combined a genetically sensitive design and multiple time points to investigate cognitive content specificity in anxiety and depressive disorder symptoms across anxiety sensitivity dimensions, a cognitive distortion implicated in both disorders.

METHOD

Phenotypic and genetic correlations between anxiety sensitivity dimensions, anxiety and depressive disorder symptoms were examined at five waves of data collection within childhood, adolescence and early adulthood in two representative twin studies (n pairs = 300 and 1372).

RESULTS

The physical concerns dimension of anxiety sensitivity (fear of bodily symptoms) was significantly associated with anxiety but not depression at all waves. Genetic influences on physical concerns overlapped substantially more with anxiety than depression. Conversely, mental concerns (worry regarding cognitive control) were phenotypically more strongly associated with depression than anxiety. Social concerns (fear of publicly observable symptoms of anxiety) were associated with both anxiety and depression in adolescence. Genetic influences on mental and social concerns were shared to a similar extent with both anxiety and depression.

CONCLUSIONS

Phenotypic patterns of cognitive specificity and broader genetic associations between anxiety sensitivity dimensions, anxiety and depressive disorder symptoms were similar at all waves. Both disorder-specific and shared cognitive concerns were identified, suggesting it is appropriate to classify anxiety and depression as distinct but related disorders and confirming the clinical perspective that cognitive therapy is most likely to benefit by targeting cognitive concerns relating specifically to the individual's presenting symptoms across development.

Interpersonal cognitive biases as genetic markers for pediatric depressive symptoms: twin data from the emotions, cognitions, heredity and outcome (ECHO) study

Childhood depressive symptoms may arise from genetic and environmental risks, which act to bias the ways in which children process emotional information. Previous studies show that several "cognitive biases" are heritable and share genetic and environmental risks with depressive symptoms. Past research suggests that many cognitive biases only reflect genetic risks for depressive symptoms from adolescence. The present study sought to identify (a) when interpersonal cognitions mature as risk factors for depressive symptoms by examining whether these factors are stable and predict symptoms across time in childhood, and (b) the extent to which interpersonal cognitions reflect inherited/environmental risks on children's depressive symptoms. Results showed that there was some stability for interpersonal cognitive biases from age 8 to 10 years (rs = .32-.43). Only the absence of positive self/other perceptions, and negative peer and mother expectations at age 8 predicted depressive symptoms at age 10 (after controlling for depressive symptoms at age 8). The absence of positive self/other perceptions shared genetic influences with depressive symptoms within and across time. Across middle to late childhood, interpersonal cognitions begin to operate as vulnerability-trait factors for depressive symptoms, gradually reflecting distal genetic risks on symptoms.

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.

Child care, socio-economic status and problem behavior: a study of gene-environment interaction in young Dutch twins

The influences of formal child care before age 4 on behavioral problems at 3, 5, and 7 years of age were assessed in 18,932 Dutch twins (3,878 attended formal child care). The effect of formal child care was studied on the average level of problem behavior and as moderator of genetic and non-genetic influences, while taking into account effects of sex and parental socio-economic status (SES). There was a small association between attending formal child care and higher externalizing problems, especially when SES was low. Heritability was lower for formal child care and in lower SES conditions. These effects were largest at age 7 and for externalizing problems. In 7 year-old boys and girls, the difference in heritability between the formal child care group of low SES and the home care group of high SES was 30% for externalizing and ~20% for internalizing problems. The decrease in heritability was explained by a larger influence of the environment, rather than by a decrease in genetic variance. These results support a bioecological model in which heritability is lower in circumstances associated with more problem behavior.

Pediatric anxiety disorders: from neuroscience to evidence-based clinical practice

The objective of this narrative review of the literature is to describe the epidemiology, etiology, pathophysiology, diagnosis, and treatment of pediatric anxiety disorders. We aim to guide clinicians in understanding the biology of anxiety disorders and to provide general guidelines for the proper diagnoses and treatment of these conditions early in life. Anxiety disorders are prevalent, associated with a number of negative life outcomes, and currently under-recognized and under-treated. The etiology involves both genes and environmental influences modifying the neural substrate in a complex interplay. Research on pathophysiology is still in its infancy, but some brain regions, such as the amygdala and the prefrontal cortex, have been implicated in fear and anxiety. Current practice is to establish diagnosis based purely on clinical features, derived from clinical interviews with the child, parents, and teachers. Treatment is effective using medication, cognitive behavioral therapy, or a combination of both. An introduction to the neuroscience behind anxiety disorders combined with an evidence-based approach may help clinicians to understand these disorders and treat them properly in childhood.

Genetic and environmental influences on relationship between anxiety sensitivity and anxiety subscales in children

Anxiety sensitivity, a belief that symptoms of anxiety are harmful, has been proposed to influence development of panic disorder. Recent research suggests it may be a vulnerability factor for many anxiety subtypes. Moderate genetic influences have been implicated for both anxiety sensitivity and anxiety, however, little is known about the aetiology of the relationship between these traits in children. Self-reports of anxiety sensitivity and anxiety symptoms were collected from approximately 300 twin pairs at two time points. Partial correlations indicated that anxiety sensitivity at age 8 was broadly associated with most anxiety subtypes at age 10 (r=0.11-0.17, p<0.05). The associations were largely unidirectional, underpinned by stable genetic influences. Non-shared environment had unique influences on variables. Phenotypic results showed that anxiety sensitivity is a broad predictor of anxiety symptoms in childhood. Genetic results suggest that childhood is a developmental period characterised by genetic stability and time-specific environmental influences on anxiety-related traits.

Intergenerational transmission of risk for social inhibition: the interplay between parental responsiveness and genetic influences

To better understand mechanisms underlying the intergenerational transmission of social anxiety, we used a prospective adoption design to examine the roles of genetic influences (inferred from birth mothers' social phobia) and rearing environment (adoptive mothers' and fathers' responsiveness) on the development of socially inhibited, anxious behaviors in children between 18 and 27 months of age. The sample consisted of 275 adoption-linked families, each including an adopted child, adoptive parents, and a birth mother. Results indicated that children whose birth mothers met criteria for the diagnosis of social phobia showed elevated levels of observed behavioral inhibition in a social situation at 27 months of age if their adoptive mothers provided less emotionally and verbally responsive rearing environments at 18 months of age. Conversely, in the context of higher levels of maternal responsiveness, children of birth mothers with a history of social phobia did not show elevated levels of behavioral inhibition. These findings on maternal responsiveness were replicated in a model predicting parent reports of child social anxiety. The findings are discussed in terms of gene-environment interactions in the intergenerational transmission of social anxiety.

Gene-environment interaction in panic disorder and posttraumatic stress disorder

Gene-environment interaction is a form of causal interplay, whereby genetic effects on phenotypic variation change as a function of environmental exposure. While conceptually appealing, there is still much debate on the veracity and the relevance of this form of etiological interdependence for psychiatric disorders. By focusing on panic disorder (PD) and posttraumatic stress disorder (PTSD), this article outlines why gene-environment interaction is controversial, why it can be important for both researchers and clinicians, and how it is investigated by quantitative genetic, molecular genetic, and genomic strategies. It is suggested that gene-environment interaction effects are more reliable and meaningful when they can be harnessed to pinpoint specific biological pathways and mechanisms. In psychiatry, this can be guided by phenotypic dissection and realized by adopting intermediate phenotypes of a physiological nature, such as carbon dioxide sensitivity for PD, or gene expression profiling after stress for PTSD. A developmental framework of reference and the possibility of transferring the investigation to animal models are additional key elements in this debate.

Developmental aspects of mood disorders

Rates of depression double in the transition to adolescence. Symptoms of depression in adolescence also predict adult mood disorders. From a preventative perspective, research into the risk factors for adolescent depression is critical. Simultaneously, there is also growing interest in understanding why adolescence reflects a particularly critical period for the onset of early mood symptoms. Here, we review (a) the role of social, genetic, neural and cognitive factors in explaining individual differences in the propensity to develop symptoms in adolescence, and (b) whether changes in these factors may explain why adolescence is a particularly sensitive period for the onset of depressive symptoms. Finally, we speculate on whether novel social stressors interact with 'genetic innovation' to produce changes in brain circuitry structure and function and associated changes in emotion regulation abilities and social understanding-to increase emergence of symptoms in adolescence.

5-HTTLPR and early childhood adversities moderate cognitive and emotional processing in adolescence

BACKGROUND

Polymorphisms in the promoter region of the serotonin transporter gene (5-HTTLPR) and exposure to early childhood adversities (CA) are independently associated with individual differences in cognitive and emotional processing. Whether these two factors interact to influence cognitive and emotional processing is not known.

METHODOLOGY AND PRINCIPAL FINDINGS

We used a sample of 238 adolescents from a community study characterised by the presence of the short allele of 5-HTTLPR (LL, LS, SS) and the presence or absence of exposure to CA before 6 years of age. We measured cognitive and emotional processing using a set of neuropsychological tasks selected predominantly from the CANTAB® battery. We found that adolescents homozygous for the short allele (SS) of 5-HTTLPR and exposed to CA were worse at classifying negative and neutral stimuli and made more errors in response to ambiguous negative feedback. In addition, cognitive and emotional processing deficits were associated with diagnoses of anxiety and/or depressions.

CONCLUSION AND SIGNIFICANCE

Cognitive and emotional processing deficits may act as a transdiagnostic intermediate marker for anxiety and depressive disorders in genetically susceptible individuals exposed to CA.

The Genesis 12–19 (G1219) Study: A Twin and Sibling Study of Gene–Environment Interplay and Adolescent Development in the UK

The Genesis 12–19 (G1219) Study is an ongoing longitudinal study of a sample of UK twin pairs, non-twin sibling pairs, and their parents. G1219 was initially designed to examine the role of gene–environment interplay in adolescent depression. However, since then data have continued to be collected from both parents and their offspring into young adulthood. This has allowed for longitudinal analyses of depression and has enabled researchers to investigate multiple phenotypes and to ask questions about intermediate mechanisms. The study has primarily focused on emotional development, particularly depression and anxiety, which have been assessed at multiple levels of analysis (symptoms, cognitions, and relevant environmental experiences). G1219 has also included assessment of a broader range of psychological phenotypes ranging from antisocial behaviors and substance use to sleep difficulties, in addition to multiple aspects of the environment. DNA has also been collected. The first wave of data collection began in the year 1999 and the fifth wave of data collection will be complete before the end of 2012. In this article, we describe the sample, data collection, and measures used. We also summarize some of the key findings to date.

Investigating the genetic and environmental bases of biases in threat recognition and avoidance in children with anxiety problems

Background

Adults with anxiety show biased categorization and avoidance of threats. Such biases may emerge through complex interplay between genetics and environments, occurring early in life. Research on threat biases in children has focuses on a restricted range of biases, with insufficient focus on genetic and environmental origins. Here, we explore differences between children with and without anxiety problems in under-studied areas of threat bias. We focused both on associations with anxious phenotype and the underlying gene-environmental correlates for two specific processes: the categorisation of threat faces and avoidance learning.

Method

Two-hundred and fifty 10-year old MZ and DZ twin pairs (500 individuals) completed tasks assessing accuracy in the labelling of threatening facial expressions and in the acquisition of avoidant responses to a card associated with a masked threatening face. To assess whether participants met criteria for an anxiety disorder, parents of twins completed a self-guided computerized version of the Development and Well-being Assessment (DAWBA). Comparison of MZ and DZ twin correlations using model-fitting were used to compute estimates of genetic, shared and non-shared environmental effects.

Results

Of the 500 twins assessed, 25 (5%) met diagnostic criteria for a current anxiety disorder. Children with anxiety disorders were more accurate in their ability to recognize disgust faces than those without anxiety disorders, but were commensurate on identifying other threatening face emotions (angry, fearful, sad). Children with anxiety disorders but also more strongly avoided selecting a conditioned stimulus than non-anxious children. While recognition of socially threatening faces was moderately heritable, avoidant responses were heavily influenced by the non-shared environment.

Conclusion

These data add to other findings on threat biases in anxious children. Specifically, we found biases in the labelling of some negative-valence faces and in the acquisition of avoidant responses. While non-shared environmental effects explained all of the variance on threat avoidance, some of this may be due to measurement error.

Genetic risk by experience interaction for childhood internalizing problems: converging evidence across multiple methods

BACKGROUND

Identifying how genetic risk interacts with experience to predict psychopathology is an important step toward understanding the etiology of mental health problems. Few studies have examined genetic risk by experience interaction (G×E) in the development of childhood psychopathology.

METHODS

We used both co-twin and parent mental health as markers of genetic risk to test whether G×E predicted internalizing problems in a sample of 8-year-old twins. Multi-instrument composites were used to characterize both parent and child psychopathology, and five experiential risk factors (socioeconomic status, single parent upbringing, negative parent-child interactions, number of negative life events, negative impact of negative life events) composed a cumulative risk index.

RESULTS

We found consistent evidence for G×E for child internalizing problems, with significant interaction effects emerging both when genetic risk was indexed by co-twin mental health and when it was based on parent mental health. When co-twin mental health was used to estimate genetic risk, child internalizing problems were more heritable for children at low rather than high experiential risk. When parent mental health was used to estimate genetic risk, the association between genetic risk and internalizing problems was stronger for children at elevated experiential risk. Consideration of the interaction effect sizes helps to reconcile these findings.

CONCLUSIONS

Our results suggest that the processes involved in both diathesis-stress and bioecological models of development may operate for child internalizing problems. Effect sizes indicated that the main effects of genetic and experiential risk were much better predictors of child internalizing problems than was their interaction.

Distinct neural signatures of threat learning in adolescents and adults

Most teenage fears subside with age, a change that may reflect brain maturation in the service of refined fear learning. Whereas adults clearly demarcate safe situations from real dangers, attenuating fear to the former but not the latter, adolescents' immaturity in prefrontal cortex function may limit their ability to form clear-cut threat categories, allowing pervasive fears to manifest. Here we developed a discrimination learning paradigm that assesses the ability to categorize threat from safety cues to test these hypotheses on age differences in neurodevelopment. In experiment 1, we first demonstrated the capacity of this paradigm to generate threat/safety discrimination learning in both adolescents and adults. Next, in experiment 2, we used this paradigm to compare the behavioral and neural correlates of threat/safety discrimination learning in adolescents and adults using functional MRI. This second experiment yielded three sets of findings. First, when labeling threats online, adolescents reported less discrimination between threat and safety cues than adults. Second, adolescents were more likely than adults to engage early-maturing subcortical structures during threat/safety discrimination learning. Third, adults' but not adolescents' engagement of late-maturing prefrontal cortex regions correlated positively with fear ratings during threat/safety discrimination learning. These data are consistent with the role of dorsolateral regions during category learning, particularly when differences between stimuli are subtle [Miller EK, Cohen JD (2001) Annu Rev Neurosci 24:167-202]. These findings suggest that maturational differences in subcortical and prefrontal regions between adolescent and adult brains may relate to age-related differences in threat/safety discrimination.

Gene-environment interactions in panic disorder and CO₂ sensitivity: Effects of events occurring early in life

Heterogeneous life events (LE) precede the onset of-and potentially increase the susceptibility to-panic disorder (PD). It remains unknown whether LE can act as moderators in the context of gene-by-environment interactions (G×E) that alter the susceptibility to PD and the related trait of CO₂ sensitivity, nor it is known whether such moderation may depend on occurrence of events at different epochs in life. In 712 general population twins we analyzed by Maximum Likelihood analyses of ordinal data whether life (major- and stressful) events moderate the genetic risk for PD and CO₂ sensitivity, as indexed by the 35% CO₂ /65% O₂ challenge. For CO₂ sensitivity, best-fitting models encompassed both additive and interactional effects that increased linearly with the cumulative number and severity (SEV) of events in lifetime. By analyzing the moderation effect of cumulative SEV separately for events that had occurred in adulthood (between age 18 and 37) or during childhood-adolescence (before the 18th birthday), we found evidence of G×E only within the childhood-adolescence window of risk, although twins had rated the childhood-adolescence events as significantly (P = 0.001) less severe than those having occurred during adulthood. For PD, all interactional terms could be dropped without significant worsening of the models' fit. Consistently with a diathesis-stress model, LE appear to act as moderators of the genetic variance for CO₂ sensitivity. Childhood-adolescence appears to constitute a sensitive period to the action of events that concur to alter the susceptibility to this panic-related trait.

Familial risk factors in social anxiety disorder: calling for a family-oriented approach for targeted prevention and early intervention

Within the last decade, social anxiety disorder (SAD) has been identified as a highly prevalent and burdensome disorder. Both the characterization of its symptomatology and effective treatment options are widely documented. Studies particularly indicate that SAD aggregates in families and has its onset in early adolescence. Given the family as an important context for children's cognitive, emotional and behavioural development, familial risk factors could be expected to significantly contribute to the reliable detection of populations at risk for SAD. Reviewing studies on familial risk factors for SAD argues for the importance of parental psychopathology and unfavourable family environment, but also denotes to several shortcomings such as cross-sectional designs, short follow-up periods, diverging methodologies and the focus on isolated factors. Using a prospective longitudinal study that covers the high-risk period for SAD, including a broader spectrum of putative risk factors may help to overcome many of the methodological limitations. This review sets out to develop a more family-oriented approach for predicting the onset and maintenance of SAD that may be fruitful to derive targeted prevention and early intervention in SAD.

Childhood and adolescent anxiety and depression: beyond heritability

OBJECTIVE

To review the methodology of behavior genetics studies addressing research questions that go beyond simple heritability estimation and illustrate these using representative research on childhood and adolescent anxiety and depression.

METHOD

The classic twin design and its extensions may be used to examine age and gender differences in the genetic determinants of complex traits and disorders, the role of genetic factors in explaining comorbidity, the interaction of genes and the environment, and the effect of social interaction among family members. An overview of the methods typically employed to address such questions is illustrated by a review of 34 recent studies on childhood anxiety and depression.

RESULTS

The review provides relatively consistent evidence for small to negligible sex differences in the genetic etiology of childhood anxiety and depression, a substantial role of genetic factors in accounting for the temporal stability of these disorders, a partly genetic basis of the comorbidity between anxiety and depression, a possible role of the interaction between genotype and the environment in affecting liability to these disorders, a role of genotype-environment correlation, and a minor, if any, etiological role of sibling interaction.

CONCLUSION

The results clearly demonstrate a role for genetic factors in the etiology and temporal stability of individual differences in childhood anxiety and depression. Clinical implications of the findings are discussed.

Panic disorder: a review of DSM-IV panic disorder and proposals for DSM-V

This review covers the literature since the publication of DSM-IV on the diagnostic criteria for panic attacks (PAs) and panic disorder (PD). Specific recommendations are made based on the evidence available. In particular, slight changes are proposed for the wording of the diagnostic criteria for PAs to ease the differentiation between panic and surrounding anxiety; simplification and clarification of the operationalization of types of PAs (expected vs. unexpected) is proposed; and consideration is given to the value of PAs as a specifier for all DSM diagnoses and to the cultural validity of certain symptom profiles. In addition, slight changes are proposed for the wording of the diagnostic criteria to increase clarity and parsimony of the criteria. Finally, based on the available evidence, no changes are proposed with regard to the developmental expression of PAs or PD. This review presents a number of options and preliminary recommendations to be considered for DSM-V.

BDNF gene polymorphism (Val66Met) predicts amygdala and anterior hippocampus responses to emotional faces in anxious and depressed adolescents

A polymorphism of the human Brain Derived Neurotrophic Factor (BDNF) gene that produces a valine-to-methionine substitution at codon 66 (Val66Met) is linked to adult anxiety and mood disorders, possibly through effects on brain circuitry function. Associations between BDNF gene variants and brain activity have not been explored in anxious and depressed adolescents. The current study investigated the association between BDNF genotype and amygdala-hippocampal responses to emotional stimuli in adolescents with anxiety disorders and/or major depressive disorder (MDD) and in healthy adolescents. Twenty-seven unmedicated patients with acutely-impairing current anxiety disorders and/or MDD and 31 healthy adolescents, matched on age, gender and IQ, rated their fear of fearful, angry, neutral and happy facial expressions during collection of fMRI data on the amygdala and hippocampus. Left and right amygdala and hippocampal responses were analyzed using repeated-measures analyses of variance models, with diagnosis (patients, healthy) and genotype (Met-carriers, Val/Val homozygotes) as between-group factors and facial expression (fearful, angry, neutral, happy) as a within-subject factor. Significant effects of diagnosis and diagnosis-by-genotype interactions (F's>4, p's<0.05) characterized activations in amygdala and anterior hippocampal regions. Greater activations in patients than healthy adolescents were found. Critically, these hyperactivations were modulated by BDNF genotype: Met-carriers showed greater neural responses of emotional faces than Val/Val homozygotes in patients only. These data are first to demonstrate the contribution of BDNF gene variants to the neural correlates of adolescent anxiety and depression. Early "gene-brain" linkages may lay the foundation for longer-term patterns of neural dysfunction in affective disorders.

Pharmacological alterations of anxious behaviour in mice depending on both strain and the behavioural situation

A previous study comparing non-emotive mice from the strain C57BL/6/ByJ with ABP/Le mice showed ABP/Le to be more anxious in an open-field situation. In the present study, several compounds affecting anxiety were assayed on ABP/Le and C57BL/6/ByJ mice using three behavioural models of anxiety: the elevated plus-maze, the light-dark discrimination test and the free exploratory paradigm. The compounds used were the full benzodiazepine receptor agonist, chlordiazepoxide, and the antagonist, flumazenil, the GABA(A) antagonist, bicuculline, the full 5-HT(1A) agonist 8-OH-DPAT, and the mixed 5-HT(1A)/5-HT(1B) agonist, RU 24969. Results showed the effect of the compounds to be dependent on both the strain and the behavioural task. Several compounds found to be anxiolytic in ABP/Le mice had an anxiogenic effect on C57BL/6/ByJ mice. More behavioural changes were observed for ABP/Le in the elevated plus-maze, but the clearest findings for C57BL/6/ByJ mice were observed in the light-dark discrimination apparatus. These data demonstrate that anxious behaviour is a complex phenomenon which cannot be described by a single behavioural task nor by the action of a single compound.

Gene-environment interplay in internalizing disorders: consistent findings across six environmental risk factors

BACKGROUND

Behavior genetic methods can help to elucidate gene-environment (G-E) interplay in the development of internalizing (INT) disorders (i.e., major depression and anxiety disorders). To date, however, no study has conducted a comprehensive analysis examining multiple environmental risk factors with the purpose of delineating general mechanisms of G-E influence in the development of INT disorders.

METHODS

The sample consisted of 1315 male and female twin pairs participating in the age 17 assessment of the Minnesota Twin Family Study. Quantitative G-E interplay models were used to examine how genetic and environmental risk for INT disorders changes as a function of environmental context. Multiple measures and informants were employed to construct composite measures of INT disorders and six environmental risk factors including: stressful life events, mother-child and father-child relationship problems, antisocial and prosocial peer affiliation, and academic achievement and engagement.

RESULTS

Significant moderation effects were detected between each environmental risk factor and INT such that in the context of greater environmental adversity, nonshared environmental factors became more important in the etiology of INT symptoms.

CONCLUSION

Our results are consistent with the interpretation that environmental stressors have a causative effect on the emergence of INT disorders. The consistency of our results suggests a general mechanism of environmental influence on INT disorders regardless of the specific form of environmental risk.

Individual differences in children's facial expression recognition ability: The role of nature and nurture

We examined genetic and environmental influences on recognition of facial expressions in 250 pairs of 10-year-old monozygotic (83 pairs) and dizygotic (167 pairs) twins. Angry, fearful, sad, disgusted, and happy faces varying in intensity (15%-100%), head orientation, and eye gaze were presented in random order across 160 trials. Total correct recognition responses to each facial expression comprised the dependent variables. Twin data examined genetic and environmental contributions to variables and their correlations. Results support a common psychometric factor influenced primarily by additive genetic influences across expressions with discrimination of specific expressions due largely to non-shared environmental influences.

Finding gene-environment interactions for generalised anxiety disorder

It is becoming increasingly apparent that genetic research into psychiatric disorders would benefit from consideration of the environment because these risk mechanisms are likely to interact. Despite generalised anxiety disorder (GAD) being one of the most prevalent disorders presented in primary care, there is a paucity of published studies of gene-environment interactions (G x E) for this phenotype. This article describes how our current knowledge of GAD is useful in designing studies of G x E for GAD. To increase the chances of identifying replicable G x E for GAD further information is needed with regards to: defining and measuring GAD, difficulties co-occurring with GAD, quantitative genetic estimations for GAD, specific genes associated with GAD, and specific environmental risks for GAD.

Elucidating risk mechanisms of gene-environment interactions on pediatric anxiety: integrating findings from neuroscience

Recent findings of gene-environment interaction on child and adolescent anxiety generate interest in mechanisms through which genetic risks are expressed. Current findings from neuroscience suggest avenues for exploring putative mechanisms. Specifically recent documentations of abnormality in brain function among anxious adolescents may reflect the end-result of gene expression. In turn these inherited predispositions may increase the likelihood of psychopathology in the presence of stress. The aim of the current article is to consider putative mechanisms reflecting genetic sensitivity to the environment (G x E). Thus we review data implicating biased processing of threat information and anomalies in brain circuitry in the expression of pediatric anxiety. These data suggest that links across development among genes, brain, psychological processes, and behavior are far from established. Accordingly, the article proposes strategies for examining these links. Exploring these relationships during development is crucial, given that these early life processes may potentially shape longer-term patterns of emotional behavior, and therefore life-long trajectories of anxiety.