Early trauma and increased risk for physical aggression during adulthood: the moderating role of MAOA genotype

Neurobiology of Aggression-Review of Recent Findings and Relationship with Alcohol and Trauma

Aggression can be conceptualized as any behavior, physical or verbal, that involves attacking another person or animal with the intent of causing harm, pain or injury. Because of its high prevalence worldwide, aggression has remained a central clinical and public safety issue. Aggression can be caused by several risk factors, including biological and psychological, such as genetics and mental health disorders, and socioeconomic such as education, employment, financial status, and neighborhood. Research over the past few decades has also proposed a link between alcohol consumption and aggressive behaviors. Alcohol consumption can escalate aggressive behavior in humans, often leading to domestic violence or serious crimes. Converging lines of evidence have also shown that trauma and posttraumatic stress disorder (PTSD) could have a tremendous impact on behavior associated with both alcohol use problems and violence. However, although the link between trauma, alcohol, and aggression is well documented, the underlying neurobiological mechanisms and their impact on behavior have not been properly discussed. This article provides an overview of recent advances in understanding the translational neurobiological basis of aggression and its intricate links to alcoholism and trauma, focusing on behavior. It does so by shedding light from several perspectives, including in vivo imaging, genes, receptors, and neurotransmitters and their influence on human and animal behavior.

Maternal Education Potentially Moderates the MAOA uVNTR Effects on Externalizing Behavior in Black South African Children

Interactions between the MAOA uVNTR and rearing environment are suggested to influence the developmental manifestations of childhood internalizing and externalizing behavior. However, few studies in the MAOA literature have included continental African children, or focused on non-clinical samples. We explored the main and interactive effects of the MAOA uVNTR (high and low activity alleles) in Black South African male (n = 478) and female (n = 540) children who were part of the longitudinal Birth to Twenty Plus cohort. Historical data on birth weight, gestational age at delivery, socioeconomic status, and maternal education were combined with genotypic information and analyzed using regression modeling. We found no significant main effects for the MAOA uVNTR on childhood behavior in either sex. A significant interaction (p = .04) was identified between MAOA and maternal education, suggesting that externalizing behavior in boys carrying a low activity MAOA allele varied in direct proportion to the education levels of their mothers. However, the model fit failed to reach significance, possibly due to our inclusion of only non-clinical pre-pubertal males. No significant interactions were detected for female children. Our findings lend tentative credibility to the Environmental Sensitivity metaframework, which suggests that MAOA is an important plasticity factor in childhood development.

Bright side of the MAOA-uVNTR on trait and situational forgiveness

The stress-and-coping theory of forgiveness posits that forgiveness and aggression are alternative ways of coping with stress of interpersonal offences. Inspired by the link between aggression and MAOA-uVNTR (a genetic variant involving in catabolism of monoamines), we investigated the relationship between this variant and forgiveness with two studies. Study 1 examined the relationship between the MAOA-uVNTR and trait forgiveness in students, and study 2 examined the effect of this variant on third-party forgiveness in response to situational offences in male inmates. The results showed that the MAOA-H (a high activity allele) was associated with higher trait forgiveness in male students and greater third-party forgiveness to accidentally committed harm and attempted but failed harm in male inmates than the MAOA-L. These findings highlight the bright side of MAOA-uVNTR on trait and situational forgiveness.

Theorizing the Role of Dopaminergic Polymorphic Risk Alleles with Intermittent Explosive Disorder (IED), Violent/Aggressive Behavior and Addiction: Justification of Genetic Addiction Risk Severity (GARS) Testing

Scientific studies have provided evidence that there is a relationship between violent and aggressive behaviors and addictions. Genes involved with the reward system, specifically the brain reward cascade (BRC), appear to be associated with various addictions and impulsive, aggressive, and violent behaviors. In our previous research, we examined the Taq A1 allele (variant D2 dopamine receptor gene) and the DAT-40 base repeat (a variant of the dopamine transporter gene) in 11 Caucasian boys at the Brown School in San Marcus, Texas, diagnosed with intermittent explosive disorder. Thirty supernormal controls were screened to exclude several reward-deficit behaviors, including pathological violence, and genotyped for the DRD2 gene. Additionally, 91 controls were screened to exclude ADHD, pathological violence, alcoholism, drug dependence, and tobacco abuse, and their results were compared with DAT1 genotype results. In the schoolboys vs. supercontrols, there was a significant association with the D2 variant and a trend with the dopamine transporter variant. Results support our hypothesis and the involvement of at least two gene risk alleles with adolescent violent/aggressive behaviors. This study and the research presented in this paper suggest that violent/aggressive behaviors are associated with a greater risk of addiction, mediated via various genes linked to the BRC. This review provides a contributory analysis of how gene polymorphisms, especially those related to the brain reward circuitry, are associated with violent behaviors.

Interaction effects of the 5-HTT and MAOA-uVNTR gene variants on pre-attentive EEG activity in response to threatening voices

Both the serotonin transporter polymorphism (5-HTTLPR) and the monoamine oxidase A gene (MAOA-uVNTR) are considered genetic contributors for anxiety-related symptomatology and aggressive behavior. Nevertheless, an interaction between these genes and the pre-attentive processing of threatening voices -a biological marker for anxiety-related conditions- has not been assessed yet. Among the entire sample of participants in the study with valid genotyping and electroencephalographic (EEG) data (N = 140), here we show that men with low-activity MAOA-uVNTR, and who were not homozygous for the 5-HTTLPR short allele (s) (n = 11), had significantly larger fearful MMN amplitudes -as driven by significant larger ERPs to fearful stimuli- than men with high-activity MAOA-uVNTR variants (n = 20). This is in contrast with previous studies, where significantly reduced fearful MMN amplitudes, driven by increased ERPs to neutral stimuli, were observed in those homozygous for the 5-HTT s-allele. In conclusion, using genetic, neurophysiological, and behavioral measurements, this study illustrates how the intricate interaction between the 5-HTT and the MAOA-uVNTR variants have an impact on threat processing, and social cognition, in male individuals (n = 62).

Childhood Trauma, the Combination of MAO-A and COMT Genetic Polymorphisms and the Joy of Being Aggressive in Forensic Psychiatric Patients

Aggression and violent offenses are common amongst forensic psychiatric patients. Notably, research distinguishes two motivationally distinct dimension of aggression–instrumental and reactive aggression. Instrumental aggression comprises of appetitive, goal-directed aggressive acts, whereas reactive aggression consists of affective, defensive violence with both their biological basis remaining largely unknown. Childhood trauma and functional genetic polymorphisms in catecholamines converting enzymes, such as mono-amino-oxidase A (MAO-A) and catechol-o-methyltransferase (COMT) have been suggested to augment an aggressive behavioral response in adulthood. However, it warrants clarification if these factors influence one or both types of aggression. Furthermore, it remains elusive, if having a combination of unfavorable enzyme genotypes and childhood maltreatment further increases violent behavior. Hence, we set out to address these questions in the current study. First, analysis revealed an overall marginally increased frequency of the unfavorable MAO-A genotype in the test population. Second, each gene polymorphisms together with a traumatic childhood significantly increased the AFAS (Appetitive and Facilitative Aggression Scale) scores for both reactive and appetitive aggression. Third, having a combination of both disadvantageous genotypes and a negative childhood served as a minor positive predictor for increased reactive aggression, but had a strong influence on the joy of being aggressive.

Association of variable number of tandem repeats (VNTR) and T941G polymorphism of monoamine oxidase (MAO-A) gene with aggression in Pakistani subjects

Background

Human behavioral traits are known to be significantly heritable. Certain individuals have a greater tendency of negative behavioral aspects including aggression. The quest to identify tunderlying genetic causes has led to identification of a number of genetic markers, one of them is the monoamine oxidase-A (MAO-A) gene.

Objective

We aimed to genotype a variable number of tandem repeats (VNTRs) in the promoter region and a functional SNP within this gene (T941G, dbSNP ID: rs6323) in the recruited cohort of 482 subjects.

Methods

After DNA isolation, genotyping was done by PCR-RFLP and the results were confirmed by sequencing.

Results

For VNTRs, the results showed, highest frequency of 3.5 repeats in males and 4 repeats in females in the promoter region. The genotype frequencies for the SNP in cases were GG=16.3%, TG=20.6% and TT=63.1%, while in controls, the frequencies were GG=12.7%, TG=6.3%, and TT=81.0%. The allele frequencies were significantly different between cases and controls (p=0.015; OR=1.51; CI=1.085–2.102).

Conclusion

The selected VNTR and SNP appeared to be significantly associated with aggression. These VNTRs and SNP have not been studied previously in the Pakistani population, hence they represent a unique ethnic group. These results, however, would have to be replicated in larger cohorts.

From warrior genes to translational solutions: novel insights into monoamine oxidases (MAOs) and aggression

The pervasive and frequently devastating nature of aggressive behavior calls for a collective effort to understand its psychosocial and neurobiological underpinnings. Regarding the latter, diverse brain areas, neural networks, neurotransmitters, hormones, and candidate genes have been associated with antisocial and aggressive behavior in humans and animals. This review focuses on the role of monoamine oxidases (MAOs) and the genes coding for them, in the modulation of aggression. During the past 20 years, a substantial number of studies using both pharmacological and genetic approaches have linked the MAO system with aggressive and impulsive behaviors in healthy and clinical populations, including the recent discovery of MAALIN, a long noncoding RNA (lncRNA) regulating the MAO-A gene in the human brain. Here, we first provide an overview of the MAOs and their physiological functions, we then summarize recent key findings linking MAO-related enzymatic and gene activity and aggressive behavior, and, finally, we offer novel insights into the mechanisms underlying this association. Using the existing experimental evidence as a foundation, we discuss the translational implications of these findings in clinical practice and highlight what we believe are outstanding conceptual and methodological questions in the field. Ultimately, we propose that unraveling the specific role of MAO in aggression requires an integrated approach, where this question is pursued by combining psychological, radiological, and genetic/genomic assessments. The translational benefits of such an approach include the discovery of novel biomarkers of aggression and targeting the MAO system to modulate pathological aggression in clinical populations.

The role of monoamine oxidase A in the neurobiology of aggressive, antisocial, and violent behavior: A tale of mice and men

Over the past two decades, research has revealed that genetic factors shape the propensity for aggressive, antisocial, and violent behavior. The best-documented gene implicated in aggression is MAOA (Monoamine oxidase A), which encodes the key enzyme for the degradation of serotonin and catecholamines. Congenital MAOA deficiency, as well as low-activity MAOA variants, has been associated with a higher risk for antisocial behavior (ASB) and violence, particularly in males with a history of child maltreatment. Indeed, the interplay between low MAOA genetic variants and early-life adversity is the best-documented gene × environment (G × E) interaction in the pathophysiology of aggression and ASB. Additional evidence indicates that low MAOA activity in the brain is strongly associated with a higher propensity for aggression; furthermore, MAOA inhibition may be one of the primary mechanisms whereby prenatal smoke exposure increases the risk of ASB. Complementary to these lines of evidence, mouse models of Maoa deficiency and G × E interactions exhibit striking similarities with clinical phenotypes, proving to be valuable tools to investigate the neurobiological mechanisms underlying antisocial and aggressive behavior. Here, we provide a comprehensive overview of the current state of the knowledge on the involvement of MAOA in aggression, as defined by preclinical and clinical evidence. In particular, we show how the convergence of human and animal research is proving helpful to our understanding of how MAOA influences antisocial and violent behavior and how it may assist in the development of preventative and therapeutic strategies for aggressive manifestations.

Tulve N. A Systematic Review and Meta-Analysis Investigating the Relationship between Exposures to Chemical and Non-Chemical Stressors during Prenatal Development and Childhood Externalizing Behaviors

Childhood behavioral outcomes have been linked to low quality intrauterine environments caused by prenatal exposures to both chemical and non-chemical stressors. The effect(s) from the many stressors a child can be prenatally exposed to may be influenced by complex interactive relationships that are just beginning to be understood. Chemical stressors influence behavioral outcomes by affecting the monoamine oxidase A (MAOA) enzyme, which is involved in serotonin metabolism and the neuroendocrine response to stress. Non-chemical stressors, particularly those associated with violence, have been shown to influence and exacerbate the externalizing behavioral outcomes associated with low MAOA activity and slowed serotonin metabolism. The adverse developmental effects associated with high stress and maternal drug use during pregnancy are well documented. However, research examining the combined effects of other non-chemical and chemical stressors on development and childhood outcomes as a result of gestational exposures is scarce but is an expanding field. In this systematic review, we examined the extant literature to explore the interrelationships between exposures to chemical and non-chemical stressors (specifically stressful/traumatic experiences), MAOA characteristics, and childhood externalizing behaviors. We observed that exposures to chemical stressors (recreational drugs and environmental chemicals) are significantly related to externalizing behavioral outcomes in children. We also observed that existing literature examining the interactions between MAOA characteristics, exposures to chemical stressors, and traumatic experiences and their effects on behavioral outcomes is sparse. We propose that maternal stress and cortisol fluctuations during pregnancy may be an avenue to link these concepts. We recommend that future studies investigating childhood behaviors include chemical and non-chemical stressors as well as children’s inherent genetic characteristics to gain a holistic understanding of the relationship between prenatal exposures and childhood behavioral outcomes.

The relationships among MAOA, COMT Val158Met, and 5-HTTLPR polymorphisms, newborn stress reactivity, and infant temperament

INTRODUCTION

Variance in hypothalamic-pituitary-adrenal (HPA) axis reactivity is considered to be one of the sources of differences in infant temperament. The cortisol enters into interactions with dopamine and serotonin, so it is expected that polymorphisms in genes coding monoamine metabolism influence both HPA axis reactivity and temperament.

METHODS

We therefore explore the relationship among 5-HTTLPR S/L, MAOA H/L, and COMT Val158Met polymorphisms, the stress reaction of newborn infants after a heel stick blood draw (measured by determining salivary cortisol at three time points), and temperament assessed at the age of 3 months using Rothbart's Infant Behavior Questionnaire-Revised (IBQ-R) with a sample of 84 infants.

RESULTS

The decrease in the salivary cortisol correlated with nine primary scales and all three secondary scales of IBQ-R. Children with a greater cortisol decrease were assessed as less susceptible to negative emotions, more extraverted, and more regulated. The polymorphisms that were observed were related both to the course of the stress reaction and to temperament. The 5-HTTLPR S allele was connected to higher scores for Negative Emotionality and lower scores for Orienting/Regulatory Capacity. The presence of the MAOA L allele predisposed its carriers to higher scores for Negative Emotionality, lower scores for Orienting/Regulatory Capacity, and a lower decrease in cortisol. The Met allele of COMT Val158Met polymorphism was connected to a higher Positive Affectivity/Surgency and Orienting/Regulatory Capacity and a greater cortisol decrease.

CONCLUSIONS

Contrary to previous studies referring mainly basal cortisol and its increase, the results of our study emphasize the importance of cortisol elimination in infant temperament. Another interesting finding was a higher cortisol increase, higher Distress to Limitations, Negative Emotionality, and Approach in MAOA LL homozygotes which are traditionally understood as more vulnerable toward early stress in developing later externalizing behavior.

Sex-Dimorphic Interactions of MAOA Genotype and Child Maltreatment Predispose College Students to Polysubstance Use

Polysubstance use (PSU) is highly prevalent among college students. Recent evidence indicates that PSU is based on gene x environment (G×E) interactions, yet the specific biosocial factors underlying this problem remain elusive. We recently reported that lifetime use of tobacco and cannabis in college students is influenced by the interaction of the X-linked MAOA (monoamine oxidase A) gene and child maltreatment. Building on these premises, here we evaluated whether the same G×E interaction may also predict PSU in this population. Students of a large Midwestern university (n = 470; 50.9% females) took part in a computer survey for substance use, as well as childhood trauma exposure, using the Child Trauma Questionnaire (CTQ). DNA was extracted from their saliva samples and genotyped for MAOA variable-number of tandem repeat (VNTR) variants. Findings indicated that the highest number of substances were used by male students harboring low-activity MAOA alleles with a history of childhood emotional abuse. In contrast, female homozygous high-activity MAOA carriers with a history of emotional and physical abuse reported consumption of the greatest number of substances. Our results indicate that PSU among college students is influenced by the interaction of MAOA and child maltreatment in a sex-specific fashion. Further studies are warranted to understand the mechanisms of sex differences in the biosocial interplays underlying PSU in this at-risk group.

Protein-protein interactions underlying the behavioral and psychological symptoms of dementia (BPSD) and Alzheimer's disease

Alzheimer’s Disease (AD) is a devastating neurodegenerative disorder currently affecting 45 million people worldwide, ranking as the 6^th highest cause of death. Throughout the development and progression of AD, over 90% of patients display behavioral and psychological symptoms of dementia (BPSD), with some of these symptoms occurring before memory deficits and therefore serving as potential early predictors of AD-related cognitive decline. However, the biochemical links between AD and BPSD are not known. In this study, we explored the molecular interactions between AD and BPSD using protein-protein interaction (PPI) networks built from OMIM (Online Mendelian Inheritance in Man) genes that were related to AD and two distinct BPSD domains, the Affective Domain and the Hyperactivity, Impulsivity, Disinhibition, and Aggression (HIDA) Domain. Our results yielded 8 unique proteins for the Affective Domain (RHOA, GRB2, PIK3R1, HSPA4, HSP90AA1, GSK3beta, PRKCZ, and FYN), 5 unique proteins for the HIDA Domain (LRP1, EGFR, YWHAB, SUMO1, and EGR1), and 6 shared proteins between both BPSD domains (APP, UBC, ELAV1, YWHAZ, YWHAE, and SRC) and AD. These proteins might suggest specific targets and pathways that are involved in the pathogenesis of these BPSD domains in AD.

Childhood trauma as a predictor of reoffending in a Northern Irish probation sample

BACKGROUND

It is well-documented that there is a high prevalence rate of childhood trauma experiences among the prison population, and studies have found a link between childhood trauma and later acts of violence.

OBJECTIVE

The aim of the current study was to investigate whether childhood trauma (i.e., physical, sexual, emotional abuse and physical neglect) among offenders who have served a life sentence in Northern Ireland was associated with general and violent reoffending patterns. The study also explored the relationship between childhood trauma resulting from the sectarian conflict "The Troubles" in the region and its impact on reoffending.

METHOD

The casefiles of 100 offenders were coded for trauma experiences and official reoffending data was extracted. Logistic regression analysis was performed to explore the relationship between trauma and reoffending.

RESULTS

The most common form of childhood trauma were emotional abuse and/or emotional neglect (n = 43), conflict-related trauma (n = 43) and physical abuse (n = 40). Only age (OR .91) and conflict-related trauma (OR 5.57) emerged as significant predictors (p < .05) of general reoffending at any time post release. Similarly, only age (OR .92) and conflict-related trauma (OR 4.57) emerged as significant predictors (p < .05) of violent reoffending. Although it did not reach significance (p =  .09), childhood physical abuse was related to an increase in the odds of violently reoffending, of a large magnitude (OR 4.09).

CONCLUSIONS

Conflict-related trauma significantly predicted general and violent reoffending among offenders with previous violent convictions.

Parenting Interacts With Plasticity Genes in Predicting Behavioral Outcomes in Preschoolers

BACKGROUND

Public health and pediatric nurses typically focus on supporting parenting to reduce the likelihood of children's behavioral problems. Studies have identified interactions between early exposures to stress in caregiving and child genotype in predicting children's behavioral problems, such that certain genotypes connote greater differential susceptibility or plasticity to environmental stressors. We sought to uncover the interaction between observational measures of parent-child relationship quality and genotype in predicting early-onset behavioral problems in 24-month-olds, using prospective methods.

METHODS

We conducted a secondary analysis of data collected on a subsample of 176 women and their infants enrolled during pregnancy in the ongoing Alberta Pregnancy Outcomes and Nutrition (APrON) cohort study. Inclusion criteria required mothers to be ≥18 years of age, English speaking and ≤22 weeks gestational age at enrollment. Genetic data were obtained from blood leukocytes and buccal epithelial cell samples, collected from infants at three months of age. For each child, the presence of plasticity alleles was determined for BDNF, CNR1, DRD2/ANKK1, DRD4, DAT1, 5-HTTLPR, and MAOA and an overall index was calculated to summarize the number of plasticity alleles present. Observational assessments of parent-child relationship quality (sensitivity, controlling, and unresponsiveness) were conducted at six months of age. Children's internalizing (e.g., emotionally reactive, anxious/depressed, somatic complaint, withdrawn) and externalizing (e.g., aggression, inattention) behaviors were assessed at 24 months of age. After extracting genetic data, a maximum likelihood method for regressions was employed with Akaike Information Criterion (AIC) for model selection.

RESULTS

When parents were less responsive and children possessed more plasticity alleles, children were more likely to be emotionally reactive, anxious/depressed, report somatic complaints, and withdrawn, while when parents were less responsive and children possessed fewer plasticity alleles, children were less likely to display these internalizing behaviors, in a differentially susceptible manner. Furthermore, when parents were more responsive, and children possessed more plasticity alleles, children were less likely to display internalizing behaviors (P = 0.034). Similarly, children who possessed either the CNR1-A plasticity allele (P = 0.010) or DAT1 9-repeat plasticity allele (P = 0.036) and experienced more/less parental control displayed more/fewer externalizing problems, respectively, in a differentially susceptible manner.

CONCLUSIONS

The plasticity index score interacted with parental unresponsiveness in predicting anxiety and depressive behavioral problems in children, while individual genetic variants interacted with parental controlling behavior in predicting aggression and inattention in children, suggestive of differential susceptibility to caregiving. Especially in the context of nursing interventions designed to support childrearing and children's development, nurses need to be aware of the interactions between child genotype and parenting in understanding how well interventions will work in promoting optimal child behavior.

Association of MAOA genetic variants and resilience with psychosocial stress: A longitudinal study of Syrian refugees

Early childhood trauma can have profound and lifelong effects on adult mental health and psychosocial wellbeing. Nevertheless, responses to trauma are highly variable. Genetic variants may help explain variation in responses to trauma by identifying alleles that associate with changes in mental health measures. Protective factors, such as resilience, likely also play an important role in responses to trauma. The effects of genetic variants, in combination with protective factors, on psychosocial health are not well understood, particularly in non-Western contexts. In this study, we test the relative influence of genetic variants of monoamine oxidase A (MAOA, a gene proposed to influence the impact of childhood trauma on adult violence and antisocial behavior), levels of resilience, and exposure to traumatic events on psychosocial stress and mental health trajectories over time. We use data from a cohort of 12-18-year-old Syrian refugees who were forcibly displaced to neighboring Jordan (n = 399). DNA samples and survey data on trauma exposure, resilience (CYRM-12), and psychosocial stress were collected at three time points: baseline, ~13 weeks, and ~48 weeks. Using multilevel models, we identified an association of MAOA variant, in males only, with symptom scores of psychosocial stress on the Perceived Stress Scale (PSS) over time (p = 8.1 x 10⁻⁴). We also found that resilience is strongly associated with PSS (p = 7.9 x 10⁻⁹), underscoring the importance of protective factors in influencing levels of psychosocial stress. Furthermore, there was an additive effect wherein the sharpest reductions in perceived psychosocial stress are seen in low-activity MAOA males with low trauma exposure or high resilience levels. Our results highlight the value of studies that integrate genetic and psychosocial factors to better understand complex phenotypes, such as responses to trauma in contexts of high trauma exposure.

Understanding the Scientific Basis of Post-traumatic Stress Disorder (PTSD): Precision Behavioral Management Overrides Stigmatization

Post-traumatic stress disorder (PTSD) is a severe polygenic disorder triggered by environmental factors. Many polymorphic genes, particularly the genetic determinants of hypodopaminergia (low dopamine function), associate with a predisposition to PTSD as well as substance use disorder. Support from the National Institutes of Health for neuroimaging research and molecular, genetic applied technologies has improved understanding of brain reward circuitry functions that have inspired the development of new innovative approaches to their early diagnosis and treatment of some PTSD symptomatology and addiction. This review presents psychosocial and genetic evidence that vulnerability or resilience to PTSD can theoretically be impacted by dopamine regulation. From a neuroscience perspective, dopamine is widely accepted as a major neurotransmitter. Questions about how to modulate dopamine clinically in order to treat and prevent PTSD and other types of reward deficiency disorders remain. Identification of genetic variations associated with the relevant genotype-phenotype relationships can be characterized using the Genetic Addiction Risk Score (GARS®) and psychosocial tools. Development of an advanced genetic panel is under study and will be based on a new array of genes linked to PTSD. However, for now, the recommendation is that enlistees for military duty be given the opportunity to voluntarily pre-test for risk of PTSD with GARS, before exposure to environmental triggers or upon return from deployment as part of PTSD management. Dopamine homeostasis may be achieved via customization of neuronutrient supplementation "Precision Behavioral Management" (PBM™) based on GARS test values and other pro-dopamine regulation interventions like exercise, mindfulness, biosensor tracking, and meditation.

MAOA variants differ in oscillatory EEG & ECG activities in response to aggression-inducing stimuli

Among the genetic variations in the monoamine oxidase A (MAOA) gene, upstream variable number tandem repeats (uVNTRs) of the promoter have been associated with individual differences in human physiology and aggressive behaviour. However, the evidence for a molecular or neural link between MAOA uVNTRs and aggression remains ambiguous. Additionally, the use of inconsistent promoter constructs in previous studies has added to the confusion. Therefore, it is necessary to demonstrate the genetic function of MAOA uVNTR and its effects on multiple aspects of aggression. Here, we identified three MAOA alleles in Koreans: the predominant 3.5R and 4.5R alleles, as well as the rare 2.5R allele. There was a minor difference in transcriptional efficiency between the 3.5R and 4.5R alleles, with the greatest value for the 2.5R allele, in contrast to existing research. Psychological indices of aggression did not differ among MAOA genotypes. However, our electroencephalogram and electrocardiogram results obtained under aggression-related stimulation revealed oscillatory changes as novel phenotypes that vary with the MAOA genotype. In particular, we observed prominent changes in frontal γ power and heart rate in 4.5R carriers of men. Our findings provide genetic insights into MAOA function and offer a neurobiological basis for various socio-emotional mechanisms in healthy individuals.

Violence exposure in an urban city: A GxE interaction with aggressive and impulsive behaviors

BACKGROUND

Previous research has demonstrated a reciprocal relationship between community violence exposure and disruptive behavior problems among youth. No study to date, however, has explored the potential interaction between violence exposure in early adolescence and genetics.

METHODS

We explore the gene x environment interaction's impact on teacher-rated aggressive and impulsive behaviors. Violence exposure during the middle school years was assessed using self-report. Genetic data collection occurred in emerging adulthood. A polygenic score was created using findings from a conduct disorder symptomatology genome-wide association study.

RESULTS

Three longitudinal classes of teacher reported aggressive and impulsive behavior were identified. We found a significant relationship between violence exposure and class membership. There was a significant GxE interaction, such that those with below average levels of the polygenic score and who were exposed to violence were more likely to be in the moderately high aggressive and impulsive class as compared to the no to low class.

CONCLUSIONS

These findings highlight the influence of genetic risk together with violence exposure on adolescent problem behavior. Although youth may have little control over the environments in which they live, interventions can and should focus on helping all youth.

Elevated empathy in adults following childhood trauma

Traumatic events increase the risk of depression, but there is also evidence that adversity can lead to posttraumatic growth, including increased compassion and prosocial behavior. To date there is no empirical research pinpointing childhood trauma to an increase in trait empathy in adulthood. Although somewhat counter-intuitive, this might be predicted if trauma not only increases fear of future threat but also renders the individual more sensitive to suffering in others. We explored this possible link using multiple studies, self-report measures, and non-clinical samples. Results across samples and measures showed that, on average, adults who reported experiencing a traumatic event in childhood had elevated empathy levels compared to adults who did not experience a traumatic event. Further, the severity of the trauma correlated positively with various components of empathy. These findings suggest that the experience of a childhood trauma increases a person’s ability to take the perspective of another and to understand their mental and emotional states, and that this impact is long-standing. Future research needs to test if this is seen on performance measures, and how these findings extend to clinical populations.

MAOA genotype influences neural response during an inhibitory task in adolescents with conduct disorder

Conduct disorder (CD), a common psychiatric disorder in children and adolescents, is characterized by encroaching upon other rights and violations of age-appropriate social expectations repeatedly and persistently. Individuals with CD often have high aggressiveness and low inhibitory capacity. The monoamine oxidase A (MAOA) gene has long been associated with aggression. Effects of MAOA genotype on inhibitory control have been examined in general population. Several studies had revealed reduced activation in prefrontal areas, especially the anterior cingulate cortex (ACC), in low-expression MAOA (MAOA-L) allele carriers compared to high-expression MAOA (MAOA-H) allele carriers. However, little is known about its genetic risk influences on inhibitory processes in clinical samples. In this study, functional magnetic resonance imaging (fMRI) was administered to a sample of adolescent boys with CD during the performance of a GoStop task, 29 of whom carrying MAOA-L allele and 24 carrying MAOA-H allele. Relative to MAOA-H carriers, MAOA-L carriers in CD showed more pronounced deactivation in the precuneus, supplementary motor area (SMA) and dorsal anterior cingulate cortex (dACC). Deactivation within the default mode network (DMN) and inhibitory-related areas in MAOA-L carriers may be related to compensation for low sensitivity to inhibition and/or an atypical allocation of cognitive resources. The results suggested a possible neural mechanism through which MAOA affects inhibitory processes in a clinical sample.

Preliminary Effectiveness Study of Coping Power Program for Aggressive Children in Pakistan

Aggression is a characteristic feature of many psychiatric disorders. To address the scarceness for evidence-based interventions for behavioral problems in Pakistan, we evaluated the effectiveness of culturally adapted version of Coping Power Program. The purpose of the study was to determine the extent to which Coping Power Program is capable of reducing aggressive behavior and improving competent behavior, when delivered in a different culture, i.e., Pakistan. With randomized control trial (RCT) of pre- and post-testing, 112 fourth grade boys were allocated to Coping Power intervention condition and waitlist control condition. The intervention group showed significant reduction in aggression at post assessment, in comparison to control group. Boys who received Coping Power intervention also showed improvements in behavior, social skills, and social cognitive processes, with better anger control and problem solving strategies, in comparison to the control group. The results of the study provide preliminary evidence, supporting the effectiveness of Coping Power Program for Pakistani children. Despite its limitations, the results of this study are promising and suggest that Coping Power is an effective intervention to reduce behavioral problems and promote healthy and positive behaviors in children, even when implemented in different contexts with greater potential for violence exposure.

Tobacco and cannabis use in college students are predicted by sex-dimorphic interactions between MAOA genotype and child abuse

BACKGROUND

Postsecondary students in Western countries exhibit a high prevalence of cannabis and tobacco use disorders. The etiology of these problems is contributed by several psychosocial factors, including childhood adversity and trauma; however, the mechanisms whereby these environmental determinants predispose to the use of these substances remain elusive, due to our poor knowledge of genetic and biological moderators. Converging evidence points to the monoamine oxidase A (MAOA) gene as a moderator of the effects of lifetime stress on the initiation of substance use.

AIMS

Building on these premises, in this study, we analyzed whether MAOA upstream variable number tandem repeat (uVNTR) alleles interact with child maltreatment history to predict for lifetime cannabis and tobacco consumption.

MATERIALS AND METHODS

Five hundred college students (age: 18-25 years) from a large Midwestern University were surveyed for their child maltreatment history (encompassing emotional, physical, and sexual abuse, as well as emotional and physical neglect) and lifetime consumption of cannabis and tobacco. Saliva samples were obtained to determine the MAOA uVNTR genotype of each participant.

RESULTS

In female students, lifetime tobacco and cannabis use was predicted by the interaction of physical and emotional abuse with high-activity MAOA allelic variants; conversely, in males, the interaction of low-activity MAOA alleles and physical abuse was associated with lifetime use of tobacco, but not cannabis.

DISCUSSION

These findings collectively suggest that the vulnerability to smoke tobacco and cannabis is predicted by sex-dimorphic interactions of MAOA gene with childhood abuse.

CONCLUSION

These biosocial underpinnings of tobacco and cannabis use may prove important in the development of novel personalized preventive strategies for substance use disorders in adolescents.

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

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

The Regulation of Monoamine Oxidase A Gene Expression by Distinct Variable Number Tandem Repeats

The monoamine oxidase A (MAOA) uVNTR (upstream variable number tandem repeat) is one of the most often cited examples of a gene by environment interaction (GxE) in relation to behavioral traits. However, MAOA possesses a second VNTR, 500 bp upstream of the uVNTR, which is termed d- or distal VNTR. Furthermore, genomic analysis indicates that there are a minimum of two transcriptional start sites (TSSs) for MAOA, one of which encompasses the uVNTR within the 5' untranslated region of one of the isoforms. Through expression analysis in semi-haploid HAP1 cell lines genetically engineered in order to knockout (KO) either the uVNTR, dVNTR, or both VNTRs, we assessed the effect of the two MAOA VNTRs, either alone or in combination, on gene expression directed from the different TSSs. Complementing our functional analysis, we determined the haplotype variation of these VNTRs in the general population. The expression of the two MAOA isoforms was differentially modulated by the two VNTRs located in the promoter region. The most extensively studied uVNTR, previously considered a positive regulator of the MAOA gene, did not modulate the expression of what it is considered the canonical isoform, while we found that the dVNTR positively regulated this isoform in our model. In contrast, both the uVNTR and the dVNTR were found to act as negative regulators of the second less abundant MAOA isoform. The haplotype analysis for these two VNTRs demonstrated a bias against the presence of one of the potential variants. The uVNTR and dVNTR differentially affect expression of distinct MAOA isoforms, and thus, their combined profiling offers new insights into gene-regulation, GxE interaction, and ultimately MAOA-driven behavior.

Early-life adversity and long-term neurobehavioral outcomes: epigenome as a bridge?

Accumulating evidence suggests that adversities at critical periods in early life, both pre- and postnatal, can lead to neuroendocrine perturbations, including hypothalamic-pituitary-adrenal axis dysregulation and inflammation persisting up to adulthood. This process, commonly referred to as biological embedding, may cause abnormal cognitive and behavioral functioning, including impaired learning, memory, and depressive- and anxiety-like behaviors, as well as neuropsychiatric outcomes in later life. Currently, the regulation of gene activity by epigenetic mechanisms is suggested to be a key player in mediating the link between adverse early-life events and adult neurobehavioral outcomes. Role of particular genes, including those encoding glucocorticoid receptor, brain-derived neurotrophic factor, as well as arginine vasopressin and corticotropin-releasing factor, has been demonstrated in triggering early adversity-associated pathological conditions. This review is focused on the results from human studies highlighting the causal role of epigenetic mechanisms in mediating the link between the adversity during early development, from prenatal stages through infancy, and adult neuropsychiatric outcomes. The modulation of epigenetic pathways involved in biological embedding may provide promising direction toward novel therapeutic strategies against neurological and cognitive dysfunctions in adult life.

Sex differences modulating serotonergic polymorphisms implicated in the mechanistic pathways of risk for depression and related disorders

Despite consistent observations of sex differences in depression and related emotional disorders, we do not yet know how these sex differences modulate the effects of genetic polymorphisms implicated in risk for these disorders. This Mini-Review focuses on genetic polymorphisms of the serotonergic system to illustrate how sex differences might modulate the neurobiological pathways involved in the development of depression. We consider the interacting role of environmental factors such as early-life stress. Given limited current knowledge about this topic, we highlight methodological considerations, challenges, and guidelines for future research. © 2016 Wiley Periodicals, Inc.

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.

The interaction between monoamine oxidase A and punitive discipline in the development of antisocial behavior: Mediation by maladaptive social information processing

Previous studies demonstrate that boys' monoamine oxidase A (MAOA) genotype interacts with adverse rearing environments in early childhood, including punitive discipline, to predict later antisocial behavior. Yet the mechanisms by which MAOA and punitive parenting interact during childhood to amplify risk for antisocial behavior are not well understood. In the present study, hostile attributional bias and aggressive response generation during middle childhood, salient aspects of maladaptive social information processing, were tested as possible mediators of this relation in a sample of 187 low-income men followed prospectively from infancy into early adulthood. Given racial-ethnic variation in MAOA allele frequencies, analyses were conducted separately by race. In both African American and Caucasian men, those with the low-activity MAOA allele who experienced more punitive discipline at age 1.5 generated more aggressive responses to perceived threat at age 10 relative to men with the high-activity variant. In the African American subsample only, formal mediation analyses indicated a marginally significant indirect effect of maternal punitiveness on adult arrest records via aggressive response generation in middle childhood. The findings suggest that maladaptive social information processing may be an important mechanism underlying the association between MAOA × Parenting interactions and antisocial behavior in early adulthood. The present study extends previous work in the field by demonstrating that MAOA and harsh parenting assessed in early childhood interact to not only predict antisocial behavior in early adulthood, but also predict social information processing, a well-established social-cognitive correlate of antisocial behavior.

The relationship between childhood trauma, emotion recognition, and irritability in schizophrenia patients

This study investigated the relationship between childhood trauma, irritability, and emotion recognition, in schizophrenia patients during a psychotic break. Thirty-six schizophrenia inpatients and 36 healthy controls were assessed with the Irritability Questionnaire (IRQ) and two facial emotion recognition tasks, the Emotion Discrimination Test (EDT) and Emotion Identification Test (EIT). Patients were further assessed with the Structured Clinical Interview for DSM III-R Axis II Disorders (SCID-II), the Positive and Negative Symptom Scale (PANSS), and the Childhood Trauma Questionnaire-28 (CTQ-28). EDT and EIT performance was significantly impaired in patients compared to healthy controls. Furthermore, patients tended to misidentify sad, surprised, or angry faces as showing fear, and this misidentification correlated with the patients' irritability. Childhood adversity increased irritability both directly and indirectly through emotion misidentification.

Maoa and Maob polymorphisms and personality traits in suicide attempters and healthy controls: a preliminary study

Serotonergic neurotransmission dysfunctions have been well documented in patients with suicidal behaviour. We investigated monoamine oxidase A (MAOA: rs2064070, rs6323, rs909525) and B (MAOB: rs1799836, rs2311013, rs2205655) genetic modulation of personality traits (Temperament and Character Inventory, TCI) as endophenotype for suicidal behaviour. 108 suicide attempters and 286 healthy controls of German origin were screened. Among females, allelic analyses revealed associations between MAOA rs6323 A allele and higher Harm Avoidance in suicide attempters and MAOB rs2205655 A allele and higher Cooperativeness scores in healthy controls. Among males, MAOA rs909525 A allele was associated with higher Reward Dependence in suicide attempters. Multivariate analyses controlling for age and educational level mainly confirmed results. Case-control analyses in this subsample do not differ from our previously reported one. Despite of the small sample size, a possible involvement of these genes in the modulation of personality traits closely related to suicidal behaviour cannot be excluded.

Bipolar Disorder and Early Emotional Trauma: A Critical Literature Review on Indicators of Prevalence Rates and Clinical Outcomes

LEARNING OBJECTIVES

After participating in this activity, learners should be better able to:• Evaluate the prevalence of early emotional trauma in patients with bipolar disorder (BD)• Assess the impact of these traumas on patients and on their development of BD OBJECTIVES: We performed a systematic literature review to (1) evaluate the prevalence of early emotional trauma (EET) in patients with bipolar disorder (BD) and the impact of these traumas on the development of the disorder, and (2) integrate the findings of our review with those previously reported by Fisher and Hosang, Daruy-Filho and colleagues, and Maniglio.

METHODS

The literature search was performed on PubMed, SciELO, and PsycINFO databases using the keywords bipolar disorder, early trauma, physical abuse, emotional abuse, sexual abuse, maltreatment, adversity, and neglect.

RESULTS

Twenty-eight articles were selected and analyzed. Taken together, the articles described a high prevalence of EET in BD, consisting mainly of emotional neglect/abuse (approximately 40%), particularly when compared to healthy subjects. The review also identified substantial evidence regarding an association between the presence of EET, early disease onset, rapid cycling, comorbidity with anxiety/stress disorders, and cannabis use.

CONCLUSION

The integration of the current findings with the identified studies reveals that (1) the methodological limitations noted by Daruy-Filho and colleagues have been largely resolved in more recent studies and (2) the presence of EET in patients with BD is associated with worse clinical outcomes, particularly early disease onset, presence of clinical or psychiatric comorbidities, suicide, and presence of psychotic episodes/symptoms. The review shows that patients with BD experience more traumatic situations than controls and that emotional trauma is the most frequent type of trauma in this group.

The forensic use of behavioral genetics in criminal proceedings: Case of the MAOA-L genotype

The role of behavioral genetic evidence in excusing and mitigating criminal behavior is unclear. Research has suggested that a low activity genotype of the enzyme monoamine oxidase (MAOA-L) may increase the risk for aggressive and antisocial behavior. By examining criminal proceedings in which MAOA-L genotype evidence was introduced, we explored the forensic uses of behavioral genetic science. Westlaw and LexisNexis legal databases were electronically searched for cases from 1995 to 2016 to identify court documents from cases involving the MAOA-L genotype. Evidence of the MAOA-L genotype was included in records from 11 criminal cases (9 U.S. and 2 Italian). In the guilt phase, genotype evidence was ruled admissible in one of two cases, and may have contributed to a conviction on a lesser charge. In the sentencing phase, genotype evidence was admissible in four of five cases, one of which ended with a lesser sentence. Five cases used genotype evidence for post-conviction appeals, two of which resulted in sentence reductions. Even when charges or sentences are reduced it is difficult to gauge the effect of evidence of the MAOA-L genotype. Genotype evidence may lack persuasive effect because the impact of the allele on a particular accused is difficult to establish.

Neuroanatomical Abnormalities in Violent Individuals with and without a Diagnosis of Schizophrenia

Several structural brain abnormalities have been associated with aggression in patients with schizophrenia. However, little is known about shared and distinct abnormalities underlying aggression in these subjects and non-psychotic violent individuals. We applied a region-of-interest volumetric analysis of the amygdala, hippocampus, and thalamus bilaterally, as well as whole brain and ventricular volumes to investigate violent (n = 37) and non-violent chronic patients (n = 26) with schizophrenia, non-psychotic violent (n = 24) as well as healthy control subjects (n = 24). Shared and distinct volumetric abnormalities were probed by analysis of variance with the factors violence (non-violent versus violent) and diagnosis (non-psychotic versus psychotic), adjusted for substance abuse, age, academic achievement and negative psychotic symptoms. Patients showed elevated vCSF volume, smaller left hippocampus and smaller left thalamus volumes. This was particularly the case for non-violent individuals diagnosed with schizophrenia. Furthermore, patients had reduction in right thalamus size. With regard to left amygdala, we found an interaction between violence and diagnosis. More specifically, we report a double dissociation with smaller amygdala size linked to violence in non-psychotic individuals, while for psychotic patients smaller size was linked to non-violence. Importantly, the double dissociation appeared to be mostly driven by substance abuse. Overall, we found widespread morphometric abnormalities in subcortical regions in schizophrenia. No evidence for shared volumetric abnormalities in individuals with a history of violence was found. Finally, left amygdala abnormalities in non-psychotic violent individuals were largely accounted for by substance abuse. This might be an indication that the association between amygdala reduction and violence is mediated by substance abuse. Our results indicate the importance of structural abnormalities in aggressive individuals.

The role of monoamine oxidase A in aggression: Current translational developments and future challenges

Drawing upon the recent resurgence of biological criminology, several studies have highlighted a critical role for genetic factors in the ontogeny of antisocial and violent conduct. In particular, converging lines of evidence have documented that these maladaptive manifestations of aggression are influenced by monoamine oxidase A (MAOA), the enzyme that catalyzes the degradation of brain serotonin, norepinephrine and dopamine. The interest on the link between MAOA and aggression was originally sparked by Han Brunner's discovery of a syndrome characterized by marked antisocial behaviors in male carriers of a nonsense mutation of this gene. Subsequent studies showed that MAOA allelic variants associated with low enzyme activity moderate the impact of early-life maltreatment on aggression propensity. In spite of overwhelming evidence pointing to the relationship between MAOA and aggression, the neurobiological substrates of this link remain surprisingly elusive; very little is also known about the interventions that may reduce the severity of pathological aggression in genetically predisposed subjects. Animal models offer a unique experimental tool to investigate these issues; in particular, several lines of transgenic mice harboring total or partial loss-of-function Maoa mutations have been shown to recapitulate numerous psychological and neurofunctional endophenotypes observed in humans. This review summarizes the current knowledge on the link between MAOA and aggression; in particular, we will emphasize how an integrated translational strategy coordinating clinical and preclinical research may prove critical to elucidate important aspects of the pathophysiology of aggression, and identify potential targets for its diagnosis, prevention and treatment.

The neurobiological basis of human aggression: A review on genetic and epigenetic mechanisms

Aggression is an evolutionary conserved behavior present in most species including humans. Inadequate aggression can lead to long-term detrimental personal and societal effects. Here, we differentiate between proactive and reactive forms of aggression and review the genetic determinants of it. Heritability estimates of aggression in general vary between studies due to differing assessment instruments for aggressive behavior (AB) as well as age and gender of study participants. In addition, especially non-shared environmental factors shape AB. Current hypotheses suggest that environmental effects such as early life stress or chronic psychosocial risk factors (e.g., maltreatment) and variation in genes related to neuroendocrine, dopaminergic as well as serotonergic systems increase the risk to develop AB. In this review, we summarize the current knowledge of the genetics of human aggression based on twin studies, genetic association studies, animal models, and epigenetic analyses with the aim to differentiate between mechanisms associated with proactive or reactive aggression. We hypothesize that from a genetic perspective, the aminergic systems are likely to regulate both reactive and proactive aggression, whereas the endocrine pathways seem to be more involved in regulation of reactive aggression through modulation of impulsivity. Epigenetic studies on aggression have associated non-genetic risk factors with modifications of the stress response and the immune system. Finally, we point to the urgent need for further genome-wide analyses and the integration of genetic and epigenetic information to understand individual differences in reactive and proactive AB. © 2015 Wiley Periodicals, Inc.

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.

Interacting effect of MAOA genotype and maternal prenatal smoking on aggressive behavior in young adulthood

Findings on the etiology of aggressive behavior have provided evidence for an effect both of genetic factors, such as variation in the monoamine oxidase A (MAOA) gene, and adverse environmental factors. Recent studies have supported the existence of gene × environment interactions, with early experiences playing a key role. In the present study, the effects of prenatal nicotine exposure, MAOA genotype and their interaction on aggressive behavior during young adulthood were examined. In a sample of 272 young adults (129 males, 143 females) from an epidemiological cohort study, smoking during pregnancy was measured with a standardized parent interview at the offspring's age of 3 months. Aggressive behavior was assessed between the ages of 19 and 25 years using the Young Adult Self-Report. DNA was genotyped for the MAOA 5' untranslated region variable number of tandem repeats polymorphism (VNTR). Results revealed a significant interaction between MAOA and smoking during pregnancy, indicating higher levels of aggressive behavior in young adults carrying the MAOA low-expressing genotype who had experienced prenatal nicotine exposure (n = 8, p = .025). In contrast, in carriers of the MAOA high-expressing genotype, maternal smoking during pregnancy had no effect on aggressive behavior during young adulthood (n = 20, p = .145). This study extends earlier findings demonstrating an interaction between MAOA genotype and prenatal nicotine exposure on aggressive behavior into young adulthood. The results point to the long-term adverse effects of smoking during pregnancy on the offspring's mental health, possibly underlining the importance of smoking cessation during pregnancy. According to the nature of the study (particularly sample size and power), analyses are exploratory and results need to be interpreted cautiously.

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.

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

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

Monoamine oxidase A polymorphism moderates stability of attention problems and susceptibility to life stress during adolescence

Attention problems affect a substantial number of children and adolescents and are predictive of academic underachievement and lower global adaptive functioning. Considerable variability has been observed with regard to the individual development of attention problems over time. In particular, the period of adolescence is characterized by substantial maturation of executive functioning including attentional processing, with the influence of genetic and environmental factors on individual trajectories not yet well understood. In the present investigation, we evaluated whether the monoamine oxidase A functional promoter polymorphism, MAOA-LPR, plays a role in determining continuity of parent-rated attention problems during adolescence. At the same time, a potential effect of severe life events (SLEs) was taken into account. A multi-group path analysis was used in a sample of 234 adolescents (149 males, 85 females) who took part in an epidemiological cohort study at the ages of 11 and 15 years. Attention problems during early adolescence were found to be a strong predictor of attention problems in middle adolescence. However, in carriers of the MAOA-LPR low-activity variant (MAOA-L), stability was found to be significantly higher than in carriers of the high-activity variant (MAOA-H). Additionally, only in MAOA-L carriers did SLEs during adolescence significantly impact on attention problems at the age of 15 years, implying a possible gene × environment interaction. To conclude, we found evidence that attention problems during adolescence in carriers of the MAOA-L allele are particularly stable and malleable to life stressors. The present results underline the usefulness of applying a more dynamic GxE perspective.

MAOA-VNTR polymorphism modulates context-dependent dopamine release and aggressive behavior in males

A recent [(18)F]FDOPA-PET study reports negative correlations between dopamine synthesis rates and aggressive behavior. Since dopamine is among the substrates for monoamine oxidase A (MAOA), this investigation examines whether functional allelic variants of the MAOA tandem repeat (VNTR) promotor polymorphism, which is known to modulate aggressive behavior, influences dopamine release and aggression in response to violent visual stimuli. We selected from a genetic prescreening sample, strictly case-matched groups of 2×12 healthy male subjects with VNTRs predictive of high (MAOA-High) and low (MAOA-Low) MAOA expression. Subjects underwent pairs of PET sessions (dopamine D2/3 ligand [(18)F]DMFP) while viewing a movie of neutral content, versus violent content. Directly afterwards, aggressive behavior was assessed by the Point Subtraction Aggression Paradigm (PSAP). Finally, PET data of 23 participants and behavioral data of 22 participants were analyzed due to post hoc exclusion criteria. In the genetic prescreening sample MAOA-Low carriers had significantly increased scores on the Buss-Perry Aggression Questionnaire. In the PET-study-group, aggressive behavior under the emotional neutral condition was significantly higher in the MAOA-Low group. Interestingly, the two MAOA-groups showed inverse dopaminergic and behavioral reactions to the violent movie: The MAOA-High group showed higher dopamine release and increased aggression after the violent movie; MAOA-Low subjects showed decreases in aggressive behavior and no consistent dopamine release. These results indicate a possible impact of the MAOA-promotor polymorphism on the neurobiological modulation of aggressive behavior. However, the data do not support approaches stating that MAOA-Low fosters aggression by a simple pro-dopaminergic mechanism.

Are there associations between early emotional trauma and anxiety disorders? Evidence from a systematic literature review and meta-analysis

BACKGROUND

Previous studies indicate a possible association between early emotional trauma (EET) and the development of anxiety disorders (ADs) in adult life. However, no previous studies have compiled the findings of such studies and analyzed their statistical significance. Therefore, the objective of this study was to conduct a systematic literature review and meta-analysis to determine possible associations between EET and three ADs (panic, generalized anxiety, and social anxiety disorders).

METHODS

A systematic search was conducted in PubMed, PsycInfo, and Scielo with no publication date limitations. A total of 2127 studies were found, 32 studies of which were selected for the systematic review and 13 studies of which were selected for the meta-analysis.

RESULTS

High prevalence rates of different EETs were observed among the individuals with ADs (median: 18%-45%). The results of the meta-analysis indicated that individuals with EETs were 1.9- to 3.6-fold more likely to develop ADs compared with a control group of healthy individuals. Emotional traumas were the main risk factor for social anxiety disorder. However, no specific associations were found for the other ADs.

CONCLUSIONS

EET is a risk factor for ADs, underscoring the importance of preventive measures to combat the development of these disorders. Moreover, the identification of EETs among patients with ADs is essential for implementing remedial measures to minimize the impact and damage arising from this association by decreasing the risk and severity of symptoms and to improve the response rate to treatment of ADs.

Lifetime trauma victimization and PTSD in relation to psychopathy and antisocial personality disorder in a sample of incarcerated women and men

Purpose

– Antisocial personality disorder (ASPD) and psychopathy are similar, but distinct, psychiatric conditions that are common in male and female inmates; a segment of the population with high rates of trauma exposure. It is unclear whether specific types of lifetime trauma are associated with ASPD and psychopathy in incarcerated women and men. Furthermore, the unique roles of post-traumatic stress disorder (PTSD) symptom severity and trauma victimization in antisocial personality disturbance are not well-understood. The paper aims to discuss these issues.

Design/methodology/approach

– This study investigated associations between trauma variables (different kinds of traumatic experiences and PTSD) and antisocial personality variables (ASPD and psychopathy) in a sample of incarcerated women and men who participated in a randomized clinical trial for major depressive disorder. In total, 88 incarcerated men and women were assessed for ASPD diagnosis, psychopathy severity, PTSD symptom severity, and history of physical, sexual, and crime-related trauma. Regression analyses predicted ASPD or psychopathy from trauma variables, controlling for gender.

Findings

– Physical trauma was the only form of trauma that was significantly related to psychopathy. Physical trauma and crime-related trauma were associated with ASPD. PTSD symptom severity was not associated with psychopathy or ASPD.

Originality/value

– There are associations between some kinds of lifetime trauma exposure and current ASPD/psychopathy in the target sample, but these associations do not appear to be mediated through current PTSD symptoms.