Neural correlates of proactive and reactive aggression in adolescent twins

Cortical volume alterations in the limbic network in adolescents with high reactive aggression

Previous studies show aggression-related structural alterations in frontal and limbic brain regions. Most studies have focused on overall aggression, instead of its subtypes, and on specific regions instead of networks. This study aims to identify both brain networks and regions that are associated with reactive and proactive subtypes of aggression. Structural MRI data were collected from 340 adolescents (125 F/215 M) with a mean age of 16.29 (SD = 1.20). Aggression symptomology was indexed via the Reactive Proactive Aggression Questionnaire (RPQ). Freesurfer was used to estimate Cortical Volume (CV) from seven networks and regions within specific networks associated with aggression. Two multivariate analyses of covariance (MANCOVAs) were conducted on groups for low versus higher reactive and proactive RPQ scores. Our reactive aggression MANCOVA showed a main effect in CV [F(14,321) = 1.935, p = 0.022,ηp2 = 0.078] across all the 7-Networks. Unpacking this main effect revealed significant volumetric differences in the right Limbic Network (LN) (p = 0.029) and the Temporal Pole (p = 0.011), where adolescents in the higher reactive aggression group showed higher cortical volumes. Such findings are consistent with region/voxel-specific analyses that have associated atypical structure within the LN and reactive aggression. Moreover, the temporal pole is highly interconnected with regions important in the regulation and initiation of reactive aggression.

Brain-based gene expression and corresponding behavioural relevance of risk genes for broad antisocial behaviour

Antisocial behaviour (ASB) involves persistent irresponsible, delinquent activities violating rights and safety of others. A meta-analysis of genome-wide association studies revealed significant genetic associations with ASB, yet their brain expression patterns and behavioural relevance remain unclear. Our investigation of fifteen genes associated with ASB examined their biological role and distribution across tissues, integrating post-mortem brain sample data from the Allen-Human-Brain Atlas and the Genotype-Tissue Expression project. We found that these genes were differentially expressed in the brain, particularly in regions like the cerebellum, putamen, and caudate, and were notably downregulated in the pancreas. Single cell type expression analysis revealed that ASB-associated genes had strong correlations with ductal and endothelial cells in the pancreas, indicating a possible metabolic influence on ASB. Certain genes like NTN1, SMAD5, NCAM2, and CDC42EP3 displayed specificity for cognitive terms including chronic pain, heart rate, and aphasia. These expression patterns aligned with neurocognitive domains related to thinking, and learning, distress, motor skills, as determined by fMRI analysis. This study connects specific brain gene expression with potential genetic and metabolic factors in ASB, offering novel insights into its biological basis and possible interdisciplinary approaches to understanding and addressing aggressive behaviours.

Examining Narcissistic Traits in Relation To Reactive and Proactive Aggression in Children At-Risk for Attention Deficit/Hyperactivity Disorder

The current study examined narcissistic traits in relation to proactive and reactive functions of aggression in a sample of children at-risk for attention-deficit/hyperactivity disorder (ADHD). Children ages 7-13 years (N = 110) were recruited from a pediatric ADHD assessment clinic. Caregivers completed the Antisocial Process Screening Device. Caregivers and teachers completed a measure of proactive and reactive aggression. In regression analyses controlling for ADHD and oppositional defiant disorder symptom severity and sex, narcissism was uniquely associated with higher caregiver-reported proactive aggression but not reactive aggression. Findings suggest that narcissism is uniquely related to proactive aggression in children at-risk for ADHD. Consideration of narcissistic traits may aid the prediction of behavioral issues and aggression in children and may be a potential intervention target. Future research should investigate if clinical interventions addressing narcissistic behaviors are effective for reducing proactive aggression in children.

Is Being Male a Marker of Aggression? Evidence for the Decoupling of Sex and Gender Role Orientation

OBJECTIVES

This study explores whether sex differences in reactive aggression (RA) and proactive aggression (PA) are attributable to sex, gender role orientation, or their interaction and explores the neuroanatomical characteristics of these sex differences.

METHODS

In a sample of 108 males and 126 females, we examined the sex-by-gender role orientation interaction on RA, PA, and brain gray matter volume (GMV). Then, we explored the relationship between aggression and regional GMV.

RESULTS

When the effects of sex and gender role orientation on aggression were disentangled, there were no sex differences in RA, regardless of gender role orientation. However, sex differences (male > female) in PA were observed within the masculine group but not within the feminine group. Brain imaging results revealed sex differences (male > female) on the right inferior frontal gyrus GMV, a region involved in cognitive control, within the masculine group. Moreover, a negative association between PA and the right inferior frontal gyrus GMV was observed in masculine females rather than masculine males.

CONCLUSIONS

These findings indicate that gender role orientation has a more significant effect on aggression than sex, particularly with regard to PA, and hint that the goal of cognitive control involved in displaying PA differs in masculine males and masculine females.

Relationships between Grey Matter Volume in the Bilateral Superior Frontal Gyrus and Reactive Aggression Varied by Level of Traditional Masculinity

Although previous behavioral studies have associated reactive aggression (RA) and proactive aggression (PA) with traditional masculinity, further investigation is needed into the traditional masculinity-linked neuroanatomical characteristics of RA and PA. This study analyzed the traditional masculinity-by-aggression interaction in 705 participants (350 men) by measuring grey matter volume (GMV). We have expanded on previous studies and found that traditional masculinity was not associated with RA and PA when not controlled for traditional femininity. However, the association appeared when controlling for it. Furthermore, we found significant traditional masculinity-by-RA interactions on the GMV in the bilateral superior frontal gyrus, a region known to be involved in cognitive control. When traditional masculinity scores were 1 standard deviation above the mean, there was a positive correlation between RA and the GMV in the bilateral superior frontal gyrus. Conversely, when traditional masculinity scores were 1 standard deviation below the mean, there was a negative correlation between RA and the GMV in the region. However, no traditional masculinity-linked neuroanatomical characteristics of PA were found. The results indicated that individuals with high/low traditional masculinity perceived RA as a different outcome (gain or loss) of self-control. The results supported an opportunity to develop prevention or intervention strategies for RA.

The neurofunctional basis of human aggression varies by levels of femininity

Aggression can be categorized into reactive aggression (RA) and proactive aggression (PA) based on their underlying motivations. However, previous research has rarely identified the relationship between femininity and RA/PA, and there is a lack of understanding regarding the femininity-related neurofunctional basis of these aggressive behaviors. Thus, this study first examined the relationships between femininity and aggression, then explored the aggression-by-femininity interactions on the fractional amplitude of low-frequency fluctuations using resting-state fMRI among 705 university participants (mean age = 19.14 ± 0.99). The behavioral data indicated that femininity was more negatively associated with RA and PA when masculinity was controlled for. Additionally, the neural data revealed that femininity-specific relationships of RA in the left middle occipital gyrus (i.e. individuals with low femininity had positive relationships between RA and the left middle occipital gyrus, whereas those with high femininity had negative relationships) as well as of PA in the left middle frontal gyrus (i.e. individuals with high femininity showed significant negative relationships, whereas those with low femininity did not exhibit significant relationships). These findings reflect that individuals with varying levels of femininity exhibit distinct neural bases when expressing different subtypes of aggression, which are associated with societal expectations of gender.

Self-esteem and cortical thickness correlate with aggression in healthy children: A surface-based analysis

Aggressive behavior can have serious physical, psychological, and social consequences. However, little is known about the personality and neurological antecedents underlying aggressive behavior in children. The objective of this study was to investigate the relationship between self-esteem, aggression, and brain structure (i.e., cortical thickness and surface area) in a population of healthy children (N = 78; 9-12 years; mean age: 9.95 ± 0.90 years). The results revealed that self-esteem showed a negative association with aggression and significantly predicted aggressive behavior. No gender differences were found in aggression and its neural correlates. We performed the cortical parcellation method to further explore the neural foundations underlying the association of self-esteem with aggression. Children with higher aggression had increased cortical thickness in four clusters after multiple comparison correction: right medial orbitofrontal cortex, right lateral orbitofrontal cortex, right superior frontal gyrus, and left insula. In a mediation analysis, cortical thickness in the right medial orbitofrontal cortex contributed to the effect of self-esteem on aggression. These findings extend our understanding of morphological correlates of aggression in children, suggesting that an increased cortical thickness in childhood is a potential mechanism linking low self-esteem to aggression.

Prefrontal cortex structural and developmental associations with callous-unemotional traits and aggression

Youths with high levels of callous-unemotional (CU) traits and aggression are at an increased risk for developing antisocial behaviours into adulthood. In this population, neurostructural grey matter abnormalities have been observed in the prefrontal cortex. However, the directionality of these associations is inconsistent, prompting some to suggest they may vary across development. Although similar neurodevelopmental patterns have been observed for other disorders featuring emotional and behavioural dysregulation, few studies have tested this hypothesis for CU traits, and particularly not for aggression subtypes. The current study sought to examine grey matter correlates of CU traits and aggression (including its subtypes), and then determine whether these associations varied by age. Fifty-four youths (10-19 years old) who were characterized for CU traits and aggression underwent MRI. Grey matter volume and surface area within the anterior cingulate cortex was positively associated with CU traits. The correlation between CU traits and medial orbitofrontal cortex (mOFC) volume varied significantly as a function of age, as did the correlation between reactive aggression and mOFC surface area. These associations became more positive with age. There were no significant findings for proactive/total aggression. Results are interpreted considering the potential for delayed cortical maturation in youths with high CU traits/aggression.

Brain Anatomy in Boys with Conduct Disorder: Differences Among Aggression Subtypes

Aggression is a core feature of conduct disorder (CD), but the motivation, execution of aggression may vary. A deeper understanding of the neural substrates of aggressive behaviours is critical for effective clinical intervention. Seventy-six Boys with CD (50 with impulsive aggression (I-CD) and 26 with premeditated aggression (P-CD)) and 69 healthy controls (HCs) underwent a structural MRI scan and behavioural assessments. Whole-brain analyses revealed that, compared to HCs, the I-CD group showed significant cortical thinning in the right frontal cortex, while the P-CD group demonstrated significant folding deficits in the bilateral superior parietal cortex. Both types of aggression negatively correlated with the left amygdala volume, albeit in different ways. The present results demonstrated that the complex nature of aggression relies on differentiated anatomical substrates, highlighting the importance of exploring differential circuit-targeted interventions for CD patients.

Psychological distress and aggression among adolescents with internet gaming disorder symptoms

The present study aimed to investigate the current situation of internet gaming disorder (IGD) in Chinese adolescents and explore the impact of IGD-related factors on adolescent aggression. We hypothesized that IGD symptoms in adolescents would be associated with aggressive behavior and that risk factors for IGD symptoms could increase the aggressive tendencies of adolescents. To verify the above hypothesis, a cross-sectional survey of junior and senior high school students from southern, southwestern, central, and eastern China was conducted. A total of 9306 valid questionnaires were collected. The results showed that the prevalence of IGD symptoms was 1.78 % among Chinese adolescents. The adolescents in the disordered gamer group had the most severe IGD symptoms, with the highest levels of psychological distress and aggression. Interestingly, adolescents in the casual gamer group had the lowest psychological distress and aggression scores. Linear regression analysis further showed that higher levels of aggression were significantly associated with male sex, younger age, more severe psychological distress and IGD symptoms, and more violent game exposure. Our results suggested that excessive online gaming not only contributes to psychological distress in adolescents but also increases their levels of aggressive behavior. Apart from male sex and younger age, severe IGD symptoms and psychological distress are the most important predictors of the development of aggressive behavior.

Empathy deficit in male patients with schizophrenia and its relationships with impulsivity and premeditated violence

Objective

To explore the pattern of empathy characteristics in male patients with schizophrenia (SCH) and to examine whether empathy deficit is associated with impulsivity and premeditated violence.

Methods

One hundred and fourteen male SCH patients were enrolled in this study. The demographic data of all patients were collected and the subjects were divided into two groups, namely, the violent group, including 60 cases, and the non-violent group, comprising 54 cases, according to the Modified Overt Aggression Scale (MOAS). The Chinese version of the Interpersonal Reactivity Index-C (IRI-C) was used to evaluate empathy and the Impulsive/Predicted Aggression Scales (IPAS) was employed to assess the characteristics of aggression.

Results

Among the 60 patients in the violent group, 44 patients had impulsive aggression (IA) and 16 patients had premeditated aggression (PM) according to the IPAS scale. In the violent group, the scores of the four subfactors of the IRI-C, i.e., perspective taking (PT), fantasy (FS), personal distress (PD), and empathy concern (EC), were significantly lower than in the non-violent group. Stepwise logistic regression showed that PM was independent influencing factor for violent behaviors in SCH patients. Correlation analysis revealed that EC of affective empathy was positively correlated with PM but not with IA.

Conclusion

SCH patients with violent behavior had more extensive empathy deficits compared with non-violent SCH patients. EC, IA and PM are independent risk factors of violence in SCH patients. Empathy concern is an important index to predict PM in male patients with SCH.

Mindful Coping Power Effects on Children's Autonomic Nervous System Functioning and Long-Term Behavioral Outcomes

Mindful Coping Power (MCP) was developed to enhance the effects of the Coping Power (CP) preventive intervention on children's reactive aggression by integrating mindfulness training into CP. In prior pre-post analyses in a randomized trial of 102 children, MCP improved children's self-reported anger modulation, self-regulation, and embodied awareness relative to CP but had fewer comparative effects on parent- and teacher-reported observable behavioral outcomes, including reactive aggression. It was hypothesized that MCP-produced improvements in children's internal awareness and self-regulation, if maintained or strengthened over time with ongoing mindfulness practice, would yield improvements in children's observable prosocial and reactive aggressive behavior at later time points. To appraise this hypothesis, the current study examined teacher-reported child behavioral outcomes at a one-year follow-up. In the current subsample of 80 children with one-year follow-up data, MCP produced a significant improvement in children's social skills and a statistical trend for a reduction in reactive aggression compared with CP. Further, MCP produced improvements in children's autonomic nervous system functioning compared with CP from pre- to post-intervention, with a significant effect on children's skin conductance reactivity during an arousal task. Mediation analyses found that MCP-produced improvements in inhibitory control at post-intervention mediated program effects on reactive aggression at the one-year follow-up. Within-person analyses with the full sample (MCP and CP) found that improvements in respiratory sinus arrhythmia reactivity were associated with improvements in reactive aggression at the one-year follow-up. Together, these findings indicate that MCP is an important new preventive tool to improve embodied awareness, self-regulation, stress physiology, and observable long-term behavioral outcomes in at-risk youth. Further, children's inhibitory control and autonomic nervous system functioning emerged as key targets for preventive intervention.

Neural correlates of Type A personality: Type A personality mediates the association of resting-state brain activity and connectivity with eating disorder symptoms

BACKGROUND

Type A personality (TAP) was characterized by impatience, competitiveness, aggressiveness, and hostility. Higher TAP was proved to be associated with more eating disorder symptoms (EDS). While little is known about the underlying neural substrates of TAP and how TAP is linked to EDS at the neural level.

METHODS

To investigate the neural basis of TAP, we adopted fractional amplitude of low-frequency fluctuations (fALFF) and resting-state functional connectivity (RSFC) via resting-state functional magnetic resonance imaging (rs-fMRI) (N = 1620). Mediation models were examined to explore the relationship between TAP, EDS, and brain activity.

RESULTS

TAP was associated with decreased fALFF in the left middle frontal gyrus (MFG) and increased fALFF in the left precentral gyrus (PreCG). Furthermore, TAP was positively correlated to RSFC between the left MFG and left inferior temporal gyrus (ITG) and between the left PreCG and right middle temporal gyrus (MTG). Mediation analysis showed TAP fully mediated the association of the left MFG activity, MFG-ITG connectivity, and PreCG-MTG connectivity with EDS.

LIMITATIONS

The cross-sectional design of this study precludes us from specifying the causal relationship in the associations we observed.

CONCLUSIONS

Our results suggested spontaneous activity in the left MFG and PreCG is associated with TAP, and even in general sample, people with higher TAP showed more EDS. The present study is the first to investigate the neurobiological underpinnings of TAP in a large sample and further offered new insights into the relation between TAP and EDS from a neural basis perspective.

Non-angry aggressive arousal and angriffsberietschaft: A narrative review of the phenomenology and physiology of proactive/offensive aggression motivation and escalation in people and other animals

Human aggression typologies largely correspond with those for other animals. While there may be no non-human equivalent of angry reactive aggression, we propose that human proactive aggression is similar to offense in other animals' dominance contests for territory or social status. Like predation/hunting, but unlike defense, offense and proactive aggression are positively reinforcing, involving dopamine release in accumbens. The drive these motivational states provide must suffice to overcome fear associated with initiating risky fights. We term the neural activity motivating proactive aggression "non-angry aggressive arousal", but use "angriffsberietschaft" for offense motivation in other animals to acknowledge possible differences. Temporal variation in angriffsberietschaft partitions fights into bouts; engendering reduced anti-predator vigilance, redirected aggression and motivational over-ride. Increased aggressive arousal drives threat-to-attack transitions, as in verbal-to-physical escalation and beyond that, into hyper-aggression. Proactive aggression and offense involve related neural activity states. Cingulate, insular and prefrontal cortices energize/modulate aggression through a subcortical core containing subnuclei for each aggression type. These proposals will deepen understanding of aggression across taxa, guiding prevention/intervention for human violence.

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.

Association between lower-level of environmental lead exposure and reactive and proactive aggression in youth: Sex differences

Lead exposure during childhood has been associated with a variety of negative outcomes, including antisocial/aggressive behavior. However, different subtypes of antisocial behavior have been found to have different neurobiological correlates, and it is unclear whether lead exposure is related to specific subtypes of aggressive behavior. The objective of the study was to examine relationships between childhood blood lead levels (BLL) and proactive and reactive aggression. Further, given prior findings of sex differences in the effects of lead exposure, we examine whether there are sex differences in these relationships. In a sample of 818 youth (47.2% girls) ages 10-13 in China, we assessed BLL and administered the Reactive Proactive Aggression Questionnaire. Results show that BLLs were associated with reactive, but not proactive aggression. There was a significant interaction between BLL and sex in predicting aggression; boys with higher BLL scored higher in both proactive and reactive aggression than boys with lower BLL, but these differences were not present for girls. These findings suggest that lead exposure may have broad effects on antisocial behavior, but that boys may be more susceptible than girls. These findings may provide insights to identifying protective factors that could be potential targets for intervention.

Predicting youth aggression with empathy and callous unemotional traits: A Meta-analytic review

Historically, empathy has been thought to motivate prosocial behaviour and inhibit aggressive behaviour. Contrary to current assumptions and theoretical support, a meta-analysis revealed a small effect of empathy on aggression among adults (Vachon, Lynam, & Johnson, 2014). The current study sought to determine whether broadening the focus from empathy to include other socially relevant affective characteristics (i.e., callous-unemotional traits) was advantageous in predicting aggressive behaviour. As little is known about the strength of this association among youth, the current study meta-analytically examined 192 unique effect sizes drawn from published and unpublished studies reporting on samples of children and adolescents. Analyses were conducted across general, cognitive, and emotional empathy, as well as callous-unemotional traits, and general, direct, indirect, proactive, and reactive aggression. Significant variability was noted across effect sizes. Consistent with a prior meta-analysis involving adults (Vachon et al., 2014), small to moderate associations were identified between aggression and traditional measures of empathy (i.e., general, emotional, cognitive); these effects ranged from r = -0.06 to -0.26. Among broader measures of emotional style (i.e., callous-unemotional traits), moderate to large effects were found; ranging from r = 0.30 to 0.37. Results suggested that broader affective measures may be more strongly associated with aggression than empathy alone. The results raise questions about the nature of empathy assessment and indicate the utility of targeting multiple emotion-related factors during treatment to effectively reduce aggressive behaviour. In particular, the results underscore of the importance of considering the limited prosocial emotions specifier (perhaps trans-diagnostically given the varied nature of the sample) when considering implications for prognosis and treatment targets.

A systematic review of neural, cognitive, and clinical studies of anger and aggression

Anger and aggression have large impact on people's safety and the society at large. In order to provide an intervention to minimise aggressive behaviours, it is important to understand the neural and cognitive aspects of anger and aggression. In this systematic review, we investigate the cognitive and neural aspects of anger-related processes, including anger-related behaviours and anger reduction. Using this information, we then review prior existing methods on the treatment of anger-related disorders as well as anger management, including mindfulness and cognitive behavioural therapy. At the cognitive level, our review that anger is associated with excessive attention to anger-related stimuli and impulsivity. At the neural level, anger is associated with abnormal functioning of the amygdala and ventromedial prefrontal cortex. In conclusions, based on cognitive and neural studies, we here argue that mindfulness based cognitive behavioural therapy may be better at reducing anger and aggression than other behavioural treatments, such as cognitive behavioural therapy or mindfulness alone. We provide key information on future research work and best ways to manage anger and reduce aggression. Importantly, future research should investigate how anger related behaviours is acquired and how stress impacts the development of anger.

Reactive vs proactive aggression: A differential psychobiological profile? Conclusions derived from a systematic review

INTRODUCTION

Scholars have established subcategories of aggressive behavior in order to better understand this construct. Specifically, a classification based on motivational underpinnings makes it possible to differentiate between reactive and proactive aggression. Whereas reactive aggression is characterized by emotional lability, which means it is prone to impulsive reactions after provocation, proactive aggression is driven by low emotionality and high levels of instrumentality to obtain benefits. Some authors have conceived these two types as having a dichotomous nature, but others argue against this conceptualization, considering a complementary model more suitable. Hence, neuroscientific research might help to clarify discussions about their nature because biological markers do not present the same biases as psychological instruments.

AIM

The main objective of this study was to carry out a systematic review of studies that assess underlying biological markers (e.g., genes, brain, psychophysiological, and hormonal) of reactive and proactive aggression.

METHODS

To carry out this review, we followed PRISMA quality criteria for reviews, using five digital databases complemented by hand-searching.

RESULTS

The reading of 3993 abstracts led to the final inclusion of 157 papers that met all the inclusion criteria. The studies included allow us to conclude that heritability accounted for approximately 45% of the explained variance in both types of aggression, with 60% shared by both, especially, for overt and physical expression forms, and 10% specific to each type. Regarding allelic risk factors, whereas low functioning variants affecting serotonin transport and monoaminoxidase increased the risk of reactive aggression, high functioning variants were associated with proactive aggression. Furthermore, brain analysis revealed an overlap between the two types of aggression and alterations in the volume of the amygdala and temporal cortex. Moreover, high activation of the medial prefrontal cortex (PFC) facilitated proneness to both types of aggression equally. Whereas stimulation of the right ventrolateral (VLPFC) and dorsolateral (DLPFC) reduced proneness to aggression, inhibition of the left DLPFC increased it. Finally, psychophysiological and hormonal correlates in general did not clearly differentiate between the two types because they were equally related to each type (e.g., low basal cortisol and vagal variability in response to acute stress) CONCLUSIONS: This study reinforces the complementary model of both types of aggression instead of a dichotomous model. Additionally, this review also offers background about several treatments (i.e., pharmacological, non-invasive brain techniques…) to reduce aggression proneness.

Cold-Blooded and on Purpose: A Review of the Biology of Proactive Aggression

Proactive aggression (PA) is a planned and unprovoked form of aggression that is most often enacted for personal gain or in anticipation of a reward. Frequently described as "cold-blooded" or goal oriented, PA is thought to be associated with low autonomic arousal. With this view in mind, we performed a scoping review of the biological correlates of PA and identified 74 relevant articles. Physiological findings indicated a robust association between PA and reduced resting heart rate, and to a lesser extent a relationship between PA and decreased heart rate and skin conductance reactivity, perhaps indicating dampened sympathetic function. The twin literature identified PA as a heritable trait, but little evidence implicates specific genes in the pathogenesis of PA. Neuroimaging studies of PA pinpoint impaired amygdala function in the assessment and conditioning of aversive stimuli, which may influence the establishment of behavioral patterns. Nodes of the default mode network were identified as possible neural correlates of PA, suggesting that altered function of this network may be involved in the genesis of PA. Given the overlap of PA with reactive aggression and the overall behavioral complexity of PA, it is clear that multiple endophenotypes of PA exist. This comprehensive review surveys the most salient neurobiologically informed research on PA.

Cortical Correlates of Impulsive Aggressive Behavior in Pediatric Bipolar Disorder

Background: Impulsive aggression represents a frequent characteristic of pediatric bipolar disorder (PBD). Cortical alterations associated with impulsive aggression and its multiple facets have not been investigated yet in youth with bipolar disorder. Aim: To investigate the relationship between cortical thickness and facets of impulsive aggression in youth with PBD. Materials and Methods: Twenty-three youth with PBD and 23 healthy controls (HC) were administered the aggression questionnaire (AQ) and underwent 3T magnetic resonance imaging scan. Cortical thickness was assessed with FreeSurfer. Canonical correlation analyses were used to investigate the relationship between AQ total and subscale scores and cortical thickness in youth with PBD. Results: Youth with PBD had increased scores in the subscales of AQ-anger and AQ-hostility and cortical thinning in in areas belonging to the affective network (AN), frontoparietal network (FPN) and cingulo-opercular network (CON), i.e., right rostral anterior cingulate, right caudal anterior cingulate, right lateral orbitofrontal, right medial orbitofrontal, left and right inferior parietal, left posterior cingulate, left and right supramarginal left lingual cortices. Greater thickness in these networks positively correlated with the AQ-hostility subscale and negatively correlated with AQ-anger subscale. Conclusions: The opposite patterns observed between areas belonging to AN, FPN, CON, and the two facets of IA, namely anger and hostility, corroborate clinical findings supporting the different nature of these two constructs.

Voxel-based morphometry and cortical thickness in combat veterans suffering from impulsive aggression

BACKGROUND

Problems with impulsive aggression occur in many forms of psychiatric dysfunction, and are a common complaint among combat veterans. The present study sought to examine the neuroanatomical correlates of combat-related impulsive aggression.

METHODS

T1-weighted magnetic resonance images were acquired from 29 male veterans with impulsive aggression and 30 non-aggressive combat controls. Subcortical volumetry was conducted with the amygdala and hippocampus and their main constituent subdivisions as regions-of-interest (ROIs) (basolateral, centromedial amygdala; head, body, tail of hippocampus). Cortical thickness measurements were extracted for the dorsolateral prefrontal cortex, orbitofrontal cortex, and anterior cingulate cortex. Within-group correlations with psychometric measures were also explored.

RESULTS

No significant group differences in cortical thickness or subcortical grey matter volumes were observed for any of the ROIs. Also, no significant correlations with any of the psychometric measures were recorded. Exploratory whole-brain analysis of cortical thickness revealed a significant group × anxiety interaction effect in a cluster located in the left lingual gyrus.

CONCLUSIONS

The current findings indicate that problems with impulsive aggression may not be directly associated with alterations in cortical thickness or amygdalar/hippocampal (sub)volumes. The observed interplay between impulsive aggression problems and anxiety-related symptoms is consistent with prior work showing the two phenomena may share the same underlying (neural) mechanisms.

Vitamin D sufficiency attenuates the effect of early social adversity on child antisocial behavior

BACKGROUND

Vitamin D insufficiency and child antisocial behavior are public health concerns. It is unknown whether vitamin D plays a role in antisocial outcomes. This study examines whether higher levels of vitamin D can act as a protective factor against antisocial behavior for children who are exposed to early social adversity.

METHODS

In a community sample of 300 children aged 11-12 years (151 females, 149 males), serum concentrations of 25-hydroxyvitamin D [25(OH)D] were assessed alongside early social adversity, and both parent and child-reported antisocial behavior.

RESULTS

Vitamin D moderated the association between early social adversity and multiple antisocial outcomes. Higher social adversity was associated with greater antisocial behavior among vitamin D-insufficient [25(OH)D < 30 ng/mL], but not vitamin D-sufficient children [25(OH)D ⩾ 30 ng/mL], after adjusting for other variables. Results from child reports of antisocial behavior were replicated with parent reports, providing support for the robustness of the findings. At serum 25(OH)D concentrations above 27.16-30.69 ng/mL (close to 30 ng/mL, the recommended optimal vitamin D level for pediatric populations), the effect of social adversity on antisocial behavior outcomes was nullified.

CONCLUSIONS

To our knowledge, this study is the first to document that a nutritional factor, vitamin D, can potentially confer resilience to antisocial behavior. Our findings in a pediatric population suggest a possible role of vitamin D supplementation in interventions to reduce antisocial behavior, which may be further investigated in future randomized controlled trials.

Cingulum White Matter Integrity as a Mediator Between Harm Avoidance and Hostility

As a textbook manifestation of an aggressive attitude, hostility can pose a serious threat to both an individual's life and the security of society at large. Past evidence suggests that some anxiety-related traits may be more prone to giving rise to hostility. However, many aspects of hostility, such as, determining the susceptible temperament for hostility, the neural basis of hostility, and the underlying mechanisms through which having a susceptible temperament generates hostility in a healthy brain, remain unclear. In this study, we sought to delve into these questions by assessing temperament and brain white matter integrity using self-report questionnaires and diffusion tensor imaging in a sizable sample of healthy adults (n = 357). First, we investigated the relationship between hostility and the four temperaments of the Cloninger model. Then, we investigated which white matter tracts were significantly correlated with hostility using a whole-brain analysis. Finally, we used a mediation analysis to explore the tripartite relationship between vulnerability temperament, the fractional anisotropy (FA) value of the white matter, and hostility. Our results suggest that a harm avoidance temperament may be susceptible to hostility and that the cingulum may be a key white matter region responsible for hostility. Based on these results, we developed a temperament-brain-attitude pathway showing how harm avoidance temperament could affect the brain and ultimately lead to hostility.

An overlapping pattern of cerebral cortical thinning is associated with both positive symptoms and aggression in schizophrenia via the ENIGMA consortium

BACKGROUND

Positive symptoms are a useful predictor of aggression in schizophrenia. Although a similar pattern of abnormal brain structures related to both positive symptoms and aggression has been reported, this observation has not yet been confirmed in a single sample.

METHOD

To study the association between positive symptoms and aggression in schizophrenia on a neurobiological level, a prospective meta-analytic approach was employed to analyze harmonized structural neuroimaging data from 10 research centers worldwide. We analyzed brain MRI scans from 902 individuals with a primary diagnosis of schizophrenia and 952 healthy controls.

RESULTS

The result identified a widespread cortical thickness reduction in schizophrenia compared to their controls. Two separate meta-regression analyses revealed that a common pattern of reduced cortical gray matter thickness within the left lateral temporal lobe and right midcingulate cortex was significantly associated with both positive symptoms and aggression.

CONCLUSION

These findings suggested that positive symptoms such as formal thought disorder and auditory misperception, combined with cognitive impairments reflecting difficulties in deploying an adaptive control toward perceived threats, could escalate the likelihood of aggression in schizophrenia.

Disinhibition and Detachment in Adolescence: A Developmental Cognitive Neuroscience Perspective on the Alternative Model for Personality Disorders

Personality pathology often emerges during adolescence, but attempts to understand its neurocognitive basis have traditionally been undermined by problems associated with the categorical classification of personality disorders. In contrast, dimensional models of personality pathology, such as the Alternative Model for Personality Disorders (AMPD) in DSM-5, may provide a stronger foundation for neurobiological investigations of maladaptive individual differences in personality. As an example, we review studies of the adolescent development of reward processing and cognitive control and connect these systems to the normal personality hierarchy and to two dimensions included in the AMPD - Detachment and Disinhibition. We argue that by linking developmental changes in these systems to the AMPD, researchers will be better positioned to understand the relationship between neurocognitive development and the expression of personality pathology in adolescence and early adulthood.

Mobile Phone Addiction and Risk-Taking Behavior among Chinese Adolescents: A Moderated Mediation Model

Objectives: The mobile phone (MP) is an indispensable digital device in adolescents’ daily lives in the contemporary era, but being addicted to MP can lead to more risk-taking behavior. However, little is known about the mediating and moderating mechanisms underlying this relation. To address the gaps in the literature, the present study examined the idea that MP addiction is associated with reduced self-control, which further associates with increased risk-taking behavior. In addition, this study also investigated the moderation effect of adolescent sex in the association between MP addiction and self-control. Methods: A three-wave longitudinal study, each wave spanning six months apart, was conducted in a sample of Chinese adolescents (final N = 333, 57.4% girls). Results: Results of the moderated mediation model suggest that after controlling for demographic variables and baseline levels of self-control and risk-taking behavior, MP addiction at T1 positively predicted increased risk-taking behavior at T3 through reduced self-control at T2 for girls but not for boys. Conclusions: Theoretically, these findings contribute to the understanding about the working processes in the association between MP addiction and risk-taking behavior in adolescents. Practically, the results implied that boosting self-control appeared as a promising way to reduce girls’ risk-taking behavior, particularly for those who are addicted to MPs.

Specific cortical and subcortical alterations for reactive and proactive aggression in children and adolescents with disruptive behavior

Maladaptive aggression, as present in conduct disorder (CD) and, to a lesser extent, oppositional defiant disorder (ODD), has been associated with structural alterations in various brain regions, such as ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC), amygdala, insula and ventral striatum. Although aggression can be subdivided into reactive and proactive subtypes, no neuroimaging studies have yet investigated if any structural brain alterations are associated with either of the subtypes specifically. Here we investigated associations between aggression subtypes, CU traits and ADHD symptoms in predefined regions of interest.

T1-weighted magnetic resonance images were acquired from 158 children and adolescents with disruptive behavior (ODD/CD) and 96 controls in a multi-center study (aged 8–18). Aggression subtypes were assessed by questionnaires filled in by participants and their parents. Cortical volume and subcortical volumes and shape were determined using Freesurfer and the FMRIB integrated registration and segmentation tool. Associations between volumes and continuous measures of aggression were established using multilevel linear mixed effects models.

Proactive aggression was negatively associated with amygdala volume (b = -10.7, p = 0.02), while reactive aggression was negatively associated with insula volume (b = -21.7, p = 0.01). No associations were found with CU traits or ADHD symptomatology. Classical group comparison showed that children and adolescents with disruptive behavior had smaller volumes than controls in (bilateral) vmPFC (p = 0.003) with modest effect size and a reduced shape in the anterior part of the left ventral striatum (p = 0.005).

Our study showed negative associations between reactive aggression and volumes in a region involved in threat responsivity and between proactive aggression and a region linked to empathy. This provides evidence for aggression subtype-specific alterations in brain structure which may provide useful insights for clinical practice.

Structural brain changes in young males addicted to video-gaming

Excessive video gaming has a number of psychological and social consequences. In this study, we looked at possible changes in gray and white matter and asked whether these changes are correlated to psychological measures. Twentynine players of violent videogames (mean daily playing time 4.7 h) and age matched controls were subjected to a battery of questionnaires assessing aggression, empathy, hostility, internet addiction and psychological well-being. Diffusion tensor and 3D T1-weighted MR images were obtained to examine gray (via voxel-based morphometry) and white (via tract-based spatial statistics) matter changes. Widespread regions of decreased gray matter in the players were found but no region showed increased intensity of gray matter. Density of gray matter showed a negative correlation with the total length of playing in years in the right posterior cingulate gyrus, left pre- and postcentral gyrus, right thalamus, among others. Furthermore, fractional anisotropy, a marker for white matter structure, was decreased in the left and right cingulum in the players. Both, gray and white matter changes correlated with measures of aggression, hostility, self esteem, and the degree of internet addiction. This study thus shows profound changes of brain structure as a function of excessive playing of violent video games.

Variants of the Aggression-Related RBFOX1 Gene in a Population Representative Birth Cohort Study: Aggressiveness, Personality, and Alcohol Use Disorder

Background: Recently, RBFOX1, a gene encoding an RNA binding protein, has consistently been associated with aggressive and antisocial behavior. Several loci in the gene have been nominally associated with aggression in genome-wide association studies, the risk alleles being more frequent in the general population. We have hence examined the association of four RBFOX1 single nucleotide polymorphisms, previously found related to aggressive traits, with aggressiveness, personality, and alcohol use disorder in birth cohort representative samples. Methods: We used both birth cohorts of the Estonian Children Personality Behavior and Health Study (ECPBHS; original n = 1,238). Aggressiveness was assessed using the Buss-Perry Aggression Questionnaire and the Lifetime History of Aggressiveness structured interview at age 25 (younger cohort) or 33 (older cohort). Big Five personality at age 25 was measured with self-reports and the lifetime occurrence of alcohol use disorder assessed with the MINI interview. RBFOX1 polymorphisms rs809682, rs8062784, rs12921846, and rs6500744 were genotyped in all participants. Given the restricted size of the sample, correction for multiple comparisons was not applied. Results: Aggressiveness was not significantly associated with the RBFOX1 genotype. RBFOX1 rs8062784 was associated with neuroticism and rs809682 with extraversion. Two out of four analyzed RBFOX1 variants, rs8062784 and rs12921846, were associated with the occurrence of alcohol use disorder. Conclusions: In the birth cohort representative sample of the ECPBHS, no association of RBFOX1 with aggressiveness was found, but RBFOX1 variants affected basic personality traits and the prevalence of alcohol use disorder. Future studies on RBFOX1 should consider the moderating role of personality and alcohol use patterns in aggressiveness.

Understanding Brain Mechanisms of Reactive Aggression

PURPOSE OF REVIEW

To review the current literature on biobehavioral mechanisms involved in reactive aggression in a transdiagnostic approach.

RECENT FINDINGS

Aggressive reactions are closely related to activations in the brain's threat circuitry. They occur in response to social threat that is experienced as inescapable, which, in turn, facilitates angry approach rather than fearful avoidance. Provocation-induced aggression is strongly associated with anger and deficits in cognitive control including emotion regulation and inhibitory control. Furthermore, the brain's reward system plays a particular role in anger-related, tit-for-tat-like retaliatory aggression in response to frustration. More research is needed to further disentangle specific brain responses to social threat, provocation, and frustration. A better understanding of the psychological and neurobiological mechanisms involved in reactive aggression may pave the way for specific mechanism-based treatments, involving biological or psychotherapeutic approaches or a combination of the two.

Personality traits and negative affect mediate the relationship between cortical thickness of superior frontal cortex and aggressive behavior

Aggression reflects the psychological and physical behavior that perpetrator intends to harm victim. Initiation of aggression is influenced by the distal factors (e.g. personality) and proximate causes (e.g. affect) of perpetrator. However, few studies explored the brain structural basis of relationship between these traits and aggressive behavior. In this study, we first explored the association between cortical thickness and aggression in a large young adult sample from the Human Connectome Project. Results found aggressive behavior assessed by the Adult Self-Report was positively correlated with cortical thickness in left superior frontal gyrus (SFG), which was implicated in emotion regulation and executive function. Then, mediation analyses with distal and proximate factors separately showcased that the association between the left SFG thickness and aggressive behavior was partially mediated by negative affect (anger and sadness), and fully mediated by personality traits (agreeableness and neuroticism). Taken together, these experimental findings established dorsal prefrontal cortex as the key region in generating aggressive behavior, and gave a neutral explanation for why individuals with high negative affect and neuroticism exhibit more aggression. This study implicated the possible targeted brain region and behavioral intervention for such at-risk individuals initiating violence.

From Physical Aggression to Verbal Behavior: Language Evolution and Self-Domestication Feedback Loop

We propose that human self-domestication favored the emergence of a less aggressive phenotype in our species, more precisely phenotype prone to replace (reactive) physical aggression with verbal aggression. In turn, the (gradual) transition to verbal aggression and to more sophisticated forms of verbal behavior favored self-domestication, with the two processes engaged in a mutually reinforcing feedback loop, considering that verbal behavior entails not only less violence and better survival but also more opportunities to interact longer and socialize with more conspecifics, ultimately enabling the emergence of more complex forms of language. Whereas in the case of self-domestication, sexual selection has been proposed to work against physical aggression traits, in the case of verbal insult, the selection has been proposed to work in favor of verbal aggression. The tension between these two seemingly opposing forces gets resolved/alleviated by a tendency to replace physical aggression with verbal aggression and with verbal behavior more generally. This also helps solve the paradox of the Self-Domestication Hypothesis regarding aggression, more precisely why aggression in humans has been reduced only when it comes to reactive aggression, but not when it comes to proactive aggression, the latter exhibiting an increase in the advent of modern language. We postulate that this feedback loop was particularly important during the time period arguably between 200 and 50 kya, when humans were not fully modern, neither in terms of their skull/brain morphology and their behavior/culture nor in terms of their self-domestication. The novelty of our approach lies in (1) giving an active role to early forms of language in interacting with self-domestication processes; (2) providing specific linguistic details and functions of this early stage of grammar (including insult and humor); (3) supplying neurobiological, ontogenetic, and clinical evidence of a link between (reactive) aggression and (reactive) verbal behavior; (4) identifying proxies of the earlier stages in evolution among cognitive disorders; and (5) identifying specific points of contact and mutual reinforcement between these two processes (self-domestication and early language evolution), including reduction in physical aggression and stress/tension, as well as sexual selection.

Proactive and Reactive Aggressive Behaviors: Dimensionality of Self-Report Scales

The literature distinguishes aggressive behavior as being either proactive or reactive; however, despite being highly comorbid, they appear to possess unique correlation patterns to external variables. We propose to assess the dimensionality and latent profiles that emerged based on the Peer Aggressive Behavior Scale (PAB-S) and the Peer Aggressive and Reactive Behavior Questionnaire (PARB-Q). Confirmatory Factor Analysis (CFA) and Latent Profile Analysis (LPA) was conducted on two self-report scales in a non-representative Brazilian sample composed by 2,517 students of elementary school (1,275 girls; 50.7%), aged from seven to 16 years. CFA analyses showed inconclusive results regarding the dimensionality of the data. LPA results, for both instruments, indicated the interdependence between proactive and reactive factors. We suggest that dimensionality issues concerning human aggression might depend, at least in part, on the method used to assess the phenomenon.

Understanding Chronic Aggression and Its Treatment in Children and Adolescents

PURPOSE OF REVIEW

Youth aggression is common and has a significant burden on individuals, families, and society. However, its treatment is often a challenge for clinicians. Thus, this review will examine the current understanding of youth aggression, conceptualize aggression as a symptom rather than its own disorder, and provide an overview of treatment strategies.

RECENT FINDINGS

Youth aggression is associated with complex genetic, neurobiological, and environmental risks. Prevention strategies are of the utmost importance for at-risk families and youth. Psychosocial interventions are the first line treatment. But if not fully effective, then pharmacologic interventions-including psychostimulants, alpha-2 agonists, atomoxetine, and risperidone-have shown benefits. Other medications, such as SSRIs, can be useful in certain scenarios. It is important to conceptualize youth aggression as being a trans-diagnostic symptom in psychopathology. Determining the underlying cause of aggression will help to guide treatment.

Brain structures and functional connectivity associated with individual differences in trait proactive aggression

Although considerable efforts have been made to understand the neural underpinnings of (state) reactive aggression, which is triggered by provocation or perceived threat, little is known about the neural correlates of proactive aggression, which is driven by instrumental motivations to obtain personal gains through aggressive means and which varies dramatically across individuals in terms of tendency of appealing to such means. Here, by combining structural (grey matter density, GMD) and functional (resting-state functional connection, RSFC) fMRI, we investigated brain structures and functional networks related to trait proactive aggression. We found that individual differences in trait proactive aggression were positively associated with GMD in bilateral dorsolateral prefrontal cortex (DLPFC) and negatively correlated with GMD in posterior cingulate cortex (PCC); they were also negatively correlated with the strength of functional connectivity between left PCC and other brain regions, including right DLPFC, right IPL, right MPFC/ACC, and bilateral precuneus. These findings shed light on the differential brain bases of proactive and reactive aggressions and suggested the neural underpinnings of proactive aggression.

Developmental Origins of Chronic Physical Aggression: A Bio-Psycho-Social Model for the Next Generation of Preventive Interventions

This review describes a bio-psycho-social approach to understanding and preventing the development of chronic physical aggression. The debate on the developmental origins of aggression has historically opposed genetic and environmental mechanisms. Recent studies have shown that the frequency of physical aggression peaks in early childhood and then decreases until old age. Molecular genetic studies and twin studies have confirmed important genetic influences. However, recent epigenetic studies have highlighted the important role of environments in gene expression and brain development. These studies suggest that interrelated bio-psycho-social channels involved in the development of chronic physical aggression are generally the product of an intergenerational transmission process occurring through assortative mating, genetic inheritance, and the inheritance of physical and social environmental conditions that handicap brain functioning and support the use of physical aggression to solve problems. Given these intergenerational mechanisms and physical aggression onset in infancy, it appears clear that preventive interventions should start early in pregnancy, at the latest.

Stability of Cortical Thinning in Persons at Increased Familial Risk for Major Depressive Disorder Across 8 Years

BACKGROUND

A biological marker of vulnerability should precede onset of illness and be independent of disease course. We previously reported that cortical thinning may serve as a potential biomarker for risk for familial depression. We now test stability of the cortical thinning across 8 years, and whether thinning mediates associations between familial risk and depressive traits.

METHOD

Participants were from a 3-generation family study of depression, where 2nd and 3rd generation offspring were characterized as being at high- or low-risk for depression based on the presence/absence of major depression in the 1st generation. The analysis includes 82 offspring with anatomical MRI scans across two assessment waves, 7.8 (S.D.1.3, range: 5.2-10.9) years apart.

RESULTS

High-risk offspring had thinner bilateral superior and middle frontal gyri, and left inferior parietal lobule, at both time-points. High intra-subject correlation (0.60<r<0.91) and intra-class correlation (0.72-0.78) of thickness measures across time points was detected within the above regions; rank order by effect size and region was also preserved across time. The thinning was stable despite changes in scanning platform (Siemens Sonata vs. GE Signa), field-strength (1.5 vs. 3T), and participant age and clinical course. Thinning at the first time-point predicted anger and hostility at the second, and mediated the relationship between familial risk and these traits.

CONCLUSION

The study provides evidence for cortical thinning as a stable biomarker for familial vulnerability for depressive illness, which supports the ability to detect persistent and clinically relevant anatomical findings irrespective of MRI platform.

Brain structural correlates of irritability: Findings in a large healthy cohort

Irritability and nonviolent aggression are common behavioral features across the population, yet there is limited neurobiological research into subclinical phenotypes representing the lower edge of a symptom continuum ranging from slight irritability to criminal violence. We studied brain structural correlates of irritability in a large healthy cohort to test the hypothesis of associations with fronto-limbic brain structures implicated in mood regulation. In a large multicenter effort, we recruited 409 mentally healthy adults from the community, who received T1-weighted high-resolution 3 T MRI scans. These structural scans were automatically preprocessed for voxel- and surface-based morphometry measurements with the CAT 12 toolbox implemented in SPM 12. Subclinical aggressive symptoms were assessed using the SCL-90-R aggression/hostility subscale and then correlated with cortical volume (VBM), and cortical thickness and gyrification. VBM analysis showed significant (P < 0.05, FDR-corrected at peak-level) positive correlations of cortical volume with SCL-90-R aggression subscale values in large clusters spanning bilateral anterior cingulate and orbitofrontal cortices and left lingual and postcentral gyri. Surface-based morphometry yielded mostly uncorrected positive correlations with cortical thickness in bilateral precentral gyri and with gyrification in left insula and superior temporal gyrus. Our findings imply an association of subclinical aggressive symptoms with cortical volume in areas important for emotion awareness and regulation, which might also be related to cortical adaptation to mental stress. These results overlap with several findings on impulsive aggression in patients suffering from affective and disruptive behavior disorders. They also suggest a biological symptom continuum manifesting in these brain areas. Hum Brain Mapp 38:6230-6238, 2017. © 2017 Wiley Periodicals, Inc.