How genes and the social environment moderate each other

The missing hallmark of health: psychosocial adaptation

The eight biological hallmarks of health that we initially postulated (Cell. 2021 Jan 7;184(1):33-63) include features of spatial compartmentalization (integrity of barriers, containment of local perturbations), maintenance of homeostasis over time (recycling & turnover, integration of circuitries, rhythmic oscillations) and an array of adequate responses to stress (homeostatic resilience, hormetic regulation, repair & regeneration). These hallmarks affect all eight somatic strata of the human body (molecules, organelles, cells, supracellular units, organs, organ systems, systemic circuitries and meta-organism). Here we postulate that mental and socioeconomic factors must be added to this 8×8 matrix as an additional hallmark of health ("psychosocial adaptation") and as an additional stratum ("psychosocial interactions"), hence building a 9×9 matrix. Potentially, perturbation of each of the somatic hallmarks and strata affects psychosocial factors and vice versa. Finally, we discuss the (patho)physiological bases of these interactions and their implications for mental health improvement.

Challenges in studying the interplay of genes and environment. A study of childhood financial distress moderating genetic predisposition for peak smoking

Smoking is one of the leading causes of preventable disease and death in the U.S., and it is strongly influenced both by genetic predisposition and childhood adversity. Using polygenic indices (PGIs) of predisposition to smoking, we evaluate whether childhood financial distress (CFD; a composite measure of financial adversity) moderates genetic risk in explaining peak-cigarette consumption in adulthood. Using the Health and Retirement Study (HRS), we find a substantial reduction in the relationship between genetic risk and peak smoking for those who did not suffer financial adversity in childhood. Among adult smokers who grew up in high-CFD households, a one standard deviation higher PGI is associated with 2.9 more cigarettes smoked per day at peak. By contrast, among smokers who grew up in low-CFD households, this gradient is reduced by 37 percent (or 1.1 fewer). These results are robust to controlling for a host of prime confounders. By contrast, we find no evidence of interactions between the PGI and typical measures of childhood SES such as parental education - a null result that we replicate in the Wisconsin Longitudinal Study (WLS) and the English Longitudinal Study of Aging (ELSA). This suggests the role of childhood financial distress in the relationship with peak smoking is distinct from that of low childhood SES, with high CFD potentially reflecting more acute distress than do measures of low childhood SES. Our evidence also suggests low childhood SES is a weaker proxy for acute distress, providing an alternative explanation for the childhood SES null result.

Implementing Core Genes and an Omnigenic Model for Behaviour Traits Prediction in Genomics

A high number of genome variants are associated with complex traits, mainly due to genome-wide association studies (GWAS). Using polygenic risk scores (PRSs) is a widely accepted method for calculating an individual's complex trait prognosis using such data. Unlike monogenic traits, the practical implementation of complex traits by applying this method still falls behind. Calculating PRSs from all GWAS data has limited practical usability in behaviour traits due to statistical noise and the small effect size from a high number of genome variants involved. From a behaviour traits perspective, complex traits are explored using the concept of core genes from an omnigenic model, aiming to employ a simplified calculation version. Simplification may reduce the accuracy compared to a complete PRS encompassing all trait-associated variants. Integrating genome data with datasets from various disciplines, such as IT and psychology, could lead to better complex trait prediction. This review elucidates the significance of clear biological pathways in understanding behaviour traits. Specifically, it highlights the essential role of genes related to hormones, enzymes, and neurotransmitters as robust core genes in shaping these traits. Significant variations in core genes are prominently observed in behaviour traits such as stress response, impulsivity, and substance use.

The impact of dopamine receptor D4, temperamental negativity, and household chaos on young twins' externalizing behaviors

Biological and genetic factors, as well as contextual influences, contribute to the etiology of externalizing behaviors in children and adolescents. The current project used a longitudinal design to examine how individual vulnerability for externalizing behavior is influenced by the interplay among biological/genetic and environmental factors, and how this occurs across development. We investigated the influence of dopamine receptor D4 genotype (DRD4), child temperament, and household chaos on children's externalizing behaviors using a sample of twins/triplets tested at the ages of 4 and 5 years (n = 229), including a subset of these who were tested again in middle childhood (ages 7-13 years; n = 174). Multilevel linear regression modeling demonstrated that the DRD4-7repeat genotype, 4-year-old negative affectivity, and household chaos at the age of 4 years were related to 5-year-old externalizing behaviors. Stability in externalizing behaviors from the age of 5 years to middle childhood was demonstrated. A significant interaction between DRD4 and household chaos showed that children with no 7-repeat DRD4 alleles had significantly higher levels of externalizing in homes with extremely low levels of parent-reported chaos, suggesting a "goodness-of-fit" pattern of gene-environment interaction. These findings suggest that risk for childhood externalizing behaviors is likely multifaceted and differs across developmental periods.

Associations between error-related negativity and childhood anxiety risk differ based on socioeconomic status

Children from lower socioeconomic status (SES) families are at increased risk for anxiety problems, though knowledge of the pathways by which SES predicts children's anxiety outcomes remains scant. Limited work suggests SES as a moderator of links between early development and anxiety outcomes but has not used a longitudinal framework or a multimethod approach. In this preregistered study, SES was tested as a simultaneous moderator of putatively biologically (error-related negativity [ERN]) and contextually (authoritarian parenting) based pathways of anxiety risk from ages 3 (Mage = 3.59), 4 (Mage = 4.57), and 5 (Mage = 5.52) [N = 121; 59% female]. Families were largely White and Non-Hispanic and reported a broad range of income (less than $15,000 to $90,001 or greater) from 2014 to 2017. We hypothesized that putatively biological pathways would be the strongest predictors of child outcomes at high SES and that putatively contextual pathways would be the strongest predictors of child outcomes at low SES. Consistent with expectations, smaller ERN across ages 3 and 4 was associated with greater anxious behaviors at age 5, but only at high SES. SES did not moderate parenting-based pathways of risk. Results are partially consistent with previous work suggesting that putatively biological pathways are more robust predictors of child outcomes at high SES than at low SES. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Genetic Risk, Neighborhood Characteristics, and Behavioral Difficulties Among African American Adolescents Living in Very Low-Income Neighborhoods

Behavioral difficulties among African American youth are disproportionately detrimental to their future well-being compared to when demonstrated by White American youth. The majority of gene-environment studies of behavior have been conducted with European ancestry samples, limiting our knowledge of these processes among African Americans. This study examined the influence of positive and negative neighborhood conditions, in the context of genetic risk, on behavioral difficulties among low-income African American adolescents. Data were from the Genes, Environment, and Neighborhood Initiative study of African American youth in high-poverty neighborhoods, n = 524, M age = 15.89, SD = 1.42. DNA samples were collected using the Oragene Discovery 500 series, and polygenic risk scores for behavioral difficulties computed. Neighborhood informal social control, social cohesion, physical disorder, and social disorder were assessed. Adolescent alcohol use, hyperactivity/inattention and conduct problems were examined as outcomes. After controlling for polygenic risk, lower levels of neighborhood social disorder and higher levels of social cohesion were associated with fewer youth-reported hyperactivity/inattention and conduct problems. Less social disorder also was associated with fewer parent-reported behavioral difficulties. Neighborhood characteristics did not moderate associations between genetic risk and the outcomes. Higher levels of positive and lower levels of negative neighborhood characteristics can be associated with lower levels of behavioral difficulties among African American youth living in poverty, even after taking into account genetic risk.

Using genetic designs to identify likely causal environmental contributions to psychopathology

The multifactorial nature of psychopathology, whereby both genetic and environmental factors contribute risk, has long been established. In this paper, we provide an update on genetically informative designs that are utilized to disentangle genetic and environmental contributions to psychopathology. We provide a brief reminder of quantitative behavioral genetic research designs that have been used to identify potentially causal environmental processes, accounting for genetic contributions. We also provide an overview of recent molecular genetic approaches that utilize genome-wide association study data which are increasingly being applied to questions relevant to psychopathology research. While genetically informative designs typically have been applied to investigate the origins of psychopathology, we highlight how these approaches can also be used to elucidate potential causal environmental processes that contribute to developmental course and outcomes. We highlight the need to use genetically sensitive designs that align with intervention and prevention science efforts, by considering strengths-based environments to investigate how positive environments can mitigate risk and promote children's strengths.

Joint Attention in Human and Chimpanzee Infants in Varied Socio-Ecological Contexts

Joint attention (JA) is an early manifestation of social cognition, commonly described as interactions in which an infant looks or gestures to an adult female to share attention about an object, within a positive emotional atmosphere. We label this description the JA phenotype. We argue that characterizing JA in this way reflects unexamined assumptions which are, in part, due to past developmental researchers' primary focus on western, middle-class infants and families. We describe a range of cultural variations in caregiving practices, socialization goals, and parenting ethnotheories as an essential initial step in viewing joint attention within inclusive and contextualized perspectives. We begin the process of conducting a decolonized study of JA by considering the core construct of joint attention (i.e., triadic connectedness) and adopting culturally inclusive definitions (labeled joint engagement [JE]). Our JE definitions allow for attention and engagement to be expressed in visual and tactile modalities (e.g., for infants experiencing distal or proximal caregiving), with various social partners (e.g., peers, older siblings, mothers), with a range of shared topics (e.g., representing diverse socialization goals, and socio-ecologies with and without toys), and with a range of emotional tone (e.g., for infants living in cultures valuing calmness and low arousal, and those valuing exuberance). Our definition of JE includes initiations from either partner (to include priorities for adult-led or child-led interactions). Our next foundational step is making an ecological commitment to naturalistic observations (Dahl, 2017, Child Dev Perspect, 11(2), 79-84): We measure JE while infants interact within their own physical and social ecologies. This commitment allows us to describe JE as it occurs in everyday contexts, without constraints imposed by researchers. Next, we sample multiple groups of infants drawn from diverse socio-ecological settings. Moreover, we include diverse samples of chimpanzee infants to compare with diverse samples of human infants, to investigate the extent to which JE is unique to humans, and to document diversity both within and between species. We sampled human infants living in three diverse settings. U.K. infants (n = 8) were from western, middle-class families living near universities in the south of England. Nso infants (n = 12) were from communities of subsistence farmers in Cameroon, Africa. Aka infants (n = 10) were from foraging communities in the tropical rain forests of Central African Republic, Africa. We coded behavioral details of JE from videotaped observations (taken between 2004 and 2010). JE occurred in the majority of coded intervals (Mdn = 68%), supporting a conclusion that JE is normative for human infants. The JA phenotype, in contrast, was infrequent, and significantly more common in the U.K. (Mdn = 10%) than the other groups (Mdn < 3%). We found significant within-species diversity in JE phenotypes (i.e., configurations of predominant forms of JE characteristics). We conclude that triadic connectedness is very common in human infants, but there is significant contextualization of behavioral forms of JE. We also studied chimpanzee infants living in diverse socio-ecologies. The PRI/Zoo chimpanzee infants (n = 7) were from captive, stable groups of mixed ages and sexes, and included 4 infants from the Chester Zoo, U.K. and 3 from the Primate Research Institute, Kyoto University, Japan. The Gombe chimpanzee infants (n = 12) were living in a dynamically changing, wild community in the Gombe National Park, Tanzania, Africa. Additionally, we include two Home chimpanzee infants who were reared from birth by a female scientist, in the combined U.S., middle-class contexts of home and university cognition laboratory. JE was coded from videotaped observations (taken between 1993 and 2006). JE occurred during the majority of coded intervals (Mdn = 64%), consistent with the position that JE is normative for chimpanzee infants. The JA phenotype, in contrast, was rare, but more commonly observed in the two Home chimpanzee infants (in 8% and 2% of intervals) than in other chimpanzee groups (Mdns = 0%). We found within-species diversity in the configurations comprising the JE phenotypes. We conclude that triadic connectedness is very common in chimpanzee infants, but behavioral forms of joint engagement are contextualized. We compared JE across species, and found no species-uniqueness in behavioral forms, JE characteristics, or JE phenotypes. Both human and chimpanzee infants develop contextualized social cognition. Within-species diversity is embraced when triadic connectedness is described with culturally inclusive definitions. In contrast, restricting definitions to the JA phenotype privileges a behavioral form most valued in western, middle-class socio-ecologies, irrespective of whether the interactions involve human or chimpanzee infants. Our study presents a model for how to decolonize an important topic in developmental psychology. Decolonization is accomplished by defining the phenomenon inclusively, embracing diversity in sampling, challenging claims of human-uniqueness, and having an ecological commitment to observe infant social cognition as it occurs within everyday socio-ecological contexts. It is essential that evolutionary and developmental theories of social cognition are re-built on more inclusive and decolonized empirical foundations.

Social Epidemiology: Past, Present, and Future

In a context where epidemiologic research has been heavily influenced by a biomedical and individualistic approach, the naming of “social epidemiology” allowed explicit emphasis on the social production of disease as a powerful explanatory paradigm and as critically important for interventions to improve population health. This review briefly highlights key substantive areas of focus in social epidemiology over the past 30 years, reflects on major advances and insights, and identifies challenges and possible future directions. Future opportunities for social epidemiology include grounding research in theoretically based and systemic conceptual models of the fundamental social drivers of health; implementing a scientifically rigorous yet realistic approach to drawing conclusions about social causes; using complementary methods to generate valid explanations and identify effective actions; leveraging the power of harmonization, replication, and big data; extending interdisciplinarity and diversity; advancing emerging critical approaches to understanding the health impacts of systemic racism and its policy implications; going global; and embracing a broad approach to generating socially useful research.

Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Financial strain moderates genetic influences on self-rated health: support for diathesis-stress model of gene-environment interplay

Data from the Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium were used to examine predictions of different models of gene-by-environment interaction to understand how genetic variance in self-rated health (SRH) varies at different levels of financial strain. A total of 11,359 individuals from 10 twin studies in Australia, Sweden, and the United States contributed relevant data, including 2,074 monozygotic and 2,623 dizygotic twin pairs. Age ranged from 22 to 98 years, with a mean age of 61.05 (SD = 13.24). A factor model was used to create a harmonized measure of financial strain across studies and items. Twin analyses of genetic and environmental variance for SRH incorporating age, age², sex, and financial strain moderators indicated significant financial strain moderation of genetic influences on self-rated health. Moderation results did not differ across sex or country. Genetic variance for SRH increased as financial strain increased, matching the predictions of the diathesis-stress and social comparison models for components of variance. Under these models, environmental improvements would be expected to reduce genetically based health disparities.

An investigation into DNA methylation patterns associated with risk preference in older individuals

Risk preference is a complex trait governed by psycho-social, environmental and genetic determinants. We aimed to examine how an individual’s risk preference associates with their epigenetic profile.

Risk preferences were ascertained by asking participants of the Northern Ireland COhort for the Longitudinal study of Ageing to make a series of choices between hypothetical income scenarios. From these, four risk preference categories were derived, ranging from risk-averse to risk-seeking. Illumina’s Infinium High-Density Methylation Assay was used to evaluate the status of 862,927 CpGs.

Risk preference and DNA methylation data were obtained for 1,656 individuals. The distribution of single-site DNA methylation levels between risk-averse and risk-seeking individuals was assessed whilst adjusting for age, sex and peripheral white cell counts. In this discovery cohort, 55 CpGs were identified with significantly different levels of methylation (p≤x10⁻⁵) between risk-averse and risk-seeking individuals when adjusting for the maximum number of covariates. No CpGs were significantly differentially methylated in any of the risk preference groups at an epigenome-wide association level (p<9x10⁻⁸) following covariate adjustment.

Protein-coding genes NWD1 and LRP1 were among the genes in which the top-ranked dmCpGs were located for all analyses conducted. Mutations in these genes have previously been linked to neurological conditions.

Epigenetic modifications have not previously been linked to risk-aversion using a population cohort, but may represent important biomarkers of accumulated, complex determinants of this trait. Several striking results from this study support further analysis of DNA methylation as an important link between measurable biomarkers and health behaviours.

Hallmarks of Health

Health is usually defined as the absence of pathology. Here, we endeavor to define health as a compendium of organizational and dynamic features that maintain physiology. The biological causes or hallmarks of health include features of spatial compartmentalization (integrity of barriers and containment of local perturbations), maintenance of homeostasis over time (recycling and turnover, integration of circuitries, and rhythmic oscillations), and an array of adequate responses to stress (homeostatic resilience, hormetic regulation, and repair and regeneration). Disruption of any of these interlocked features is broadly pathogenic, causing an acute or progressive derailment of the system coupled to the loss of numerous stigmata of health.

Estimating the influence of adolescent delinquent behavior on adult health using sibling fixed effects

Despite the well-established link between juvenile delinquency and socioeconomic attainment in adulthood, less is known about whether engagement in delinquent behavior during adolescence shapes adult health outcomes. This study examines the association between juvenile delinquency and adult physical and mental health, and whether this association is confounded by unobserved family heterogeneity. Moreover, this study explores the potential underlying mechanisms through which juvenile delinquency shapes adult physical and mental health. Using data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) 1994-1995 (Wave 1) and 2007-2008 (Wave 4), we adopted a sibling fixed effect approach to account for genetic factors, family environment, and childhood social contexts such as school and neighborhood effects. The conventional OLS results show that engagement in delinquent behavior during adolescence strongly predicts higher levels of Framingham cardiovascular disease (CVD) risk score and depressive symptoms in adulthood. Once we account for family-specific heterogeneity, however, the point estimates of the associations of delinquency with CVD risk score and depressive symptoms are attenuated by 33% and 45%, respectively. Despite this attenuation, the association of juvenile delinquency with adult health is robust: a one standard-deviation increase in juvenile delinquency is associated with approximately 8 and 6 percent of one standard-deviation increases in CVD risk and depressive symptoms, respectively. Our mediation analyses suggest that a combination of several mediating pathways jointly explain the association between juvenile delinquency with adult health. The most consistent and significant mediating pathways connecting juvenile delinquency to both physical and mental health included disruption in student-teacher relationship, smoking, criminal justice contact, and educational attainment. Moreover, while binge drinking explained part of the association between delinquency and CVD risk score, student-friend relationship partially mediated the association with depression.

Revisiting the relationship between perceived discrimination and health: Evidence from sibling models with multiple health measures

Perceived discrimination (PD) is known to be significantly related to health outcomes. This link, however, warrants further scrutiny due to the possibility of unobserved family-level confounding. Using the Add Health and sibling fixed-effect approach, we examine whether the relationship between PD and health is confounded by family background characteristics such as genetics, family environment, and childhood social context (school and neighborhood effects). While the naive OLS models exhibit significant associations between PD and both physical and psychological health outcomes, our preferred sibling fixed-effect estimates reveal that the observed associations between PD and physical health outcomes are confounded by shared family background. In contrast, the observed associations for psychological health, self-reported health, and some of health behavior outcomes are robust to adjustment for sibling fixed-effects. Furthermore, we find similar overall patterns in the link between PD and health across races/ethnicities.

Using an adoption design to test genetically based differences in risk for child behavior problems in response to home environmental influences

Differential susceptibility theory (DST) posits that individuals differ in their developmental plasticity: some children are highly responsive to both environmental adversity and support, while others are less affected. According to this theory, "plasticity" genes that confer risk for psychopathology in adverse environments may promote superior functioning in supportive environments. We tested DST using a broad measure of child genetic liability (based on birth parent psychopathology), adoptive home environmental variables (e.g., marital warmth, parenting stress, and internalizing symptoms), and measures of child externalizing problems (n = 337) and social competence (n = 330) in 54-month-old adopted children from the Early Growth and Development Study. This adoption design is useful for examining DST because children are placed at birth or shortly thereafter with nongenetically related adoptive parents, naturally disentangling heritable and postnatal environmental effects. We conducted a series of multivariable regression analyses that included Gene × Environment interaction terms and found little evidence of DST; rather, interactions varied depending on the environmental factor of interest, in both significance and shape. Our mixed findings suggest further investigation of DST is warranted before tailoring screening and intervention recommendations to children based on their genetic liability or "sensitivity."

The Intergenerational Transmission of Early Educational Advantages: New Results Based on an Adoption Design

Sociological research has traditionally emphasized the importance of post-birth factors (i.e., social, economic, and cultural capital) in the intergenerational transmission of educational advantages, to the neglect of potentially consequential pre-birth endowments (e.g., heritable traits) that are passed from parent to child. In this study, we leverage an experiment of nurture-children who were adopted at birth into nonrelative families-in an effort to simultaneously model the effects associated with both pathways. To do so, we fit a series of simple linear regression models that relate the academic achievement of adopted children to the educational attainments of their adoptive and biological parents, using U.S. data from a recent nationwide sample of birth and adoptive families (the Early Growth and Development Study). Because our dataset includes both "genetic" and "environmental" relatives, but not "genetic-and-environmental" relatives, the separate contributions of each pathway can be identified, as well as possible interactions between the two. Our results show that children's early achievements are influenced not only by the attainments of their adoptive parents, but also the attainments of their birth parents-suggesting the presence of environmental and genetically mediated effects. Supplementary analyses provide little evidence of effect moderation, using both distal and proximate measures of the childhood environment to model gene-by-environment interactions. These findings are robust to a variety of parameterizations, withstand a series of auxiliary checks, and remain intact even after controlling for intrauterine exposures and other measurable variables that could compromise our design. The implications of our results for theory and research in the stratification literature, and for those interested in educational mobility, are discussed.

Does Maternal Warmth Moderate Longitudinal Associations Between Infant Attention Control and Children's Inhibitory Control?

Attention control (AC) is thought to play an important role in the development of inhibitory control (IC) in children, yet there are few longitudinal studies of this association. This study used a prospective parent-child adoption design (N = 361 children) to examine whether maternal warmth at child age 27 months moderated the link between AC during infancy and IC during childhood. Tobit regression analyses indicated that low levels of infant AC at 9 months predicted low levels of IC at 6 years, controlling for birth parent IC, prenatal risk, infant distress to limitations, child sex, and openness of adoption. Adoptive mother warmth at 27 months moderated this association. In the context of higher levels of maternal warmth, the longitudinal association between low AC and low IC was attenuated. Thus, high levels of early maternal warmth may help diminish the effects of extant risk for IC deficits.

The Early Growth and Development Study: A Dual-Family Adoption Study from Birth Through Adolescence

The Early Growth and Development Study (EGDS) is a prospective adoption study of birth parents, adoptive parents and adopted children (n = 561 adoptees). The original sample has been expanded to include siblings of the EGDS adoptees who were reared by the birth mother and assessed beginning at age 7 years (n = 217 biological children), and additional siblings in both the birth and adoptive family homes, recruited when the adoptees were 8-15 years old (n = 823). The overall study aims are to examine how family, peer and contextual processes affect child and adolescent adjustment, and to examine their interplay (mediation, moderation) with genetic influences. Adoptive and birth parents were originally recruited through adoption agencies located throughout the USA following the birth of a child. Assessments are ongoing and occurred in 9 month's intervals until the adoptees turned 3 years of age, and in 1 to 2 year intervals thereafter through age 15. Data collection includes the following primary constructs: child temperament, behavior problems, mental health, peer relations, executive functioning, school performance and health; birth and adoptive parent personality characteristics, mental health, health, context, substance use, parenting and marital relations; and the prenatal environment. Findings highlight the power of the adoption design to detect environmental influences on child development and provide evidence of complex interactions and correlations between genetic, prenatal environmental and postnatal environmental influences on a range of child outcomes. The study sample, procedures and an overview of findings are summarized and ongoing assessment activities are described.

IGEMS: The Consortium on Interplay of Genes and Environment Across Multiple Studies - An Update

The Interplay of Genes and Environment across Multiple Studies (IGEMS) is a consortium of 18 twin studies from 5 different countries (Sweden, Denmark, Finland, United States, and Australia) established to explore the nature of gene-environment (GE) interplay in functioning across the adult lifespan. Fifteen of the studies are longitudinal, with follow-up as long as 59 years after baseline. The combined data from over 76,000 participants aged 14-103 at intake (including over 10,000 monozygotic and over 17,000 dizygotic twin pairs) support two primary research emphases: (1) investigation of models of GE interplay of early life adversity, and social factors at micro and macro environmental levels and with diverse outcomes, including mortality, physical functioning and psychological functioning; and (2) improved understanding of risk and protective factors for dementia by incorporating unmeasured and measured genetic factors with a wide range of exposures measured in young adulthood, midlife and later life.

Utilising Genetically-Informed Research Designs to Better Understand Family Processes and Child Development: Implications for Adoption and Foster Care Focused Interventions

Understanding the interplay between genetic factors and family environmental processes (e.g., inter-parental relationship quality, positive versus negative parenting practices) and children's mental health (e.g., anxiety, depression, conduct problems, ADHD) in the contexts of adoption and foster-care research and practice is critical for effective prevention and intervention programme development. Whilst evidence highlights the importance of family environmental processes for the mental health and well-being of children in adoption and foster care, there is relatively limited evidence of effective interventions specifically for these families. Additionally, family-based interventions not specific to the context of adoption and foster-care typically show small to medium effects, and even where interventions are efficacious, not all children benefit. One explanation for why interventions may not work well for some is that responses to intervention may be influenced by an individual's genetic make-up. This paper summarises how genetically-informed research designs can help disentangle genetic from environmental processes underlying psychopathology outcomes for children, and how this evidence can provide improved insights into the development of more effective preventative intervention targets for adoption and foster-care families. We discuss current difficulties in translating behavioural genetics research to prevention science, and provide recommendations to bridge the gap between behavioural genetics research and prevention science, with lessons for adoption and foster-care research and practice.

Adverse Childhood Experiences and Their Relation to Parenting Stress and Parenting Practices

The objective of this study was to understand the relationship between the early adverse childhood experiences (ACEs) of parents and their later parenting stress and practices. At the baseline visit of an 8-week course of cognitive behavioral therapy, parenting women completed the Parenting Stress Index-Short Form (PSI-SF) and the Positive Parenting Practices (PPP) scale. Linear regression procedures were used to assess the relationship between a parent's own early experience of ACEs and current parenting stress and practices, including if there was a dose-response relationship. For the PSI-SF, significant dose-response relationships were observed between ACEs and the PSI Total Stress score (p < 0.05) and the difficult child subscale (p < 0.05). Additionally, a relationship was suggested with the parental distress subscale (p < 0.10). No significant relationships were found between ACEs and the parent-child dysfunctional interaction subscale of the PSI-SF or the PPP scale. Given the association observed between ACEs and parenting stress, it is important that future psychosocial interventions and policy initiatives preventing ACEs are developed.

Parenting and prenatal risk as moderators of genetic influences on conduct problems during middle childhood

This study examines interactions of heritable influences, prenatal substance use, and postnatal parental warmth and hostility on the development of conduct problems in middle childhood for boys and girls. Participants are 561 linked families, collected in 2 cohorts, including birth parents, adoptive parents, and adopted children. Heritable influences on internalizing and externalizing (including substance use) problems were derived from birth mothers' and fathers' symptoms, diagnoses, and age of onset from diagnostic interviews, and the proportion of first-degree relatives with the same type of problems. Smoking during pregnancy (SDP) and alcohol use during pregnancy were assessed retrospectively from birth mothers at 5 months postpartum. Earlier externalizing problems and parental warmth and hostility and were assessed at 1 assessment prior to the outcome (Cohort II: 4.5 years; Cohort I: 7 years). Conduct problems were symptoms from a diagnostic interview assessed at age 6 (Cohort II) or 8 (Cohort I). Findings from regression analyses suggest that (a) SDP plays an important role for the development of conduct problems, (b) some relatively well-accepted effects (e.g., parental hostility) were less important when simultaneously considering multiple factors influencing the development of conduct problems, and (c) main effects of genetic risk and SDP, and interactions among genetic risk and postnatal warmth, SDP and postnatal warmth, and genetic risk, SDP, and postnatal hostility for conduct problems were important for boys' but not girls' conduct problems. Replication is needed, but the current results provide preliminary but empirically grounded hypotheses for future research testing complex developmental models of conduct problems. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Intellectual Investment, Dopaminergic Gene Variation, and Life Events: A Critical Examination

Need for Cognition (NFC) and Openness to Ideas are intellectual investment traits that are characterized by a tendency to seek out, engage in and enjoy effortful cognitive activity. Little, however, is known about the extent to which they are influenced by genetic and environmental factors. With the present contribution, we aim at furthering our knowledge on the mechanisms underlying intellectual investment traits by following-up on a recent investigation of the role of dopaminergic gene variation in intellectual investment. Employing a standard approach that relied on null-hypothesis significance testing, we found that, first, two dopaminergic genetic variants interacted in modulating individual differences in NFC, but not in Openness to Ideas; that, second, negative life events played a role in the modulation of Openness to Ideas, but not of NFC; and that, third, negative life events as assessed using another measure were only marginally related to Openness to Ideas while positive life events were associated with both Openness to Ideas and NFC, with the latter effect being also dependent on DRD4 exon III genotype. However, employing a Bayesian approach, the assumption of a genetic effect on investment traits was overall not supported, while the assumption of a role of positive life events in the modulation of investment traits could be confirmed, with a tentative increment in the prediction of NFC by adding an interaction of positive life events and DRD4 variation to the main effect of positive life events. Our findings underscore the importance to use different approaches in the field of personality neuroscience. To gain deeper insight into the basis of personality traits does not only require to consider genetic as well as environmental influences and their interplay, but also requires more differentiated statistical analyses that can at least in part tackle the often inconsistent findings in this field.

Gene-environment interaction of monoamine oxidase A in relation to antisocial behaviour: current and future directions

Since the pioneering finding of Caspi and co-workers in 2002 that exposure to childhood maltreatment predicted later antisocial behaviour (ASB) in male carriers of the low-activity MAOA-uVNTR allele, frequent replication studies have been published. Two meta-analyses, one in 2006 and the other in 2014, confirmed the original findings by Caspi and co-workers. In the present paper, we review the literature, note some methodological aspects of candidate gene–environment interaction (cG×E) studies and suggest some future directions. Our conclusions are as follows. (1) The direction of the effect in a cG×E model may differ according to the positive and negative environmental background of the population. (2) There is a predictor-intersection problem such that when measuring one type of maltreatment in a person, other kinds of maltreatment often co-occur. Other forms of abuse are implicitly considered in statistical models; therefore, it is difficult to draw conclusions about the effects of timing and the severity of different forms of stressful life events in relation to ASB. (3) There is also an outcome-intersection problem because of the major intersection of ASB and other forms of mental health problems. It is likely that the G×E with MAOA is related to a common unmeasured factor. (4) For the G×E model, in which the effect of the gene on the outcome variable is dependent on other predictor variables, theoretically, hypothesis-driven statistical modelling is needed.

Does the heritability of cognitive abilities vary as a function of parental education? Evidence from a German twin sample

A well-known hypothesis in the behavioral genetic literature predicts that the heritability of cognitive abilities is higher in the presence of higher socioeconomic contexts. However, studies suggest that the effect of socioeconomic status (SES) on the heritability of cognitive ability may not be universal, as it has mostly been demonstrated in the United States, but not in other Western nations. In the present study we tested whether the importance of genetic and environmental effects on cognitive abilities varies as a function of parental education in a German twin sample. Cognitive ability scores (general, verbal, and nonverbal) were obtained on 531 German twin pairs (192 monozygotic, 339 dizygotic, ranging from 7 to 14 years of age; M_age = 10.25, SD = 1.83). Data on parental education were available from mothers and fathers. Results for general cognitive ability and nonverbal ability indicated no significant gene x parental education interaction effect. For verbal ability, a significant nonshared environment (E) x parental education interaction was found in the direction of greater nonshared environmental influences on verbal abilities among children raised by more educated parents.

Annual Research Review: Interparental conflict and youth psychopathology: an evidence review and practice focused update

The quality of the interparental relationship is recognized as an important influence on child and adolescent psychopathology. Historically, clinically oriented research on this topic has focused on the impacts of parental divorce and domestic violence as primary interparental relationship influences on child outcomes, to the relative neglect of dimensional or qualitative features of the couple/interparental relationship for youth (child and adolescent) psychopathology. Recent research has highlighted that children are affected by attributes of interparental conflict, specifically how parents express and manage conflicts in their relationship, across a continuum of expressed severity and negativity - ranging from silence to violence. Furthermore, new evidence highlights that children's emotional, behavioral, social, academic outcomes, and future interpersonal relationships are adversely affected by conflict between parents/carers whether adults are living together or not (i.e. married or separated), or where children are or are not genetically related to their rearing parents (e.g. adoption). We review evidence and present an integrated theoretical model, highlighting how children are affected by interparental conflict and what this evidence base means for effective intervention and prevention program development, as well as the development of possible cost-benefit models. Additionally, we review policy implications of this research and highlight some very recent examples of UK-based policy focusing on addressing the interparental relationship and its impact on youth psychopathology.

Examining Morning HPA Axis Activity as a Moderator of Hostile, Over-reactive Parenting on Children's Skills for Success in School

This study examined children's morning HPA axis activation as a moderator of links between hostile, over-reactive parenting at age 4.5 years and children's skills for success in school (higher executive function and literacy, and less externalizing behavior) at age 6. Participants included 361 adoptive families. Parenting was self-reported. HPA axis activation was measured by basal levels in morning cortisol. Executive function and literacy were assessed via standardized tasks. Externalizing behavior was reported by teachers. Results indicated that hostile, over-reactive parenting predicted more externalizing behavior and lower executive functioning regardless of children's morning HPA axis activation. HPA axis activation moderated the effects of hostile, over-reactive parenting on literacy. Among children with moderate to high morning HPA axis activation (approximately 60% of the sample), harsh parenting was linked with lower literacy; children with low morning HPA axis activation exhibited better literacy in the context of more hostile, over-reactive parenting. Yet, across the sample, hostile, over-reactive parenting remained in the low to moderate range, not in the high range. Findings are discussed in the context of considering not only whether children's stress system activation moderates responses to their environments, but also how these processes operate for different developmental outcomes.

Individual biological sensitivity to environmental influences: testing the differential susceptibility properties of the 5HTTLPR polymorphism in relation to depressive symptoms and delinquency in two adolescent general samples

The gene–environment interaction research field in psychiatry has traditionally been dominated by the diathesis–stress framework, where certain genotypes are assumed to confer increased risk for adverse outcomes in a stressful environment. In later years, theories of differential susceptibility, or biological sensitivity, suggest that candidate genes that interact with environmental events do not exclusively confer a risk for behavioural or psychiatric disorders but rather seem to alter the sensitivity to both positive and negative environmental influences. The present study investigates the susceptibility properties of the serotonin transporter-linked polymorphic region (5HTTLPR) in relation to depressive symptoms and delinquency in two separate adolescent community samples: n = 1457, collected in 2006; and n = 191, collected in 2001. Two-, three-, and four-way interactions between the 5HTTLPR, positive and negative family environment, and sex were found in relation to both depressive symptoms and delinquency. However, the susceptibility properties of the 5HTTLPR were distinctly less pronounced in relation to depressive symptoms. If the assumption that the 5HTTLPR induces differential susceptibility to both positive and negative environmental influences is correct, the previous failures to measure and control for positive environmental factors might be a possible explanation for former inconsistent findings within the research field.

Personality as an intermediate phenotype for genetic dissection of alcohol use disorder

Genetic and environmental interactive influences on predisposition to develop alcohol use disorder (AUD) account for the high heterogeneity among AUD patients and make research on the risk and resiliency factors complicated. Several attempts have been made to identify the genetic basis of AUD; however, only few genetic polymorphisms have consistently been associated with AUD. Intermediate phenotypes are expected to be in-between proxies of basic neuronal biological processes and nosological symptoms of AUD. Personality is likely to be a top candidate intermediate phenotype for the dissection of the genetic underpinnings of different subtypes of AUD. To date, 38 studies have investigated personality traits, commonly assessed by the Cloninger's Tridimensional Personality Questionnaire (TPQ) or Temperament and Character Inventory (TCI), in relation to polymorphisms of candidate genes of neurotransmitter systems in alcohol-dependent patients. Particular attention has been given to the functional polymorphism of the serotonin transporter gene (5-HTTLPR), however, leading to contradictory results, whereas results with polymorphisms in other candidate monoaminergic genes (e.g., tryptophan hydroxylase, serotonin receptors, monoamine oxidases, dopamine receptors and transporter) are sparse. Only one genome-wide association study has been performed so far and identified the ABLIM1 gene of relevance for novelty seeking, harm avoidance and reward dependence in alcohol-dependent patients. Studies investigating genetic factors together with personality could help to define more homogenous subgroups of AUD patients and facilitate treatment strategies. This review also urges the scientific community to combine genetic data with psychobiological and environmental data to further dissect the link between personality and AUD.

Extending Previous cG×I Findings on 5-HTTLPR's Moderation of Intervention Effects on Adolescent Substance Misuse Initiation

This study addresses replication in candidate gene × environment interaction (cG×E) research by investigating if the key findings from Brody, Beach, Philibert, Chen, and Murry (2009) can be detected using data (N = 1,809) from the PROSPER substance use preventive intervention delivery system. Parallel to Brody et al., this study tested the hypotheses that substance misuse initiation would increase faster from age 11 to age 14 and be higher at age 14 among: (a) 5-HTTLPR short carrier adolescents versus long homozygotes, (b) control versus intervention adolescents, and (c) 5-HTTLPR short carriers in the control condition versus all other participants. The hypotheses were generally supported and results were consistent with Brody et al.'s cG×I finding. Results are discussed in light of replication issues in cG×E research and implications for intervention.

Does Growing up in Urban Compared to Rural Areas Shape Primary Emotional Traits?

Growing up in urban areas represents a possible risk factor in the genesis of psychopathologies. The aim of the present study was to investigate the link between urbanicity variables and indicators for psychiatric disorders. We investigated a potential association between primary emotional traits and urbanicity variables in 324 individuals from Germany and 713 individuals from China. Higher scores in the urbanicity index in childhood were inversely associated with FEAR and SADNESS only in adult Chinese females. These effects seemed to be driven by living in Chinese mega-cities, because a parallel sample from Germany and China (contrasting upbringing in cities with the categories <10,000 inhabitants, ≥10,000 inhabitants (but <100,000), and ≥100,000 inhabitants) resulted in weaker, but more similar effects in females in both countries. Additional associations could be observed with higher PLAY and urban upbringing in Chinese males. The results seem surprising, given an expectation of adverse emotional effects from growing up in todays' mega-cities compared to rural areas. Although we do not want to over-interpret our findings (given rather small correlations and multiple testing issues), they should encourage researchers to consider including urbanicity variables in personality neuroscience and personality oriented clinical psychiatric research.

Environmental risks outweigh dopaminergic genetic risks for alcohol use and abuse from adolescence through early adulthood

BACKGROUND

Alcohol use is a primary public health concern, particularly among adolescents and young adults. Based on the rapidly growing field of gene-environment models, this study assessed the combined role of environmental and dopamine-related genetic correlates of early alcohol use and abuse.

METHODS

Multilevel growth models assessed trajectories of alcohol use and intoxication and ordered logistic regressions assessed alcohol use disorder among a sample of 12,437 youth from the nationally representative Add Health study who were followed from mid-adolescence through early adulthood.

RESULTS

Endogenous and exogenous stressful life events and social norms supportive of alcohol use from parents and peers were significant predictors of alcohol use, intoxication, and alcohol use disorder, with consistent patterns across males and females. In contrast, a dopamine-system genetic risk score (GRS) was not associated with alcohol use trajectories nor alcohol use disorder in early adulthood, although weak connections emerged between the GRS and growth trajectories of intoxication, indicating that higher GRS predicted more frequent episodes of intoxication during the transition to adulthood but not during adolescence or later 20s. No evidence of gene-environment interactions emerged.

CONCLUSIONS

Results extend a substantial body of prior research primarily assessing single genetic polymorphisms in the dopamine system, suggesting that dopaminergic GRSs may be associated with more problematic alcohol behaviors at some developmental periods, but further, that social norms and stressful life experiences are more consistent correlates of early and problematic alcohol use among youth. These environmental factors present potential targets for research manipulating contexts to identify causal pathways.

The Neurobiological Mechanisms of Generalized Anxiety Disorder and Chronic Stress

Two classification systems are now at the forefront of clinical psychiatric research: (1) Diagnostic and Statistical Manual, Fifth Edition and (2) the National Institutes of Mental Health Research Domain Criteria. Herein, we propose that these two classification systems are complementary rather than mutually exclusive, and when combined provide important information for understanding aspects of the pathophysiology related to Generalized Anxiety Disorder (GAD). The neurobiological literature for GAD and one relevant research domain criteria component, sustained threat, are reviewed from multiple units of analysis (genetic, neuroimaging, neuroendocrine, and psychophysiological). It is hypothesized that generating a comprehensive, biologically based understanding of the relationship between GAD, sustained threat, and the measureable units of analysis will provide information critical to design the most effective treatments.

Early inherited risk for anxiety moderates the association between fathers' child-centered parenting and early social inhibition

Studies of the role of the early environment in shaping children's risk for anxiety problems have produced mixed results. It is possible that inconsistencies in previous findings result from a lack of consideration of a putative role for inherited influences moderators on the impact of early experiences. Early inherited influences not only contribute to vulnerabilities for anxiety problems throughout the lifespan, but can also modulate the ways that the early environment impacts child outcomes. In the current study, we tested the effects of child-centered parenting behaviors on putative anxiety risk in young children who differed in levels of inherited vulnerability. We tested this using a parent-offspring adoption design and a sample in which risk for anxiety problems and parenting behaviors were assessed in both mothers and fathers. Inherited influences on anxiety problems were assessed as anxiety symptoms in biological parents. Child-centered parenting was observed in adoptive mothers and fathers when children were 9 months old. Social inhibition, an early temperament marker of anxiety risk, was observed at child ages 9 and 18 months. Inherited influences on anxiety problems moderated the link between paternal child-centered parenting during infancy and social inhibition in toddlerhood. For children whose birth parents reported high levels of anxiety symptoms, greater child-centered parenting in adoptive fathers was related to greater social inhibition 9 months later. For children whose birth parents reported low levels of anxiety symptoms, greater child-centered parenting in adoptive fathers was related to less social inhibition across the same period.

The Socioeconomic Pathways Leading to Romantic Relationship Outcomes: A Genetically Informed Early Life Course Investigation

The present study tests a multilevel comprehensive model incorporating both life course processes and genetic influences leading to young adults' romantic relationship quality using data from 1,560 adolescents over 13 years in the nationally representative Add Health sample. Results provided evidence of a socioeconomic mediating pathway linking early family and community contexts to young adults' romantic relationship quality, and novel evidence for both direct and interactive genetic associations that relate to these mediating pathways. A cumulative genetic index showed (a) direct associations with young adults' socioeconomic attainment and (b) interactions with community adversity and mothers' marital stability on young adults' achieved socioeconomic context and relationship quality.

Physical and verbal aggressive behavior and COMT genotype: Sensitivity to the environment

Catechol-O-methyltransferase (COMT) genotype has been implicated as a vulnerability factor for several psychiatric diseases as well as aggressive behavior, either directly, or in interaction with an adverse environment. The present study aimed at investigating the susceptibility properties of COMT genotype to adverse and favorable environment in relation to physical and verbal aggressive behavior. The COMT Val158Met polymorphism was genotyped in a Swedish population-based cohort including 1,783 individuals, ages 20-24 years (47% males). A significant three-way interaction was found, after correction for multiple testing, between COMT genotype, exposure to violence, and parent-child relationship in association with physical but not verbal aggressive behavior. Homozygous for the Val allele reported lower levels of physical aggressive behavior when they were exposed to violence and at the same time experienced a positive parent-child relationship compared to Met carriers. Thus, susceptibility properties of COMT genotype were observed in relation to physical aggressive behavior supporting the hypothesis that COMT genotypes are modifying the sensitivity to environment that confers either risk or protection for aggressive behavior. As these are novel findings, they warrant further investigation and replication in independent samples. © 2016 Wiley Periodicals, Inc.

Dependence of Gene-by-Environment Interactions (GxE) on Scaling: Comparing the Use of Sum Scores, Transformed Sum Scores and IRT Scores for the Phenotype in Tests of GxE

Estimates of gene-environment interactions (GxE) in behavior genetic models depend on how a phenotype is scaled. Inappropriately scaled phenotypes result in biased estimates of GxE and can sometimes even suggest GxE in the direction opposite to its true direction. Previously proposed solutions are mathematically complex, computationally demanding and may prove impractical for the substantive researcher. We, therefore, evaluated two simple-to-use alternatives: (1) straightforward non-linear transformation of sum scores and (2) factor scores from an appropriate item response theory (IRT) model. Within Purcell's (2002) GxM framework, both alternatives provided less biased parameter estimates, and improved false and true positive rates than using a raw sum score. These approaches are, therefore, recommended over using raw sum scores in tests of GxE. Circumstances under which IRT factor scores versus transformed sum scores should be preferred are discussed.

Differential Susceptibility of the Developing Brain to Contextual Adversity and Stress

A swiftly growing volume of literature, comprising both human and animal studies and employing both observational and experimental designs, has documented striking individual differences in neurobiological sensitivities to environmental circumstances within subgroups of study samples. This differential susceptibility to social and physical environments operates bidirectionally, in both adverse and beneficial contexts, and results in a minority subpopulation with remarkably poor or unusually positive trajectories of health and development, contingent upon the character of environmental conditions. Differences in contextual susceptibility appear to emerge in early development, as the interactive and adaptive product of genetic and environmental attributes. This paper surveys what is currently known of the mechanisms or mediators of differential susceptibility, at the levels of temperament and behavior, physiological systems, brain circuitry and neuronal function, and genetic and epigenetic variation. It concludes with the assertion that differential susceptibility is inherently grounded within processes of biological moderation, the complexities of which are at present only partially understood.

Underlying Mechanisms of Gene-Environment Interactions in Externalizing Behavior: A Systematic Review and Search for Theoretical Mechanisms

Over the last decade, several candidate genes (i.e., MAOA, DRD4, DRD2, DAT1, 5-HTTLPR, and COMT) have been extensively studied as potential moderators of the detrimental effects of postnatal family adversity on child externalizing behaviors, such as aggression and conduct disorder. Many studies on such candidate gene by environment interactions (i.e., cG × E) have been published, and the first part of this paper offers a systematic review and integration of their findings (n = 53). The overview shows a set of heterogeneous findings. However, because of large differences between studies in terms of sample composition, conceptualizations, and power, it is difficult to determine if different findings indeed illustrate inconsistent cG × E findings or if findings are simply incomparable. In the second part of the paper, therefore, we argue that one way to help resolve this problem is the development of theory-driven a priori hypotheses on which biopsychosocial mechanisms might underlie cG × E. Such a theoretically based approach can help us specify our research strategies, create more comparable findings, and help us interpret different findings between studies. In accordance, we describe three possible explanatory mechanisms, based on extant literature on the concepts of (1) emotional reactivity, (2) reward sensitivity, and (3) punishment sensitivity. For each mechanism, we discuss the link between the putative mechanism and externalizing behaviors, the genetic polymorphism, and family adversity. Possible research strategies to test these mechanisms, and implications for interventions, are discussed.

5-HTTLPR Expression Outside the Skin: An Experimental Test of the Emotional Reactivity Hypothesis in Children

Background

There is increasing evidence that variation in the promoter region of the serotonin transporter gene SLC6A4 (i.e., the 5-HTTLPR polymorphism) moderates the impact of environmental stressors on child psychopathology. Emotional reactivity −the intensity of an individual’s response to other’s emotions− has been put forward as a possible mechanism underlying these gene-by-environment interactions (i.e., G×E). Compared to children homozygous for the L-allele (LL-genotypes), children carrying an S-allele (SS/SL-genotypes), specifically when they have been frequently exposed to negative emotions in the family environment, might be more emotionally reactive and therefore more susceptible to affective environmental stressors. However, the association between 5-HTTLPR and emotional reactivity in children has not yet been empirically tested. Therefore, the goal of this study was to test this association in a large-scale experiment.

Methods

Children (N = 521, 52.5% boys, Mage = 9.72 years) were genotyped and randomly assigned to happy, angry or neutral dynamic facial expressions and vocalizations. Motor and affective emotional reactivity were assessed through children’s self-reported negative and positive affect (n = 460) and facial electromyography activity (i.e., fEMG: the zygomaticus or “smile” muscle and the corrugator or “frown” muscle, n = 403). Parents reported on their negative and positive parenting behaviors.

Results

Children mimicked and experienced the emotion they were exposed to. However, neither motor reactivity nor affective reactivity to these emotions depended on children’s 5-HTTLPR genotype: SS/SL-genotypes did not manifest any stronger response to emotional stimuli than LL-genotypes. This finding remained the same when taking the broader family environment into account, controlling for kinship, age, gender and genetic ancestry, and when including a tri-allelic factor.

Conclusions

We found no evidence for an association between the 5-HTTLPR polymorphism and children’s emotional reactivity. This finding is important, in discounting one potential underlying endophenotype of G×E between the 5-HTTLPR and affective environmental stressors.

Chronic stress and brain plasticity: Mechanisms underlying adaptive and maladaptive changes and implications for stress-related CNS disorders

Stress responses entail neuroendocrine, autonomic, and behavioral changes to promote effective coping with real or perceived threats to one's safety. While these responses are critical for the survival of the individual, adverse effects of repeated exposure to stress are widely known to have deleterious effects on health. Thus, a considerable effort in the search for treatments to stress-related CNS disorders necessitates unraveling the brain mechanisms responsible for adaptation under acute conditions and their perturbations following chronic stress exposure. This paper is based upon a symposium from the 2014 International Behavioral Neuroscience Meeting, summarizing some recent advances in understanding the effects of stress on adaptive and maladaptive responses subserved by limbic forebrain networks. An important theme highlighted in this review is that the same networks mediating neuroendocrine, autonomic, and behavioral processes during adaptive coping also comprise targets of the effects of repeated stress exposure in the development of maladaptive states. Where possible, reference is made to the similarity of neurobiological substrates and effects observed following repeated exposure to stress in laboratory animals and the clinical features of stress-related disorders in humans.

Differential Susceptibility: The Genetic Moderation of Peer Pressure on Alcohol Use

Although peer pressure can influence adolescents' alcohol use, individual susceptibility to these pressures varies across individuals. The dopamine receptor D4 gene (DRD4) is a potential candidate gene that may influence adolescents' susceptibility to their peer environment due to the role dopamine plays in reward sensation during social interaction. We hypothesized that DRD4 genotype status would moderate the impact of 7th-grade antisocial peer pressure on 12th-grade lifetime alcohol use (n = 414; 58.7% female; 92.8% White). The results revealed significant main effects for antisocial peer pressure, but no main effects for DRD4 genotype on lifetime alcohol use. Adolescent DRD4 genotype moderated the association between peer pressure and lifetime alcohol use. For individuals who carried at least one copy of the DRD4 7-repeat allele (7+), antisocial peer pressure was associated with increased lifetime alcohol use. These findings indicate that genetic sensitivity to peer pressure confers increased alcohol use in late adolescence.

Inherited and environmental influences on a childhood co-occurring symptom phenotype: Evidence from an adoption study

Risk factors for the childhood development of co-occurring internalizing and externalizing symptoms are not well understood, despite a high prevalence and poor clinical outcomes associated with this co-occurring phenotype. We examined inherited and environmental risk factors for co-occurring symptoms in a sample of children adopted at birth and their birth mothers and adoptive mothers (N = 293). Inherited risk factors (i.e., birth mothers' processing speed and internalizing symptoms) and environmental risk factors (i.e., adoptive mothers' processing speed, internalizing symptoms, and uninvolved parenting) were examined as predictors for the development of internalizing-only, externalizing-only, or co-occurring symptoms using structural equation modeling. Results suggested a unique pattern of predictive factors for the co-occurring phenotype, with risk conferred by adoptive mothers' uninvolved parenting, birth mothers' slower processing speed, and the birth mothers' slower processing speed in tandem with adoptive mothers' higher internalizing symptoms. Additional analyses indicated that when co-occurring-symptom children were incorporated into internalizing and externalizing symptom groups, differential risk factors for externalizing and internalizing symptoms emerged. The findings suggest that spurious results may be found when children with co-occurring symptoms are not examined as a unique phenotypic group.

Genotypes do not confer risk for delinquency but rather alter susceptibility to positive and negative environmental factors: gene-environmentinteractions of BDNF Val66Met, 5-HTTLPR, and MAOA-uVNTR [corrected]

BACKGROUND

Previous evidence of gene-by-environment interactions associated with emotional and behavioral disorders is contradictory. Differences in findings may result from variation in valence and dose of the environmental factor, and/or failure to take account of gene-by-gene interactions. The present study investigated interactions between the brain-derived neurotrophic factor gene (BDNF Val66Met), the serotonin transporter gene-linked polymorphic region (5-HTTLPR), the monoamine oxidase A (MAOA-uVNTR) polymorphisms, family conflict, sexual abuse, the quality of the child-parent relationship, and teenage delinquency.

METHODS

In 2006, as part of the Survey of Adolescent Life in Västmanland, Sweden, 1 337 high-school students, aged 17-18 years, anonymously completed questionnaires and provided saliva samples for DNA analyses.

RESULTS

Teenage delinquency was associated with two-, three-, and four-way interactions of each of the genotypes and the three environmental factors. Significant four-way interactions were found for BDNF Val66Met × 5-HTTLPR×MAOA-uVNTR × family conflicts and for BDNF Val66Met × 5-HTTLPR×MAOA-uVNTR × sexual abuse. Further, the two genotype combinations that differed the most in expression levels (BDNF Val66Met Val, 5-HTTLPR LL, MAOA-uVNTR LL [girls] and L [boys] vs BDNF Val66Met Val/Met, 5-HTTLPR S/LS, MAOA-uVNTR S/SS/LS) in interaction with family conflict and sexual abuse were associated with the highest delinquency scores. The genetic variants previously shown to confer vulnerability for delinquency (BDNF Val66Met Val/Met × 5-HTTLPR S × MAOA-uVNTR S) were associated with the lowest delinquency scores in interaction with a positive child-parent relationship.

CONCLUSIONS

Functional variants of the MAOA-uVNTR, 5-HTTLPR, and BDNF Val66Met, either alone or in interaction with each other, may be best conceptualized as modifying sensitivity to environmental factors that confer either risk or protection for teenage delinquency.

Developmental differences in early adolescent aggression: a gene × environment × intervention analysis

Aggression-related problems such as assault and homicide among adolescents and young adults exact considerable social and economic costs. Although progress has been made, additional research is needed to help combat this persistent problem. Several lines of research indicate that parental hostility is an especially potent predictor of adolescent aggression, although most longitudinal research has focused on clarifying the direction of effects. In this study, we used longitudinal data from the PROSPER project (N = 580; 54.8% female), a primarily rural Caucasian preventative intervention sample, to examine developmental change in early- to mid-adolescent aggressive behavior problems (age 11-16 years). In addition, we examined maternal hostility as a predictor of developmental change in aggression and the PROSPER preventative intervention, designed to reduce substance use and aggression, as a potential influence on this association. Lastly, several studies indicate that variation in the DRD4 7-repeat gene moderates both parenting and intervention influences on externalizing behavior. Accordingly, we examined the potential moderating role of DRD4. As hypothesized, there was a significant maternal hostility by intervention interaction indicating that the intervention reduced the negative impact of maternal hostility on adolescent change in aggressive behavior problems. DRD4 7-repeat status (7+ vs. 7-) further conditioned this association whereby control group 7+ adolescents with hostile mothers showed increasing aggressive behavior problems. In contrast, aggression decreased for 7+ adolescents with similarly hostile mothers in the intervention. Implications for prevention are discussed as well as current perspectives in candidate gene-by-environment interaction research.

Genetic vulnerability to diabetes and obesity: does education offset the risk?

The prevalence of type 2 diabetes (T2D) and obesity has recently increased dramatically. These common diseases are likely to arise from the interaction of multiple genetic, socio-demographic and environmental risk factors. While previous research has found genetic risk and education to be strong predictors of these diseases, few studies to date have examined their joint effects. This study investigates whether education modifies the association between genetic background and risk for type 2 diabetes (T2D) and obesity. Using data from non-Hispanic Whites in the Health and Retirement Study (HRS, n = 8398), we tested whether education modifies genetic risk for obesity and T2D, offsetting genetic effects; whether this effect is larger for individuals who have high risk for other (unobserved) reasons, i.e., at higher quantiles of HbA1c and BMI; and whether effects differ by gender. We measured T2D risk using Hemoglobin A1c (HbA1c) level, and obesity risk using body-mass index (BMI). We constructed separate genetic risk scores (GRS) for obesity and diabetes respectively based on the most current available information on the single nucleotide polymorphism (SNPs) confirmed as genome-wide significant predictors for BMI (29 SNPs) and diabetes risk (39 SNPs). Linear regression models with years of schooling indicate that the effect of genetic risk on HbA1c is smaller among people with more years of schooling and larger among those with less than a high school (HS) degree compared to HS degree-holders. Quantile regression models show that the GRS × education effect systematically increased along the HbA1c outcome distribution; for example the GRS × years of education interaction coefficient was -0.01 (95% CI = -0.03, 0.00) at the 10th percentile compared to -0.03 (95% CI = -0.07, 0.00) at the 90th percentile. These results suggest that education may be an important socioeconomic source of heterogeneity in responses to genetic vulnerability to T2D.

Profiles of observed infant anger predict preschool behavior problems: moderation by life stress

Using both traditional composites and novel profiles of anger, we examined associations between infant anger and preschool behavior problems in a large, longitudinal data set (N = 966). We also tested the role of life stress as a moderator of the link between early anger and the development of behavior problems. Although traditional measures of anger were largely unrelated to later behavior problems, profiles of anger that dissociated typical from atypical development predicted behavior problems during preschool. Moreover, the relation between infant anger profiles and preschool behavior problems was moderated such that, when early life stress was low, infants with atypical profiles of early anger showed more preschool behavior problems than did infants with normative anger profiles. However, when early life stress was high, infants with atypical and normative profiles of infant anger did not differ in preschool behavior problems. We conclude that a discrete emotions approach including latent profile analysis is useful for elucidating biological and environmental developmental pathways to early problem behaviors.