Serotonin transporter gene moderates the development of emotional problems among children following bullying victimization

Polygenic risk score and peer victimisation independently predict depressive symptoms in adolescence: results from the Quebec Longitudinal Study of Children Development

BACKGROUND

Peer victimisation has been associated with depressive symptoms during adolescence, however not all peer victimised adolescents will exhibit such symptoms. This study tested whether having a genetic predisposition to developing depression increased the risk of experiencing depressive symptoms in peer victimised youth. To date, no study has explored such gene-environment interaction using a polygenic risk score for depression (PRS-depression) in the context of peer victimisation and depressive symptoms in adolescence.

METHODS

The sample included 748 participants born in 1997/98 from the Quebec Longitudinal Study of Child Development with genotype data and prospectively collected information on peer victimisation (12-13 years) obtained from both self- and teacher-reports, as well as self-reported depressive symptoms (15-17 years). The PRS-depression was based on the genome-wide association meta-analysis of broad depression by Howard et al. (2019).

RESULTS

Self- and teacher-reported peer victimisation in early adolescence were both associated with depressive symptoms in adolescence (β = 0.34, p < .001; β = 0.14, p = .001 respectively), and this association remained significant when accounting for PRS-depression (β = 0.33, p < .001; β = 0.13, p = .002 respectively). PRS-depression was independently associated with depressive symptoms, but there was no significant PRS-depression by peer victimisation interaction (self-reported and teacher-reported). PRS-depression was correlated with self-reported, but not teacher-reported, peer victimisation.

CONCLUSIONS

Our findings suggested that a partial measure of an individual's genetic predisposition to depression, as measured by PRS-depression, and being exposed to peer victimisation (self- and teacher-reported) were independently associated with depressive symptoms in adolescence. Furthermore, PRS-depression did not exacerbate the risk of depressive symptoms among adolescents who had been peer victimised. Lastly, we found evidence of a gene-environment correlation between PRS-depression and self-reported peer victimisation. Future studies are needed to replicate this finding and to further understand the role of genetic predispositions in experiencing depressive symptoms following peer victimisation.

The body keeps the score: The neurobiological profile of traumatized adolescents

Trauma-related disorders are debilitating psychiatric conditions that affect people who have directly or indirectly witnessed adversities. Experiencing multiple types of traumas appears to be common during childhood, and even more so during adolescence. Dramatic brain/body transformations occurring during adolescence may provide a highly responsive substrate to external stimuli and lead to trauma-related vulnerability conditions, such as internalizing (anxiety, depression, anhedonia, withdrawal) and externalizing (aggression, delinquency, conduct disorders) problems. Analyzing relations among neuronal, endocrine, immune, and biochemical signatures of trauma and internalizing and externalizing behaviors, including the role of personality traits in shaping these conducts, this review highlights that the marked effects of traumatic experience on the brain/body involve changes at nearly every level of analysis, from brain structure, function and connectivity to endocrine and immune systems, from gene expression (including in the gut) to the development of personality.

Perspective: Gestational Tryptophan Fluctuation Altering Neuroembryogenesis and Psychosocial Development

Tryptophan, as the sole precursor of serotonin, mainly derived from diets, is essential for neurodevelopment and immunomodulation. Gestational tryptophan fluctuation may account for the maternal-fetal transmission in determining neuroembryogenesis with long-lasting effects on psychological development. Personality disorders and social exclusion are related to psychosocial problems, leading to impaired social functioning. However, it is not clear how the fluctuation in mother-child transmission regulates the neuroendocrine development and gut microbiota composition in progeny due to that tryptophan metabolism in pregnant women is affected by multiple factors, such as diets (tryptophan-enriched or -depleted diet), emotional mental states (anxiety, depression), health status (hypertension, diabetes), and social support as well as stresses and management skills. Recently, we have developed a non-mammal model to rationalize those discrepancies without maternal effects. This perspective article outlines the possibility and verified the hypothesis in bully-victim research with this novel model: (1). Summarizes the effects of the maternal tryptophan administration on the neuroendocrine and microbial development in their offspring; (2). Highlights the inconsistency and limitations in studying the relationship between gestational tryptophan exposure and psychosocial development in humans and viviparous animals; and (3). Evidences that embryonic exposure to tryptophan and its metabolite modify bullying interactions in the chicken model. With the current pioneer researches on the biomechanisms underlying the bully-victim interaction, the perspective article provides novel insights for developing appropriate intervention strategies to prevent psychological disorders among individuals, especially those who experienced prenatal stress, by controlling dietary tryptophan and medication therapy during pregnancy.

Parent-child relationship and child anger proneness in infancy and attachment security at toddler age: a short-term longitudinal study of mother- and father-child dyads

Early parent-child relationship and child negative emotionality have both been studied as contributors to attachment security, but few studies have examined whether negative emotionality can moderate effects of parent-child relationship on security and whether the process is comparable across mother- and father-child dyads and different security measures. In 102 community families, we observed parent-child shared positive affect and infants' anger proneness at 7 months, and attachment security at 15 months, using observer-rated Attachment Q-Set (AQS) and a continuous measure derived from Strange Situation Paradigm (SSP). For mother-child dyads, high shared positive affect and low anger proneness were associated with AQS security. Those effects were qualified by their interaction: Variations in shared positive affect were associated with security only for relatively more anger-prone children.  That effect reflected the diathesis-stress model. For father-child dyads, shared positive affect was associated with security. There were no effects for SSP security with either parent.

Inhibitory control mediates the interaction between serotonin transporter gene (5-HTTLPR) and peer victimization on adolescent depressive symptoms

Many efforts have been devoted to investigating the effect of the interaction between the serotonin transporter gene (5-HTTLPR) and environment (G × E) on depression, but they yield mixed results. The inconsistency has suggested that G × E effects may be more complex than originally conceptualized, and further study is warranted. This study explored the association among 5-HTTLPR, peer victimization and depressive symptoms and the underlying mediating role of inhibitory control in this association. A total of 871 Chinese Han adolescents (M_age = 15.32 years, 50.3% girls) participated and provided saliva samples from which the 5-HTTLPR was genotyped. This study found that 5-HTTLPR interacted with peer victimization in predicting depressive symptoms. Adolescents carrying L allele reported more depressive symptoms than SS carriers when exposed to higher level of peer victimization. Furthermore, adolescents' inhibitory control deficits mediated the association between 5-HTTLPR × peer victimization and depressive symptoms. These findings suggested that one pathway in which G × E may confer vulnerability to depressive symptoms is through disruptions to adolescents' inhibitory control system.

Biological correlates of early life stressful events in major depressive disorder

Major depressive disorder (MDD) is the most common psychiatric disorder and responds for important psychosocial consequences. Stressful life events, especially early life stress (ELS), contribute to an increased probability to develop MDD, leading in particular to severe and chronic manifestation and unfavorable treatment outcome. The association between ELS and MDD seems to have biological bases, consisting in dysregulations occurring at different levels. The aim of this narrative review is to propose an overview of the literature ranging from genetic, epigenetic, expression and protein to neuroimaging correlates underlying this relationship. A search on Pubmed of studies assessing biological correlates of ELS in MDD development, focusing on human studies conducted in both peripheral and brain tissues, was performed. Evidence indicated that the hypothalamic-pituitary-adrenal (HPA) axis and the serotonergic, dopaminergic, neurotrophin and oxytocin systems might play a role in the mediation between ELS and MDD. The most consistent results were found for genetic and epigenetic studies and indicated a joint involvement of the systems mentioned. Expression studies are less numerous and point to an involvement of stress-related systems. Concerning protein studies, the main mediators are markers related to the inflammatory and immune systems. Neuroimaging studies aiming at evaluating brain alterations connecting ELS and MDD in relation to biomarkers indicated the hippocampus, the amygdala and the frontal cortex as important anatomical mediators. These findings can build the bases for future research and clinical interventions; indeed, the clarification of biological mechanisms mediating the relationship between ELS and MDD can lead to new and individualized preventive and therapeutic possibilities.

The Association of Childhood Experience of Peer Bullying with DSM-IV Psychiatric Disorders and Suicidality in Adults: Results from a Nationwide Survey in Korea

BACKGROUND

Few studies have examined the association between childhood bullying and adulthood mental disorders based on the Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria. We investigated the association of childhood peer bullying with Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) psychiatric disorders and suicidality in adults.

METHODS

A total of 5,102 respondents aged 18 or over completed the Korean version of the Composite International Diagnostic Interview for DSM-IV psychiatric disorders and a questionnaire for suicidal ideas, plans, and attempts. We evaluated peer bullying using an item in the Adverse Childhood Experiences International Questionnaire. Logistic regression analyses were used to identify the association between victimization of peer bullying, adult psychiatric disorders, and suicidality.

RESULTS

Around 8.8% of the general population in Korea reported the experience of being bullied when growing up. Bullying experience was associated with an increase in the adulthood prevalence of nicotine use disorders (adjusted odds ratio [aOR], 2.47; 95% confidence interval [CI], 1.75-3.49), alcohol use disorders (aOR, 1.93; 95% CI, 1.49-2.51), mood disorders (aOR, 4.23; 95% CI, 3.01-5.94), and anxiety disorders (aOR, 2.89; 95% CI, 1.89-4.43) after adjusting for sociodemographic variables. Among anxiety disorders, the OR for post-traumatic stress disorder (aOR, 9.95; 95% CI, 5.62-17.63) was notably high. Frequent victimization (many times) was significantly associated with suicidality even after adjusting for sociodemographic variables and lifetime prevalence of psychiatric disorders, whereas occasional victimization (once or a few times) was not.

CONCLUSION

Childhood bullying experience was associated with adult psychiatric disorders and suicidality. The findings indicated the importance of the early detection and management of childhood peer bullying to reduce detrimental adulthood consequences.

5-HTTLPR-brain-derived neurotrophic factor (BDNF) gene interactions and early adverse life events effect on impulsivity in suicide attempters

OBJECTIVES

An expanding body of research suggests that childhood adverse experiences can lead to different negative health outcomes, including attempted suicide. Serotonergic genes such as the promoter region of the serotonin transporter gene (5-HTTLPR) have been associated both with impulsivity in suicide attempts and reactivity to environmental stress exposure. BDNF gene may play an epigenetic role.

METHODS

We studied the influence of childhood stressful events and 5-HTTLPR genotype on impulsivity measured by Barratt Impulsivity Scale (BIS-10) in a multicentre sample of 1,655 suicide attempters (69.4% women, 30.6% men; mean age 40.13 years). A co-dominant additive genetic model was used for the statistical analyses. Interaction between 5-HTTLPR genotype and early trauma exposure was tested using moderated and multiple regression techniques. Interaction plots were used to explore BDNF genotype modulation.

RESULTS

Mildly higher impulsivity scores were found in men with SS compared with SL or LL genotypes, and men with childhood emotional and physical abuse. Interaction analyses showed that combination of 5-HTTLPR-SS genotype and early trauma exposure increase impulsivity scores independently. Impulsivity scores were not affected by the modulation of BDNF genes.

CONCLUSIONS

Childhood trauma and 5-HTTLPR genotype seem to be independently involved in suicide attempts, sharing a common pathway of increasing impulsivity.

Annual Research Review: The persistent and pervasive impact of being bullied in childhood and adolescence: implications for policy and practice

BACKGROUND

We have known for some time that being bullied was associated with children's and adolescents' adjustment difficulties and well-being. In recent years, we have come to recognise that the impact of childhood bullying victimisation on the development of mental health problems is more complex. This paper aims to review the evidence for an independent contribution of childhood bullying victimisation to the development of poor outcomes throughout the life span, including mental, physical and socioeconomic outcomes, and discuss the implications for policy and practice.

FINDINGS

Existing research indicates that (a) being bullied in childhood is associated with distress and symptoms of mental health problems. This large body of evidence supports actions aimed at reducing the occurrence of bullying behaviours; (b) the consequences of childhood bullying victimisation can persist up to midlife and, in addition to mental health, can impact physical and socioeconomic outcomes. These new findings indicate that interventions should also focus on supporting victims of bullying and helping them build resilience; (c) research has identified some factors that predispose children to be targeted by bullying behaviours. These studies suggest that public health interventions could aim at preventing children from becoming the target of bullying behaviours from an early age.

CONCLUSIONS

It is a truism to emphasise that further work is needed to understand why and how young people's aspirations are often cut short by this all too common adverse social experience. In parallel, we must develop effective strategies to tackle this form of abuse and its consequences for the victims. Addressing bullying in childhood could not only reduce children's and adolescents' mental health symptoms but also prevent psychiatric and socioeconomic difficulties up to adulthood and reduce considerable costs for society.

Correlates of bullying and its relationship with psychiatric disorders in Lebanese adolescents

Understanding the contextual determinants of bullying behavior is pivotal for effective interventions. This paper describes the prevalence of bullying, its socio-demographic correlates and factors influencing its relationship with psychiatric disorders among a population-based sample of adolescents from Beirut recruited through a two-stage cluster sampling design. Recruited participants (n = 510) and their parents completed a battery of questionnaires and interviews including the Development and Wellbeing Assessment (DAWBA) and the Peer-Relations Questionnaire (PRQ). We found that around 30% of the adolescent participants were involved in bullying. Younger age, lower family income, lower parental education, receiving private tutoring, having an anxiety disorder and having a disruptive behavior disorder were correlated with being bullied by peers while lower family income, repeating a school-grade, and having a disruptive behavior disorder were associated with bullying others. Several factors including gender, age group, family income, and attending private versus public schools moderated the relationship between bullying behavior and having psychiatric disorders. Our findings thus highlight the complexity of the association between psychiatric disorders and bullying in settings like Lebanon.

Preschoolers' genetic, physiological, and behavioral sensitivity factors moderate links between parenting stress and child internalizing, externalizing, and sleep problems

This study examined three potential moderators of the relations between maternal parenting stress and preschoolers' adjustment problems: a genetic polymorphism-the short allele of the serotonin transporter (5-HTTLPR, ss/sl allele) gene, a physiological indicator-children's baseline respiratory sinus arrhythmia (RSA), and a behavioral indicator-mothers' reports of children's negative emotionality. A total of 108 mothers (M_age  = 30.68 years, SD_age  = 6.06) reported on their parenting stress as well as their preschoolers' (M_age  = 3.50 years, SD_age  = 0.51, 61% boys) negative emotionality and internalizing, externalizing, and sleep problems. Results indicated that the genetic sensitivity variable functioned according to a differential susceptibility model; however, the results involving physiological and behavioral sensitivity factors were most consistent with a diathesis-stress framework. Implications for prevention and intervention efforts to counter the effects of parenting stress are discussed.

Peer Problems and Hyperactivity-Impulsivity Among Norwegian and American Children: The Role of 5-HTTLPR

Peer problems are linked to attention deficit hyperactivity disorder (ADHD) symptoms and the serotonin system is thought to be involved in ADHD-related behavior. Hence, from a Gene × Environment perspective, the serotonin transporter 5-HTTLPR may play a moderating role. In two large community samples, the moderating role of 5-HTTLPR was examined related to more hyperactivity-impulsivity symptoms (HI symptoms) predicted by more peer problems. In Study 1, involving 642 Norwegian children, results indicated that for s-allele carriers only, caregiver-reported peer problems at age 4 predicted more parent-reported HI symptoms at age 6. In Study 2, similar results emerged involving 482 American children. Discussion focuses on differential sensitivity to the adverse effects of poor peer relations.

Co-Development of Personality and Friendships Across the Lifespan

Abstract. This article examines changes in the co-development of personality characteristics and friendships across the lifespan. We address how personality traits shape friendship development (i.e., selection effects) and how friendships shape personality traits (i.e., socialization effects). By integrating separate empirical studies, we look at how selection and socialization effects change across the lifespan. A review of longitudinal research supports our hypothesis that selection effects on friendships intensify during adolescence, peak in young adulthood, and diminish throughout middle and late adulthood. Socialization effects through friendships seem to be moderately sized during adolescence, then small to negligible from young adulthood onwards. For future directions, we discuss effects of the transactional development of friendships and personality regarding associated dispositions within individuals, associated individuals within friendship dyads, and individuals associated within wider social networks.

Psychiatric outcomes of bullying victimization: a study of discordant monozygotic twins

BACKGROUND

Bullying victimization in childhood is associated with a broad array of serious mental health disturbances, including anxiety, depression, and suicidal ideation and behavior. The key goal of this study was to evaluate whether bullying victimization is a true environmental risk factor for psychiatric disturbance using data from 145 bully-discordant monozygotic (MZ) juvenile twin pairs from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) and their follow-up into young adulthood.

METHOD

Since MZ twins share an identical genotype and familial environment, a higher rate of psychiatric disturbance in a bullied MZ twin compared to their non-bullied MZ co-twin would be evidence of an environmental impact of bullying victimization. Environmental correlations between being bullied and the different psychiatric traits were estimated by fitting structural equation models to the full sample of MZ and DZ twins (N = 2824). Environmental associations were further explored using the longitudinal data on the bullying-discordant MZ twins.

RESULTS

Being bullied was associated with a wide range of psychiatric disorders in both children and young adults. The analysis of data on the MZ-discordant twins supports a genuine environmental impact of bullying victimization on childhood social anxiety [odds ratio (OR) 1.7], separation anxiety (OR 1.9), and young adult suicidal ideation (OR 1.3). There was a shared genetic influence on social anxiety and bullying victimization, consistent with social anxiety being both an antecedent and consequence of being bullied.

CONCLUSION

Bullying victimization in childhood is a significant environmental trauma and should be included in any mental health assessment of children and young adults.

Environmental and genetic determinants of childhood depression: The roles of DAT1 and the antenatal environment

Research on adolescent and adult populations has linked depression to variation in several monoaminergic genes, but genetic association studies on depression in children are limited. Additionally, few studies have investigated whether stressors occurring very early in development moderate the influence of certain genes on depression. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) from monoaminergic genes interacted with measures of early life stress to influence depressive symptoms in children. Participants were members of the Auckland Birthweight Collaborative cohort. Small for gestational age (SGA) and maternal stress during pregnancy were measured at birth and used as indicators of early life stress. At age 11, depressive symptoms were measured using the Centre for Epidemiological Studies Depression Scale for Children (CES-DC) and DNA samples were collected for genotyping. A two-way ANOVA revealed that SGA and a SNP from the dopamine transporter gene DAT1 had an interactive effect on children's depressive symptoms. Specifically, symptoms were greater in children born SGA who are T homozygous for the rs1042098 SNP. These findings suggest that adverse intrauterine environments leading to low birth weight also seem to exacerbate the effects of certain DAT1 variants on depression.

Take your mind off it: Coping style, serotonin transporter linked polymorphic region genotype (5-HTTLPR), and children's internalizing and externalizing problems

Individuals with the short variant of the serotonin transporter linked polymorphic region gene are more susceptible than individuals homozygous for the long allele to the effects of stressful life events on risk for internalizing and externalizing problems. We tested whether individual differences in coping style explained this increased risk for problem behavior among youth who were at both genetic and environmental risk. Participants included 279 children, ages 8-11, from the Children's Experiences and Development Study. Caregivers and teachers reported on children's internalizing and externalizing symptoms, and caregivers and children on children's exposure to harsh parenting and parental warmth in middle childhood, and traumatic events. Children reported how frequently they used various coping strategies. Results revealed that short/short homozygotes had higher levels of internalizing problems compared with long allele carriers and that short allele carriers had higher levels of externalizing problems compared with long/long homozygotes under conditions of high cumulative risk. Moreover, among children who were homozygous for the short allele, those who had more cumulative risk indicators less frequently used distraction coping strategies, which partly explained why they had higher levels of internalizing problems. Coping strategies did not significantly mediate Gene × Environment effects on externalizing symptoms.

The Unexpected Effects of Beneficial and Adverse Social Experiences during Adolescence on Anxiety and Aggression and Their Modulation by Genotype

Anxiety and aggression are part of the behavioral repertoire of humans and animals. However, in their exaggerated form both can become maladaptive and result in psychiatric disorders. On the one hand, genetic predisposition has been shown to play a crucial modulatory role in anxiety and aggression. On the other hand, social experiences have been implicated in the modulation of these traits. However, so far, mainly experiences in early life phases have been considered crucial for shaping anxiety-like and aggressive behavior, while the phase of adolescence has largely been neglected. Therefore, the aim of the present study was to elucidate how levels of anxiety-like and aggressive behavior are shaped by social experiences during adolescence and serotonin transporter (5-HTT) genotype. For this purpose, male mice of a 5-HTT knockout mouse model including all three genotypes (wildtype, heterozygous and homozygous 5-HTT knockout mice) were either exposed to an adverse social situation or a beneficial social environment during adolescence. This was accomplished in a custom-made cage system where mice experiencing the adverse environment were repeatedly introduced to the territory of a dominant opponent but had the possibility to escape to a refuge cage. Mice encountering beneficial social conditions had free access to a female mating partner. Afterwards, anxiety-like and aggressive behavior was assessed in a battery of tests. Surprisingly, unfavorable conditions during adolescence led to a decrease in anxiety-like behavior and an increase in exploratory locomotion. Additionally, aggressive behavior was augmented in animals that experienced social adversity. Concerning genotype, homozygous 5-HTT knockout mice were more anxious and less aggressive than heterozygous 5-HTT knockout and wildtype mice. In summary, adolescence is clearly an important phase in which anxiety-like and aggressive behavior can be shaped. Furthermore, it seems that having to cope with challenge during adolescence instead of experiencing throughout beneficial social conditions leads to reduced levels of anxiety-like behavior.

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.

Genetic and Neuroimaging Features of Personality Disorders: State of the Art

Personality disorders often act as a common denominator for many psychiatric problems, and studies on personality disorders contribute to the etiopathology, diagnosis, and treatment of many mental disorders. In recent years, increasing evidence from various studies has shown distinctive features of personality disorders, and that from genetic and neuroimaging studies has been especially valuable. Genetic studies primarily target the genes encoding neurotransmitters and enzymes in the serotoninergic and dopaminergic systems, and neuroimaging studies mainly focus on the frontal and temporal lobes as well as the limbic-paralimbic system in patients with personality disorders. Although some studies have suffered due to unclear diagnoses of personality disorders and some have included few patients for a given personality disorder, great opportunities remain for investigators to launch new ideas and technologies in the field.

Considering the Genetic and Environmental Overlap Between Bullying Victimization, Delinquency, and Symptoms of Depression/Anxiety

Emerging evidence from longitudinal research suggests that bullied children are more likely to develop antisocial tendencies and mental health problems later in life. Less research, however, has used genetically sensitive research designs to control for genetic confounding and examine whether the well-supported association between bullying victimization and maladaptive development is partially accounted for by common genetic and environmental influences. Using sibling data from the National Longitudinal Survey of Youth 1997, the current study used a series of bivariate liability-threshold models to disentangle the genetic and environmental influences on observed covariance between repeated bullying victimization, delinquent involvement, and symptoms of depression/anxiety. Results revealed that common additive genetic and nonshared environmental effects accounted for the covariance in liability between bullying victimization and delinquent involvement as well as bullying victimization and symptoms of depression/anxiety. The results suggest the presence of genotype-environment correlation (rGE) between repeated victimization and maladaptive development.

Bullying by peers in childhood and effects on psychopathology, suicidality, and criminality in adulthood

Bullying is shown to be associated with adverse outcomes in cross-sectional studies, but only a few studies have prospectively examined the effects of childhood bullying on adult outcomes. Our Series paper focuses on prospective longitudinal studies that used large, population-based, community samples analysed through quantitative methods and published between 1960 and 2015. We describe the results of childhood bullying in adulthood in three of the most burdensome areas: psychopathology, suicidality, and criminality. We note that the different groups involved (ie, victims, bullies, and bully-victims) are at risk of difficulties later in life, but their risk profiles differ and the contributions are probably not independent. Controlling for confounders reduces the risk and sometimes eliminates it. Victims are at a high risk of internalising disorders. Bullies seem to be at risk of later externalising disorders and criminality, mainly violent crime and illicit drug misuse. Bully-victims seem to be at risk of internalising disorders, externalising disorders, and criminality, but not all studies examined bully-victims as a separate group. Boys and girls differ in their long-term outcomes. A dose effect exists in which frequent bullying involvement in childhood is most strongly associated with adult adversities. Future studies need to control for additional factors (including genetic, psychosocial, and environmental) to account for the mechanisms behind the reported longitudinal associations.

Long-term effects of bullying

Bullying is the systematic abuse of power and is defined as aggressive behaviour or intentional harm-doing by peers that is carried out repeatedly and involves an imbalance of power. Being bullied is still often wrongly considered as a 'normal rite of passage'. This review considers the importance of bullying as a major risk factor for poor physical and mental health and reduced adaptation to adult roles including forming lasting relationships, integrating into work and being economically independent. Bullying by peers has been mostly ignored by health professionals but should be considered as a significant risk factor and safeguarding issue.

Why some children with externalising problems develop internalising symptoms: testing two pathways in a genetically sensitive cohort study

BACKGROUND

Children with externalising problems are at risk of developing internalising problems as they grow older. The pathways underlying this developmental association remain to be elucidated. We tested two processes that could explain why some children with externalising problems develop internalising symptoms in preadolescence: a mediation model whereby the association between early externalising and later new internalising symptoms is explained by negative experiences; and a genetic model, whereby genes influence both problems.

METHODS

We used data from the Environmental Risk (E-Risk) Study, a 1994-1995 birth cohort of 2,232 twins born in England and Wales. We assessed externalising and internalising problems using combined mothers' and teachers' ratings at age 5 and 12. We measured bullying victimisation, maternal dissatisfaction and academic difficulties between age 7 and 10 and used linear regression analyses to test the effects of these negative experiences on the association between early externalising and later internalising problems. We employed a Cholesky decomposition to examine the genetic influences on the association.

RESULTS

Children with externalising problems at age 5 showed increased rates of new internalising problems at age 12 (r = .24, p < .001). Negative experiences accounted for some of the association between early externalising and later internalising problems. Behavioural-genetic analyses indicated that genes influencing early externalising problems also affected later internalising problems.

CONCLUSIONS

Our findings highlight the role of genetic influences in explaining why some children with externalising problems develop internalising symptoms in preadolescence. Negative experiences also contribute to the association, possibly through gene-environment interplay. Mental health professionals should monitor the development of internalising symptoms in young children with externalising problems.

Effects of persisting emotional impact from child abuse and norepinephrine transporter genetic variation on antidepressant efficacy in major depression: a pilot study

Objective

Previous studies suggest child abuse and serotonergic polymorphism influence depression susceptibility and anti-depressant efficacy. Polymorphisms of the norepinephrine transporter (NET) may also be involved. Research in the area is possibly clouded by under reporting of abuse in researcher trials.

Methods

Adults (n=51) with major depressive disorder has 8 weeks treatment with escitalopram or venlafaxine. Abuse history was obtained, the ongoing emotional impact of which was measured with the 15-item impact of event scale (IES-15). The 17-item Hamilton Depression Rating Scale (HDRS) was applied serially. Two NET polymorphisms (rs2242446 and rs5569) were assayed, blinded to HDRS ratings and abuse history.

Results

No subjects reporting abuse with high impact in adulthood (IES-15 ≥26, n=12) remitted; whereas 77% reporting low impact (IES-15 <26; n=26) remitted (p<0.001). Subjects reporting high impact abuse (n=12) had a 50-fold (95% confidence interval=4.85–514.6) greater odds of carrying rs2242446-TT genotype, but the small sample size leaves this finding vulnerable to type I error.

Conclusion

The level of persisting impact of child abuse appears relevant to antidepressant efficacy, with susceptibility to such possibly being influence by NET rs2242446 polymorphism. Larger studies may be merited to expand on this pilot level finding given potential for biomarker utility.

Peer Victimization and DRD4 Genotype Influence Problem Behaviors in Young Children

Decades of research supports the presence of significant genetic influences on children's internalizing (emotional), externalizing (acting out), and social difficulties, including victimization. Additionally, being victimized has been shown to relate to further behavioral problems. The current study assessed the nature of the gene-environment relationships between the DRD4 gene, peer victimization, and externalizing and internalizing difficulties in 6- to 10-year-old children. 174 children (56 % girls; 88.6 % Caucasian, 3.4 % African American, 8 % mixed race or Mayan) and their parents were administered victimization and problem behavior questionnaires, and DRD4 was genotyped for the children. An interaction between genes (DRD4) and environment (victimization) was significant and supported the differential susceptibility model for verbal victimization and child-reported externalizing behaviors. Children with the DRD4 7-repeat allele were differentially responsive to the verbal victimization environment, such that those experiencing little to no victimization reported significantly lower levels of externalizing behaviors, but if they experienced high amounts of victimization, they reported the highest levels of externalizing behaviors. Thus, consideration of how genes and environment affect children's experiences of victimization prior to adolescence is essential for understanding the trajectory of both externalizing and internalizing behaviors during adolescent development.

An update on the interaction between the serotonin transporter promoter variant (5-HTTLPR), stress and depression, plus an exploration of non-confirming findings

In the three years since the most recent meta-analysis of the association between the serotonin transported promoter polymorphism (5-HTTLPR), stress and the development of depression, another 27 studies have been published on this issue, which is an increase of 50% more studies than were previously reviewed. In addition, previous findings of inconsistency of results across studies argued for further exploration of this relationship. From the 81 studies identified to June 2013, the significant relationship between the short form of the 5-HTTLPR was confirmed (p=.0000009), which is stronger than the relationship reported in the most recent meta-analysis in 2011. However, nearly 26% of the 81 studies reviewed failed to show any significant association between the 5-HTTLPR, stress and depression, and four studies found opposite results to those expected. Examination of the methodologies of all studies failed to indicate any flaws in the opposite or unequivocal studies, and the latter had larger sample sizes than those studies which supported the expected association, arguing that the null results were not an outcome of insufficient statistical power. The need to consider aspects of samples and measures of depression, particularly the presence of subtypes of depression in future research is discussed.

Genetic Heterogeneity in Adolescents' Depressive Symptoms in Response to Victimization

This study had two objectives: first, to determine the degree to which experiences of victimization by peers during adolescence led to a subsequent rise in depressive symptoms, and second, to identify genetic markers that predict depressive reactivity to victimization. We used a cohort sequential design to obtain a longitudinal sample of 1,475 adolescents (3,263 observations) in Grades 8 to 12 (56% female; 47% Black, 46% White). Multilevel growth curve models were used to assess whether victimization predicted depressive symptoms 6 months later, beyond baseline trajectories for depressive symptoms. We modeled the interactive effects of peer victimization with three genetic polymorphisms (on 5-HTTLPR, DRD2 TaqIA, and BDNF Val66Met) on depressive symptoms. Although victimization predicted subsequent depressive symptoms, there was substantial heterogeneity in the magnitude of the effect of victimization. Val alleles, associated with higher brain-derived neurotrophic factor (BDNF) functioning, predicted more sensitivity to victimization. Neither DRD2 TaqIA, a marker associated with dopaminergic functioning, nor 5-HTTLPR, a marker associated with serotonin activity, was associated with sensitivity to victimization. The social stress of peer victimization triggers depressive symptoms most strongly in individuals who are homozygous for the Val allele on the BDNF Val/Met polymorphism. This polymorphism has been linked with sensitivity to social defeat in animal models. Future research should explore behavioral, cognitive, and emotional explanations of the effects of BDNF Val/Met on responsivity to victimization.

The biological effects of childhood trauma

Trauma in childhood is a psychosocial, medical, and public policy problem with serious consequences for its victims and for society. Chronic interpersonal violence in children is common worldwide. Developmental traumatology, the systemic investigation of the psychiatric and psychobiological effects of chronic overwhelming stress on the developing child, provides a framework and principles when empirically examining the neurobiological effects of pediatric trauma. This article focuses on peer-reviewed literature on the neurobiological sequelae of childhood trauma in children and in adults with histories of childhood trauma.

Chronic bullying victimization across school transitions: the role of genetic and environmental influences

We investigated the antecedents and consequences of chronic victimization by bullies across a school transition using a genetically sensitive longitudinal design. Data were from the Environmental Risk Longitudinal Twin Study (E-Risk), an epidemiological cohort of 2,232 children. We used mothers' and children's reports of bullying victimization during primary school and early secondary school. Children who experienced frequent victimization at both time points were classed as "chronic victims" and were found to have an increased risk for mental health problems and academic difficulties compared to children who were bullied only in primary school, children bullied for the first time in secondary school, and never-bullied children. Biometric analyses revealed that stability in victimization over this period was influenced primarily by genetic and shared environmental factors. Regression analyses showed that children's early characteristics such as preexistent adjustment difficulties and IQ predicted chronic versus transitory victimization. Family risk factors for chronic victimization included socioeconomic disadvantage, low maternal warmth, and maltreatment. Our results suggest that bullying intervention programs should consider the role of the victims' behaviors and family background in increasing vulnerability to chronic victimization. Our study highlights the importance of widening antibullying interventions to include families to reduce the likelihood of children entering a pathway toward chronic victimization.

A longitudinal examination of psychological, behavioral, academic, and relationship consequences of dating abuse victimization among a primarily rural sample of adolescents

PURPOSE

It is widely held that being victimized by a dating partner during adolescence has negative consequences, yet few longitudinal studies have examined those consequences. This longitudinal study examined the effects of psychological and physical (including sexual) dating abuse victimization on internalizing symptoms, substance use, academic aspirations and grades, and relationships with friends and family.

METHODS

This four-wave longitudinal study (N = 3,328), conducted in two rural North Carolina counties, spanned grades 8 to 12. Random coefficient analyses were used to examine prospective lagged effects of each type of dating abuse on each outcome and to examine sex and grade as moderators of lagged effects.

RESULTS

Consequences varied by type of dating abuse experienced and sex. For both boys and girls, psychological victimization predicted increased alcohol use and physical victimization predicted increased cigarette use. For girls, physical victimization predicted increased marijuana use, and psychological victimization predicted increased internalizing symptoms; the latter effect was only marginally significant for boys. Physical victimization marginally predicted decreases in the number of close friends for boys. Neither type of victimization predicted increased family conflict or decreased academic aspirations or grades, nor was there evidence that consequences varied by grade.

CONCLUSIONS

Although causation cannot be concluded with longitudinal designs, our findings suggest that being victimized by a dating partner may result in detrimental consequences for adolescents. The findings demonstrate the importance of identifying and implementing evidence-based interventions for preventing dating abuse, including efforts to prevent psychological abuse specifically.

Dopamine receptor D4 gene moderates the effect of positive and negative peer experiences on later delinquency: The Tracking Adolescents' Individual Lives Survey study

The quality of adolescents' relationships with peers can have a lasting impact on later psychosocial adjustment, mental health, and behavior. However, the effect of peer relations on later problem behavior is not uniformly strong, and genetic factors might influence this association. This study used four-wave longitudinal (11–19 years) data (n = 1,151) from the Tracking Adolescents' Individual Lives Survey, a Dutch cohort study into adolescent development to test whether the dopamine receptor D4 polymorphism moderates the impact of negative (i.e., victimization) and positive peer experiences (i.e., social well-being) on later delinquency. Contrary to our expectations, results showed that carriers of the dopamine receptor D4 gene 4-repeat homozygous variant instead of those carrying the 7-repeat allele were more susceptible to the effects of both peer victimization and social well-being on delinquency later in adolescence. Findings of our study are discussed in light of other studies into genetic moderation of peer effects on adolescent development and the possibility that developmental specifics in adolescence, such as maturation processes in brain structure and functioning, may affect the interplay of environmental and genetic factors in this period in life.

Impact of bullying in childhood on adult health, wealth, crime, and social outcomes

Bullying is a serious problem for schools, parents, and public-policymakers alike. Bullying creates risks of health and social problems in childhood, but it is unclear if such risks extend into adulthood. A large cohort of children was assessed for bullying involvement in childhood and then followed up in young adulthood in an assessment of health, risky or illegal behavior, wealth, and social relationships. Victims of childhood bullying, including those that bullied others (bully-victims), were at increased risk of poor health, wealth, and social-relationship outcomes in adulthood even after we controlled for family hardship and childhood psychiatric disorders. In contrast, pure bullies were not at increased risk of poor outcomes in adulthood once other family and childhood risk factors were taken into account. Being bullied is not a harmless rite of passage but throws a long shadow over affected people's lives. Interventions in childhood are likely to reduce long-term health and social costs.

Vulnerability to depression: a moderated mediation model of the roles of child maltreatment, peer victimization, and serotonin transporter linked polymorphic region genetic variation among children from low socioeconomic status backgrounds

Child maltreatment, peer victimization, and a polymorphism of the serotonin transporter gene (5-HTTLPR) were examined as predictors of depressive symptomatology. Children (M age = 11.26, SD = 1.65), including 156 maltreated and 145 nonmaltreated children from comparable low socioeconomic backgrounds, provided DNA samples and self-reports of relational peer victimization, overt peer victimization, and depressive symptoms. Path analysis showed that relational and overt victimization mediated the association between child maltreatment and depressive symptoms. Bootstrapping procedures were used to test moderated mediation and demonstrated that genotype moderated the indirect effects of relational and overt victimization on child depressive symptoms, such that victimized children with the long/long variation were at an increased risk for depressive symptoms compared to victimized children carrying a short allele. Results highlight the utility of examining process models that incorporate biological and psychological factors contributing to the development of depressive symptomatology and provide direction toward understanding and promoting resilience among high-risk youth from a multiple levels of analysis approach.

Peer victimization in childhood and internalizing problems in adolescence: a prospective longitudinal study

Traumatic childhood experiences have been found to predict later internalizing problems. This prospective longitudinal study investigated whether repeated and intentional harm doing by peers (peer victimization) in childhood predicts internalizing symptoms in early adolescence. 3,692 children from the Avon Longitudinal Study of Parents and Children (ALSPAC), as well as their mothers and teachers, reported on bullying in childhood (7-10 years) and internalizing problems in early adolescence (11-14 years). Controlling for prior psychopathology, family adversity, gender and IQ, being a victim of bullying was associated with higher overall scores, as well as increased odds of scoring in the severe range (>90(th) percentile) for emotional and depression symptoms. Victims were also more likely to show persistent depression symptoms over a 2-year period. These associations were found independent of whether mothers, teachers or the children reported on bullying. It is concluded that peer victimization in childhood is a precursor of both short-lived and persistent internalizing symptoms, underlining the importance of environmental factors such as peer relationships in the etiology of internalizing problems.

Adult psychiatric outcomes of bullying and being bullied by peers in childhood and adolescence

IMPORTANCE

Both bullies and victims of bullying are at risk for psychiatric problems in childhood, but it is unclear if this elevated risk extends into early adulthood.

OBJECTIVE

To test whether bullying and/or being bullied in childhood predicts psychiatric problems and suicidality in young adulthood after accounting for childhood psychiatric problems and family hardships.

DESIGN

Prospective, population-based study.

SETTING

Community sample from 11 counties in Western North Carolina.

PARTICIPANTS

A total of 1420 participants who had being bullied and bullying assessed 4 to 6 times between the ages of 9 and 16 years. Participants were categorized as bullies only, victims only, bullies and victims (hereafter referred to as bullies/victims), or neither.

MAIN OUTCOME MEASURE

Psychiatric outcomes, which included depression, anxiety, antisocial personality disorder, substance use disorders, and suicidality (including recurrent thoughts of death, suicidal ideation, or a suicide attempt), were assessed in young adulthood (19, 21, and 24-26 years) by use of structured diagnostic interviews. RESULTS Victims and bullies/victims had elevated rates of young adult psychiatric disorders, but also elevated rates of childhood psychiatric disorders and family hardships. After controlling for childhood psychiatric problems or family hardships, we found that victims continued to have a higher prevalence of agoraphobia (odds ratio [OR], 4.6 [95% CI, 1.7-12.5]; P < .01), generalized anxiety (OR, 2.7 [95% CI, 1.1-6.3]; P < .001), and panic disorder (OR, 3.1 [95% CI, 1.5-6.5]; P < .01) and that bullies/victims were at increased risk of young adult depression (OR, 4.8 [95% CI, 1.2-19.4]; P < .05), panic disorder (OR, 14.5 [95% CI, 5.7-36.6]; P < .001), agoraphobia (females only; OR, 26.7 [95% CI, 4.3-52.5]; P < .001), and suicidality (males only; OR, 18.5 [95% CI, 6.2-55.1]; P < .001). Bullies were at risk for antisocial personality disorder only (OR, 4.1 [95% CI, 1.1-15.8]; P < .04).

CONCLUSIONS AND RELEVANCE

The effects of being bullied are direct, pleiotropic, and long-lasting, with the worst effects for those who are both victims and bullies.

Gene-environment studies and borderline personality disorder: a review

We review recent gene-environment studies relevant to borderline personality disorder, including those focusing on impulsivity, emotion sensitivity, suicidal behavior, aggression and anger, and the borderline personality phenotype itself. Almost all the studies reviewed suffered from a number of methodological and statistical problems, limiting the conclusions that currently can be drawn. The best evidence to date supports a gene-environment correlation (rGE) model for borderline personality traits and a range of adverse life events, indicating that those at risk for BPD are also at increased risk for exposure to environments that may trigger BPD. We provide suggestions regarding future research on GxE interaction and rGE effects in borderline personality.