Examining the role of passive gene–environment correlation in childhood depression using a novel genetically sensitive design

Exploring the differentiation of behavioural and emotional problems across childhood: A prospective longitudinal cohort study

Background

An individual's overall burden of behavioural and emotional problems across childhood is associated with increased likelihood of later mental health conditions. However, the relative extent of behavioural versus emotional problems - that is, the extent to which the domains are differentiated from one another - may provide additional information about who is at risk of developing a mental health condition. Here, we seek to validate differentiation as an independent predictor of later mental health conditions, and to explore its aetiology.

Methods

We analysed data from ~79,000 children in the population-based Norwegian Mother, Father, and Child Cohort Study, and linked health-care registries. In preregistered analyses, we modelled the extent and rate of differentiation of behavioural and emotional problems between ages 1.5-5 years, and estimated associations with later symptoms (age 8) and diagnoses (after age 8). We also explored the aetiology of differentiation by estimating associations with early life exposures and, in a subset of 23,945 full siblings, assessing the impact of accounting for unobserved familial confounding.

Results

Differentiation of behavioural and emotional problems was associated with later symptoms and diagnoses of mental health conditions, independent of total problems. Maternal at-risk drinking (β = 0.04 [0.02, 0.06]) and parental relationship problems (β = 0.04 [0.02, 0.05]) were associated with higher behavioural relative to emotional problems at age 5. Maternal prenatal distress (|β| = 0.04 [0.03, 0.06]), concurrent distress (|β| = 0.04 [0.02, 0.06]) and parental education (|β| = 0.05 [0.04, 0.07]) predicted higher emotional relative to behavioural problems at age 5. Estimates for maternal prenatal distress and at-risk drinking were consistent across both unadjusted and adjusted analyses accounting for unobserved familial risk.

Conclusions

Differentiation of behavioural and emotional problems in early childhood represents a valid source of inter-individual variability linked to the later emergence of psychopathology and may be relevant for early detection and prevention strategies for mental health.

Parenting in the Context of the Child: Genetic and Social Processes

The focus on the role of parenting in child development has a long-standing history. When measures of parenting precede changes in child development, researchers typically infer a causal role of parenting practices and attitudes on child development. However, this research is usually conducted with parents raising their own biological offspring. Such research designs cannot account for the effects of genes that are common to parents and children, nor for genetically influenced traits in children that influence how they are parented and how parenting affects them. The aim of this monograph is to provide a clearer view of parenting by synthesizing findings from the Early Growth and Development Study (EGDS). EGDS is a longitudinal study of adopted children, their birth parents, and their rearing parents studied across infancy and childhood. Families (N = 561) were recruited in the United States through adoption agencies between 2000 and 2010. Data collection began when adoptees were 9 months old (males = 57.2%; White 54.5%, Black 13.2%, Hispanic/Latinx 13.4%, Multiracial 17.8%, other 1.1%). The median child age at adoption placement was 2 days (M = 5.58, SD = 11.32). Adoptive parents were predominantly in their 30s, White, and coming from upper-middle- or upper-class backgrounds with high educational attainment (a mode at 4-year college or graduate degree). Most adoptive parents were heterosexual couples, and were married at the beginning of the project. The birth parent sample was more racially and ethnically diverse, but the majority (70%) were White. At the beginning of the study, most birth mothers and fathers were in their 20s, with a mode of educational attainment at high school degree, and few of them were married. We have been following these family members over time, assessing their genetic influences, prenatal environment, rearing environment, and child development. Controlling for effects of genes common to parents and children, we confirmed some previously reported associations between parenting, parent psychopathology, and marital adjustment in relation to child problematic and prosocial behavior. We also observed effects of children's heritable characteristics, characteristics thought to be transmitted from parent to child by genetic means, on their parents and how those effects contributed to subsequent child development. For example, we found that genetically influenced child impulsivity and social withdrawal both elicited harsh parenting, whereas a genetically influenced sunny disposition elicited parental warmth. We found numerous instances of children's genetically influenced characteristics that enhanced positive parental influences on child development or that protected them from harsh parenting. Integrating our findings, we propose a new, genetically informed process model of parenting. We posit that parents implicitly or explicitly detect genetically influenced liabilities and assets in their children. We also suggest future research into factors such as marital adjustment, that favor parents responding with appropriate protection or enhancement. Our findings illustrate a productive use of genetic information in prevention research: helping parents respond effectively to a profile of child strengths and challenges rather than using genetic information simply to identify some children unresponsive to current preventive interventions.

The Contagion of Psychopathology across Different Psychiatric Disorders: A Comparative Theoretical Analysis

Psychopathology is often studied and treated from an individual-centered approach. However, studies have shown that psychological distress is often best understood from a contextual, environmental perspective. This paper explores the literature on emotional contagion and symptom transmission in psychopathology, i.e., the complex ways in which one person's psychological distress may yield symptoms among others in his/her close environment. We argue that emotions, cognitions, and behaviors often do not stay within the borders of the individual, but rather represent intricate dynamic experiences that are shared by individuals, as well as transmitted between them. While this claim was comprehensively studied in the context of some disorders (e.g., secondary traumatization and the "mimicking" of symptoms among those close to a trauma survivor), it was very scarcely examined in the context of others. We aim to bridge this gap in knowledge by examining the literature on symptom transmission across four distinct psychiatric disorders: PTSD, major depression, OCD, and psychosis. We first review the literature on emotional contagion in each disorder separately, and then we subsequently conduct a comparative analysis highlighting the shared and differential mechanisms underlying these processes in all four disorders. In this era of transdiagnostic conceptualizations of psychopathology, such an examination is timely, and it may carry important clinical implications.

Multiomic biological approaches to the study of child abuse and neglect

Childhood maltreatment, occurring in up to 20-30% of the population, remains far too common, and incorporates a range of active and passive factors, from abuse, to neglect, to the impacts of broader structural and systemic adversity. Despite the effects of childhood maltreatment and adversity on a wide range of adult physical and psychological negative outcomes, not all individuals respond similarly. Understanding the differential biological mechanisms contributing to risk vs. resilience in the face of developmental adversity is critical to improving preventions, treatments, and policy recommendations. This review begins by providing an overview of childhood abuse, neglect, maltreatment, threat, and toxic stress, and the effects of these forms of adversity on the developing body, brain, and behavior. It then examines examples from the current literature of genomic, epigenomic, transcriptomic, and proteomic discoveries and biomarkers that may help to understand risk and resilience in the aftermath of trauma, predictors of traumatic exposure risk, and potential targets for intervention and prevention. While the majority of genetic, epigenetic, and gene expression analyses to date have focused on targeted genes and hypotheses, large-scale consortia are now well-positioned to better understand interactions of environment and biology with much more statistical power. Ongoing and future work aimed at understanding the biology of childhood adversity and its effects will help to provide targets for intervention and prevention, as well as identify paths for how science, health care, and policy can combine efforts to protect and promote the psychological and physiological wellbeing of future generations.

Family-Based Designs that Disentangle Inherited Factors from Pre- and Postnatal Environmental Exposures: In Vitro Fertilization, Discordant Sibling Pairs, Maternal versus Paternal Comparisons, and Adoption Designs

Identifying environmental risk and protective exposures that have causal effects on health is an important scientific goal. Many environmental exposures are nonrandomly allocated and influenced by dispositional factors including inherited ones. We review family-based designs that can separate the influence of environmental exposures from inherited influences shared between parent and offspring. We focus on prenatal exposures. We highlight that the family-based designs that can separate the prenatal environment from inherited confounds are different to those that are able to pull apart later-life environmental exposures from inherited confounds. We provide a brief review of the literature on maternal smoking during pregnancy and offspring attention-deficit/hyperactivity disorder (ADHD) and conduct problems; these inconsistencies in the literature make a review useful and this illustrates that results of family-based genetically informed studies are inconsistent with a causal interpretation for this exposure and these two offspring outcomes.

Parenting Stress Plays a Mediating Role in the Prediction of Early Child Development from Both Parents' Perinatal Depressive Symptoms

Maternal postnatal depression has been associated with a broad range of developmental risk among children. However, there has been less focus on disentangling the effects of pre- and postnatal depressive symptoms, as well as examining the symptoms of both parents. This study aims to investigate the separate effects of pre- and postnatal depressive symptoms in mothers and fathers, and parents' differential effects on child social-emotional, cognitive, and language development at 18 months of age. Further, we investigate whether effects of depressive symptomatology on child outcomes are particularly strong when both parents evinced high symptom loads and whether parenting stress mediates associations between perinatal depressive symptoms and child developmental outcomes. The study used data from 1036 families participating in a community-based study from mid-pregnancy until 18 months postpartum. Depressive symptoms were assessed at seven time points (four prenatally). Within a structural equation framework, we found that parental perinatal depressive symptoms predicted child social-emotional functioning, specifically externalizing, internalizing, and dysregulation problems, as well as language developmental delay at 18 months. Controlling for postnatal symptoms we found no independent effect of prenatal depressive symptoms on any child outcomes. A differential effect was evident, linking maternal symptoms to social-emotional outcomes, and paternal symptoms to language outcomes. There was no evidence of stronger associations between depressive symptoms and child outcomes when both parents showed high symptom loads. However, parenting stress mediated most relations between parental depressive symptoms and child outcomes. Findings demonstrate the importance of including paternal depressive symptoms in both clinical and research contexts.

Rumination, Excessive Reassurance Seeking, and Stress Generation Among Early Adolescent Girls

Nolen-Hoeksema proposed that rumination increases stressful events and circumstances; however, few studies have examined this question. Thus, we explored whether (a) rumination predicted increases in the generation of chronic and acute stress, (b) excessive reassurance seeking (ERS) mediated links between rumination and stress generation, (c) rumination increased exposure to acute independent (uncontrollable) stress, and (d) rumination predicted chronic stress generation in certain domains, but not others. These questions were examined in a 1-year study of 126 early adolescent girls ( M age = 12.39 years) using contextual objective stress interviews. Findings indicated that rumination predicted increases in acute dependent interpersonal stress and chronic interpersonal stress, and ERS mediated these associations. Moreover, rumination was not associated with acute independent stress. Finally, the effect of rumination on chronic stress generation was most salient in adolescents' romantic lives and in parent-adolescent relationships. These findings suggest that ruminators create stressful interpersonal environments.

Sometimes It's Good to be Short: The Serotonin Transporter Gene, Positive Parenting, and Adolescent Depression

In threatening environments, the short (S) allele of 5-HTTLPR is proposed to augment risk for depression. However, it is unknown whether 5-HTTLPR variation increases risk for depression in environments of deprivation, lacking positive or nurturant features. Two independent longitudinal studies (n = 681 and 176, respectively) examined whether 5-HTTLPR moderated associations between low levels of positive parenting at 11-13 years and subsequent depression at 17-19 years. In both studies only LL homozygous adolescents were at greater risk for depression with decreasing levels of positive parenting. Thus, while the S allele has previously been identified as a susceptible genotype, these findings suggest that the L allele may also confer sensitivity to depression in the face of specific environmental challenges.

Does MAOA increase susceptibility to prenatal stress in young children?

BACKGROUND

We previously demonstrated a gene-by-prenatal-environment interaction whereby the monoamine oxidase A gene (MAOA) modified the impact of prenatal tobacco exposure (PTE) on adolescent disruptive behavior (DB), with the MAOA risk genotype varying by sex. We extend this work by examining whether this mechanism is evident with another common adversity, prenatal stress exposure (PSE), and whether sex differences are present earlier in development in closer proximity to exposure.

METHODS

Participants were 281 mothers and their 285 children derived from a prenatal cohort with in-depth prospective measures of PSE and PTE. We assessed DB at age 5 via dimensional developmentally-sensitive measurement. Analyses were stratified by sex based on prior evidence for sex differences.

RESULTS

Concurrent stress exposure predicted DB in children (β=0.310, p=0.001), while main effects of prenatal exposures were seen only in boys. We found a three-way interaction of MAOA×PSE×sex on DB (β=0.813, p=0.022). Boys with MAOA-H had more DB as a function of PSE, controlling for PTE (β=0.774, p=0.015), and as a function of PTE, controlling for PSE (β=0.362, p=0.037). Boys with MAOA-L did not show this susceptibility. MAOA did not interact with PSE (β=-0.133, p=0.561) nor PTE (β=-0.144; p=0.505) in predicting DB in girls. Examination of gene-environment correlation (rGE) showed a correlation between paternal MAOA-L and daughters' concurrent stress exposure (r=-0.240, p=0.013).

DISCUSSION

Findings underscore complex mechanisms linking genetic susceptibility and early adverse exposures. Replication in larger cohorts followed from the pregnancy through adolescence is suggested to elucidate mechanisms that appear to have varying developmental expression.

Genetic and Environmental Influences on Parent-Child Conflict and Child Depression Through Late Adolescence

Few studies have investigated potential gender differences in the genetic and environmental influences on the prospective associations between parent-child conflict and later depression, a notable gap given substantial gender differences in rates of depression and suggestive evidence of differences in the etiology of depression among females and males. To fill this gap, we evaluated whether the prospective relationship between parent-child conflict and major depressive disorder symptoms varied as a function of parent-child gender composition. A combined twin and adoption sample was used (53% female; 85% European ancestry), containing 1,627 adolescent sibling pairs (789 monozygotic twin pairs, 594 dizygotic/full-biological pairs, 244 genetically unrelated pairs) with assessments at two time points in adolescence (approximate ages 15 and 18). Prospective associations between parent-child conflict and subsequent adolescent depression were explained predominately through common genetic influences for mother-daughter and mother-son pairs but less so for father-daughter and father-son pairs. Results support the notion that processes of gene-environment correlation involved in the prospective associations between parent-child conflict, and later adolescent depression appear to be less relevant to father-child relationships in comparison to mother-child relationships. Notably, results did not show that parent-child conflict was more relevant to the etiology of major depressive disorder (MDD) for girls than boys; gender differences in depression do not appear to be due to differences in the associations between parent-child conflict and child depression.

Parent and peer influences on emerging adult substance use disorder: A genetically informed study

The present study utilizes longitudinal data from a high-risk community sample to examine the unique effects of genetic risk, parental knowledge about the daily activities of adolescents, and peer substance use on emerging adult substance use disorders (SUDs). These effects are examined over and above a polygenic risk score. In addition, this polygenic risk score is used to examine gene-environment correlation and interaction. The results show that during older adolescence, higher adolescent genetic risk for SUDs predicts less parental knowledge, but this relation is nonsignificant in younger adolescence. Parental knowledge (using mother report) mediates the effects of parental alcohol use disorder (AUD) and adolescent genetic risk on risk for SUD, and peer substance use mediates the effect of parent AUD on offspring SUD. Finally, there are significant gene-environment interactions such that, for those at the highest levels of genetic risk, less parental knowledge and more peer substance use confers greater risk for SUDs. However, for those at medium and low genetic risk, these effects are attenuated. These findings suggest that the evocative effects of adolescent genetic risk on parenting increase with age across adolescence. They also suggest that some of the most important environmental risk factors for SUDs exert effects that vary across level of genetic propensity.

Normal personality traits, rumination and stress generation among early adolescent girls

This study examined associations between personality and stress generation. Expanding upon prior work, we examined (a) the role of Positive Emotionality (PE), Negative Emotionality (NE), and Constraint (CON), and their lower-order facets, as predictors of acute and chronic interpersonal stress generation; (b) whether personality moderated effects of rumination on stress generation; and (c) whether personality increased exposure to independent (uncontrollable) stress. These questions were examined in a one-year study of 126 adolescent girls (M age = 12.39 years) using contextual stress interviews. NE predicted increases in acute and chronic interpersonal stress generation, but not independent stress. NE, CON and affiliative PE each moderated the effect of rumination on chronic interpersonal stress generation. These effects were driven by particular lower-order traits.

Antenatal depression and children's developmental outcomes: potential mechanisms and treatment options

During the last decade there has been increased recognition of the prevalence of antenatal depression as well as an expansion in research examining the impact of maternal mood during pregnancy on offspring development. The aim of this review was to summarise the theoretical underpinnings and empirical evidence regarding the impact of antenatal depression on children's developmental outcomes. Biological mechanisms hypothesised to account for an association between antenatal depression and adverse offspring outcomes are first identified including the functioning of the prenatal Hypothalamic Pituitary Adrenal (HPA) axis and epigenetic processes. A systematic literature search is then conducted of studies examining the impact of antenatal depression on child development. In general, studies examining associations between antenatal depression and offspring temperament, cognitive and emotional outcomes reveal either no effect of the prenatal environment or small effects that often attenuate following adjustment for other antenatal and postnatal risk factors. In contrast, an independent effect of antenatal depression on children's conduct problems and antisocial behaviour is a well-replicated finding. There is emerging evidence that exposure to depression during pregnancy impacts negatively on offspring biology, although the findings are complex and require replication. Psychological and pharmacological treatments of antenatal depression are then reviewed, considering whether antidepressant medication exerts harmful effects on the foetus. We close by proposing that antenatal depression is an early marker of a developmental cascade to future mental health problems for both mothers and offspring.

Gene–environment correlation in developmental psychopathology

Modern research acknowledges that psychopathology and individual differences in normal development are the joint products of both biological and social influences. Although there have been numerous publications on Gene × Environment interactions in the past decade, gene–environment correlation is another important form of gene–environment interplay that has received less attention. This Special Section demonstrates, using a range of methodological approaches, the importance of gene–environment correlation in developmental psychopathology. Several types of gene–environment correlation are described, including passive, evocative, and active. Other studies highlight the potential for gene–environment correlation to obscure associations between risk exposures and child psychopathology. Future directions for gene–environment correlation research are discussed.