Mothers' prenatal stress and their children's antisocial outcomes--a moderating role for the dopamine D4 receptor (DRD4) gene

Genetics of child aggression, a systematic review

Excessive and persistent aggressiveness is the most common behavioral problem that leads to psychiatric referrals among children. While half of the variance in childhood aggression is attributed to genetic factors, the biological mechanism and the interplay between genes and environment that results in aggression remains elusive. The purpose of this systematic review is to provide an overview of studies examining the genetics of childhood aggression irrespective of psychiatric diagnosis. PubMed, PsycINFO, and MEDLINE databases were searched using predefined search terms for aggression, genes and the specific age group. From the 652 initially yielded studies, eighty-seven studies were systematically extracted for full-text review and for further quality assessment analyses. Findings show that (i) investigation of candidate genes, especially of MAOA (17 studies), DRD4 (13 studies), and COMT (12 studies) continue to dominate the field, although studies using other research designs and methods including genome-wide association and epigenetic studies are increasing, (ii) the published articles tend to be moderate in sizes, with variable methods of assessing aggressive behavior and inconsistent categorizations of tandem repeat variants, resulting in inconclusive findings of genetic main effects, gene-gene, and gene-environment interactions, (iii) the majority of studies are conducted on European, male-only or male-female mixed, participants. To our knowledge, this is the first study to systematically review the effects of genes on youth aggression. To understand the genetic underpinnings of childhood aggression, more research is required with larger, more diverse sample sets, consistent and reliable assessments and standardized definition of the aggression phenotypes. The search for the biological mechanisms underlying child aggression will also benefit from more varied research methods, including epigenetic studies, transcriptomic studies, gene system and genome-wide studies, longitudinal studies that track changes in risk/ameliorating factors and aggression-related outcomes, and studies examining causal mechanisms.

Early-Life Adversities Are Associated With Lower Expected Value Signaling in the Adult Brain

BACKGROUND

Early adverse experiences are assumed to affect fundamental processes of reward learning and decision making. However, computational neuroimaging studies investigating these circuits in the context of adversity are sparse and limited to studies conducted in adolescent samples, leaving the long-term effects unexplored.

METHODS

Using data from a longitudinal birth cohort study (n = 156; 87 female), we investigated associations between adversities and computational markers of reward learning (i.e., expected value, prediction errors). At age 33 years, all participants completed a functional magnetic resonance imaging-based passive avoidance task. Psychopathology measures were collected at the time of functional magnetic resonance imaging investigation and during the COVID-19 pandemic. We applied a principal component analysis to capture common variations across 7 adversity measures. The resulting adversity factors (factor 1: postnatal psychosocial adversities and prenatal maternal smoking; factor 2: prenatal maternal stress and obstetric adversity; factor 3: lower maternal stimulation) were linked with psychopathology and neural responses in the core reward network using multiple regression analysis.

RESULTS

We found that the adversity dimension primarily informed by lower maternal stimulation was linked to lower expected value representation in the right putamen, right nucleus accumbens, and anterior cingulate cortex. Expected value encoding in the right nucleus accumbens further mediated the relationship between this adversity dimension and psychopathology and predicted higher withdrawn symptoms during the COVID-19 pandemic.

CONCLUSIONS

Our results suggested that early adverse experiences in caregiver context might have a long-term disruptive effect on reward learning in reward-related brain regions, which can be associated with suboptimal decision making and thereby may increase the vulnerability of developing psychopathology.

Lifespan adversities affect neural correlates of behavioral inhibition in adults

Introduction

Growing evidence suggests that adverse experiences have long-term effects on executive functioning and underlying neural circuits. Previous work has identified functional abnormalities during inhibitory control in frontal brain regions in individuals exposed to adversities. However, these findings were mostly limited to specific adversity types such as maltreatment and prenatal substance abuse.

Methods

We used data from a longitudinal birth cohort study (n = 121, 70 females) to investigate the association between adversities and brain responses during inhibitory control. At the age of 33 years, all participants completed a stop-signal task during fMRI and an Adult Self-Report scale. We collected seven prenatal and postnatal adversity measures across development and performed a principal component analysis to capture common variations across those adversities, which resulted in a three-factor solution. Multiple regression analysis was performed to identify links between adversities and brain responses during inhibitory control using the identified adversity factors to show the common effect and single adversity measures to show the specific contribution of each adversity. To find neural correlates of current psychopathology during inhibitory control, we performed additional regression analyses using Adult Self-Report subscales.

Results

The first adversity factor reflecting prenatal maternal smoking and postnatal psychosocial adversities was related to higher activation during inhibitory control in bilateral inferior frontal gyri, insula, anterior cingulate cortex, and middle temporal gyri. Similar results were found for the specific contribution of the adversities linked to the first adversity factor. In contrast, we did not identify any significant association between brain responses during inhibitory control and the second adversity factor reflecting prenatal maternal stress and obstetric risk or the third adversity factor reflecting lower maternal sensitivity. Higher current depressive symptoms were associated with higher activation in the bilateral insula and anterior cingulate cortex during inhibitory control.

Conclusion

Our findings extended previous work and showed that early adverse experiences have a long-term effect on the neural circuitry of inhibitory control in adulthood. Furthermore, the overlap between neural correlates of adversity and depressive symptomatology suggests that adverse experiences might increase vulnerability via neural alterations, which needs to be investigated by future longitudinal research.

Prenatal stress and child externalizing behavior: effects of maternal perceived stress and cortisol are moderated by child sex

BACKGROUND

Externalizing behavior problems are related to social maladjustment. Evidence indicates associations between prenatal stress and child behavioral outcomes. It remains unclear how psychological distress vs. biological correlates of stress (cortisol) differentially predict externalizing behavior, and how their effects might differ as a function of child sex.

METHOD

108 pregnant women from the community collected salivary cortisol and reported their perceived stress during each trimester of pregnancy. At child age 9 years (M = 9.01, SD = 0.55), 70 mothers and children reported on child behavior. Structural equation modelling was used to analyze how cortisol levels and perceived stress during pregnancy predicted current child externalizing behavior, considering the moderating effect of child sex.

RESULTS

Perceived stress predicted higher externalizing behavior in boys (β = 0.42, p = 0.009) and lower externalizing behavior in girls (β = - 0.56, p = 0.014). Cortisol predicted lower externalizing behavior in boys (β = - 0.81, p < .001) and was not related to girls' externalizing behavior (β = 0.37, p = 0.200).

DISCUSSION/CONCLUSION

Prenatal stress affected externalizing behavior differently in girls vs. boys. These response patters in turn differed for indicators of psychological vs. biological maternal stress, encouraging an integrated approach. Findings indicate that perceived stress and cortisol may affect child development via different trajectories.

Psychological legacies of intergenerational trauma under South African apartheid: Prenatal stress predicts greater vulnerability to the psychological impacts of future stress exposure during late adolescence and early adulthood in Soweto, South Africa

BACKGROUND

South Africa's rates of psychiatric morbidity are among the highest in sub-Saharan Africa and are foregrounded by the country's long history of political violence during apartheid. Growing evidence suggests that in utero stress exposure is a potent developmental risk factor for future mental illness risk, yet the extent to which the psychiatric effects of prenatal stress impact the next generation are unknown. We evaluate the intergenerational effects of prenatal stress experienced during apartheid on psychiatric morbidity among children at ages 17-18 and also assess the moderating effects of maternal age, social support, and past household adversity.

METHODS

Participants come from Birth-to-Twenty, a longitudinal birth cohort study in Soweto-Johannesburg, South Africa's largest peri-urban township which was the epicentre of violent repression and resistance during the final years of the apartheid regime. Pregnant women were prospectively enrolled in 1990 and completed questionnaires assessing social experiences, and their children's psychiatric morbidity were assessed at ages 17-18.

RESULTS

Full data were available from 304 mother-child pairs in 2007-8. Maternal prenatal stress in 1990 was not directly associated greater psychiatric morbidity during at ages 17-18. Maternal age and past household adversity moderated the intergenerational mental health effects of prenatal stress such that children born to younger mothers and late adolescent/young adult children experiencing greater household adversity exhibited worse psychiatric morbidity at ages 17-18. Social support did not buffer against the long-term psychiatric impacts of prenatal stress.

CONCLUSIONS

Greater prenatal stress from apartheid predicted adverse psychiatric outcomes among children born to younger mothers and adolescents/young adults who experienced greater concurrent stress. Our findings suggest that prenatal stress may affect adolescent mental health, have stress-sensitising effects, and represent possible intergenerational effects of trauma experienced under apartheid in this sample.

Prevalence of Common Alleles of Some Stress Resilience Genes among Adolescents Born in Different Periods Relative to the Socioeconomic Crisis of the 1990s in Russia

Social stress is common among people and is considered one of the causes of the declining birth rate. Predisposition to stress and stress-induced disorders is largely determined genetically. We hypothesized that due to differences in stress resistance, carriers of different genetic variants of genes associated with stress resilience and stress-induced diseases may have dissimilar numbers of offspring under conditions of long-term social stress. To test this hypothesis, a comparative analysis of frequencies of seven common polymorphic regions [exon 3 variable number of tandem repeats (VNTR) of the DRD4 gene, rs4680 of COMT, STin2 VNTR and the 5-HTTLPR (rs774676466) insertion/deletion polymorphism of SLC6A4, rs4570625 of TPH2, rs6265 of BDNF, and rs258747 of NR3C1] was performed on standardized groups of randomly selected adolescents born before, during, and after severe socioeconomic deprivation (the crisis of the 1990s in Russia). There were significant differences in frequencies of "long" alleles of the DRD4 gene (p = 0.020, χ² = 5.492) and rs4680 (p = 0.022, χ² = 5.289) in the "crisis" group as compared to the combined "noncrisis" population. It is possible that the dopaminergic system had an impact on the successful adaptation of a person to social stress.

Stress During Pregnancy and the Development of Diseases in the offspring: A Systematic-Review and Meta-Analysis

OBJECTIVE

The goal of this systematic-review and meta-analysis was to assess whether high maternal stress during pregnancy is associated with the development of pediatric pathology.

DESIGN

Epidemiological peer-reviewed studies published in English or Spanish assessing associations between maternal stress during pregnancy and psychiatric and medical diseases were selected.

PARTICIPANTS

We retrieved 73,024 citations; 42 studies meeting inclusion criteria were assessed. Overall sample included 65,814,076 women.

FINDINGS

Overall odds ratio for the development of a medical disease was OR=1.24 (CI₉₅=1.11, 1.39), Z=3.85, p<.01. Overall odds ratio for psychiatric disorders was OR=1.28 (CI₉₅=1.06, 1.56), Z=2.54, p<.02. Multivariate meta-analysis showed a significant coefficient for autism spectrum disorder studies, B=0.42, SE=0.16, Z=2.67, p<.01. We found a significant overall effect size for autism spectrum disorder (OR=1.45 [CI₉₅=1.24, 1.70], Z=4.69, p<.01). In terms of medical diseases, studies including obesity and infantile colic presented a significant overall effect size, as OR=1.20 (CI₉₅=1.03, 1.39), Z=2.41, p<.02. The highest effect size was found regarding the first trimester (B=1.62, SE=0.16, Z=9.90, p<.01).

KEY CONCLUSIONS

We concluded that exposure to high levels of stress during pregnancy are associated with autism spectrum disorder, obesity, and infantile colic in offspring.

IMPLICATIONS FOR PRACTICE

Maternal stress during pregnancy should be addressed to tackle its potential impact in health across the life span.

Effect of Methylphenidate on Resting-State Connectivity in Adolescents With a Disruptive Behavior Disorder: A Double-Blind Randomized Placebo-Controlled fMRI Study

Some studies suggest that methylphenidate (MPH) might be an effective treatment for antisocial and aggressive behavior in adolescence. However, little is known about the mechanism of action of MPH in adolescents with this kind of psychopathology. MPH is a dopamine and norepinephrine reuptake inhibitor and thus it is likely to affect dopaminergic mesocorticolimbic pathways. This is the first study to investigate the effect of MPH on resting-state connectivity of three mesolimbic seed regions with the rest of the brain in clinical referred male adolescents with a disruptive behavior disorder (DBD). Thirty-six male DBD adolescents and 31 male healthy controls (HCs) were included. DBD subjects were randomly allocated to a single dose of MPH (DBD-MPH, n = 20) or placebo (DBD-PCB, n = 16). Seed-based resting-state functional connectivity of the nucleus accumbens (NAcc), amygdala, and ventral tegmental area (VTA) with the rest of the brain was compared between groups. The NAcc seed showed increased connectivity in DBD-PCB compared to HC with the occipital cortex, posterior cingulate cortex (PCC), precuneus, and inferior parietal lobule (IPL) and increased connectivity in DBD-PCB compared to DBD-MPH with occipital cortex, IPL, and medial frontal gyrus. The amygdala seed showed increased connectivity in DBD-PCB compared to HC with the precuneus and PCC. The VTA seed showed increased connectivity in the DBD-MPH compared to the DBD-PCB group with a cluster in the postcentral gyrus and a cluster in the supplementary motor cortex/superior frontal gyrus. Both NAcc and amygdala seeds showed no connectivity differences in the DBD-MPH compared to the HC group, indicating that MPH normalizes the increased functional connectivity of mesolimbic seed regions with areas involved in moral decision making, visual processing, and attention.

Effects of Maternal Chewing on Prenatal Stress-Induced Cognitive Impairments in the Offspring via Multiple Molecular Pathways

We aimed to investigate the effects of maternal chewing on prenatal stress-induced cognitive impairments in the offspring and to explore the molecular pathways of maternal chewing in a mice model. Maternal chewing ameliorated spatial learning impairments in the offspring in a Morris water maze test. Immunohistochemistry and Western blot findings revealed that maternal chewing alleviated hippocampal neurogenesis impairment and increased the expression of hippocampal brain-derived neurotrophic factor in the offspring. In addition, maternal chewing increased the expression of glucocorticoid receptor (GR) and 11β-hydroxysteroid dehydrogenase isozyme 2 (11β-HSD2) and decreased the expression of 11β-HSD1 in the placenta, thereby attenuating the increase of glucocorticoid in the offspring. Furthermore, maternal chewing increased the expression of 11β-HSD2, FK506-binding protein 51 (FKBP51) and FKBP52 and decreased the expression of 11β-HSD1, thereby increasing hippocampal nuclear GR level. In addition, maternal chewing attenuated the increase in expression of DNMT1 and DNMT3a and the decrease in expression of histone H3 methylation at lysine 4, 9, 27 and histone H3 acetylation at lysine 9 induced by prenatal stress in the offspring. Our findings suggest that maternal chewing could ameliorate prenatal stress-induced cognitive impairments in the offspring at least in part by protecting placenta barrier function, alleviating hippocampal nuclear GR transport impairment and increasing the hippocampal brain-derived neurotrophic factor (BDNF) level.

Influencing factors and correlation of anxiety, psychological stress sources, and psychological capital among women pregnant with a second child in Guangdong and Shandong Province

BACKGROUND

After the one-child policy has been effective for over 30 years, China implemented the universal two-child policy in 2015. The number of high-risk pregnant women had increased dramatically ever since, increasing negative health outcomes for both mothers and children. Our study aims to investigate the status of anxiety, psychological stress sources, and psychological capital among women pregnant with a second child, and to assess influencing factors and correlations, providing scientific basis for promoting women's health during pregnancy.

METHODS

We recruited 513 participants from maternity hospitals in Guangdong and Shandong Province. All participants completed the Zung Self-Rating Anxiety Scale (SAS), Pregnant women psychological stress sources questionnaire and the psychological capital questionnaire (PCQ-24).

RESULTS

The prevalence of anxiety of women pregnant with a second child was 27.5%. The score of psychological stress sources was 74.93 ± 16.07. The risk factors for the anxiety of the women pregnant with a second child included low education level of the husband, gender expectation and the sources of psychological stress of the pregnant woman. The risk factors for psychological stress were dissatisfaction of residence and unplanned pregnancy. The main factors influencing psychological capital were the participants' education level, whether they have learned antenatal care knowledge and satisfaction with the residence.

LIMITATIONS

All participants were recruited only from tertiary hospitals in Guangdong and Shandong province.

CONCLUSIONS

Anxiety and psychological stress is prevalent during pregnancy among women pregnant with a second child in Guangdong and Shandong. Psychological capital was a protective factor for anxiety.

The prevalence and risk of DSM-IV axis I disorder in adults with early-life earthquake stress: A cross-sectional study

OBJECTIVES

Tangshan earthquake which had a magnitude of 7.8 killed approximately 250,000 people in China in 1976. In the present study, we sought to determine the prevalence and risks of mental disorders in adults who experienced earthquake as an infant or in the prenatal period.

METHODS

This cross-sectional cohort study recruited participants based on the urban resident registry of Tangshan, Hebei province, 2013 using a multistage stratified cluster sampling method with selection probabilities proportional to size. We recruited subjects who were born between July 29, 1975 and April 28, 1978 that was one year before and 1.9 years after the occurrence of Tangshan Earthquake, respectively. Current psychiatric diagnoses and lifetime psychiatric diagnoses were obtained through the Structured Clinical Interview for DSM-IV Axis I Disorders Patient Research Version. Unconditional logistic regression analysis was performed to analyze risk factors of mental disorders.

RESULTS

Totally1380 subjects were included with 392 subjects exposed to the earthquake in the fetal period, 399 subjects who experienced the earthquake during their infancy, and 589 subjects who had no exposure to the earthquake. Twenty-one (2.7%; current 1.9%) subjects exposed to earthquake were diagnosed with major depressive disorderversus 2.3% (current 1.5%) in the non-exposure group. Five (0.6%; current 0.6%) subjects with exposure to earthquake had bipolar disorder versus 0.9% in the non-exposure group.Thirteen (1.6%; current 1.6%) subjects with exposure to earthquake had schizophreniaversus 0.2% in the non-exposure group (P=0.006). Furthermore, 5.2% (current 3.7%) subjects with exposure to earthquake had anxiety disorders versus 5.7% (current 3.9%) in the non-exposure group. Moreover, 8.1% (current 7.0%)subjects with exposure to earthquake had alcohol use disorders versus 7.1% (current 5.3%) in the non-exposure group. Furthermore, the prevalence of schizophrenia of the prenatal exposure group (2.3%) was significantly higher than the other two groups (χ² = 10.273, P = 0.006); however, no statistically significant difference was found in the current and lifetime prevalence of other DSM-IV axis I disorders among the three groups (P > 0.05). Our multivariate regression analysis showed that prenatal earthquake stress exposure was not a significant risk of any of the lifetime or current DSD-IV axis I disorders.

CONCLUSION

Adults who were exposed to earthquake in the prenatal period had a significantly higher rate of schizophrenia than those who were not exposed or who experienced earthquake in their infancy. No statistically significant difference was found in the current and lifetime prevalence of other DSM-IV axis I disorders between those exposed and those not exposed to earthquake. Furthermore, prenatal earthquake stress exposure was not a significant risk of any of the lifetime or current DSD-IV axis I disorders.

Effects of Interaction Between DRD4 Methylation and Prenatal Maternal Stress on Methylphenidate-Induced Changes in Continuous Performance Test Performance in Youth with Attention-Deficit/Hyperactivity Disorder

OBJECTIVES

Environmental factors may interact with genetic factors via the epigenetic process, and this interaction can contribute to inter-individual variability in the treatment response. The purpose of this study was to investigate the interaction effects between dopamine receptor D4 (DRD4) methylation and prenatal maternal stress on the methylphenidate (MPH) response of youth with attention-deficit/hyperactivity disorder (ADHD).

METHODS

This study was an 8-week open-label trial of MPH that included 74 ADHD youth. We investigated the associations between MPH treatment response, which was defined as a score ≤2 on the Clinical Global Impressions-Improvement (CGI-I) scale, and the methylation of 28 cytosine-guanine dinucleotide (CpG) sites of DRD4. Additionally, the interaction effects between DRD4 methylation and prenatal maternal stress on changes in Continuous Performance Test (CPT) scores after MPH treatment were investigated.

RESULTS

Although there were no significant sites that showed significant association with treatment response, there was a significant interaction effect of the methylation of CpG7 and prenatal maternal stress on changes in omission errors of the CPT following treatment (p = 0.0001).

CONCLUSIONS

The present findings indicate that the interaction between methylation of CpG7 of DRD4 and prenatal maternal stress may be predictive of the treatment response to MPH in youth with ADHD.

Prenatal intimate partner violence exposure predicts infant biobehavioral regulation: Moderation by the brain-derived neurotrophic factor (BDNF) gene

The ability to regulate stress is a critical developmental milestone of early childhood that involves a set of interconnected behavioral and physiological processes and is influenced by genetic and environmental stimuli. Prenatal exposure to traumatic stress and trauma, including intimate partner violence (IPV), increases risk for offspring biobehavioral regulation problems during childhood and adolescence. Although individual differences in susceptibility to prenatal stress have been largely unexplored, a handful of studies suggest children with specific genetic characteristics are most vulnerable to prenatal stress. We evaluated the brain-derived neurotrophic factor Val66Met gene (BDNF) as a moderator of the effect of prenatal IPV exposure on infant temperamental and cortisol regulation in response to a psychosocial challenge. Ninety-nine mother–infant dyads recruited from the community were assessed when infants (51% female) were 11 to 14 months. Maternal reports of IPV during pregnancy and infant temperament were obtained, and infant saliva was collected for genotyping and to assess cortisol reactivity (before and after the Strange Situation Task). Significant genetic moderation effects were found. Among infants with the BDNF Met allele, prenatal IPV predicted worse temperamental regulation and mobilization of the cortisol response, while controlling for infant postnatal exposure to IPV, other maternal traumatic experiences, and infant sex. However, prenatal IPV exposure was not associated with temperamental or cortisol outcomes among infant carriers of the Val/Val genotype. Findings are discussed in relation to prenatal programming and biological susceptibility to stress.

Prenatal stress and genetic risk: How prenatal stress interacts with genetics to alter risk for psychiatric illness

Risk for neuropsychiatric disorders is complex and includes an individual's internal genetic endowment and their environmental experiences and exposures. Embryonic development captures a particularly complex period, in which genetic and environmental factors can interact to contribute to risk. These environmental factors are incorporated differently into the embryonic brain than postnatal one. Here, we comprehensively review the human and animal model literature for studies that assess the interaction between genetic risks and one particular environmental exposure with strong and complex associations with neuropsychiatric outcomes-prenatal maternal stress. Gene-environment interaction has been demonstrated for stress occurring during childhood, adolescence, and adulthood. Additional work demonstrates that prenatal stress risk may be similarly complex. Animal model studies have begun to address some underlying mechanisms, including particular maternal or fetal genetic susceptibilities that interact with stress exposure and those that do not. More specifically, the genetic underpinnings of serotonin and dopamine signaling and stress physiology mechanisms have been shown to be particularly relevant to social, attentional, and internalizing behavioral changes, while other genetic factors have not, including some growth factor and hormone-related genes. Interactions have reflected both the diathesis-stress and differential susceptibility models. Maternal genetic factors have received less attention than those in offspring, but strongly modulate impacts of prenatal stress. Priorities for future research are investigating maternal response to distinct forms of stress and developing whole-genome methods to examine the contributions of genetic variants of both mothers and offspring, particularly including genes involved in neurodevelopment. This is a burgeoning field of research that will ultimately contribute not only to a broad understanding of psychiatric pathophysiology but also to efforts for personalized medicine.

Gene-environment interaction and psychiatric disorders: Review and future directions

Empirical studies suggest that psychiatric disorders result from a complex interplay between genetic and environmental factors. Most evidence for such gene-environment interaction (GxE) is based on single candidate gene studies conducted from a Diathesis-Stress perspective. Recognizing the short-comings of candidate gene studies, GxE research has begun to focus on genome-wide and polygenic approaches as well as drawing on different theoretical concepts underlying GxE, such as Differential Susceptibility. After reviewing evidence from candidate GxE studies and presenting alternative theoretical frameworks underpinning GxE research, more recent approaches and findings from whole genome approaches are presented. Finally, we suggest how future GxE studies may unpick the complex interplay between genes and environments in psychiatric disorders.

An exploration of common dopaminergic variants and behavior problems in siblings at high risk for autism spectrum disorder

Younger siblings of children with ASD often exhibit elevated internalizing and externalizing problems. We investigated common dopaminergic variants (DRD4 and DRD2) in relation to behavior problems at 36 months. Genotypes linked to less efficient dopaminergic functioning were associated with higher internalizing problems in high-risk siblings.

Exposure to intimate partner violence in utero and infant internalizing behaviors: Moderation by salivary cortisol-alpha amylase asymmetry

Guided by the main tenets of contemporary models of the developmental origins of health and disease, this study evaluated whether individual differences in reactivity of the hypothalamic-pituitary-adrenal (HPA) axis and Sympathetic Nervous System (SNS) moderate the effect of prenatal exposure to trauma on internalizing and externalizing behaviors during infancy. Participants were a community sample of 182 mothers (M age=25years, 43% Caucasian, 33% Black/African American, 24% Biracial/Other) and their infants (59% girls; M age=11.8months). Each mother completed questionnaires that assessed IPV experienced during pregnancy and also reported on her infant's behavior problems. Infant saliva samples (later assayed for cortisol and sAA) were collected before and after a frustrating task (i.e., arm restraint). Results revealed that the association between in utero IPV and infant internalizing behaviors was most pronounced for infants with asymmetrical HPA-SNS (i.e., high-cortisol and low-sAA) reactivity to frustration, and least pronounced for infants with symmetrical HPA-SNS (i.e., low-cortisol and low-sAA or high-cortisol and high-sAA) reactivity to frustration. Higher levels of externalizing behavior, in contrast, were associated with higher levels of prenatal IPV but unrelated to either cortisol or sAA reactivity to stress. Findings replicate documented associations between maternal IPV exposure during pregnancy and offspring risk. Moreover, findings advance our understanding of individual differences in the developmental origins of health and disease and provide additional evidence that assessing multiple stress biomarkers contributes to a more comprehensive understanding of individual vulnerability to adversity.

Prenatal programming of postnatal plasticity for externalizing behavior: Testing an integrated developmental model of genetic and temperamental sensitivity to the environment

Although both gene- and temperament-environment interactions contribute to the development of youth externalizing problems, it is unclear how these factors jointly affect environmental sensitivity over time. In a 7-year longitudinal study of 232 children (aged 5-10) with and without ADHD, we employed moderated mediation to test a developmentally sensitive mechanistic model of genetic and temperamental sensitivity to prenatal and postnatal environmental factors. Birth weight, a global measure of the prenatal environment, moderated predictions of child negative emotionality from a composite of dopaminergic polymorphisms (i.e., DRD4 and DAT1), such that birth weight inversely predicted negative emotionality only for children with genetic plasticity. Negative emotionality, in turn, predicted externalizing behavior 4-5 years later, beyond genetic and postnatal parenting effects. Finally, birth weight moderated the indirect effect of dopaminergic genotypes on externalizing problems through negative emotionality, partially supporting a prenatal programming model. We discuss theoretical and empirical implications for models of environmental sensitivity.

Respiratory sinus arrhythmia in the fourth decade of life depends on birth weight and the DRD4 gene: Implications for understanding the development of emotion regulation

INTRODUCTION

The long allele of the DRD4 gene can confer different behavioral and emotional phenotypes depending upon environmental exposure, although the physiological changes underlying these phenotypes are not fully known. We sought to extend this work by assessing the interaction of the DRD4 gene and exposure to perinatal adversity (indexed by extremely low birth weight [ELBW]) on resting respiratory sinus arrhythmia (RSA), a neurophysiological measure of emotion regulation, in adulthood.

METHODS

We examined the interaction between the DRD4 gene and perinatal adversity on RSA at age 30-35 in a longitudinal cohort of ELBW survivors (n = 49) and NBW controls (n = 63). Buccal DNA samples were genotyped for short and long carriers of the exon III DRD4 VNTR gene. Resting RSA was assessed by electrocardiogram.

RESULTS

We report an interaction between birth weight status and DRD4 gene (F = 9.42, p = 0.003) in predicting RSA, such that DRD4 long carriers had the highest and lowest resting RSA depending on whether they were born NBW or ELBW, respectively. DRD4 short carriers were less sensitive to birth weight. Additionally, reduced RSA was correlated with a history of major depressive disorder, suggesting it was a reliable index of emotion dysregulation.

DISCUSSION

These results suggest that the perinatal environment influences autonomic nervous system functioning in individuals with genotypes that confer additional sensitivity. Whether the long-term autonomic outcomes of this environmental sensitivity are beneficial or detrimental appears to depend on the quality of the early life environment, and may influence the development of emotion regulatory and psychiatric problems in adulthood.

Cannabis use by women during pregnancy does not influence infant DNA methylation of the dopamine receptor DRD4

Background: Maternal cannabis use in pregnancy is linked with long-term adverse behavioral outcomes in offspring. Epigenetic processes established in utero that affect dopaminergic (reward) signaling may mediate risks. Associations between cannabis use and offspring DNA methylation have not been investigated; however, maternal tobacco smoking in pregnancy is associated with distinct patterns of DNA methylation at birth and beyond. Objectives: To determine whether maternal cannabis use is associated with methylation of the dopamine receptor gene DRD4 promoter in infants. Methods: Mothers in the Triple B study provided detailed information on drug use in each trimester of pregnancy. Buccal swabs were collected from neonates at 8 weeks (n = 804, 51.7% male, and 48.3% female). DRD4 promoter DNA methylation was measured using SEQUENOM MassARRAY. Results: Fifty-seven of the women in the study reported drug use during pregnancy, of whom 44 used cannabis. Of 19 cytosine-phosphate-guanine dinucleotides (CpG) units tested in DRD4, gestational cannabis use was associated with offspring methylation at 1 CpG unit in multivariate models (β + 1.48, CI: 0.02 to 2.93, and p = 0.047). At another site there was weak evidence that both cannabis and other drug use were independently associated with increased methylation, while the association with tobacco was in the reverse direction (cannabis use β + 0.67, CI: −0.12 to 1.46, and p = 0.09; other drug use β + 1.11, CI: 0.17 to 2.05, and p = 0.02; tobacco use β −0.41, CI: −0.85 to 0.03, and p = 0.07). None of the associations would remain significant after correction for multiple testing. Conclusion: There is no strong evidence that maternal cannabis use in pregnancy is associated with offspring DRD4 methylation.

Ventral striatum and amygdala activity as convergence sites for early adversity and conduct disorder

Childhood family adversity (CFA) increases the risk for conduct disorder (CD) and has been associated with alterations in regions of affective processing like ventral striatum (VS) and amygdala. However, no study so far has demonstrated neural converging effects of CFA and CD in the same sample. At age 25 years, functional MRI data during two affective tasks, i.e. a reward (N = 171) and a face-matching paradigm (N = 181) and anatomical scans (N = 181) were acquired in right-handed currently healthy participants of an epidemiological study followed since birth. CFA during childhood was determined using a standardized parent interview. Disruptive behaviors and CD diagnoses during childhood and adolescence were obtained by diagnostic interview (2-19 years), temperamental reward dependence was assessed by questionnaire (15 and 19 years).CFA predicted increased CD and amygdala volume. Both exposure to CFA and CD were associated with a decreased VS response during reward anticipation and blunted amygdala activity during face-matching. CD mediated the effect of CFA on brain activity. Temperamental reward dependence was negatively correlated with CFA and CD and positively with VS activity. These findings underline the detrimental effects of CFA on the offspring's affective processing and support the importance of early postnatal intervention programs aiming to reduce childhood adversity factors.

Prenatal maternal depression and child serotonin transporter linked polymorphic region (5-HTTLPR) and dopamine receptor D4 (DRD4) genotype predict negative emotionality from 3 to 36 months

Prenatal maternal depression and a multilocus genetic profile of two susceptibility genes implicated in the stress response were examined in an interaction model predicting negative emotionality in the first 3 years. In 179 mother-infant dyads from the Maternal Adversity, Vulnerability, and Neurodevelopment cohort, prenatal depression (Center for Epidemiologic Studies Depressions Scale) was assessed at 24 to 36 weeks. The multilocus genetic profile score consisted of the number of susceptibility alleles from the serotonin transporter linked polymorphic region gene (5-HTTLPR): no long-rs25531(A) (LA: short/short, short/long-rs25531(G) [LG], or LG/LG] vs. any LA) and the dopamine receptor D4 gene (six to eight repeats vs. two to five repeats). Negative emotionality was extracted from the Infant Behaviour Questionnaire-Revised at 3 and 6 months and the Early Child Behavior Questionnaire at 18 and 36 months. Mixed and confirmatory regression analyses indicated that prenatal depression and the multilocus genetic profile interacted to predict negative emotionality from 3 to 36 months. The results were characterized by a differential susceptibility model at 3 and 6 months and by a diathesis-stress model at 36 months.

Aggressive behavior in humans: Genes and pathways identified through association studies

Aggressive behavior has both genetic and environmental components. Many association studies have been performed to identify genetic factors underlying aggressive behaviors in humans. In this review we summarize the previous work performed in this field, considering both candidate gene (CGAS) and genome-wide association studies (GWAS), excluding those performed in samples where the primary diagnosis is a psychiatric or neurological disorder other than an aggression-related phenotype. Subsequently, we have studied the enrichment of pathways and functions in GWAS data. The results of our searches show that most CGAS have identified associations with genes involved in dopaminergic and serotonergic neurotransmission and in hormone regulation. On the other hand, GWAS have not yet identified genome-wide significant associations, but top nominal findings are related to several signaling pathways, such as axon guidance or estrogen receptor signaling, and also to neurodevelopmental processes and synaptic plasticity. Future studies should use larger samples, homogeneous phenotypes and standardized measurements to identify genes that underlie aggressive behaviors in humans. © 2016 Wiley Periodicals, Inc.

Genetics of aggressive behavior: An overview

The Research Domain Criteria (RDoC) address three types of aggression: frustrative non-reward, defensive aggression and offensive/proactive aggression. This review sought to present the evidence for genetic underpinnings of aggression and to determine to what degree prior studies have examined phenotypes that fit into the RDoC framework. Although the constructs of defensive and offensive aggression have been widely used in the animal genetics literature, the human literature is mostly agnostic with regard to all the RDoC constructs. We know from twin studies that about half the variance in behavior may be explained by genetic risk factors. This is true for both dimensional, trait-like, measures of aggression and categorical definitions of psychopathology. The non-shared environment seems to have a moderate influence with the effects of shared environment being unclear. Human molecular genetic studies of aggression are in an early stage. The most promising candidates are in the dopaminergic and serotonergic systems along with hormonal regulators. Genome-wide association studies have not yet achieved genome-wide significance, but current samples are too small to detect variants having the small effects one would expect for a complex disorder. The strongest molecular evidence for a genetic basis for aggression comes from animal models comparing aggressive and non-aggressive strains or documenting the effects of gene knockouts. Although we have learned much from these prior studies, future studies should improve the measurement of aggression by using a systematic method of measurement such as that proposed by the RDoC initiative.

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.

Development and the epigenome: the 'synapse' of gene-environment interplay

This paper argues that there is a revolution afoot in the developmental science of gene-environment interplay. We summarize, for an audience of developmental researchers and clinicians, how epigenetic processes - chromatin structural modifications that regulate gene expression without changing DNA sequences - may offer a strong, parsimonious account for the convergence of genetic and contextual variation in the genesis of adaptive and maladaptive development. Epigenetic processes may play a plausible explanatory role in understanding: divergent trajectories and sexual dimorphisms in brain development; statistical interactions between genes and environments; the biological embedding of early psychosocial adversities; the linkages of such adversities to disorders of mental health; the striking individual variation in the strength of those linkages; the molecular origins of critical and sensitive periods; and the transgenerational inheritance of risk and protection. Taken together, these arguments converge in a claim that epigenetic processes constitute a promising and illuminating point of connection - a 'synapse' - between genes and environments.

Association between the dopamine D4 receptor gene exon III variable number of tandem repeats and political attitudes in female Han Chinese

Twin and family studies suggest that political attitudes are partially determined by an individual's genotype. The dopamine D4 receptor gene (DRD4) exon III repeat region that has been extensively studied in connection with human behaviour, is a plausible candidate to contribute to individual differences in political attitudes. A first United States study provisionally identified this gene with political attitude along a liberal-conservative axis albeit contingent upon number of friends. In a large sample of 1771 Han Chinese university students in Singapore, we observed a significant main effect of association between the DRD4 exon III variable number of tandem repeats and political attitude. Subjects with two copies of the 4-repeat allele (4R/4R) were significantly more conservative. Our results provided evidence for a role of the DRD4 gene variants in contributing to individual differences in political attitude particularly in females and more generally suggested that associations between individual genes, and neurochemical pathways, contributing to traits relevant to the social sciences can be provisionally identified.

Studying longitudinal trajectories in animal models of psychiatric illness and their translation to the human condition

Many forms of psychopathology and/or psychiatric illness can occur through the pathways of altered environmental sensitivity, impulsivity, social functioning, and anxious responding. While these traits are also heritable, environmental conditions are known to play a critical role. The genetic factors that contribute to these traits may be adaptive in certain contexts, but can - under the environmental conditions commonly faced among modern humans - also be key moderators of risk for psychopathological outcomes. This article will discuss how animal studies inform us of the various environmental mechanisms through which prenatal or early postnatal environmental challenge can produce long-term effects on behavior and will briefly address how pre-copulatory, pre-natal and early postnatal epigenetic effects can contribute to persistent alterations in offspring behavior. Its main focus will be how nonhuman primate studies have helped us to understand how genetic vulnerability factors can moderate responses to early environmental factors, suggesting pathways through which early stress might produce long-term effects, thus pointing to systems that might moderate risk for psychiatric illnesses in humans.

Transgenerational Transmission of Stress Pathology

Abstract. The impact of the environment early in life on long-term outcomes is well known. Stressful experiences during pre- and postnatal development can modulate the genetic programming of specific brain circuits underlying emotional and cognitive aspects of behavioral adaptation to stressful experiences later in life. Furthermore, there is documented evidence for gene-environment interactions in the context of early-life stress. Identical gene variants can be associated with different phenotypes depending on environmental factors. DNA methylation, an enzymatically-catalyzed modification of the DNA, is the mechanism through which phenotypes are regulated. The dynamics and plasticity of epigenetic mechanisms can have short-term, long-term, or transgenerational consequences. In epigenetic research, rodent models have targeted several behavioral and emotional phenotypes. These models have contributed significantly to our understanding of the environmental regulation of the developmental brain in early life. This review will highlight studies with rats and mice on epigenetic processes in fetal programming of stress-related mental disorders.

Stress and the social brain: behavioural effects and neurobiological mechanisms

Stress often affects our social lives. When undergoing high-level or persistent stress, individuals frequently retract from social interactions and become irritable and hostile. Predisposition to antisocial behaviours - including social detachment and violence - is also modulated by early life adversity; however, the effects of early life stress depend on the timing of exposure and genetic factors. Research in animals and humans has revealed some of the structural, functional and molecular changes in the brain that underlie the effects of stress on social behaviour. Findings in this emerging field will have implications both for the clinic and for society.

Genetics in child and adolescent psychiatry: methodological advances and conceptual issues

Discovering the genetic basis of early-onset psychiatric disorders has been the aim of intensive research during the last decade. We will first selectively summarize results of genetic research in child and adolescent psychiatry by using examples from different disorders and discuss methodological issues, emerging questions and future directions. In the second part of this review, we will focus on how to link genetic causes of disorders with physiological pathways, discuss the impact of genetic findings on diagnostic systems, prevention and therapeutic interventions. Finally we will highlight some ethical aspects connected to genetic research in child and adolescent psychiatry. Advances in molecular genetic methods have led to insights into the genetic architecture of psychiatric disorders, but not yet provided definite pathways to pathophysiology. If replicated, promising findings from genetic studies might in some cases lead to personalized treatments. On the one hand, knowledge of the genetic basis of disorders may influence diagnostic categories. On the other hand, models also suggest studying the genetic architecture of psychiatric disorders across diagnoses and clinical groups.

The conditioning of intervention effects on early adolescent alcohol use by maternal involvement and dopamine receptor D4 (DRD4) and serotonin transporter linked polymorphic region (5-HTTLPR) genetic variants

Data drawn from the in-home subsample of the PROSPER intervention dissemination trial were used to investigate the moderation of intervention effects on underage alcohol use by maternal involvement and candidate genes. The primary gene examined was dopamine receptor D4 (DRD4). Variation in this gene and maternal involvement were hypothesized to moderate the influence of intervention status on alcohol use. The PROSPER data used were drawn from 28 communities randomly assigned to intervention or comparison conditions. Participating youth were assessed in five in-home interviews from sixth to ninth grades. A main effect of sixth-grade pretest maternal involvement on ninth-grade alcohol use was found. Neither intervention status nor DRD4 variation was unconditionally linked to ninth-grade drinking. However, moderation analyses revealed a significant three-way interaction among DRD4 status, maternal involvement, and intervention condition. Follow-up analyses revealed that prevention reduced drinking risk, but only for youth with at least one DRD4 seven-repeat allele who reported average or greater pretest levels of maternal involvement. To determine if this conditional pattern was limited to the DRD4 gene, we repeated analyses using the serotonin transporter linked polymorphic region site near the serotonin transporter gene. The results for this supplemental analysis revealed a significant three-way interaction similar but not identical to that found for DRD4.

DRD4 and susceptibility to peer influence on alcohol use from adolescence to adulthood

BACKGROUND

The long allele of DRD4 is associated with greater susceptibility to peer influences on alcohol use in young adulthood, but it is unclear whether this increased susceptibility extends to other developmental periods. This study examined the interactive effects of DRD4 polymorphism and friends' alcohol use from adolescence to adulthood.

METHODS

Participants (N = 340; 59% female; 98% White) reported on their own and their friends' alcohol use at four time points between mean ages 17 and 33. Autoregressive cross-lagged models evaluated reciprocal relationships between friends' alcohol use and participants' own alcohol use and frequency of heavy drinking over time. Multigroup modeling tested differences in model paths and covariances across high vs. low risk DRD4 polymorphisms.

RESULTS

Alcohol use at age 33 was predicted by previous friends' alcohol use and correlated with current friends' alcohol use only for carriers of the DRD4 long allele. Regardless of DRD4 genotype, friends' alcohol use at age 17 predicted greater alcohol use and more frequent heavy drinking at age 23. Alcohol use and/or heavy drinking predicted greater friends' alcohol use at later time points for both genotype groups across adolescence and adulthood.

CONCLUSIONS

The long allele of DRD4 is associated with increased susceptibility to peer influences on alcohol use in young adulthood, but not earlier in development. Adults with the long allele of DRD4 may benefit from interventions educating them about this risk and equipping them with strategies to reduce affiliations with and influence of drinking friends.

Are infants differentially sensitive to parenting? Early maternal care, DRD4 genotype and externalizing behavior during adolescence

Insensitive and unresponsive caregiving during infancy has been linked to externalizing behavior problems during childhood and adolescence. The 7-repeat (7r) allele of the dopamine D4 receptor (DRD4) gene has meta-analytically been associated with a heightened susceptibility to adverse as well as supportive environments. In the present study, we examined long-term effects of early maternal care, DRD4 genotype and the interaction thereof on externalizing and internalizing psychopathology during adolescence. As part of an ongoing epidemiological cohort study, early maternal care was assessed at child's age 3 months during a nursing and playing situation. In a sample of 296 offspring, externalizing and internalizing symptoms were assessed using a psychiatric interview conducted at age 15 years. Parents additionally filled out a questionnaire on their children's psychopathic behaviors. Results indicated that adolescents with the DRD4 7r allele who experienced less responsive and stimulating early maternal care exhibited more symptoms of ADHD and CD/ODD as well as higher levels of psychopathic behavior. In accordance with the hypothesis of differential susceptibility, 7r allele carriers showed fewer ADHD symptoms and lower levels of psychopathic behavior when exposed to especially beneficial early caregiving. In contrast, individuals without the DRD4 7r allele proved to be insensitive to the effects of early maternal care. This study replicates earlier findings with regard to an interaction between DRD4 genotype and early caregiving on externalizing behavior problems in preschoolers. It is the first one to imply continuity of this effect until adolescence.

Interaction between prenatal stress and dopamine D4 receptor genotype in predicting aggression and cortisol levels in young adults

RATIONALE

Considerable evidence suggests that genetic factors combine with environmental influences to impact on the development of aggressive behavior. A genetic variant that has repeatedly been reported to render individuals more sensitive to the presence of adverse experiences, including stress exposure during fetal life, is the seven-repeat allele of the dopamine D4 receptor (DRD4) gene.

OBJECTIVES

The present investigation concentrated on the interplay of prenatal maternal stress and DRD4 genotype in predicting self-reported aggression in young adults. As disruption of the hypothalamic-pituitary-adrenal system has been discussed as a pathophysiological pathway to aggression, cortisol stress reactivity was additionally examined.

METHODS

As part of an epidemiological cohort study, prenatal maternal stress was assessed by maternal interview 3 months after childbirth. Between the ages of 19 and 23 years, 298 offspring (140 males, 158 females) completed the Young Adult Self-Report to measure aggressive behavior and were genotyped for the DRD4 gene. At 19 years, 219 participants additionally underwent the Trier Social Stress Test to determine cortisol reactivity.

RESULTS

Extending earlier findings with respect to childhood antisocial behavior, the results revealed that, under conditions of higher prenatal maternal stress, carriers of the DRD4 seven-repeat allele displayed more aggression in adulthood (p = 0.032). Moreover, the same conditions which seemed to promote aggression were found to predict attenuated cortisol secretion (p = 0.028).

CONCLUSIONS

This is the first study to indicate a long-term impact of prenatal stress exposure on the cortisol stress response depending on DRD4 genotype.

Role of CNR1 polymorphisms in moderating the effects of psychosocial adversity on impulsivity in adolescents

Enhanced endocannabinoid signaling has been implicated in typically adolescent behavioral features such as increased risk-taking, impulsivity and novelty seeking. Research investigating the impact of genetic variants in the cannabinoid receptor 1 gene (CNR1) and of early rearing conditions has demonstrated that both factors contribute to the prediction of impulsivity-related phenotypes. The present study aimed to test the hypothesis of an interaction of the two most studied CNR1 polymorphisms rs806379 and rs1049353 with early psychosocial adversity in terms of affecting impulsivity in 15-year-olds from an epidemiological cohort sample followed since birth. In 323 adolescents (170 girls, 153 boys), problems of impulse control and novelty seeking were assessed using parent-report and self-report, respectively. Exposure to early psychosocial adversity was determined in a parent interview conducted at the age of 3 months. The results indicated that impulsivity increased following exposure to early psychosocial adversity, with this increase being dependent on CNR1 genotype. In contrast, while individuals exposed to early adversity scored higher on novelty seeking, no significant impact of genotype or the interaction thereof was detected. This is the first evidence to suggest that the interaction of CNR1 gene variants with the experience of early life adversity may play a role in determining adolescent impulsive behavior. However, given that the reported findings are obtained in a high-risk community sample, results are restricted in terms of interpretation and generalization. Future research is needed to replicate these findings and to identify the mediating mechanisms underlying this effect.