Association of maternal dopamine transporter genotype with negative parenting: evidence for gene x environment interaction with child disruptive behavior

Cortisol Reactivity and Observed Parenting among Mothers of Children with and without ADHD

OBJECTIVE

Neurobiological models suggest links between maternal cortisol reactivity and parenting; however, no studies have examined cortisol reactivity and parenting in mothers of school-age children with ADHD.

METHOD

We examined the relationship between observed parenting and maternal cortisol reactivity in two laboratory contexts: the Trier Social Stress Task (TSST) and parenting-child interaction (PCI). Mothers of children with (N = 24) and without (N = 36) ADHD participated.

RESULTS

During the TSST, greater cortisol output and increase were associated with decreased positive and increased negative parenting. However, during the PCI, cortisol output was associated with increased self-reported and observed positive parenting, and decreased observed negative parenting. Cortisol change during the PCI was associated with decreased observed positive parenting and increased self-reported negative parenting. Among mothers of children with ADHD, cortisol output during the PCI was negatively associated with negative, inconsistent parenting. Change in cortisol predicted more inconsistent discipline and corporal punishment.

CONCLUSION

Findings contribute to an integrative biological, psychological, and cognitive process model of parenting in families of children with ADHD.

Children’s ADHD and Dysregulation Problems, DAT1 Genotype and Methylation, and their Interplay with Family Environment

Background

International literature has underlined the complex interplay between genetic and environmental variables in shaping children’s emotional-behavioral functioning.

Objective

This study aimed to explore the dynamic relationship between children’s Dopamine Transporter (DAT1) genotype and methylation, and maternal and paternal affective environment, on children’s Attention Deficit Hyperactivity Disorder (ADHD) problems and dysregulation problems.

Method

In a community sample of 76 families with school-aged children, we assessed children’s DAT1 genotype and methylation, their own ADHD problems and dysregulation profile (CBCL 6–18 DP), and maternal and paternal psychopathological risk, parenting stress, and marital adjustment. Hierarchical regressions were carried out to verify the possible moderation of children’s genotype on the relationship between children’s methylation and psychopathological risk, parental environment and children’s methylation, and parental environment and children’s psychopathological risk.

Results

The levels of methylation at M1 CpG significantly predicted ADHD problems among children with 10/10 genotype, whereas high levels of methylation at M6 CpG predicted low ADHD problems for children with 9/x genotype. High levels of methylation at M3 CpG were associated with high scores of CBCL DP. DAT1 genotype moderated the relationship between maternal and paternal variables with children’s methylation and psychopathological risk. The scores of maternal and paternal Dyadic Adjustment Scale showed indirect effects on children’s methylation and psychopathological risk in relation to those exerted by risk factors.

Conclusion

Our study has supported the emerging evidence on the complex nature of children’s emotional-behavioral functioning and the associated risk and protective factors, with important implications for the planning of preventive programs.

DAT1 and Its Psychological Correlates in Children with Avoidant/Restrictive Food Intake Disorder: A Cross-Sectional Pilot Study

International research has underlined the role played by children’s and maternal psychopathological symptoms on the onset of avoidant/restrictive food intake disorder (ARFID) in early childhood. No study has considered the possible interplay between children’s dopamine transporter (DAT1) genotype and methylation, dysregulation problems and maternal psychopathological risk. This study aimed to investigate the complex relationship between these variables, considering the possible mediation role played by children’s DAT1 methylation on the relationship between mothers’ psychopathological risk and children’s dysregulation problems, moderated by children’s DAT1 genotype. Our sample consisted of 94 early children and their mothers, divided into four subgroups, based on children’s ARFID subtypes (irritable/impulsive (I/I), sensory food aversions (SFA), post-traumatic feeding disorders subtypes (PTFD), and a non-clinical group (NC)). We addressed children’s dysregulation problems and maternal psychopathological risk, and collected children’s DNA through buccal swabs. Results showed that children’s 9/x genotype was associated with PTFD and NC groups, whereas the 10/10 genotype was associated with the SFA group, with large effect size. There were significant large differences in the study groups on children’s DAT1 total methylation, children’s dysregulation problems, and maternal psychopathological risk. Children’s DAT1 methylation did not mediate the relationship between mother’s psychopathological risk and children’s dysregulation problems, but there was a significant large direct effect. Children’s 9/x genotype moderated the relationship between maternal psychopathological risk and children’s DAT1 methylation but, respectively, with a large and small effect. Our pilot study suggested that the relationship between children’s DAT1 genotype and methylation, dysregulation problems, and maternal psychopathological risk has a crucial contribution to ARFID.

The Dopamine D4 Receptor (DRD4) Exon 3 VNTR Contributes to Adaptive Personality Differences in an Italian Small Island Population

The search for evolutionary forces shaping the diversity of human personality traits encouraged studies that have found that islanders are relatively closed and introverted, with little interest in the external world. The ‘personality gene flow’ hypothesis was proposed to explain the mechanism underlying this difference, suggesting that the frequency of alleles that influence islander personality traits might progressively increase in the gene pools on islands because of selective emigration of individuals not displaying these alleles. We genotyped 96 individuals from the Italian mainland and 117 from Giglio Island, whose residents were previously assessed regarding their personality traits. We genotyped three polymorphisms: the dopamine D4 receptor (DRD4) exon 3 repeat region, the serotonin–transporter SLC6A4 5–HTTLPR indel and the dopamine transporter SLC6A3 DAT1 3′UTR repeat region. Only the DRD4 exon 3 repeat was hypothesised to show varying allele frequencies because this polymorphism could be associated with human migration and personality traits such as extraversion, openness and novelty seeking. As predicted, no differences in allele frequencies were found for the SLC6A4 and SLC6A3 polymorphisms, whereas significant differences were observed in the frequency of the DRD4 exon 3 alleles. The DRD4.2 repeat was more common in mainlanders, as expected, whereas the DRD4.7 allele was over–represented among islanders who never emigrated. This last result contradicts the suggested association of this allele with long–distance migrations. We suggest that emigration might have caused gene flow out the island that resulted in somewhat unpredictable changes in the frequencies of specific alleles, thus influencing islander personality traits. Copyright © 2013 European Association of Personality Psychology

Effects of interactions between variation in dopaminergic genes, traumatic life events, and anomalous self-experiences on psychosis proneness: Results from a cross-sectional study in a nonclinical sample

Background

There is a growing number of studies showing interactions between genetic polymorphisms associated with dopaminergic neurotransmission and traumatic life events (TLEs) on a risk of psychotic-like experiences (PLEs). Anomalous self-experiences (ASEs) have been associated both with TLEs as well as with PLEs. However, it remains unknown what is the role of ASEs in the complexity of gene–environment interactions on the emergence of PLEs.

Patients and methods

We included 445 young adults—university students from three big cities in Poland. We used the Traumatic Events Checklist to assess TLEs, the Inventory of Psychotic-Like anomalous self-experiences in order to measure ASEs, and the Prodromal Questionnaire (PQ16) to record the level of PLEs. The following gene polymorphisms, related to dopaminergic neurotransmission, were determined: the catechol-O-methyltransferase (COMT) rs4680 polymorphism, the dopamine D2 receptor (DRD2) rs6277 polymorphism, and the dopamine transporter 1 (DAT1) rs28363170 polymorphism.

Results

There was a significant effect of the interaction between the DAT1 polymorphism, a severity of ASEs, and a history of TLEs on the level of PLEs. Among the DAT1 10R/10R homozygotes with low level of ASEs, a severity of PLEs was significantly higher in individuals with a history of any TLEs. Higher scores of the PQ16 were associated with a greater severity of ASEs both in the DAT1 9R allele carriers and the DAT1 10R/10R homozygotes.

Conclusion

Our findings imply that genetic liability related to aberrant dopamine transport might impact the association between TLEs and PLEs in subjects with high levels of ASEs.

Emotional-Behavioral Regulation, Temperament and Parent-Child Interactions Are Associated with Dopamine Transporter Allelic Polymorphism in Early Childhood: A Pilot Study

International research has highlighted the role played by individual genetic polymorphism, children’s emotional-behavioral functioning, and quality of parent–child feeding interaction in shaping children’s development. Few studies have focused on the dopamine transporter (DAT1) gene in these processes. In a community sample of 81 families with young children aged between 19 and 28 months (37 males and 44 females), this pilot study aimed to explore possible relationships between children’s DAT1 genotype (9/x: 9/9, 9/19 contrasted to 10/10), their own psychological profiles, parental psychopathological risk, and the quality of mother–child and father–child feeding interactions. Children’s DAT1 genotype was assessed collecting DNA through buccal; children’s temperament and emotional-behavioral regulation, and parental psychopathological risk were assessed, respectively, through report-form and self-report instruments; then, dyadic exchanges were videotaped during a mealtime, and coded based on the Scala di Valutazione dell′Interazione Alimentare (SVIA). Results showed significant differences in the variables under study based on children’s DAT1 genotype, with a higher risk associated with the 10/10. Our findings have provided preliminary new evidence on the relationship between a different child’s polymorphisms, their own emotional-behavioral functioning, and the quality of the family environment, with important implications for the planning of more targeted prevention programs.

Negative Parenting Moderates the Prospective Association of ADHD Symptoms and Youth Social Problems

Although ADHD and negative parenting are established predictors of youth outcomes, their independent and interactive effects on youth social functioning remain unclear. We tested childhood ADHD symptoms and negative parenting as independent and interactive predictors of prospective change in social problems across a four-year follow-up. At baseline, families of 221 (33% female) children with (n = 94) and without ADHD were rigorously assessed including observed positive and negative parenting behavior, youth ADHD symptoms, as well as multi-informant ratings of youth social problems at multiple occasions. Based on multiple regression with robust standard errors and full-information maximum likelihood procedures to address missing data, ADHD symptoms positively predicted social problems, even with control of observed parenting behavior, child age and sex, oppositional defiant disorder symptoms, and baseline social problems. Additionally, a child ADHD symptoms x negative parenting interaction uniquely predicted separate parent- and teacher-rated social problems where ADHD symptoms positively predicted social problems exclusively in the context of high (+1SD) and very high (+2 SD) negative parenting, respectively. When ADHD was separated into distinct dimensions (i.e., inattention, hyperactivity), an interaction between inattention symptoms and negative parenting approached significance such that inattention symptoms positively predicted parent-rated social problems in the context of high negative parenting. We discuss the interaction between parenting and ADHD symptoms in predictions of youth social problems and implications for intervention.

Executive Functioning Mediates Predictions of Youth Academic and Social Development from Parenting Behavior

Using multiple mediation with bootstrapping, dimensions of executive functioning (i.e., inhibitory control, working memory, set shifting) were tested as mediators of predictions of academic and social outcomes from observed positive and negative parenting in 131 children followed prospectively into early adolescence. Inhibitory control and working memory mediated predictions of academic achievement, whereas inhibitory control meditated predictions of school competence from positive parenting. Additionally, working memory mediated predictions of negative social preference, but not social competence, from positive parenting. Executive functioning did not mediate predictions from negative parenting. The role of parenting in shaping youth outcomes through executive functioning is considered.

The other side of the coin: Hypersociability

Affiliative social motivation and behavior, that is, sociability that includes attachment, prosocial behavior (sharing, caring and helping) and empathy (the ability to understand and share the feelings of others), has high variability in the human population, with a portion of people outside of the normal range. While psychiatric disorders and autism spectrum disorders are typically associated with a deficit in social behavior, the opposite trait of hypersociability and indiscriminate friendliness are exhibited by individual with specific neurodevelopmental disorders and following early adverse care. Here we discuss both genetic and environmental factors that cause or increase the risk for developing pathological hypersociability from human to rodent models.

Gene-Environment Correlation Between the Dopamine Transporter Gene (DAT1) Polymorphism and Childhood Experiences of Abuse

In the present study, we investigated the possible gene-environment correlation between the dopamine transporter gene (DAT1) polymorphism and childhood experiences of abuse and neglect. Genetic information was obtained from 1,442 male and 2,178 female twins and their siblings drawn from a Finnish population-based sample. The Childhood Trauma Questionnaire was used to measure the childhood experiences of abuse and neglect. In men, the DAT1 polymorphism was associated with having experienced sexual abuse in childhood, such that men with the 9R9R genotype reported less sexual abuse experiences than men with the 9R10R or the 10R10R genotypes. In women, there was an association between the DAT1 polymorphism and childhood experiences of emotional abuse, such that women with the 9R9R genotype reported less emotional abuse experiences than women with the 9R10R or 10R10R genotypes. No other associations between the DAT1 polymorphism and childhood experiences of abuse and neglect were found. In sum, the results suggested that some genetic components might predispose children to experience childhood abuse and neglect. Possible reasons for this association were discussed.

The Contribution of Maternal ADHD Symptomatology, Maternal DAT1, and Home Atmosphere to Child ADHD Symptomatology at 7 Years of Age

Children of mothers with attention-deficit/hyperactivity disorder (ADHD) have an increased genetic and environmental risk for ADHD. The unique and interactive contributions of a maternal dopamine receptor gene (DAT1), maternal ADHD symptoms (hyperactive- impulsive, inattentive), and home atmosphere to the prediction of ADHD symptoms (hyperactive- impulsive, inattentive) in 7- year-old boys (N = 96) were examined using data from a longitudinal study of familial risk for ADHD. During the first 6 months of the study, mothers and their spouses completed a questionnaire about the mother's ADHD symptoms. Home atmosphere questionnaire data were collected 4 years later. At the 7-year assessment, mothers reported on their child's ADHD symptoms. Negative home atmosphere was significantly associated with child hyperactive-impulsive and inattentive symptoms. Maternal inattentive symptoms were significantly correlated with both child symptom dimensions. Regression models, with child genotype and maternal education controlled, showed main effects for maternal inattentive symptoms, maternal DAT1 10/10 genotype, and home atmosphere in the prediction of child inattentive symptoms. Only home atmosphere predicted child hyperactive-impulsive symptoms. There was a significant home atmosphere x maternal hyperactive-impulsive symptoms interaction in the prediction of child hyperactive-impulsive symptoms. Boys with higher levels of symptoms came from homes characterized by higher levels of negative atmosphere and had mothers with higher levels of hyperactive-impulsive symptoms. There was also a trend (p = 0.075) for a maternal DAT1 x home atmosphere interaction. Boys with higher levels of inattentive symptoms came from homes with higher levels of negative atmosphere and had mothers with the homozygous 10/10 genotype. The maternal heterozygous 9/10 genotype did not predict child symptoms.

Parental brain-derived neurotrophic factor genotype, child prosociality, and their interaction as predictors of parents' warmth

BACKGROUND

Parental warmth has been associated with various child behaviors, from effortful control to callous-unemotional traits. Factors that have been shown to affect parental warmth include heritability and child behavior. However, there is limited knowledge about which specific genes are involved, how they interact with child behavior, how they affect differential parenting, and how they affect fathers. We examined what affects paternal and maternal warmth by focusing on the child's prosocial behavior and parents' genotype, specifically a Valine to Methionine substitution at codon 66 in the brain-derived neurotrophic factor (BDNF) gene.

METHODS

Data was available from a sample of 6.5 year-old twins, consisting of 369 mothers and 663 children and 255 fathers and 458 children. Self-reports were used to assess mothers' and fathers' warmth. Child prosociality was assessed with the other-parent report and experimental assessments.

RESULTS

Mothers' warmth was not affected by their BDNF genotype, neither as a main effect nor in an interaction with child prosociality. Fathers with the Met allele scored higher on warmth. Additionally, there was a significant interaction between fathers' BDNF genotype and child prosociality. For fathers with the Met allele there was a positive association between warmth and child prosociality. Conversely, for fathers with the Val/Val genotype there was no association between warmth and child prosociality. Results were repeated longitudinally in a subsample with data on age 8-9 years. A direct within family analysis showed that fathers with the Met allele were more likely than Val/Val carriers to exhibit differential parenting toward twins who differed in their prosocial behavior. The same pattern of findings was found with mother-rated and experimentally assessed prosociality.

CONCLUSIONS

These results shed light on the genetic and environmental underpinnings of paternal behavior and differential parenting.

Thinking and doing: the effects of dopamine and oxytocin genes and executive function on mothering behaviours

Animal and human studies suggest that initial expression of maternal behaviour depends on oxytocin and dopamine systems. However, the mechanism by which these systems affect parenting behaviours and the timing of these effects are not well understood. This article explores the role of mothers' executive function in mediating the relation between oxytocin and dopamine gene variants and maternal responsiveness at 48 months post-partum. Participants (n = 157) were mothers recruited in the Maternal Adversity, Vulnerability and Neurodevelopment Study, which assesses longitudinally two cohorts of mothers and children in Canada. We examined single nucleotide polymorphisms (SNPs) related to the dopamine and oxytocin systems (DRD1 rs686, DRD1 rs265976, OXTR rs237885 and OXTR rs2254298), assessed mothers' decision-making at 48 months using the Cambridge Neurological Automated Testing Battery (CANTAB) and evaluated maternal responsiveness from videotaped interactions during the Etch-A-Sketch co-operation task. Mediation analyses showed that OXTR rs2254298 A-carriers had an indirect effect on positive parenting which was mediated by mothers' performance on decision-making task (estimate = 0.115, P < 0.005), while OXTR rs2254298 A-carriers had both direct and indirect effects on physically controlling parenting, also mediated through enhanced performance on decision-making (estimate = -0.059, P < 0.005). Dopamine SNPs were not associated with any measure of executive function or parenting (all P > 0.05). While oxytocin has previously been associated with only the early onset of maternal behaviour, we show that an OXTR polymorphism is involved in maternal behaviour at 48 months post-partum through mothers' executive function. This research highlights the importance of the oxytocin system to maternal parenting beyond infancy.

Parental Serotonin Transporter Polymorphism (5-HTTLPR) Moderates Associations of Stress and Child Behavior With Parenting Behavior

The serotonin transporter-linked polymorphic region (5-HTTLPR) is associated with caregiving in nonhuman animals and with affective and cognitive correlates of human parenting, yet its association with human parenting is largely unknown. Using a well-characterized sample of parents and offspring, we evaluated the association of parental 5-HTTLPR with observed positive and negative parenting behavior, as well as its biologically plausible moderation of child-related stress and disruptive child behavior as predictors of parenting. One hundred and sixty-two parents (86% mothers) and their 6- to 9-year-old children with and without attention-deficit/hyperactivity disorder were ascertained using multiple methods including structured interviews, rating scales, and observed parent-child interaction, yielding strong measures of key constructs. Controlling for multiple youth-level (e.g., sex, 5-HTTLPR genotype, disruptive behavior) and parent-level (e.g., demographics, depression, attention-deficit/hyperactivity disorder) factors, parents with an S allele exhibited significantly less observed positive parenting than those with the LL genotype. Significant Gene × Environment interactions were also observed: Child-related stress was negatively associated with observed parental negativity among SS/SL genotype parents but not LL genotype parents; next, observed disruptive child behavior was positively associated with parental negativity for both genotypes, but the effect was strongest in SS/SL parents. These preliminary findings suggest that parental 5-HTTLPR is uniquely associated with positive and negative parenting behavior, with more specific patterns according to child-related stress and disruptive child behavior. We consider implications for future research evaluating genetic influences on parenting as well as considerations for designing and delivering parenting-based interventions.

Genetic mechanisms of parenting

This article is part of a Special Issue "Parental Care". The complexities of parenting behavior in humans have been studied for decades. Only recently did we begin to probe the genetic and epigenetic mechanisms underlying these complexities. Much of the research in this field continues to be informed by animal studies, where genetic manipulations and invasive tools allow to peek into and directly observe the brain during the expression of maternal behavior. In humans, studies of adult twins who are parents can suggest dimensions of parenting that might be more amenable to a genetic influence. Candidate gene studies can test specific genes in association with parental behavior based on prior knowledge of those genes' function. Gene-by-environment interactions of a specific kind indicating differential susceptibility to the environment might explain why some parents are more resilient and others are more vulnerable to stressful life events. Epigenetic studies can provide the bridge often necessary to explain why some individuals behave differently from others despite common genetic influences. There is a much-needed expansion in parenting research to include not only mothers as the focus-as has been the case almost exclusively to date-but also fathers, grandparents, and other caregivers.

Parenting begets parenting: A neurobiological perspective on early adversity and the transmission of parenting styles across generations

The developing brains of young children are highly sensitive to input from their social environment. Nurturing social experience during this time promotes the acquisition of social and cognitive skills and emotional competencies. However, many young children are confronted with obstacles to healthy development, including poverty, inappropriate care, and violence, and their enhanced sensitivity to the social environment means that they are highly susceptible to these adverse childhood experiences. One source of social adversity in early life can stem from parenting that is harsh, inconsistent, non-sensitive or hostile. Parenting is considered to be the cornerstone of early socio-emotional development and an adverse parenting style is associated with adjustment problems and a higher risk of developing mood and behavioral disorders. Importantly, there is a growing literature showing that an important predictor of parenting behavior is how parents, especially mothers, were parented themselves. In this review, we examine how adversity in early-life affects mothering behavior in later-life and how these effects may be perpetuated inter-generationally. Relying on studies in humans and animal models, we consider evidence for the intergenerational transmission of mothering styles. We then describe the psychological underpinnings of mothering, including responsiveness to young, executive function and affect, as well as the physiological mediators of mothering behavior, including hormones, brain regions and neurotransmitters, and we consider how development in these relevant domains may be affected by adversity experienced in early life. Finally, we explore how genes and early experience interact to predict mothering behavior, including the involvement of epigenetic mechanisms. Understanding how adverse parenting begets adverse parenting in the next generation is critical for designing interventions aimed at preventing this intergenerational cycle of early adversity.

Genetic imaging of the association of oxytocin receptor gene (OXTR) polymorphisms with positive maternal parenting

Background: Well-validated models of maternal behavior in small-brain mammals posit a central role of oxytocin in parenting, by reducing stress and enhancing the reward value of social interactions with offspring. In contrast, human studies are only beginning to gain insights into how oxytocin modulates maternal behavior and affiliation.

Methods: To explore associations between oxytocin receptor genes and maternal parenting behavior in humans, we conducted a genetic imaging study of women selected to exhibit a wide range of observed parenting when their children were 4–6 years old.

Results: In response to child stimuli during functional magnetic resonance imaging (fMRI), hemodynamic responses in brain regions that mediate affect, reward, and social behavior were significantly correlated with observed positive parenting. Furthermore, single nucleotide polymorphisms (SNPs) (rs53576 and rs1042778) in the gene encoding the oxytocin receptor were significantly associated with both positive parenting and hemodynamic responses to child stimuli in orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and hippocampus.

Conclusions: These findings contribute to the emerging literature on the role of oxytocin in human social behavior and support the feasibility of tracing biological pathways from genes to neural regions to positive maternal parenting behaviors in humans using genetic imaging methods.

Child dopamine active transporter 1 genotype and parenting: evidence for evocative gene-environment correlations

The dopamine active transporter 1 (DAT1) gene is implicated in psychopathology risk. Although the processes by which this gene exerts its effects on risk are poorly understood, a small body of research suggests that the DAT1 gene influences early emerging negative emotionality, a marker of children's psychopathology risk. As child negative emotionality evokes negative parenting practices, the DAT1 gene may also play a role in gene-environment correlations. To test this model, children (N = 365) were genotyped for the DAT1 gene and participated in standardized parent-child interaction tasks with their primary caregiver. The DAT1 gene 9-repeat variant was associated with child negative affect expressed toward the parent during parent-child interactions, and parents of children with a 9-repeat allele exhibited more hostility and lower guidance/engagement than parents of children without a 9-repeat allele. These gene-environment associations were partially mediated by child negative affect toward the parent. The findings implicate a specific polymorphism in eliciting negative parenting, suggesting that evocative associations play a role in elevating children's risk for emotional trajectories toward psychopathology risk.

Observed positive parenting behaviors and youth genotype: evidence for gene-environment correlations and moderation by parent personality traits

Gene-environment correlations (rGE) have been demonstrated in behavioral genetic studies, but rGE have proven elusive in molecular genetic research. Significant gene-environment correlations may be difficult to detect because potential moderators could reduce correlations between measured genetic variants and the environment. Molecular genetic studies investigating moderated rGE are lacking. This study examined associations between child catechol-O-methyltransferase genotype and aspects of positive parenting (responsiveness and warmth), and whether these associations were moderated by parental personality traits (neuroticism and extraversion) among a general community sample of third, sixth, and ninth graders (N = 263) and their parents. Results showed that parent personality traits moderated the rGE association between youths' genotype and coded observations of positive parenting. Parents with low levels of neuroticism and high levels of extraversion exhibited greater sensitive responsiveness and warmth, respectively, to youth with the valine/valine genotype. Moreover, youth with this genotype exhibited lower levels of observed anger. There was no association between the catechol-O-methyltransferase genotype and parenting behaviors for parents high on neuroticism and low on extraversion. Findings highlight the importance of considering moderating variables that may influence child genetic effects on the rearing environment. Implications for developmental models of maladaptive and adaptive child outcomes, and interventions for psychopathology, are discussed within a developmental psychopathology framework.

Flexibility and adaptation of the neural substrate that supports maternal behavior in mammals

Maternal behavior is species-specific and expressed under different physiological conditions, and contexts. It is the result of neural processes that support different forms (e.g. postpartum, cycling sensitized and spontaneous maternal behavior) and modalities of mother-offspring interaction (e.g. maternal interaction with altricial/precocious young; selective/non-selective bond). To understand how the brain adapts to and regulates maternal behavior in different species, and physiological and social conditions we propose new neural models to explain different forms of maternal expression (e.g. sensitized and spontaneous maternal behavior) and the behavioral changes that occur across the postpartum period. We emphasize the changing role of the medial preoptic area in the neural circuitry that supports maternal behavior and the cortical regulation and adjustment of ongoing behavioral performance. Finally, we discuss how our accumulated knowledge about the psychobiology of mothering in animal models supports the validity of animal studies to guide our understanding of human mothering and to improve human welfare and health.

The implications of genotype-environment correlation for establishing causal processes in psychopathology

The significance of genotype-environment interplay is its focus on how causal factors, whether environmental or genetic, have their effects. It is difficult to establish causality in observational research because of the potential for reverse causation and confounding. Most environmental measures are heritable, which means that their effects on the risk for psychopathology are potentially confounded by genotype. In contrast, genetic influences on psychopathology may be mediated by their effect on environmental exposures. The existence of genetic influences on putative environmental risk factors offers both possibilities and pitfalls for research into environmental epidemiology. We use the example of parenting and its influence on childhood externalizing problems to review how genotype-environment correlations can be exploited to demonstrate causal processes in pyschopathology.

Maternal executive function, harsh parenting, and child conduct problems

BACKGROUND

Maternal executive function and household regulation both are critical aspects of optimal childrearing, but their interplay is not understood. We tested the hypotheses that (a) the link between challenging child conduct problems and harsh parenting would be strongest for mothers with poorer executive function and weakest among those with better executive function, and (b) this mechanism would be further moderated by the degree of household chaos.

METHODS

The socioeconomically diverse sample included 147 mothers of 3-to-7 year old children. Mothers completed questionnaires and a laboratory assessment of executive function.

RESULTS

Consistent with hypotheses, harsh parenting was linked with child conduct problems only among mothers with poorer executive function. This effect was particularly strong in calm, predictable environments, but was not evident in chaotic environments.

CONCLUSION

Maternal executive function is critical to minimizing harsh parenting in the context of challenging child behavior, but this self-regulation process may not operate well in chaotic environments.

DAT by perceived MC interaction on human prefrontal activity and connectivity during emotion processing

BACKGROUND

Maternal care (MC) and dopamine modulate brain activity during emotion processing in inferior frontal gyrus (IFG), striatum and amygdala. Reuptake of dopamine from the synapse is performed by the dopamine transporter (DAT), whose abundance is predicted by variation in its gene (DAT 3'VNTR; 10 > 9-repeat alleles). Here, we investigated the interaction between perceived MC and DAT 3'VNTR genotype on brain activity during processing of aversive facial emotional stimuli.

METHODS

Sixty-one healthy subjects were genotyped for DAT 3'VNTR and categorized in low and high MC individuals. They underwent functional magnetic resonance imaging while performing a task requiring gender discrimination of facial stimuli with angry, fearful or neutral expressions.

RESULTS

An interaction between facial expression, DAT genotype and MC was found in left IFG, such that low MC and homozygosity for the 10-repeat allele are associated with greater activity during processing of fearful faces. This greater activity was also inversely correlated with a measure of emotion control as scored with the Big Five Questionnaire. Moreover, MC and DAT genotype described a double dissociation on functional connectivity between IFG and amygdala.

CONCLUSION

These findings suggest that perceived early parental bonding may interact with DAT 3'VNTR genotype in modulating brain activity during emotionally relevant inputs.

Preliminary genetic imaging study of the association between estrogen receptor-α gene polymorphisms and harsh human maternal parenting

A failure of neural changes initiated by the estrogen surge in late pregnancy to reverse the valence of infant stimuli from aversive to rewarding is associated with dysfunctional maternal behavior in nonhuman mammals. Estrogen receptor-α plays the crucial role in mediating these neural effects of estrogen priming. This preliminary study examines associations between estrogen receptor-α gene polymorphisms and human maternal behavior. Two polymorphisms were associated with human negative maternal parenting. Furthermore, hemodynamic responses in functional magnetic resonance imaging to child stimuli in neural regions associated with social cognition fully mediated the association between genetic variation and negative parenting. This suggests testable hypotheses regarding a biological pathway between genetic variants and dysfunctional human maternal parenting.

Dopamine receptors D1 and D2 are related to observed maternal behavior

The dopamine pathway and especially the dopamine receptors 1 and 2 (DRD1 and DRD2) are implicated in the regulation of mothering in rats. Evidence for this in humans is lacking. Here, we show that genetic variation in both DRD1 and DRD2 genes in a sample of 187 Caucasian mothers predicts variation in distinct maternal behaviors during a 30-min mother-infant interaction at 6 months postpartum. Two DRD1 single-nucleotide polymorphisms (SNPs rs265981 and rs686) significantly associated with maternal orienting away from the infant (P = 0.002 and P = 0.003, respectively), as did DRD1 haplotypes (P = 0.03). Two DRD2 SNPs (rs1799732 and rs6277) significantly associated with maternal infant-directed vocalizing (P = 0.001 and P = 0.04, respectively), as did DRD2 haplotypes (P = 0.01). We present evidence for heterosis in DRD1 where heterozygote mothers orient away from their infants significantly less than either homozygote group. Our findings provide important evidence that genetic variation in receptors critical for mothering in non-human species also affect human maternal behaviors. The findings also highlight the importance of exploring multiple dimensions of the complex human mothering phenotype.

Parenting in adults with attention-deficit/hyperactivity disorder (ADHD)

Although the validity of adult ADHD is well established and research has identified a variety of impairments associated with the condition in adults, study of how ADHD impacts an adult's ability to parent has been relatively neglected. Parenting is a particularly important domain of functioning given the familial nature of the disorder and emerging evidence that parenting behaviors play a role in the development or maintenance of child ADHD symptoms, comorbid psychopathologies, and other associated difficulties. In this paper, we focus on three broad categories of cognitive dysfunction proposed across models of ADHD - cognitive processes (e.g., working memory, planning, and inhibitory control), self-regulation deficits (e.g., self-monitoring of performance to detect errors or the need for regulation of behavior and/or emotions), and motivational or arousal difficulties (e.g., response to incentives, delay aversion). We consider how these deficits may lead to impairments in the parenting behaviors of effective behavioral control and emotional responsiveness, and review the available evidence regarding parenting in adults with ADHD symptoms. We conclude by noting the limitations in existing studies, and argue for further research that is theoretically grounded in how core deficits of ADHD may be related to dimensions of parenting. The implications of an improved understanding of how ADHD impacts parenting for the development of early intervention or prevention programs are outlined.

Association of parental ADHD and depression with externalizing and internalizing dimensions of child psychopathology

OBJECTIVE

To study the independent association of parental depression and ADHD on three dimensions of child psychopathology among 178 children aged 5 to 10 years.

METHOD

Self-reported measures of parental depression and ADHD as well as rating scales and structure diagnostic interviews of child internalizing, ADHD, and externalizing problems were obtained.

RESULTS

Structural equation modeling indicated that parental ADHD was positively associated with a broad child problems factor after a second-order factor of child problems best accounted for the high intercorrelations among the internalizing, ADHD, and externalizing child psychopathology factors. Parental depression did not significantly predict the second-order child problems factor, but it specifically predicted the child internalizing factor.

CONCLUSION

These results suggest that parental ADHD may be a nonspecific risk factor for child psychopathology broadly, whereas parental depression may function as a specific risk factor for child internalizing problems.

Association of positive and negative parenting behavior with childhood ADHD: interactions with offspring monoamine oxidase A (MAO-A) genotype

Relatively little is known about the potential interplay between genetic and environmental influences on attention-deficit/hyperactivity disorder (ADHD), including gene-environment interaction (G×E). There is evidence that parenting behavior interacts with offspring genotype in the development of externalizing problems, but studies have largely focused on explicit maltreatment rather than differentiated measures of parenting behavior, including positive and negative parenting. We tested the interactive effects of the 30-base pair variable number tandem repeat (VNTR) polymorphism of the monoamine oxidase A gene (MAO-A) with positive and negative parenting behavior on parent- and teacher ratings of inattention and hyperactivity symptoms among 150 6-9 year-old boys with and without ADHD. Negative parenting predicted parent and teacher ratings of inattention symptoms, but only among boys with high-activity MAO-A genotype. MAO-A genotype did not moderate the association of positive parenting and parent- and teacher ratings of ADHD. We discuss the potential role of interactive exchanges between parenting behavior and child genotype in the development and persistence of ADHD and related behavior problems.

Possible genetic and epigenetic links between human inner speech, schizophrenia and altruism

Unique mental abilities have been crucial for evolutionary success of Homo sapiens and for the development of his complex social organization. However, these abilities have also become a target for mental disorders which often result in a reduced fitness and in conflicts between the individual and the conventions of society. To account for this evolutionary maladaptation, we advance a new concept: that of "mis-exaptation", derived from SJ Gould and E Vrba's concept of exaptation. Mis-exaptation is a characteristic which, although it may confer positive effects in one field of activity, may reach an inappropriate degree of specialisation to have deleterious effects in that or in another field thereby leading to a decrease in fitness of the individual. This paper considers "inner speech" as an exaptation. Although inner speech is usually a positive aid to learning and reasoning, it may also favour the emergence of mental disturbances, such as the auditory hallucinations which are characteristic of schizophrenia. There is, nevertheless, a possible evolutionary value in mis-exaptational inner speech; two traits associated with the mis-exapted state would be altruistic behaviour and heightened creativity, the latter being over-expressed in relatives of schizophrenic patients. A possible solution for the evolutionary-genetic paradox posed by altruism and schizophrenia arising from mis-exaptation will be suggested in the light of a cryptic genetic repertoire. A selection of illustrative examples of each of these mental states is presented as they appear in the pages of the European literature. This article is part of a Special Issue entitled: Brain Integration.

Investigating the genetic basis of altruism: the role of the COMT Val158Met polymorphism

Findings from twin studies yield heritability estimates of 0.50 for prosocial behaviours like empathy, cooperativeness and altruism. First molecular genetic studies underline the influence of polymorphisms located on genes coding for the receptors of the neuropeptides, oxytocin and vasopressin. However, the proportion of variance explained by these gene loci is rather low indicating that additional genetic variants must be involved. Pharmacological studies show that the dopaminergic system interacts with oxytocin and vasopressin. The present experimental study tests a dopaminergic candidate polymorphism for altruistic behaviour, the functional COMT Val158Met SNP. N = 101 healthy Caucasian subjects participated in the study. Altruism was assessed by the amount of money donated to a poor child in a developing country, after having earned money by participating in two straining computer experiments. Construct validity of the experimental data was given: the highest correlation between the amount of donations and personality was observed for cooperativeness (r = 0.32, P ≤ 0.001). Carriers of at least one Val allele donated about twice as much money as compared with those participants without a Val allele (P = 0.01). Cooperativeness and the Val allele of COMT additively explained 14.6% of the variance in donation behaviour. Results indicate that the Val allele representing strong catabolism of dopamine is related to altruism.

Monoamine transporters: vulnerable and vital doorkeepers

Transporters of dopamine, serotonin, and norepinephrine have been empirically used as medication targets for several mental illnesses in the last decades. These protein-targeted medications are effective only for subpopulations of patients with transporter-related brain disorders. Since the cDNA clonings in early 1990s, molecular studies of these transporters have revealed a wealth of information about the transporters' structure-activity relationship (SAR), neuropharmacology, cell biology, biochemistry, pharmacogenetics, and the diseases related to the human genes encoding these transporters among related regulators. Such new information creates a unique opportunity to develop transporter-specific medications based on SAR, mRNA, DNA, and perhaps transporter trafficking regulation for a number of highly relevant diseases including substance abuse, depression, schizophrenia, and Parkinson's disease.

Parent-child DRD4 genotype as a potential biomarker for oppositional, anxiety, and repetitive behaviors in children with autism spectrum disorder

The primary objective of the present study was to examine whether a combination of parent-child DRD4 genotypes results in more informative biomarkers of oppositional, separation anxiety, and repetitive behaviors in children with autism spectrum disorder (ASD). Based on prior research indicating the 7-repeat allele as a potential risk variant, participants were sorted into one of four combinations of parent-child genotypes. Owing to the possibility of parent-of-origin effects, analyses were conducted separately for mother-child (MC) and father-child (FC) dyads. Mothers completed a validated DSM-IV-referenced rating scale. Partial eta-squared (ηp(2)) was used to determine the magnitude of group differences: 0.01-0.06=small, 0.06-0.14=moderate, and >0.14=large. Analyses indicated that children in MC dyads with matched genotypes had the least (7-/7-) and most (7+/7+) severe mother-rated oppositional-defiant (ηp(2)=0.11) and separation anxiety (ηp(2)=0.19) symptoms. Conversely, youths in FC dyads with matched genotypes had the least (7-/7-) and most (7+/7+) severe obsessive-compulsive behaviors (ηp(2)=0.19) and tics (ηp(2)=0.18). Youths whose parents were both noncarriers had less severe tics than peers with at least one parental carrier, and the effect size was large (ηp(2)=0.16). There was little evidence that noncarrier children were rated more severely by mothers who were carriers versus noncarriers. Transmission Disequilibrium Test analyses provided preliminary evidence for undertransmission of the 2-repeat allele in youths with more severe tics (p=0.02). Parent genotype may be helpful in constructing prognostic biomarkers for behavioral disturbances in ASD; however, findings are tentative pending replication with larger, independent samples.