I think, therefore I am: a twin study of attributional style in adolescents

Genetic Decomposition of the Heritable Component of Reported Childhood Maltreatment

Background

Decades of research have shown that environmental exposures, including self-reports of trauma, are partly heritable. Heritable characteristics may influence exposure to and interpretations of environmental factors. Identifying heritable factors associated with self-reported trauma could improve our understanding of vulnerability to exposure and the interpretation of life events.

Methods

We used genome-wide association study summary statistics of childhood maltreatment, defined as reporting of abuse (emotional, sexual, and physical) and neglect (emotional and physical) (N = 185,414 participants). We calculated genetic correlations (rg) between reported childhood maltreatment and 576 traits to identify phenotypes that might explain the heritability of reported childhood maltreatment, retaining those with |rg| > 0.25. We specified multiple regression models using genomic structural equation modeling to detect residual genetic variance in childhood maltreatment after accounting for genetically correlated traits.

Results

In 2 separate models, the shared genetic component of 12 health and behavioral traits and 7 psychiatric disorders accounted for 59% and 56% of heritability due to common genetic variants (single nucleotide polymorphism-based heritability [h2SNP]) of childhood maltreatment, respectively. Genetic influences on h2SNP of childhood maltreatment were generally accounted for by a shared genetic component across traits. The exceptions to this were general risk tolerance, subjective well-being, posttraumatic stress disorder, and autism spectrum disorder, identified as independent contributors to h2SNP of childhood maltreatment. These 4 traits alone were sufficient to explain 58% of h2SNP of childhood maltreatment.

Conclusions

We identified putative traits that reflect h2SNP of childhood maltreatment. Elucidating the mechanisms underlying these associations may improve trauma prevention and posttraumatic intervention strategies.

Impact of OXTR Polymorphisms on Subjective Well-Being: The Intermediary Role of Attributional Style

Polymorphisms in the oxytocin receptor (OXTR) gene are related to individual differences in negative emotions, such as depressive symptoms and anxiety. However, it remains unclear what the potential roles of OXTR polymorphisms are in subjective well-being (SWB), which is negatively correlated with depressive symptoms. We examined attributional styles as mediator between SWB and five polymorphisms of the oxytocin receptor gene (OXTR rs53576, rs2254298, rs1042778, rs2268494, and rs2268490) among 627 full-time college freshmen (M_age = 20.90, SD = 0.82 for male; M_age = 20.81, SD = 0.92 for female) using structural equation modeling. The results showed that individuals with the OXTR rs2254298 AA genotype and rs53576 AA/GA genotype reported higher scores on SWB, which suggested that individuals with this genotype experienced more happiness. Moreover, external attributional style partially mediated the association between OXTR rs2254298 polymorphism and SWB (β = 0.019, 95%CI [0.001, 0.036], p = 0.035). In conclusion, our findings demonstrated that the genetic variations of OXTR played a role in the individual differences of SWB, and external attribution style could mediate the association.

Emerging Domain-Based Treatments for Pediatric Anxiety Disorders

Domain-specific cognitive training treatments for pediatric anxiety disorders rely on accurate and reliable identification of specific underlying deficits and biases in neurocognitive functions. Once identified, such biases can serve as specific targets for therapeutic intervention. Clinical translations typically reflect mechanized training protocols designed to rectify the identified biases. Here, we review and synthesize research on key neurocognitive processes that emerge as potential targets for specialized cognitive training interventions in pediatric anxiety disorders in the domains of attention, interpretation, error monitoring, working memory, and fear learning. For each domain, we describe the current status of target establishment (i.e., an association between pediatric anxiety and a specific neurocognitive process), and then review extant translational efforts regarding these targets and the evidence supporting their clinical utility in youths. We then localize each of the domains within the path leading to efficacious, evidence-supported treatments for pediatric anxiety, providing a roadmap for future research. The review indicates that specific cognitive targets in pediatric anxiety have been established in all the reviewed domains except for fear learning, where a clear target is yet to be elucidated. In contrast, evidence for clinical efficacy emerged only in the threat-related attention domain, with some preliminary findings in the domains of interpretation and working memory. The path to clinical translation in the domain of error monitoring is yet unclear. Implications and potential avenues for future research and translation are discussed.

A systematic review of treatments targeting cognitive biases in socially anxious adolescents: Special Section on "Translational and Neuroscience Studies in Affective Disorders" Section Editor, Maria Nobile MD, PhD

BACKGROUND

Adolescence is a period of brain plasticity that is affected by social and affective stimuli. Adaptive neurodevelopmental changes in the context of complex social situations may precipitate or exacerbate cognitive biases (i.e., attention and/or interpretation biases) and predispose at-risk individuals to symptoms of social anxiety.

METHODS

This systematic review followed the PRISMA guidelines. Nine adolescent studies were examined including 3 studies using Cognitive Bias Modification Training (CBMT) to target attention biases (CBMT-A), 3 studies using CBMT to target interpretation biases (CBMT-I), and 3 aimed at reducing both attention and interpretation biases.

RESULTS

The studies of CBMT-A alone did not find significant effects on cognitive and clinical outcomes. However, studies of CBMT-I alone showed some improvement in interpretation bias. The combination of CBMT-A and CBMT-I appeared promising in reducing both attentionl and interpretation biases.

LIMITATIONS

The paucity of studies and the heterogeneity across studies (e.g., format of CBMT, assessment measures) limit the calculation of overall effect sizes and the examination of predictors, moderators, and mediators of outcome.

CONCLUSIONS

Technology-driven interventions such as CBMT have the potential to extend treatments outside the clinic setting and to augment current therapies for social anxiety. Further research is needed to develop CBMT procedures that optimize learning in group and real-world settings and to identify predictors of treatment response. Understanding the neural correlates of response to CBMT may help identify future targets for intervention.

Research Review: Cognitive bias modification of interpretations in youth and its effect on anxiety: a meta-analysis

BACKGROUND

Emerging evidence suggests that cognitive bias modification of interpretations (CBM-I) is effective in altering interpretation biases and reducing anxiety in adults. Less is known about the impact of CBM-I in young people, but some recent findings, including a meta-analysis of combined cognitive bias modification of interpretation and attention techniques, have cast doubt on its clinical utility. Given the current debate, this meta-analysis sought to establish the independent effects of CBM-I on interpretations biases and anxiety in youth.

METHODS

Studies were identified through a systematic literature search of PsycINFO, Ovid MEDLINE, PsycARTICLES, Web of Science and EMBASE between January 1992 and March 2017. Eligible studies aimed to target interpretation biases; did not combine CBM-I with another intervention; included a control condition; randomly allocated participants to conditions; assessed interpretation bias and/or anxiety as an outcome; included individuals up to age 18; and did not present previously reported data. Reference lists of included articles were checked for further eligible studies, and authors were contacted for unpublished data.

RESULTS

We identified 26 studies meeting eligibility criteria that included in the meta-analysis. CBM-I had moderate effects on negative and positive interpretations (g = -0.70 and g = -0.52, respectively) and a small but significant effect on anxiety assessed after training (g = -0.17) and after a stressor (g = -0.34). No significant moderators were identified.

CONCLUSIONS

In contrast to previous meta-analytic findings, our results indicate that CBM-I has potential but weak anxiolytic effects in youth. Our findings suggest that it may be premature to disregard the potential value of CBM-I research and further research in this field is warranted.

Negative self-referential processing is associated with genetic variation in the serotonin transporter-linked polymorphic region (5-HTTLPR): Evidence from two independent studies

The current research examined whether carriers of the short 5-HTTLPR allele (in SLC6A4), who have been shown to selectively attend to negative information, exhibit a bias towards negative self-referent processing. The self-referent encoding task (SRET) was used to measure self-referential processing of positive and negative adjectives. Ratcliff's diffusion model isolated and extracted decision-making components from SRET responses and reaction times. Across the initial (N = 183) and replication (N = 137) studies, results indicated that short 5-HTTLPR allele carriers more easily categorized negative adjectives as self-referential (i.e., higher drift rate). Further, drift rate was associated with recall of negative self-referential stimuli. Findings across both studies provide further evidence that genetic variation may contribute to the etiology of negatively biased processing of self-referent information. Large scale studies examining the genetic contributions to negative self-referent processing may be warranted.

The association between paternal depressogenic cognitive styles during pregnancy and offspring depressogenic cognitive styles: an 18-year prospective cohort study

BACKGROUND

Preventing the development of depressogenic or negative cognitive styles could also prevent the development of depression, a leading public health problem worldwide. Maternal negative cognitive styles are a modifiable risk factor for the development of negative cognitive styles in offspring. However, evidence on the role of paternal negative cognitive styles is inconclusive and there have only been a few small studies, which may also have lacked statistical power.

METHODS

We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC) to investigate the association between paternal negative cognitive styles, measured when mothers were 18 weeks pregnant, and offspring negative cognitive styles 18 years later (N = 6,123). Associations were calculated using linear regression models, before and after adjustment for confounders including maternal negative cognitive styles. We compared associations before and after controlling for depression in parents and offspring, and used multiple imputation to reduce biases that may have arisen due to missing data.

RESULTS

A two-standard deviation increase in paternal negative cognitive style was associated with a 3-point increase in offspring negative cognitive style (95% CI 1.36-4.37). This association remained after adjustment for confounders and was independent of depression in both parents and offspring. The effect size was equivalent to that of maternal negative cognitive style, and was also independent of maternal negative cognitive style.

CONCLUSIONS

Our results suggest that fathers should be included in individual- and family-based interventions designed to prevent the development of depressogenic cognitive styles in adolescent offspring. This could possibly also prevent the development of depression.

Developmental change in the association between adolescent depressive symptoms and the home environment: results from a longitudinal, genetically informative investigation

BACKGROUND

Depression is already highly prevalent by late adolescence, indicating that research into its developmental emergence should consider earlier risk factors and environmental contexts. The home environment is a key context for children and adolescents throughout development. However, the nature of relationships that exist between aspects of the home environment and the development of depressive symptoms cannot be assumed. Genetically informative studies have been used to provide insights about the aetiology of such relationships, often finding them to be partly confounded by the influence of children's genes. Here, we investigate developmental change in the aetiology of the association between aspects of the home environment and depressive symptoms at the onset of adolescence.

METHODS

We used longitudinal child- and parent-report data from >5,000 twin pairs enrolled in the UK-representative Twins Early Development Study. Multivariate, genetically sensitive structural equation models were used to decompose latent variance and covariance in depressive symptoms (measured at 12 and 16 years) and aspects of the home environment (at 9 and 14 years) into genetic and environmental influences.

RESULTS

Going from childhood to adolescence, genetic influences accounted for an increasing proportion of the association [30% (16-42) of r = .44 in childhood; 40% (25-61) of r = .43 in adolescence], at the expense of shared environmental influences, which decreased from 70% (58-83) to 48% (29-62). Unique environmental influences accounted for a significant proportion of the association in adolescence only [12% (06-18)]. Developmental changes could largely be attributed to subtle shifts in the relative importance of stable aetiological factors, rather than the emergence of influences unique to adolescence.

CONCLUSIONS

These findings emphasise the importance of developmental and aetiological context in interpreting associations between aspects of the home environment and child emotional outcomes.

Annual Research Review: An expanded account of information-processing mechanisms in risk for child and adolescent anxiety and depression

BACKGROUND

Anxiety and depression occurring during childhood and adolescence are common and costly. While early-emerging anxiety and depression can arise through a complex interplay of 'distal' factors such as genetic and environmental influences, temperamental characteristics and brain circuitry, the more proximal mechanisms that transfer risks on symptoms are poorly delineated. Information-processing biases, which differentiate youth with and without anxiety and/or depression, could act as proximal mechanisms that mediate more distal risks on symptoms. This article reviews the literature on information-processing biases, their associations with anxiety and depression symptoms in youth and with other distal risk factors, to provide direction for further research.

METHODS

Based on strategic searches of the literature, we consider how youth with and without anxiety and/or depression vary in how they deploy attention to social-affective stimuli, discriminate between threat and safety cues, retain memories of negative events and appraise ambiguous information. We discuss how these information-processing biases are similarly or differentially expressed on anxiety and depression and whether these biases are linked to genetic and environmental factors, temperamental characteristics and patterns of brain circuitry functioning implicated in anxiety and depression.

FINDINGS

Biases in attention and appraisal characterise both youth anxiety and depression but with some differences in how these are expressed for each symptom type. Difficulties in threat-safety cue discrimination characterise anxiety and are understudied in depression, while biases in the retrieval of negative and overgeneral memories have been observed in depression but are understudied in anxiety. Information-processing biases have been studied in relation to some distal factors but not systematically, so relationships remain inconclusive.

CONCLUSIONS

Biases in attention, threat-safety cue discrimination, memory and appraisal may characterise anxiety and/or depression risk. We discuss future research directions that can more systematically test whether these biases act as proximal mechanisms that mediate other distal risk factors.

A longitudinal twin and sibling study of the hopelessness theory of depression in adolescence and young adulthood

BACKGROUND

Maladaptive cognitive biases such as negative attributional style and hopelessness have been implicated in the development and maintenance of depression. According to the hopelessness theory of depression, hopelessness mediates the association between attributional style and depression. The aetiological processes underpinning this influential theory remain unknown. The current study investigated genetic and environmental influences on hopelessness and its concurrent and longitudinal associations with attributional style and depression across adolescence and emerging adulthood. Furthermore, given high co-morbidity between depression and anxiety, the study investigated whether these maladaptive cognitions constitute transdiagnostic cognitive content common to both internalizing symptoms.

METHOD

A total of 2619 twins/siblings reported attributional style (mean age 15 and 17 years), hopelessness (mean age 17 years), and depression and anxiety symptoms (mean age 17 and 20 years).

RESULTS

Partial correlations revealed that attributional style and hopelessness were uniquely associated with depression but not anxiety symptoms. Hopelessness partially mediated the relationship between attributional style and depression. Hopelessness was moderately heritable (A = 0.37, 95% confidence interval 0.28-0.47), with remaining variance accounted for by non-shared environmental influences. Independent pathway models indicated that a set of common genetic influences largely accounted for the association between attributional style, hopelessness and depression symptoms, both concurrently and across development.

CONCLUSIONS

The results provide novel evidence that associations between attributional style, hopelessness and depression symptoms are largely due to shared genetic liability, suggesting developmentally stable biological pathways underpinning the hopelessness theory of depression. Both attributional style and hopelessness constituted unique cognitive content in depression. The results inform molecular genetics research and cognitive treatment approaches.

Family process and youth internalizing problems: A triadic model of etiology and intervention

Despite major advances in the development of interventions for youth anxiety and depression, approximately 30% of youths with anxiety do not respond to cognitive behavioral treatment, and youth depression treatments yield modest symptom decreases overall. Identifying networks of modifiable risk and maintenance factors that contribute to both youth anxiety and depression (i.e., internalizing problems) may enhance and broaden treatment benefits by informing the development of mechanism-targeted interventions. A particularly powerful network is the rich array of family processes linked to internalizing problems (e.g., parenting styles, parental mental health problems, and sibling relationships). Here, we propose a new theoretical model, the triadic modelof family process, to organize theory and evidence around modifiable, transdiagnostic family factors that may contribute to youth internalizing problems. We describe the model's implications for intervention, and we propose strategies for testing the model in future research. The model provides a framework for studying associations among family processes, their relation to youth internalizing problems, and family-based strategies for strengthening prevention and treatment.

Parent-offspring transaction: Mechanisms and the value of within family designs

This article is part of a Special Issue "Parental Care". Parenting is best understood as a transactional process between parents and their offspring. Each responds to cues in the other, adapting their own behavior to that of their partner. One of the goals of parenting research in the past twenty years has been to untangle reciprocal processes between parents and children in order to specify what comes from the child (child effects) and what comes from the parent (parent effects). Child effects have been found to relate to genetic, pre and perinatal, family-wide, and child-specific environmental influences. Parent effects relate to stresses in the current context (e.g. financial strain, marital conflict), personality and ethnicity but also to adverse childhood experiences (e.g. parental mental health and substance abuse, poverty, divorce). Rodent models have allowed for the specification of biological mechanisms in parent and child effects, including neurobiological and genomic mechanisms, and of the causal role of environmental experience on outcomes for offspring through random assignment of offspring-mother groupings. One of the methods that have been developed in the human and animal models to differentiate between parent and child effects has been to study multiple offspring in the family. By holding the parent steady, and studying different offspring, we can examine the similarities and differences in how parents parent multiple offspring. Studies have distinguished between family average parenting, child-specific parenting and family-wide dispersion (the within family standard deviation). These different aspects of parenting have been differentially linked to offspring behavioral phenotypes.

Parents' and Children's Cognitive Style: The Role of Parents' Practices

Depression among children is a prevalent, distressing phenomenon. Children's hope and negative attributional style are significant precursors for children's depressive symptoms. Thus, the aim of the current study is to examine parents' characteristics that contribute to children's attributional style and hope in a sample of 85 Israeli young elementary school age children (mean [SD] age, 6.70 [0.49] years) and their parents. Results demonstrated positive associations between both mothers' and fathers' positive attributional style and children's hope and positive attributional style; however, parents' hope was not associated with children's hope or with children's positive attributional style. Mothers' overprotectiveness and psychological control were negatively associated with children's hope and positive attributional style, whereas fathers' overprotectiveness was positively associated with these variables. Moreover, few parent and child sex effects were found with fathers' criticism associating negatively with boys' attributional style and hope and positively with girls' attributional style. Finally, our study demonstrated a possible advantage of the fit between mothers' and fathers' practices to children's positive attributional style and hope. Theoretical and clinical implications are discussed.

Predicting change in symptoms of depression during the transition to university: the roles of BDNF and working memory capacity

Studies on depression risk emphasize the importance of both cognitive and genetic vulnerability factors. The present study has provided the first examination of whether working memory capacity, the BDNF Val66Met polymorphism, and their interaction predict changes in symptoms of depression during the transition to university. Early in the semester, students completed a self-report measure of depressive symptoms and a modified version of the reading span task to assess working memory capacity in the presence of both neutral and negative distractors. Whole blood was genotyped for the BDNF Val66Met polymorphism. Students returned at the end of the semester to complete additional self-report questionnaires. Neither working memory capacity nor the BDNF Val66Met polymorphism predicted change in depressive symptoms either independently or in interaction with self-reported semester difficulty. The BDNF Val66Met polymorphism, however, moderated the association between working memory capacity and symptom change. Among met carriers, lower working memory capacity in the presence of negative-but not neutral-distractors was associated with increased symptoms of depression over the semester. For the val/val group, working memory capacity did not predict symptom change. These findings contribute directly to biological and cognitive models of depression and highlight the importance of examining Gene × Cognition interactions when investigating risk for depression.

A shared genetic propensity underlies experiences of bullying victimization in late childhood and self-rated paranoid thinking in adolescence

BACKGROUND

Bullying is a risk factor for developing psychotic experiences (PEs). Whether bullying is associated with particular PEs, and the extent to which genes and environments influence the association, are unknown. This study investigated which specific PEs in adolescence are associated with earlier bullying victimization and the genetic and environmental contributions underlying their association.

METHOD

Participants were 4826 twin pairs from a longitudinal community-based twin study in England and Wales who reported on their bullying victimization at the age of 12 years. Measures of specific PEs (self-rated Paranoia, Hallucinations, Cognitive disorganization, Grandiosity, Anhedonia, and parent-rated Negative Symptoms) were recorded at age of 16 years.

RESULTS

Childhood bullying victimization was most strongly associated with Paranoia in adolescence (r = .26; P < .01), with weaker associations with Hallucinations, Cognitive Disorganization, parent-rated Negative Symptoms (r = .12-.20; P < .01), Grandiosity (r = .04; P < .05), and Anhedonia (r = .00, n.s.). Bivariate twin model-fitting demonstrated that bullying victimization and Paranoia were both heritable (35% and 52%, respectively) with unique environmental influences (39% and 48%, respectively), and bullying victimization showed common environmental influences (26%). The association between bullying victimization and Paranoia operated almost entirely via genetic influences (bivariate heritability = 93%), with considerable genetic overlap (genetic correlation = .55).

CONCLUSION

In contrast to the assumed role of bullying victimization as an environmental trigger, these data suggest that bullying victimization in late childhood is particularly linked to self-rated Paranoia in adolescence via a shared genetic propensity. Clinically, individuals with a history of bullying victimization are predicted to be particularly susceptible to paranoid symptoms.

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.

Empathy as a "risky strength": a multilevel examination of empathy and risk for internalizing disorders

Learning to respond to others' distress with well-regulated empathy is an important developmental task linked to positive health outcomes and moral achievements. However, this important interpersonal skill set may also confer risk for depression and anxiety when present at extreme levels and in combination with certain individual characteristics or within particular contexts. The purpose of this review is to describe an empirically grounded theoretical rationale for the hypothesis that empathic tendencies can be "risky strengths." We propose a model in which typical development of affective and cognitive empathy can be influenced by complex interplay among intraindividual and interindividual moderators that increase risk for empathic personal distress and excessive interpersonal guilt. These intermediate states in turn precipitate internalizing problems that map onto empirically derived fear/arousal and anhedonia/misery subfactors of internalizing disorders. The intraindividual moderators include a genetically influenced propensity toward physiological hyperarousal, which is proposed to interact with genetic propensity to empathic sensitivity to contribute to neurobiological processes that underlie personal distress responses to others' pain or unhappiness. This empathic personal distress then increases risk for internalizing problems, particularly fear/arousal symptoms. In a similar fashion, interactions between genetic propensities toward negative thinking processes and empathic sensitivity are hypothesized to contribute to excess interpersonal guilt in response to others' distress. This interpersonal guilt then increases the risk for internalizing problems, especially anhedonia/misery symptoms. Interindividual moderators, such as maladaptive parenting or chronic exposure to parents' negative affect, further interact with these genetic liabilities to amplify risk for personal distress and interpersonal guilt as well as for consequent internalizing problems. Age-related increases in the heritability of depression, anxiety, and empathy-related constructs are consistent with developmental shifts toward greater influence of intraindividual moderators throughout childhood and adolescence, with interindividual moderators exerting their greatest influence during early childhood. Efforts to modulate neurobiological and behavioral expressions of genetic dysregulation liabilities and to promote adaptive empathic skills must thus begin early in development.

Prevention of depression and anxiety symptoms in adolescents: 42 and 54 months follow-up of the Aussie Optimism Program-Positive Thinking Skills

Anxiety and depression are the most commonly reported mental health problems amongst Australian children and adolescents. The Aussie Optimism: Program-Positive Thinking Skills (AOP-PTS) is a universal intervention program based on cognitive and behavioral strategies and aimed to prevent anxiety and depression in the middle primary school children aged 9–10 years old. 370 students randomly assigned to the intervention and control condition participated in the 42 and 54 months follow-up study. The intervention group received the AOP-PTS 10-week program and the control group received the regular health education curriculum. Students were assessed on anxiety, depression and attribution style at school whilst parents reported on their child’s externalizing and internalizing problems at home. Results showed there were no significant reductions across groups in the depressive and anxiety symptoms, and attribution style at either 42 or 54 months follow-up. These findings suggest that AOP-PTS has short and medium term effects but were not sustained in longer term period. Future strategies to achieve the desirable outcomes in a longitudinal study are discussed.

Aetiological overlap between obsessive-compulsive and depressive symptoms: a longitudinal twin study in adolescents and adults

BACKGROUND

Depression is commonly co-morbid with obsessive-compulsive disorder (OCD). However, it is unknown whether depression is a functional consequence of OCD or whether these disorders share a common genetic aetiology. This longitudinal twin study compared these two hypotheses.

METHOD

Data were drawn from a longitudinal sample of adolescent twins and siblings (n = 2651; Genesis 12-19 study) and from a cross-sectional sample of adult twins (n = 4920). The longitudinal phenotypic associations between OCD symptoms (OCS) and depressive symptoms were examined using a cross-lag model. Multivariate twin analyses were performed to explore the genetic and environmental contributions to the cross-sectional and longitudinal relationship between OCS and depressive symptoms.

RESULTS

In the longitudinal phenotypic analyses, OCS at time 1 (wave 2 of the Genesis 12-19 study) predicted depressive symptoms at time 2 (wave 3 of the Genesis 12-19 study) to a similar extent to which depressive symptoms at time 1 predicted OCS at time 2. Cross-sectional twin analyses in both samples indicated that common genetic factors explained 52-65% of the phenotypic correlation between OCS and depressive symptoms. The proportion of the phenotypic correlation due to common non-shared environmental factors was considerably smaller (35%). In the adolescent sample, the longitudinal association between OCS at time 1 and subsequent depressive symptoms was accounted for by the genetic association between OCS and depressive symptoms at time 1. There was no significant environmental association between OCS and later depressive symptoms.

CONCLUSIONS

The present findings show that OCS and depressive symptoms co-occur primarily due to shared genetic factors and suggest that genetic, rather than environmental, effects account for the longitudinal relationship between OCS and depressive symptoms.

Genetic and environmental influences on adolescent rumination and its association with depressive symptoms

Rumination is an important cognitive vulnerability for adolescent and adult depression. However, little is known about the aetiological origins of rumination, as well as its association with depression. Adolescent rumination (self-report) and depressive symptoms (self- and parent-report) were assessed in 674 pairs of same-gender Chinese adolescent twins (11-17 years of age). Females accounted for 53.7 % of the sample. There were significant correlations between self-reported rumination and self-reported depression (r = 0.41), as well as parent-reported adolescent depression (r = 0.22). Genetic influences were significant and modest on all three measures, ranging from 24 % to 42 %. The three measures were also significantly influenced by shared environment, ranging from 20 % to 28 %, and non-shared environmental factors, ranging from 30 % to 56 %. Moreover, the genetic correlations between rumination and depression were significant (within-rater: r(g) = 0.99; cross-rater: r(g) = 0.59) and largely accounted for the phenotypic correlations (within-rater: 68 %; cross-rater: 77 %), while non-shared environmental correlations were also significant (within-rater: r(e) = 0.26; cross-rater: r(e) = 0.12) and accounted for the remainder of the phenotypic correlations (within-rater: 32 %; cross-rater: 23 %). The shared environmental correlations were non-significant. No significant gender and age differences were found in aetiological models. These findings suggest that rumination may be an endophenotype reflecting genetic risk for depression.

Genetic and environmental etiologies of adolescent dysfunctional attitudes: a twin study

Despite the importance of dysfunctional attitudes in the development and maintenance of depression, little is known about the etiological origin of dysfunctional attitudes. The Dysfunctional Attitudes Scale for Children was administered to 674 adolescent twins derived from the Beijing Twin Study (BeTwiSt). Four hundred and thirty-nine monozygotic and 235 same-gender dizygotic twin pairs were included. Approximately 54% were females. The age range of the twins was 11-17 years. Model-fitting analyses were conducted. Biometric genetic model-fitting estimates indicated that additive genetic factors accounted for 31% (95% CI: 11%, 45%) of variance in adolescent dysfunctional attitude. The influence of shared environmental factors was small and negligible (9% [95% CI: 0%, 27%]). Non-shared environmental factors explained 60% (95% CI: 55%, 66%) of variance. Equating the estimate parameters across gender or age groups resulted in a non-significant difference of model fit, but there were trends suggesting higher heritability in females and older adolescents. Our results provide evidence for moderate heritability of dysfunctional attitudes in adolescents. Dysfunctional attitudes can be used as an endophenotype to identify risk genes for depression.

The role of gene-environment correlations and interactions in middle childhood depressive symptoms

Depression is known to be associated with a wide array of environmental factors. Such associations are due at least in part to genetic influences on both. This issue has been little explored with preadolescent children. Measures of family chaos and parenting style at age 9 and child depressive symptoms at age 12 were completed by 3,258 twin pairs from the Twins Early Development Study and their parents. Quantitative genetic modeling was used to explore common and unique genetic and environmental influences on both family environment and later depressive symptoms. Depressive symptoms at age 12 were significantly heritable. Moderate genetic effects influenced parenting style and family chaos at the age of 9, indicating gene-environment correlation. There were significant genetic correlations between family environment and depressive symptoms. There was some evidence of a Gene × Environment interaction, with stronger genetic effects on depressive symptoms for children with more suboptimal family environment. There was an Environment × Environment interaction, with effects of nonshared environment on depressive symptoms stronger for twins with more adverse parenting experiences. There is some evidence for gene-environment correlation between aspects of family environment in middle childhood and subsequent depressive symptoms. This suggests that one of the mechanisms by which genes lead to depressive symptoms may be by themselves influencing depressogenic environments.

Replication of Genome-Wide Association Studies (GWAS) loci for sleep in the British G1219 cohort

Sleep is a critical behavior shared by most higher animals. Sleep disturbances are comorbid with numerous psychiatric disorders, most notably symptoms of depression. Twin studies have suggested that genetic influences partially underlie the variation seen for numerous sleep-related traits across individuals. Recently, two Genome-Wide Association Studies (GWAS) conducted for sleep traits have revealed new candidate genes for sleep-related measures. We attempted to replicate the two most significant associations from these two studies, CACNA1C (a l-type calcium channel) with sleep latency and quality and ABCC9 (an ATP-sensitive potassium channel) with sleep duration, using the G1219 British population sample. We genotyped single-nucleotide polymorphisms (SNPs) for each of the two different sleep GWAS loci. Linear regression analyses were conducted to assess main effects of these SNPs on their corresponding sleep measures, as well as for depressive symptoms. We successfully replicated an association of a genetic variant in the CACNA1C gene (rs16929277) with sleep quality using an additive model of inheritance. A significant association of the ABCC9 gene (rs11046209) with sleep duration was seen only in a recessive models based upon a rare homozygous genotype (n = 2). There was also a significant association between a different ABCC9 gene variant (rs11046205) and depressive symptoms. These findings add further support for the involvement of calcium channels in the mechanisms regulating sleep function and suggest a possible role of the ABCC9 gene in depression.

Association between maternal depressogenic cognitive style during pregnancy and offspring cognitive style 18 years later

OBJECTIVE

Understanding the origins of negative cognitive style could provide a means to prevent adult depression. Cognitive style is an important target for intervention because although it is not possible to remove the stress and adversities in people's lives, it may be possible to modify interpretation of such adversities through cognitive style. Children may develop a negative cognitive style through modeling the style of their mothers. However, findings have been inconsistent on the association. The authors tested the hypothesis that there is an independent association between maternal and offspring depressogenic cognitive style.

METHOD

Data from over 4,000 mothers and children from the Avon Longitudinal Study of Parents and Children cohort study in the United Kingdom were used to investigate the association between maternal depressogenic cognitive style before the offspring's birth and the offspring's depressogenic cognitive style at age 18.

RESULTS

A positive association was observed between maternal and offspring cognitive styles: a one-standard-deviation increase in maternal depressogenic cognitive style score during pregnancy was significantly associated with a mean increase of 0.1 standard deviations in offspring depressogenic cognitive style score at age 18. This effect remained after adjusting for maternal and offspring depression and explained 21% of the association between maternal and offspring depression.

CONCLUSIONS

Although the mechanisms remain to be elucidated, the findings are consistent with the idea that a mother's cognitive style (irrespective of her depression status) influences that of her child. This suggests that interventions to improve a mother's cognitive style could help prevent her offspring from developing depression during adulthood.

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.

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.

Toward an integration of cognitive and genetic models of risk for depression

There is growing interest in integrating cognitive and genetic models of depression risk. We review two ways in which these models can be meaningfully integrated. First, information-processing biases may represent intermediate phenotypes for specific genetic influences. These genetic influences may represent main effects on specific cognitive processes or may moderate the impact of environmental influences on information-processing biases. Second, cognitive and genetic influences may combine to increase reactivity to environmental stressors, increasing risk for depression in a gene×cognition×environment model of risk. There is now growing support for both of these ways of integrating cognitive and genetic models of depression risk. Specifically, there is support for genetic influences on information-processing biases, particularly the link between 5-HTTLPR and attentional biases, from both genetic association and gene×environment (G×E) studies. There is also initial support for gene×cognition×environment models of risk in which specific genetic influences contribute to increased reactivity to environmental influences. We review this research and discuss important areas of future research, particularly the need for larger samples that allow for a broader examination of genetic and epigenetic influences as well as the combined influence of variability across a number of genes.

Anxiety sensitivity in adolescence and young adulthood: the role of stressful life events, 5HTTLPR and their interaction

BACKGROUND

Cognitive biases have long been hypothesized to influence the development and maintenance of symptoms of internalizing problems. Anxiety sensitivity represents one such bias and refers to sensitivity to the physical and emotional symptoms of anxiety and the belief that these are harmful. Twin studies indicate a role for both environmental and genetic influences on anxiety sensitivity. However, little work has been done specifying environments or genes involved in this phenotype. In light of this, we looked at the association between stressful life events, the serotonin transporter gene polymorphism (5HTTLPR), and anxiety sensitivity in a longitudinal sample of adolescents.

METHODS

Stressful life events and anxiety sensitivity were measured in over 1,500 individuals at three time points (mean ages 15, 17, and 20 years). 5HTTLPR was genotyped in 1,109 participants.

RESULTS

There was consistent evidence for an association between stressful life events and both anxiety sensitivity and change in anxiety sensitivity over time. Although the effect of independent stressful life events was relatively short lived, dependent stressful life events were associated with anxiety sensitivity over time. There was no evidence for a main effect of 5HTTLPR on anxiety sensitivity. 5HTTLPR genotype did not moderate the effect of stressful life events on anxiety sensitivity.

CONCLUSIONS

The current study extends previous work by showing that stressful life events, independent of the individual, explained change in cognitions associated with anxiety and depression. This effect does not, however, appear to be moderated by genotype.

Developmental risk of depression: experience matters

This article focuses on discussing risks for depression onset and the role of environmental factors in promoting resilience in children and adolescents. The authors review the current literature on specific (eg, family history of depression) and nonspecific (eg, poverty, stressful life events) risk factors for youth depression to underscore the need for prevention efforts promoting resiliency in this population.

Neurobiological markers of familial risk for depression

Major depression is associated with a wide range of neurobiological disturbances, including anomalies in the structure and function of cortical and subcortical gray matter and dysregulation of the HPA axis. In this chapter, we review research demonstrating that many of these abnormalities are also present in never-depressed offspring of adults with recurrent depression and discuss how such findings might reflect dysfunctional neuroregulatory systems that precede the onset of this disorder. We also briefly discuss candidate genes and environmental factors that have been posited to be directly involved in the transmission of neural and HPA-axis abnormalities from depressed parents to their offspring, and we review how, by obtaining a better understanding of the neurobiological markers of depression risk, we can facilitate the development of targeted strategies for the prevention and treatment of major depression.

Sleep quality and diurnal preference in a sample of young adults: associations with 5HTTLPR, PER3, and CLOCK 3111

Research investigating associations between specific genes and individual differences with regards to the quality and timing of sleep has primarily focussed on serotonin-related and clock genes. However, there are only a few studies of this type and most of those to date have not considered the possibility of gene-environment interaction. Here, we describe associations between sleep quality and diurnal preference and three functional polymorphisms: 5HTTLPR, PERIOD3, and CLOCK 3111. Furthermore, we assessed whether associations between genotypes and sleep phenotypes were moderated by negative life events-a test of gene-environment interaction. DNA from buccal swabs was collected from 947 individuals [mean age = 20.3 years (SD = 1.77), age range = 18-27 years; 61.8% female] and genotyped for the three polymorphisms. Participants completed the Pittsburgh Sleep Quality Index and the Morningness-Eveningness Questionnaire. There was a significant main effect of 5HTTLPR on sleep quality, indicating that "long-long" homozygotes experienced significantly poorer sleep quality (mean = 6.35, SD = 3.36) than carriers of at least one "short" allele (mean = 5.67, SD = 2.96; β = -0.34, P = 0.005). There were no main effects of 5HTTLPR on diurnal preference; no main effects of PERIOD3 or CLOCK on sleep quality or diurnal preference; and no significant interactions with negative life events. The main effect of the "long" 5HTTLPR allele contradicts previous research, suggesting that perhaps the effects of this gene are heterogeneous in different populations. Failure to replicate previous research in relation to PERIOD3 and CLOCK concurs with previous research suggesting that the effects of these genes are small and may be related to population composition.

Associations between diurnal preference, sleep quality and externalizing behaviours: a behavioural genetic analysis

BACKGROUND

Certain aspects of sleep co-occur with externalizing behaviours in youth, yet little is known about these associations in adults. The present study: (1) examines the associations between diurnal preference (morningness versus eveningness), sleep quality and externalizing behaviours; (2) explores the extent to which genetic and environmental influences are shared between or are unique to these phenotypes; (3) examines the extent to which genetic and environmental influences account for these associations. method: Questionnaires assessing diurnal preference, sleep quality and externalizing behaviours were completed by 1556 young adult twins and siblings.

RESULTS

A preference for eveningness and poor sleep quality were associated with greater externalizing symptoms [r=0.28 (95% CI 0.23-0.33) and 0.34 (95% CI 0.28-0.39), respectively]. A total of 18% of the genetic influences on externalizing behaviours were shared with diurnal preference and sleep quality and an additional 14% were shared with sleep quality alone. Non-shared environmental influences common to the phenotypes were small (2%). The association between diurnal preference and externalizing behaviours was mostly explained by genetic influences [additive genetic influence (A)=80% (95% CI 0.56-1.01)], as was the association between sleep quality and externalizing behaviours [A=81% (95% CI 0.62-0.99)]. Non-shared environmental (E) influences accounted for the remaining variance for both associations [E=20% (95% CI -0.01 to 0.44) and 19% (95% CI 0.01-0.38), respectively].

CONCLUSIONS

A preference for eveningness and poor sleep quality are moderately associated with externalizing behaviours in young adults. There is a moderate amount of shared genetic influences between the phenotypes and genetic influences account for a large proportion of the association between sleep and externalizing behaviours. Further research could focus on identifying specific genetic polymorphisms common to both sleep and externalizing behaviours.

A systematic evaluation and validation of subtypes of adolescent alcohol use motives: genetic and environmental contributions

BACKGROUND

Alcohol use motives are closely associated with specific profiles of alcohol use and reflect a subjectively derived decisional framework based on a motivational style of responding. Adult twin studies typically estimate the heritability of alcohol use motives to be between 7 and 42%, although relatively little is known about genetic and environmental influences upon alcohol use motives in adolescence.

METHODS

Latent class analysis (LCA) models containing 1 through 5 classes were fitted to the data derived from 1,422 adolescent twin and siblings self-reported alcohol use motives. Using twin models, we estimated the genetic, shared, and nonshared environmental influences to the class membership data derived from the LCA.

RESULTS

Four drinking motives classes were identified (family-oriented, social, enhancement/social, and coping/social). The coping/social and enhancement/social classes were differentiated from the social class on measures of depression, delinquency, and aggressive behavior. Analyses indicated that nonadditive genetic factors accounted for 76% of the variance in the coping/social motives class and additive genetic influences accounted for 66% of the variance in the social motives class. There was a moderate contribution of genetic factors and shared environmental factors influencing class membership of enhancement/social motivated drinkers (28 and 20% explained variance, respectively). Substantial shared environmental influences were revealed for membership of the family-oriented class (75%).

CONCLUSIONS

Heritable influences may predispose individuals to drink to cope with negative affect, for social reasons, and to a lesser extent for enhancement. Familial environmental influences shape family-oriented motives for drinking in adolescents.

The genetics of mood disorders

Studying the genetics of mood disorders has never been more exciting. We have moved rapidly from establishing the genetic basis of depression to asking questions about how genes are expressed. This has been made possible by the capacity to collect and sequence DNA for large samples cheaply. But "multidisciplinary" approaches investigating interrelationships between risk factors have also been increasingly adopted, encouraging collaborations between those studying genes and those studying the brain, cognition, and/or the social environment. In this review, we first describe findings from quantitative and molecular studies investigating the genetic basis of depression. Second, we present overviews of three hot topics of genetic research: gene-environment interplay, which considers how genetic factors shape exposure and responses toward the social environment; endophenotypic research, which identifies neurophysiological and psychological mediators of genetic risk; and epigenetics, which explain how early environments can foster changes in gene expression, altering subsequent emotional development.

Does childhood anxiety evoke maternal control? A genetically informed study

BACKGROUND

Despite theoretical and empirical support for an association between maternal control and child anxiety, few studies have examined the origins of this association. Furthermore, none use observer-ratings of maternal control within a genetically informative design. This study addressed three questions: 1) do children who experience maternal control report higher anxiety levels than those who do not?; 2) to what extent do genetic and environmental factors influence maternal control and child anxiety?; 3) to what extent do genetic and environmental factors influence the associations between child anxiety and maternal control?

METHOD

Five hundred and thirty 8-year-old children (from 265 twin pairs) and their mothers were observed participating in an 'etch-a-sketch' task from which maternal control was rated. Children rated their anxiety using the Screen for Child Anxiety Related Emotional Disorders.

RESULTS

Children who experienced maternal behaviour rated as 'extreme control' reported higher anxiety levels than those who did not. Maternal control was highly heritable (A = .63), high self-rated anxiety less so (h(2)(g) = .36). The overlap between high child anxiety and maternal control was primarily due to shared genetic factors.

CONCLUSIONS

These results suggest that maternal control is likely to have been elicited by children with high levels of anxiety.

Genetic influences on the cognitive biases associated with anxiety and depression symptoms in adolescents

BACKGROUND

There is a substantial overlap between genes affecting anxiety and depression. Both anxiety and depression are associated with cognitive biases such as anxiety sensitivity and attributional style. Little, however, is known about the relationship between these variables and whether these too are genetically correlated.

METHODS

Self-reports of anxiety sensitivity, anxiety symptoms, attributional style and depression symptoms were obtained for over 1300 adolescent twin and sibling pairs at two time points. The magnitude of genetic and environmental influences on the measures was examined.

RESULTS

Strongest associations were found between anxiety sensitivity and anxiety ratings at both measurement times (r=.70, .72) and between anxiety and depression (r=.62 at both time points). Correlations between the cognitive biases were modest at time 1 (r=-.12) and slightly larger at time 2 (r=-.31). All measures showed moderate genetic influence. Generally genetic correlations reflected phenotypic correlations. Thus the highest genetic correlations were between anxiety sensitivity and anxiety ratings (.86, .87) and between anxiety and depression ratings (.77, .71). Interestingly, depression ratings also showed a high genetic correlation with anxiety sensitivity (.70, .76). Genetic correlations between the cognitive bias measures were moderate (-.31, -.46).

LIMITATIONS

The sample consists primarily of twins, there are limitations associated with the twin design.

CONCLUSIONS

Cognitive biases associated with depression and anxiety are not as genetically correlated as anxiety and depression ratings themselves. Further research into the cognitive processes related to anxiety and depression will facilitate understanding of the relationship between bias and symptoms.

Children's inferential styles, 5-HTTLPR genotype, and maternal expressed emotion-criticism: An integrated model for the intergenerational transmission of depression

The authors tested a model for the intergenerational transmission of depression integrating specific genetic (5-HTTLPR), cognitive (inferential style), and environmental (mother depressive symptoms and expressed-emotion criticism [EE-Crit]) risk factors. Supporting the hypothesis that maternal depression is associated with elevated levels of stress in children's lives, mothers with a history of major depressive disorder (MDD) exhibited higher depressive symptoms across a 6-month multiwave follow-up than mothers with no depression history. In addition, partially supporting our hypothesis, levels of maternal criticism during the follow-up were significantly related to mothers' current depressive symptoms but not to history of MDD. Finally, the authors found support for an integrated Gene x Cognition x Environment model of risk. Specifically, among children with negative inferential styles regarding their self-characteristics, there was a clear dose response of 5-HTTLPR genotype moderating the relation between maternal criticism and children's depressive symptoms, with the highest depressive symptoms during the follow-up observed among children carrying 2 copies of the 5-HTTLPR lower expressing alleles (short [S] or long [LG]) who also exhibited negative inferential styles for self-characteristics and who experienced high levels of EE-Crit. In contrast, children with positive inferential styles exhibited low depressive symptoms regardless of 5-HTTLPR genotype or level of maternal criticism.

Developmental origins of cognitive vulnerabilities to depression: review of processes contributing to stability and change across time

Cognitive theories of depression have been shown to be potent predictors of future increases in depressive symptoms and disorder in children, adolescents, and adults. This article focuses on potential developmental origins of the main cognitive vulnerabilities, including dysfunctional attitudes, negative cognitive style, and rumination. We selectively review processes and factors that have been hypothesized to contribute to the emergence and stabilization of these cognitive risk factors. This review focuses on genetic factors, temperament, parents and peers as salient interpersonal influences, and stressful life events. We end with suggestions for future theory development and research. In particular, we emphasize the need for additional conceptual and empirical work integrating these disparate processes together into a coherent, developmental psychopathological model, and we highlight the coexistence of both stability and change in the development of cognitive vulnerabilities to depression across the lifespan.

Children's attentional biases and 5-HTTLPR genotype: potential mechanisms linking mother and child depression

In this study, we examined the roles of specific cognitive (attentional bias) and genetic (5-HTTLPR) risk factors in the intergenerational transmission of depression. Focusing first on the link between maternal history of major depressive disorder (MDD) and children's attentional biases, we found that children of mothers with a history of MDD during their children's lives, compared to children of mothers with no depression history, exhibited greater attentional avoidance of sad faces. This attention bias was specific to sad, rather than happy or angry, faces. There was also preliminary evidence that this relation is stronger among children carrying the 5-HTTLPR S or L(G) allele than among those homozygous for the L(A) allele. Next, conceptualizing mothers' levels of depressive symptoms during the multi-wave prospective follow-up within a vulnerability-stress framework, we found evidence for a three-way child 5-HTTLPR x attentional bias x mother depressive symptom interaction predicting children's depressive symptoms. Specifically, the relation between mother and child depressive symptom levels over time was strongest among children carrying the 5-HTTLR S or L(G) allele who also exhibited attentional avoidance of sad faces. These findings provide initial support for role of children's 5-HTTLPR genotype and attentional biases for sad faces in the intergenerational transmission of depression.

Gene-environment interplay between peer rejection and depressive behavior in children

BACKGROUND

Genetic risk for depressive behavior may increase the likelihood of exposure to environmental stressors (gene-environment correlation, rGE). By the same token, exposure to environmental stressors may moderate the effect of genes on depressive behavior (gene-environment interaction, GxE). Relating these processes to a peer-related stressor in childhood, the present study examined (1) whether genetic risk for depressive behavior in children is related to higher levels of rejection by the peer group (rGE) and (2) whether peer rejection moderates the effect of genetic factors on children's depressive behavior (GxE).

METHODS

The sample comprised 336 twin pairs (MZ pairs = 196, same-sex DZ pairs = 140) assessed in kindergarten (mean age 72.7 months). Peer acceptance/rejection was measured via peer nominations. Depressive behavior was measured through teacher ratings.

RESULTS

Consistent with rGE, a moderate overlap of genetic effects was found between peer acceptance/rejection and depressive behavior. In line with GxE, genetic effects on depressive behavior varied across levels of peer acceptance/rejection.

CONCLUSIONS

An increased genetic disposition for depressive behavior is related to a higher risk of peer rejection (rGE). However, genes play a lesser role in explaining individual differences in depressive behavior in rejected children than in accepted children (GxE).

Neuroticism, recall bias and attention bias for valenced probes: a twin study

BACKGROUND

Prior research on the nature of the vulnerability of neuroticism to psychopathology suggests biases in information processing towards emotional rather than neutral information. It is unclear to what extent this relationship can be explained by genetic or environmental factors.

METHOD

The genetic relationship between a neuroticism composite score and free recall of pleasant and unpleasant words and the reaction time on negative probes (dot-probe task) was investigated in 125 female twin pairs. Interaction effects were modelled to test whether the correlation between neuroticism and cognitive measures depended on the level of the neuroticism score.

RESULTS

The only significant correlation was between neuroticism and the proportion of recalled unpleasant words (heritability is 30%), and was only detectable at the higher end of the neuroticism distribution. This interaction effect seems to be due to environmental effects that make people in the same family more similar (e.g. parental discipline style), rather than genetic factors. An interesting sub-finding was that faster reaction times for left versus right visual field probes in the dot-probe task suggest that cognitive processing in the right hemisphere is more sensitive to subliminal (biologically relevant) cues and that this characteristic is under substantial genetic control (49%). Individual differences in reaction times on right visual field probes were due to environmental effects only.

CONCLUSIONS

There is no evidence that the predisposition of individuals to focus on negative (emotional) stimuli is a possible underlying genetic mechanism of neuroticism.

Links between parenting and extra-familial relationships: nature or nurture?

The current paper examined associations between parenting and both peer group characteristics and friendship quality within a genetically sensitive design. Participants were aged 12-19 years (approximately equal numbers of males and females), including 424 sibling pairs and 1185 twin pairs, of whom 328 were MZ, 311 were DZ same-sex, 463 were DZ opposite-sex and 83 were of unknown zygosity. The adolescents provided self-report questionnaire measures of parental discipline, friendship quality, and peer group characteristics. All three relationship measures were moderately to substantially heritable. The novel and provocative finding, that adolescents' genetic propensities are largely responsible for the overlap seen between parental discipline strategies and friendship quality, is discussed in terms of its implications for socialization theory and understanding of adolescent relationships.