Neurobiology of aggression and violence

Moral Injury: An Overview of Conceptual, Definitional, Assessment, and Treatment Issues

Moral injury (MI) is a potential clinical problem characterized by functionally impairing moral emotions, beliefs, and behaviors as well as adverse beliefs about personal or collective humanity and life's meaning and purpose. MI can arise from personal transgressive acts or from being a victim of or bearing witness to others' inhumanity. Despite widespread interest in MI, until recently, there was no reliable measure of MI as an outcome, and prior research has revealed little about its causes, consequences, and intervention approaches. This review provides background information on the history of MI, defines key terms, and critically reviews assessment tools. Additionally, we describe a social-functional theory of the etiology of MI and a social-functional rehabilitation approach to treatment. This treatment approach, which can be used by any clinician regardless of clinical context, employs cross-cutting change agents to promote lasting corrective and humanizing prosocial experiences, enhancing belonging through valued actions and relationships.

Does Resting Respiratory Sinus Arrhythmia Buffer the Link from Trait Anger to Aggression in Young Adults?

From both psychological and physiological perspectives, the current study focused on investigating the moderating role of resting respiratory sinus arrhythmia (resting RSA) in the association between trait anger and aggression. One-hundred and sixteen college students (73.28 % females, Mage= 19.15, SD = 0.92) reported their trait anger and aggression. RSA data was collected during a resting period in the laboratory. The results showed that trait anger interacted with resting RSA in predicting aggression, such that a positive association between trait anger and aggression was found among participants with lower, rather than higher, resting RSA. Our findings suggested that high resting RSA may be a protective physiological factor in the relation between trait anger and aggression among college students.

Exploring Psychotropic Medication Use in Hospitalized Children With Autism Spectrum Disorder in China: The Role of Intellectual Disability

Children and adolescents with autism spectrum disorder (ASD) frequently present with mental health comorbidities and behavioral crises, necessitating inpatient care. However, evidence-based guidelines for psychotropic medication use in specialized inpatient settings remain limited, particularly in non-Western contexts. This study examined the clinical characteristics and prescribing patterns among 269 hospitalized ASD patients (2012-2023), with a focus on how intellectual disability (ID) influences medication decisions. A retrospective analysis was conducted using electronic medical records to assess mental disorders, behavioral challenges, and psychotropic medication use at discharge. Logistic regression analyses was performed to examine factors associated with medication prescribing patterns, including the impact of ID status. Psychotropic medication use was highly prevalent (96.7%), with antipsychotics (89.96%) being the most frequently prescribed class, followed by anxiolytics (35.32%) and antidepressants (33.09%). ID was significantly associated with distinct prescribing patterns: patients with ID had 63% lower odds of antidepressant use (aOR = 0.37, p = 0.001) and 80% lower odds of ADHD medication use (aOR = 0.20, p = 0.009), while being more likely to receive antipsychotics (aOR = 2.74, p = 0.049) and experience polypharmacy (aOR = 1.89, p = 0.028). Additionally, disruptive behaviors and age were key predictors of antipsychotic use, whereas suicidal thoughts/attempts or SIBs independently predicted antidepressant prescribing. These findings suggest that ID status plays a critical role in shaping psychotropic prescribing practices beyond symptom severity alone, potentially reflecting diagnostic overshadowing and safety concerns. Future research should focus on developing tailored clinical assessment tools and treatment protocols for ASD populations with and without ID, while enhancing individualized medication monitoring to optimize therapeutic outcomes.

Why Do They Do It? The Psychology Behind Antisocial Behavior in Children and Adolescents

Antisocial Personality Disorder (ASPD) is a complex and often debilitating condition that can emerge from early behavioral disturbances in childhood and adolescence. This narrative review provides a comprehensive overview of the current understanding of ASPD in pediatric and adolescent populations, examining key diagnostic challenges, developmental trajectories, and emerging treatment approaches. Recent research underscores the critical role of the early identification of conduct disorder (CD) and oppositional defiant disorder (ODD) as precursors to ASPD. Specific attention is given to biological, environmental, and psychosocial risk factors, including genetic predispositions, family dynamics, and socio-economic adversity. Additionally, neuro-psychological research highlights deficits in executive function, emotion regulation, and social cognition, which may underline the persistent antisocial patterns. Neuroimaging studies suggest atypical neural activity in regions associated with empathy, reward processing, and impulse control. Effective intervention remains a challenge, as treatment options are limited and often complicated by co-occurring conditions, such as attention deficit hyperactivity disorder (ADHD) and mood disorders. Promising evidence supports the efficacy of integrative, multimodal approaches combining behavioral therapy, family interventions, and pharmacotherapy to reduce symptom severity and improve long-term outcomes. The review concludes by advocating for a public health approach that emphasizes prevention and early intervention, aiming to mitigate the progression to full ASPD in adulthood.

The role of the prefrontal cortex in modulating aggression in humans and rodents

Accumulating evidence suggests that the prefrontal cortex (PFC) plays an important role in aggression. However, the findings regarding the key neural mechanisms and molecular pathways underlying the modulation of aggression by the PFC are relatively scattered, with many inconsistencies and areas that would benefit from exploration. Here, we highlight the relationship between the PFC and aggression in humans and rodents and describe the anatomy and function of the human PFC, along with homologous regions in rodents. At the molecular level, we detail how the major neuromodulators of the PFC impact aggression. At the circuit level, this review provides an overview of known and potential subcortical projections that regulate aggression in rodents. Finally, at the disease level, we review the correlation between PFC alterations and heightened aggression in specific human psychiatric disorders. Our review provides a framework for PFC modulation of aggression, resolves several intriguing paradoxes from previous studies, and illuminates new avenues for further study.

Bilateral hypothalamotomy plus dominant amygdalotomy with Gamma Knife radiosurgery. A non-invasive alternative when everything has failed in the management of aggressive behavior disorder

Background

Impulsive aggression is the core symptom of intermittent explosive disorder, which can be a feature of several psychiatric disorders. There is a subset of individuals who do not respond adequately to medical treatment; they are treatment refractory. The objective of this report is to describe a case of a patient with a background of schizophrenia and concomitant refractory aggressiveness disorder, treated with two-stage bilateral hypothalamotomy and unilateral amygdalotomy with Gamma Knife radiosurgery (GKR).

Case Description

A 36-year-old male presented with a background of paranoid schizophrenia. Episodes of self- and hetero-aggressiveness were present at the initial diagnosis. High dosages of psychotropic medication were taken, and 70 sessions of electroconvulsive therapy were performed; however, no adequate response was obtained. Bilateral hypothalamotomy plus left amygdalotomy through GKR was performed. After 25 months of follow-up, a marked decrease in the frequency, degree, severity of aggressiveness and the requirement for psychotropic medications was observed.

Conclusion

Hypothalamotomy plus amygdalotomy with Gamma Knife may be an effective ablative technique for the management of refractory aggressive disorder in patients with mental illness.

A Meta-analysis of Cognitive Functioning in Intimate Partner Violence Perpetrators

Numerous psychologists have shown interest in applying neuropsychological tests to study intimate partner violence (IPV) perpetrators and gain a further understanding of the underlying nature of this type of violence. However, up until now, no meta-analysis has drawn on all the available scientific literature to calculate whether consistent differences exist between the neuropsychological performance of IPV perpetrators and other samples of men (non-violent men, IPV perpetrators with drug misuse, and other men with criminal history). The aim of this study was to carry out this calculation and also measure whether neuropsychological performance explained IPV perpetration. We conducted a meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. After initially identifying 7243 sources, we eventually included a total of 25 publications. The number of studies included for effect size calculation in each cognitive domain ranged from two to nine. Taking solely into account studies comparing IPV perpetrators with non-violent men, our findings indicate that both IPV perpetrators who misuse drugs and those who do not exhibit worse neuropsychological functioning compared to non-violent men. These differences range from moderate to large for working memory, switching attention, cognitive flexibility, planning abilities, and phonemic fluency. However, while low functioning in response IQ was only observed in IPV perpetrators without drug misuse, continuous attention performance only differed in IPV perpetrators with drug misuse. It should be noted that most conclusions were consistent. In addition, the comparison between IPV perpetrator subsamples and other types of criminal convictions only revealed differences in switching attention, with IPV perpetrators presenting worse abilities than the rest of the subsamples. Finally, we also found some support for significant associations between neuropsychological performance and both physical and psychological IPV perpetration. This meta-analysis is a significant contribution that will help inform future clinical strategies for the early detection of cognitive needs. It will also guide the implementation of new or complementary intervention programs.

Stress, hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-gonadal axis, and aggression

This comprehensive review explores the intricate relationship between the hypothalamic-pituitary-adrenal (HPA) axis, the hypothalamic-pituitary-gonadal (HPG) axis, and aggression. It provides a detailed overview of the physiology and functioning of these axes, as well as the implications for aggressive behavior. The HPA axis, responsible for the stress response, is activated in response to various stressors and can influence aggressive behavior. Glucocorticoids, such as cortisol, play a crucial role in stress-induced activation of the HPA axis and have been implicated in aggressive tendencies. Chronic stress can dysregulate the HPA axis, leading to alterations in cortisol levels and potentially contributing to aggressive behavior. The HPG axis, particularly the androgen hormone testosterone, is also closely linked to aggression. Animal and human studies have consistently shown a positive association between testosterone levels and aggression. The androgen receptors in the brain's neural circuitry play a critical role in modulating aggressive behavior. Interactions between the HPA and HPG axes further contribute to the regulation of aggression. Feedback mechanisms and crosstalk between these axes provide a complex system for the modulation of both stress and reproductive functions, which can impact aggressive behavior. Additionally,the influence of stress on reproductive functions, particularly the role of androgens in stress-induced aggression, adds further complexity to this relationship. The review also discusses the future directions and implications for clinical interventions. Understanding the neurobiological mechanisms underlying aggression requires integrating molecular, cellular, and circuit-level approaches. Translational perspectives, including animal models and human studies, can bridge the gap between basic research and clinical applications. Finally, therapeutic strategies for aggression-related disorders are explored, highlighting the importance of targeted interventions based on a comprehensive understanding of the interactions between the HPA and HPG axes. In conclusion, this review provides a comprehensive overview of the physiological and neurobiological mechanisms underlying aggression, with a specific focus on the interplay between the HPA and HPG axes. By elucidating the complex interactions between stress, hormones, and aggressive behavior, this research paves the way for future investigations and potential therapeutic interventions for aggression-related disorders.

ChMinMaxPat: Investigations on Violence and Stress Detection Using EEG Signals

BACKGROUND AND OBJECTIVES

Electroencephalography (EEG) signals, often termed the letters of the brain, are one of the most cost-effective methods for gathering valuable information about brain activity. This study presents a new explainable feature engineering (XFE) model designed to classify EEG data for violence detection. The primary objective is to assess the classification capability of the proposed XFE model, which uses a next-generation feature extractor, and to obtain interpretable findings for EEG-based violence and stress detection.

MATERIALS AND METHODS

In this research, two distinct EEG signal datasets were used to obtain classification and explainable results. The recommended XFE model utilizes a channel-based minimum and maximum pattern (ChMinMaxPat) feature extraction function, which generates 15 distinct feature vectors from EEG data. Cumulative weight-based neighborhood component analysis (CWNCA) is employed to select the most informative features from these vectors. Classification is performed by applying an iterative and ensemble t-algorithm-based k-nearest neighbors (tkNN) classifier to each feature vector. Information fusion is achieved through iterative majority voting (IMV), which consolidates the 15 tkNN classification results. Finally, the Directed Lobish (DLob) symbolic language generates interpretable outputs by leveraging the identities of the selected features. Together, the tkNN classifier, IMV-based information fusion, and DLob-based explainable feature extraction transform the model into a self-organizing explainable feature engineering (SOXFE) framework.

RESULTS

The ChMinMaxPat-based model achieved over 70% accuracy on both datasets with leave-one-record-out (LORO) cross-validation (CV) and over 90% accuracy with 10-fold CV. For each dataset, 15 DLob strings were generated, providing explainable outputs based on these symbolic representations.

CONCLUSIONS

The ChMinMaxPat-based SOXFE model demonstrates high classification accuracy and interpretability in detecting violence and stress from EEG signals. This model contributes to both feature engineering and neuroscience by enabling explainable EEG classification, underscoring the potential importance of EEG analysis in clinical and forensic applications.

Association between white matter microstructural changes and aggressiveness. A case-control diffusion tensor imaging study

Research has focused on identifying neurobiological risk factors associated with aggressive behavior in order to improve prevention and treatment efforts. This study aimed to characterize microstructural differences in white matter (WM) integrity in individuals prone to aggression. We hypothesized that altered cerebral WM microstructure may underlie normal individual variability in aggression and tested this using a case-control design in healthy individuals. Diffusion tensor imaging (DTI) was used to examine WM changes in martial artists (n = 29) and age-matched controls (n = 31). We performed tract-based spatial statistics (TBSS) to identify differences in axial diffusivity (AD), fractional anisotropy (FA) and mean diffusivity (MD) between the two groups at the whole-brain level. Martial artists were significantly more aggressive than controls, with increased MD in parietal and occipital areas and increased AD in widespread fiber tracts in the frontal, parietal and temporal areas. Positive associations between AD/MD and (physical) appetitive aggression were identified in several clusters, including the corpus callosum, the superior longitudinal fasciculus and the corona radiata. Our study found evidence for WM microstructural changes associated with aggressiveness in a community case-control sample. Longitudinal studies with larger cohorts, taking into account the dimensional nature of aggressiveness, are needed to better understand the underlying neurobiology.

Gray matter volume differences in intimate partner violence perpetrators and its role in explaining dropout and recidivism

AIM

Psychological instruments that are employed to adequately explain treatment compliance and recidivism of intimate partner violence (IPV) perpetrators present a limited ability and certain biases. Therefore, it becomes necessary to incorporate new techniques, such as magnetic resonance imaging (MRI), to be able to surpass those limitations and measure central nervous system characteristics to explain dropout (premature abandonment of intervention) and recidivism.

METHOD

The main objectives of this study were: 1) to assess whether IPV perpetrators (n = 60) showed differences in terms of their brain's regional gray matter volume (GMV) when compared to a control group of non-violent men (n = 57); 2) to analyze whether the regional GMV of IPV perpetrators before starting a tailored intervention program explain treatment compliance (dropout) and recidivism rate.

RESULTS

IPV perpetrators presented increased GMV in the cerebellum and the occipital, temporal, and subcortical brain regions compared to controls. There were also bilateral differences in the occipital pole and subcortical structures (thalamus, and putamen), with IPV perpetrators presenting reduced GMV in the above-mentioned brain regions compared to controls. Moreover, while a reduced GMV of the left pallidum explained dropout, a considerable number of frontal, temporal, parietal, occipital, subcortical and limbic regions added to dropout to explain recidivism.

CONCLUSIONS

Our study found that certain brain structures not only distinguished IPV perpetrators from controls but also played a role in explaining dropout and recidivism. Given the multifactorial nature of IPV perpetration, it is crucial to combine neuroimaging techniques with other psychological instruments to effectively create risk profiles of IPV perpetrators.

Impulsivity in first-degree relatives at risk of psychosis and mania: a systematic review and meta-analysis

Impulsivity is elevated in psychosis and during mania in bipolar disorder. Studies in unaffected relatives may help establish whether impulsivity is a heritable, state independent endophenotype. The aim of this systematic review and meta-analysis was to examine whether impulsivity is elevated in unaffected relatives of those with bipolar disorder, schizophrenia, and schizoaffective disorder, compared to controls. Databases were systematically searched up until March 2023 for articles reporting data on a behavioral or self-report measure of impulsivity in first-degree relatives and controls. Nineteen studies were included. Behavioral (10 studies, d = 0.35, p < 0.001) and self-reported impulsivity was significantly elevated in bipolar disorder relatives compared to controls (5 studies, d = 0.46, p < 0.001), with small effect sizes. Relatives of those with schizophrenia did not show significantly elevated impulsivity compared to controls on behavioral measures (6 studies, d = 0.42, p = 0.102). There were not enough studies to conduct a meta-analysis on self-report data in schizophrenia relatives or schizoaffective disorder relatives (self-report or behavioral). Study quality was good, however there was moderate to high heterogeneity in behavioral meta-analyses. Results suggest elevated impulsivity may be an endophenotype for bipolar disorder, present in an attenuated state before and after the illness and in at-risk individuals. This trait, amongst other behavioral and psychological indices, could be used to identify those who are at risk of developing bipolar disorder. Future research should refine measurement across studies and establish which components of impulsivity are affected in those at risk of psychotic and bipolar disorders.

Mapping Lesion-Related Human Aggression to a Common Brain Network

BACKGROUND

Aggression exacts a significant toll on human societies and is highly prevalent among neuropsychiatric patients. The neural mechanisms of aggression are unclear and treatment options are limited.

METHODS

Using a recently validated lesion network mapping technique, we derived an aggression-associated network by analyzing data from 182 patients who had experienced penetrating head injuries during their service in the Vietnam War. To test whether damage to this lesion-derived network would increase the risk of aggression-related neuropsychiatric symptoms, we used the Harvard Lesion Repository (N = 852). To explore potential therapeutic relevance of this network, we used an independent deep brain stimulation dataset of 25 patients with epilepsy, in which irritability and aggression are known potential side effects.

RESULTS

We found that lesions associated with aggression occurred in many different brain locations but were characterized by a specific brain network defined by functional connectivity to a hub region in the right prefrontal cortex. This network involves positive connectivity to the ventromedial prefrontal cortex, dorsolateral prefrontal cortex, frontal pole, posterior cingulate cortex, anterior cingulate cortex, temporal-parietal junction, and lateral temporal lobe and negative connectivity to the amygdala, hippocampus, insula, and visual cortex. Among all 24 neuropsychiatric symptoms included in the Harvard Lesion Repository, criminality demonstrated the most alignment with our aggression-associated network. Deep brain stimulation site connectivity to this same network was associated with increased irritability.

CONCLUSIONS

We conclude that brain lesions associated with aggression map to a specific human brain circuit, and the functionally connected regions in this circuit provide testable targets for therapeutic neuromodulation.

Stress enhances aggression in male rats with genetic stress hyper-reactivity

The current study investigated stress-induced aggressive behavior in the resident-intruder test in males of the genetically stress hyper-reactive Wistar Kyoto More Immobile (WMI), and the nearly isogenic, control Wistar Kyoto Less Immobile (WLI) strains. Tests were carried out against same-age intruders during adolescence, and same-age and juvenile intruders in adulthood. In adolescence and adulthood, prior acute restraint stress decreased social interactions and decreased aggressive behaviors of adolescents and adult WLIs. However, prior stress precipitated aggression in the adult WMI males toward both same-age, and juvenile intruders compared with control WMIs and WLIs. Trunk blood levels of testosterone and androstenedione increased in stressed WLIs, but not in WMIs, suggesting no direct role of androgens in the increased aggression of WMIs. Expressions of aggression-relevant genes showed patterns commensurate with being causative in aggressive behavior. The methyl-CpG binding protein 2 was lower in the frontal cortex of control WMIs, and in the amygdala of stressed WMIs compared with their respective WLIs. Frontal cortex expression of vasopressin receptor 1a and serotonin transporter increased, solely in WMI males after stress. As behaviors were the same toward same-age and non-threatening juvenile intruders, the stress-induced increase in confrontational behavior of the adult WMI male was not because of enhanced fear or anxiety. These results suggest that genetic stress hyper-reactivity is a risk factor for stress-induced increases in aggression in males. Additionally, as known aggression-related genes showed expression patterns paralleling aggressive behavior, this model system could identify novel molecular pathways leading to stress-enhanced aggression.

Impulsivity as a predictor of clinical and psychological outcomes in a naturalistic prospective cohort of subjects at ultra-high risk (UHR) for psychosis from Tunisia

BACKGROUND

Impulsivity is associated with serious detrimental consequences on physical, mental, behavioral and social aspects of health among patients with psychosis. The present prospective 12-month follow-up study aimed to determine the prevalence of highly impulsive individuals among Ultra High Risk (UHR) patients, how impulsivity evolves over the follow-up period, and whether impulsivity impacts clinical, psychological and functional outcomes in this population.

METHOD

UHR patients were invited to complete a battery of measurements at three-time points: at baseline, and at 6 and 12 months of follow-up. Impulsivity was assessed using both behavioral (the Wisconsin Card Sorting Test, WCST) and self-report (the Barratt Impulsiveness Scale, BIS-11) measures.

RESULTS

Findings showed that at 6 months of follow-up, higher 6-month BIS-11 attentional and motor impulsivity were significantly associated with lower quality of life and greater general psychological distress. In addition, higher baseline BIS-11 motor impulsivity significantly predicted more severe positive psychotic symptoms at 12 months of follow-up. However, WCST scores did not show any significant associations with study variables at the different times of follow-up.

CONCLUSION

Interventions targeting impulsivity in UHR individuals could help decrease psychological distress and positive psychotic symptoms' severity, as well as improve quality of life in UHR individuals.

Violent extremism in the U.S.: Causes and consequences for youth, families, schools, and communities

Violent extremism in the United States has surged over the past 25 years, with attacks on and threats to major governmental and other institutions, infrastructure (e.g., electric grid), and specific segments of the population, including immigrant and BIPOC (Black, Indigenous, and other People of Color) communities. Violent extremism can take multiple and diverse forms, such as bombings in public spaces or specific sites (e.g., house of worship, governmental office), mass and more targeted types of shootings, bombings, fire setting, and vehicle-based ramming attacks. This article provides an overview of key issues surrounding terrorism and violent extremism, especially as they can impact youth, schools, and families. Characteristics of violent extremism, radicalization processes, subsequent types of harm, and prevention approaches are discussed. Issues impacting students and schools and the work of school psychologists are also considered. The article closes with broader recommendations for moving forward.

Large-scale meta-analyses and network analyses of neural substrates underlying human escalated aggression

Escalated aggression represents a frequent and severe form of violence, sometimes manifesting as antisocial behavior. Driven by the pressures of modern life, escalated aggression is of particular concern due to its rising prevalence and its destructive impact on both individual well-being and socioeconomic stability. However, a consistent neural circuitry underpinning it remains to be definitively identified. Here, we addressed this issue by comparing brain alterations between individuals with escalated aggression and those without such behavioral manifestations. We first conducted a meta-analysis to synthesize previous neuroimaging studies on functional and structural alterations of escalated aggression (325 experiments, 2997 foci, 16,529 subjects). Following-up network and functional decoding analyses were conducted to provide quantitative characterizations of the identified brain regions. Our results revealed that brain regions constantly involved in escalated aggression were localized in the subcortical network (amygdala and lateral orbitofrontal cortex) associated with emotion processing, the default mode network (dorsal medial prefrontal cortex and middle temporal gyrus) associated with mentalizing, and the salience network (anterior cingulate cortex and anterior insula) associated with cognitive control. These findings were further supported by additional meta-analyses on emotion processing, mentalizing, and cognitive control, all of which showed conjunction with the brain regions identified in the escalated aggression. Together, these findings advance the understanding of the risk biomarkers of escalated aggressive populations and refine theoretical models of human aggression.

Altered local intrinsic neural activity and molecular architecture in internet use disorders

BACKGROUND

Internet gaming disorder (IGD) is mainly characterized by its core dysfunction in higher-order brain cortices involved in inhibitory control, whose neurobiological basis remains unclear. Then, we will investigate local intrinsic neural activity (INA) alterations in IGD, ascertain whether these potential alterations are related to clinical characteristics, and further explore the underlying molecular architecture.

METHOD

In this study, we performed the fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo) derived from resting-state functional magnetic resonance imaging (rs-fMRI) to explore the impact of IGD on local INA. Correlation analysis revealed the relationship between ReHo and fALFF in terms of group differences and clinical characteristics. Moreover, correlations between fALFF, ReHo, and PET- and SPECT-driven maps were investigated to elucidate the specific molecular architecture alternations in IGD. Finally, receiver operating characteristic curve (ROC) analysis was used to show the potential abilities of fALFF and ReHo in distinguishing individuals with IGD (IGDs) from healthy controls (HCs).

RESULT

Compared with HCs, IGDs revealed increased ReHo and fALFF in the prefrontal cortex. Significantly decreased ReHo was observed in the temporal lobe, occipital lobe, and cerebellum. In addition, the ReHo values in the cerebellum_7b_R were positively correlated with internet addiction severity. ROC curve analysis showed that ReHo and fALFF-altered brain regions could effectively distinguish IGDs from HCs. More importantly, cross-modal correlations revealed local INA changes in brain regions associated with the monoamine neurotransmitter system and the less studied cholinergic/GABAergic system.

CONCLUSION

These results suggest that local functional impairments are shown in the audiovisual and inhibitory control circuits in IGDs. This may be associated with underlying neurotransmitter system alterations. Therefore, this study provides the possibility of GABAergic receptor agonists and cholinergic receptor inhibitors for the treatment of IGD.

Patterns of Neuropsychiatric Manifestations of Ovarian Teratomas: A Systematic Review of Case Reports

Ovarian teratomas are germ cell tumors composed of multiple cell types. Ovarian teratomas may express antigens found in the nervous system or neuroendocrine proteins. These neural antigens and neuroendocrine proteins may lead to an autoimmune response with associated encephalitis. There are a growing number of case reports of autoimmune encephalitis in patients with ovarian teratomas. However, the patterns of neuropsychiatric manifestations of ovarian teratomas associated with encephalitis have not been established. The aim of this article is to conduct a systematic review to determine the patterns of neuropsychiatric manifestations of ovarian teratoma-associated encephalitis, focusing on their frequency and clinical course. Thirty-three case reports were collected and analyzed for a systematic review. The studies were full-text, peer-reviewed journal publications from April 2014 to April 2024. Fifty-eight patients were included in our study. The age group of 22-35 years old was the most reported, with 25 (43.1%) patients. The most commonly reported symptoms were memory impairment in 29 (50%) patients, hallucinations in 25 (43.1%) patients, and aggressive behavior in 23 (39.7%) patients. Neuropsychiatric symptoms had a prodromal phase of flu-like symptoms in 31 (53.4%) patients. The neuropsychiatric symptoms preceded the diagnosis of ovarian teratoma in 57 (98.3%) patients. In 53 (91.4%) patients, patients did not respond to psychiatric medications. Autoimmune antibodies to neural antigens were found in 45 (77.6%) patients, with 25 (43.1%) patients having neural tissue present in the teratoma. Treatment of the underlying teratoma and encephalitis led to full recovery in 37 (63.8%) patients. However, long-term outcomes such as relapse and mortality were discussed in only 11 (19.0%) patients. Findings suggest that neuropsychiatric symptoms correlate with teratoma-associated encephalitis and often precede tumor detection. The treatment of the teratoma led to full recovery of the neuropsychiatric manifestations; however, the long-term outcomes of the patients need to be further studied. Future research is needed on the prognosis of patients with neuropsychiatric manifestations of ovarian teratoma.

Potential association between suicide risk, aggression, impulsivity, and the somatosensory system

Aggression and impulsivity are linked to suicidal behaviors, but their relationship to the suicidal crisis remains unclear. This magnetoencephalography (MEG) study investigated the link between aggression, impulsivity, and resting-state MEG power and connectivity. Four risk groups were enrolled: high-risk (HR; n = 14), who had a recent suicidal crisis; lower-risk (LR; n = 41), who had a history of suicide attempts but no suicide attempt or ideation in the past year; clinical control (CC; n = 38), who had anxiety/mood disorders but no suicidal history; and minimal risk (MR; n = 28), who had no psychiatric/suicidal history. No difference in resting-state MEG power was observed between the groups. Individuals in the HR group with high self-reported aggression and impulsivity scores had reduced MEG power in regions responsible for sensory/emotion regulation vs. those in the HR group with low scores. The HR group also showed downregulated bidirectional glutamatergic feedback between the precuneus (PRE) and insula (INS) compared to the LR, CC, and MR groups. High self-reported impulsivity was linked to reduced PRE to INS feedback, whereas high risk-taking impulsivity was linked to upregulated INS to postcentral gyrus (PCG) and PCG to INS feedback. These preliminary findings suggest that glutamatergic-mediated sensory and emotion-regulation processes may function as potential suicide risk markers.

Physical Violence and Aggression in Parkinson's Disease: A Systematic Review

BACKGROUND

Physical violence and aggression (PVA), defined as behaviors with the potential to cause bodily injury, are unfortunate risks in the management of all-cause neurodegenerative dementias. While dementia in Parkinson's disease (PD) may not be evident for many years after clinical onset, neuropsychiatric disturbances occur at all stages of the disease. At issue is whether PVA in PD is associated with clinical factors that can be targets for prevention and management in the absence of a prevailing dementia syndrome.

OBJECTIVE

This systematic review examined the extent to which PVA in PD without dementia is a clinically significant concern and whether it is associated with factors that could warrant proactive management.

METHODS

A systematic search of 9 electronic databases used MeSH headings and equivalent terms for PD, aggression, and violence. Eligible manuscripts were original articles that were published in peer-reviewed journals and reported on adults with PD in the awake state with PVA as possible outcomes. Extracted data included study design, PD ascertainment methods and characteristics, PVA assessment methods, subject demographics, psychiatric and medical comorbidities, and pertinent results. Inciting and confounding factors were extracted from case reports. Quality assessment tools were applied in accordance with the study design (e.g., observational, qualitative, or case report).

RESULTS

The search identified 10 manuscripts: 2 observational quantitative studies (total n with PD = 545), 1 qualitative study (n with PD = 20), and 7 case reports (n = 7). The observational studies suggested that PVA is less common than other neuropsychiatric disturbances, but heterogeneous methods and quality concerns prevented further conclusions. In the case reports, all patients were male, and most were early onset. In 6 of the reports, PVA occurred in the context of bilateral subthalamic nucleus deep brain stimulation.

CONCLUSIONS

PVA, while relatively rare in PD, can be a significant management issue that is associated with select premorbid characteristics and antiparkinsonian motor treatments. As PVA may be under-reported, further understanding of its frequency, causes, risk factors, and outcomes would benefit from its systematic assessment, ideally using self-report and informant-based questionnaires.

Solving the Global Opioid Crisis: Incorporating Genetic Addiction Risk Assessment with Personalized Dopaminergic Homeostatic Therapy and Awareness Integration Therapy

Objectives

The opioid crisis in the last few decades has mounted to a global level, impacting all areas of socioeconomic, demographic, geographic, and cultural boundaries. Traditional treatments have not been deemed to show the degree of efficacy necessary to address the crisis. The authors of this review paper have set forth an unprecedented and in-depth look into multi-factorial determinants that have contributed to the opioid crisis becoming global and multi-faceted.

Methods

For this narrative review/opinion article, we searched PsychINFO, PubMed, Google Scholar, and Web of Science databases to identify relevant articles on topics including the "opioid crisis," "opioid mechanisms," "genetics and epigenetics," "neuropharmacology," and "clinical aspects of opioid treatment and prevention." Since this was not a systematic review the articles selected could represent unitential bias.

Results

Despite some success achieved through Opioid Substitution Therapy (OST) in harm reduction, the annual mortality toll in the US alone surpasses 106,699 individuals, a figure expected to climb to 165,000 by 2025. Data from the Substance Abuse and Mental Health Services Administration's (SAMHSA) National Survey on Drug Abuse and Health (NSDUH) reveals that approximately 21.4% of individuals in the US engaged in illicit drug use in 2020, with 40.3 million individuals aged 12 or older experiencing a Substance Use Disorder (SUD). Provisional figures from the Centers for Disease Control and Prevention (CDC) indicate a troubling 15% increase in overdose deaths in 2021, rising from 93,655 in 2020 to 107,622, with opioids accounting for roughly 80,816 of these deaths.

Conclusions

We advocate reevaluating the "standard of care" and shifting towards inducing dopamine homeostasis by manipulating key neurotransmitter systems within the brain's reward cascade. We propose a paradigm shift towards a novel "standard of care" that begins with incorporating Genetic Addiction Risk Severity (GARS) testing to assess pre-addiction risk and vulnerability to opioid-induced addiction; emphasis should be placed on inducing dopamine homeostasis through safe and non-addictive alternatives like KB220, and comprehensive treatment approaches that address psychological, spiritual, and societal aspects of addiction through Awareness Integration Therapy (AIT).

Studying dominance and aggression requires ethologically relevant paradigms

Although aggression is associated with several psychiatric disorders, there is no effective treatment nor a rigorous definition for "pathological aggression". Mice make a valuable model for studying aggression. They have a dynamic social structure that depends on the habitat and includes reciprocal interactions between the mice's aggression levels, social dominance hierarchy (SDH), and resource allocation. Nevertheless, the classical behavioral tests for territorial aggression and SDH in mice are reductive and have limited ethological and translational relevance. Recent work has explored the use of semi-natural environments to simultaneously study dominance-related behaviors, resource allocation, and aggressive behavior. Semi-natural setups allow experimental control of the environment combined with manipulations of neural activity. We argue that these setups can help bridge the translational gap in aggression research toward discovering neuronal mechanisms underlying maladaptive aggression.

PROTOCOL: The efficacy of nutritional interventions in reducing childhood/youth aggressive and antisocial behavior: A systematic review and meta-analysis

This is a protocol for a Campbell systematic review of intervention effectiveness. The goal of this systematic review is to answer the following questions based on the available empirical evidence: Are there nutritional interventions (dietary manipulation, fortification or supplementation) that can reduce excessive aggression towards others in children/youth? If yes, how strong is their effect and is there a difference among the three intervention types? Are there nutritional interventions that can reduce antisocial behaviors in children/youth? If yes, how strong is their effect and is there a difference among the intervention types? Are there nutritional interventions that can reduce violent offending in children/youth? If yes, how strong is their effect and is there a difference among the intervention types? Are there nutritional interventions that can reduce non-violent offending in children/youth? If yes, how strong is their effect and is there a difference among the intervention types? What implementation barriers and solutions to these exist in relation to the above nutritional interventions in children/youth?

Intimate partner violence perpetration among veterans: associations with neuropsychiatric symptoms and limbic microstructure

Background

Intimate partner violence (IPV) perpetration is highly prevalent among veterans. Suggested risk factors of IPV perpetration include combat exposure, post-traumatic stress disorder (PTSD), depression, alcohol use, and mild traumatic brain injury (mTBI). While the underlying brain pathophysiological characteristics associated with IPV perpetration remain largely unknown, previous studies have linked aggression and violence to alterations of the limbic system. Here, we investigate whether IPV perpetration is associated with limbic microstructural abnormalities in military veterans. Further, we test the effect of potential risk factors (i.e., PTSD, depression, substance use disorder, mTBI, and war zone-related stress) on the prevalence of IPV perpetration.

Methods

Structural and diffusion-weighted magnetic resonance imaging (dMRI) data were acquired from 49 male veterans of the Iraq and Afghanistan wars (Operation Enduring Freedom/Operation Iraqi Freedom; OEF/OIF) of the Translational Research Center for TBI and Stress Disorders (TRACTS) study. IPV perpetration was assessed using the psychological aggression and physical assault sub-scales of the Revised Conflict Tactics Scales (CTS2). Odds ratios were calculated to assess the likelihood of IPV perpetration in veterans with either of the following diagnoses: PTSD, depression, substance use disorder, or mTBI. Fractional anisotropy tissue (FA) measures were calculated for limbic gray matter structures (amygdala-hippocampus complex, cingulate, parahippocampal gyrus, entorhinal cortex). Partial correlations were calculated between IPV perpetration, neuropsychiatric symptoms, and FA.

Results

Veterans with a diagnosis of PTSD, depression, substance use disorder, or mTBI had higher odds of perpetrating IPV. Greater war zone-related stress, and symptom severity of PTSD, depression, and mTBI were significantly associated with IPV perpetration. CTS2 (psychological aggression), a measure of IPV perpetration, was associated with higher FA in the right amygdala-hippocampus complex (r = 0.400, p = 0.005).

Conclusion

Veterans with psychiatric disorders and/or mTBI exhibit higher odds of engaging in IPV perpetration. Further, the more severe the symptoms of PTSD, depression, or TBI, and the greater the war zone-related stress, the greater the frequency of IPV perpetration. Moreover, we report a significant association between psychological aggression against an intimate partner and microstructural alterations in the right amygdala-hippocampus complex. These findings suggest the possibility of a structural brain correlate underlying IPV perpetration that requires further research.

Aggression modulator: Understanding the multifaceted role of the dorsal raphe nucleus

Aggressive behavior is instinctively driven behavior that helps animals to survive and reproduce and is closely related to multiple behavioral and physiological processes. The dorsal raphe nucleus (DRN) is an evolutionarily conserved midbrain structure that regulates aggressive behavior by integrating diverse brain inputs. The DRN consists predominantly of serotonergic (5-HT:5-hydroxytryptamine) neurons and decreased 5-HT activity was classically thought to increase aggression. However, recent studies challenge this 5-HT deficiency model, revealing a more complex role for the DRN 5-HT system in aggression. Furthermore, emerging evidence has shown that non-5-HT populations in the DRN and specific neural circuits contribute to the escalation of aggressive behavior. This review argues that the DRN serves as a multifaceted modulator of aggression, acting not only via 5-HT but also via other neurotransmitters and neural pathways, as well as different subsets of 5-HT neurons. In addition, we discuss the contribution of DRN neurons in the behavioral and physiological aspects implicated in aggressive behavior, such as arousal, reward, and impulsivity, to further our understanding of DRN-mediated aggression modulation.

Effects of polygenes, parent-child relationship and frustration on junior high school students' aggressive behaviors

The effects of the interaction between polygenes and the parent-child relationship on junior high school students' aggressive behaviors were explored through the frameworks of gene-endophenotype-behavior and neurophysiological basis. A total of 892 junior high school students participated in this study. They were asked to complete self-reported questionnaires, and saliva samples were collected. Results showed that 5-HTTLPR, MAOA-uVNTR, COMT (rs4680), and Taq1 (rs1800497) of the DRD2 gene affected students' aggressive behaviors in an accumulative way. The polygenic risk score explained 3.4% of boys' aggression and 1.1% of girls' aggression. The interactions between polygenic risk score and parent-child conflict significantly affected the aggressive behaviors of male students, but did not show any significant effect on those of female students. The interactional effect of polygenic risk score and parent-child conflict on junior high school students' aggressive behaviors was completely mediated by frustration. However, the interaction effect of polygenic risk score and parent-child affinity on aggression was not affected by frustration. This study helps us better understand junior high school students' aggressive behaviors and promotes the prevention and correction of adolescents' problem behaviors.

Machine Learning for prediction of violent behaviors in schizophrenia spectrum disorders: a systematic review

Background

Schizophrenia spectrum disorders (SSD) can be associated with an increased risk of violent behavior (VB), which can harm patients, others, and properties. Prediction of VB could help reduce the SSD burden on patients and healthcare systems. Some recent studies have used machine learning (ML) algorithms to identify SSD patients at risk of VB. In this article, we aimed to review studies that used ML to predict VB in SSD patients and discuss the most successful ML methods and predictors of VB.

Methods

We performed a systematic search in PubMed, Web of Sciences, Embase, and PsycINFO on September 30, 2023, to identify studies on the application of ML in predicting VB in SSD patients.

Results

We included 18 studies with data from 11,733 patients diagnosed with SSD. Different ML models demonstrated mixed performance with an area under the receiver operating characteristic curve of 0.56-0.95 and an accuracy of 50.27-90.67% in predicting violence among SSD patients. Our comparative analysis demonstrated a superior performance for the gradient boosting model, compared to other ML models in predicting VB among SSD patients. Various sociodemographic, clinical, metabolic, and neuroimaging features were associated with VB, with age and olanzapine equivalent dose at the time of discharge being the most frequently identified factors.

Conclusion

ML models demonstrated varied VB prediction performance in SSD patients, with gradient boosting outperforming. Further research is warranted for clinical applications of ML methods in this field.

Identity Fusion and Aggressive Behavior Among Chinese Freshmen: The Chain Mediating Role of Depressive Mood and Sleep Quality

Aggressive behavior is considered one of the indicators of maladjustment and increases during the transition to college. Previous studies have demonstrated that having identity fusion with particular social groups significantly predicts college adjustment among freshmen. However, the relationship between identity fusion and aggressive behavior in college freshmen has rarely been studied. Thus, guided by the frustration-aggression theory, this study aimed to explore the association between identity fusion with class and aggressive behavior among Chinese college freshmen and examine the potential mediating roles of depressive mood and sleep quality. A cross-sectional survey study was carried out among 1,037 Chinese college freshmen (Mage = 19.56, SD = 1.068, 29.12% males). Class identity fusion, depressive mood, sleep quality, and aggressive behavior were measured via four self-reported questionnaires. Structural equation modeling was used to test the mediation model. Analyses showed that identity fusion was negatively related to depressive mood and aggressive behavior and positively correlated with sleep quality. The results also revealed that the direct effect of identity fusion on aggressive behavior was significant, and identity fusion can indirectly affect aggressive behavior not only through the mediation effect of depressive mood but also through the chain mediation effect of depressive mood and sleep quality. Moreover, the mediating effect of depressive mood varied by gender. These findings suggest that strategies that help freshmen promote identity fusion and those that alleviate depressive mood and sleep problem may help reduce aggressive behavior.

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.

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.

Characterizing the role of impulsivity in costly, reactive aggression using a novel paradigm

A lack of self-control has long been theorized to predict an individual's likelihood to engage in antisocial behaviors. However, existing definitions of self-control encompass multiple psychological constructs and lab-based measures of aggression have not allowed for the examination of aggression upon provocation where self-control is needed most. We introduce two versions of a novel paradigm, the Retaliate or Carry-on: Reactive AGgression Experiment (RC-RAGE) to fill this methodological gap. Using large online samples of US adults (N = 354 and N = 366), we evaluate to what extent dispositional impulsivity, self-control, aggression, and state anger contribute to aggression upon provocation when there is a financial cost involved. Results showed that costly retaliation on this task was related to trait aggression and being in an angry emotional state, but not related to social desirability. Importantly, we show that the tendency to act impulsively is a better predictor of costly retaliation than other forms of self-control, such as the ability to delay gratification, resist temptation, or plan ahead. As a browser-based task, the RC-RAGE provides a tool for the future investigation of reactive aggression in a variety of experimental settings.

The serotonin blocker Ketanserin reduces coral reef fish Ctenochaetus striatus aggressive behaviour during between-species social interactions

A multitude of species engages in social interactions not only with their conspecifics but also with other species. Such interspecific interactions can be either positive, like helping, or negative, like aggressive behaviour. However, the physiological mechanisms of these behaviours remain unclear. Here, we manipulated the serotonin system, a well-known neurohormone for regulating intraspecific aggressive behaviour, to investigate its role in interspecific aggression. We tested whether serotonin blockade affects the aggressive behaviour of a coral reef fish species (Ctenochaetus striatus) that engages in mutualistic interactions with another species, the cleaner fish (Labroides dimidiatus). Although this mutualistic cleaning relationship may appear positive, cleaner fish do not always cooperate and remove ectoparasites from the other coral reef fish ("clients") but tend to cheat and bite the client's protective layer of mucus. Client fish thus often apply control mechanisms, like chasing, to deter their cleaner fish partners from cheating. Our findings show that blocking serotonin receptors 5-HT2A and 5-HT2C with ketanserin reduced the client fish's aggressive behaviour towards cleaner fish, but in the context where the latter did not cheat. These results are evidence of the involvement of serotonin in regulating aggressive behaviour at the between-species social interactions level. Yet, the direction of effect we found here is the opposite of previous findings using a similar experimental set-up and ecological context but with a different client fish species (Scolopsis bilineatus). Together, it suggests that serotonin's role in aggressive behaviour is complex, and at least in this mutualistic ecological context, its function is species-dependent. This warrants, to some extent, careful interpretations from single-species studies looking into the physiological mechanisms of social behaviour.

Neuroanatomical correlates of aggressiveness: a case-control voxel- and surface-based morphometric study

Aggression occurs across the population ranging on a symptom continuum. Most previous studies have used magnetic resonance imaging in clinical/forensic samples, which is associated with several confounding factors. The present study examined structural brain characteristics in two healthy samples differing only in their propensity for aggressive behavior. Voxel- and surface-based morphometry (SBM) analyses were performed on 29 male martial artists and 32 age-matched male controls. Martial artists had significantly increased mean gray matter volume in two frontal (left superior frontal gyrus and bilateral anterior cingulate cortex) and one parietal (bilateral posterior cingulate gyrus and precuneus) brain clusters compared to controls (whole brain: p < 0.001, cluster level: family-wise error (FWE)-corrected). SBM analyses revealed a trend for greater gyrification indices in martial artists compared to controls in the left lateral orbital frontal cortex and the left pars orbitalis (whole brain: p < 0.001, cluster level: FWE-corrected). The results indicate brain structural differences between martial artists and controls in frontal and parietal brain areas critical for emotion processing/inhibition of emotions as well as empathic processes. The present study highlights the importance of studying healthy subjects with a propensity for aggressive behavior in future structural MRI research on aggression.

Representational similarity analysis of self- versus other-processing: Effect of trait aggressiveness

In this study, using the self/other adjective judgment task, we aimed to explore how people perceive themselves in comparison to various other people, including friends, strangers, and those they dislike. Next, using representational similarity analysis, we sought to elucidate how these perceptual similarities and differences are represented in brain activity and how aggressiveness is related to these representations. Behavioral ratings show that, on average, people tend to consider themselves more like their friends than neutral strangers, and least like people they dislike. This pattern of similarity is positively correlated with neural representation in social and cognitive circuits of the brain and negatively correlated with neural representation in emotional centers that may represent emotional arousal associated with various social objects. Aggressiveness seems to predispose a person to a pattern of behavior that is the opposite of the average pattern, that is, a tendency to think of oneself as less like one's friends and more like one's enemies. This corresponds to an increase in the similarity of the behavioral representation with the representation in the emotional centers and a decrease in its similarity with the representation in the social and cognitive centers. This can be seen as evidence that in individuals prone to aggression, behavior in the social environment may depend to a greater extent on the representation of social objects in the emotional rather than social and cognitive brain circuits.

In Vivo Serotonin 5-HT2A Receptor Availability and Its Relationship with Aggression Traits in Healthy Individuals: A Positron Emission Tomography Study with C-11 MDL100907

Serotonergic neurotransmission has been associated with aggression in several psychiatric disorders. Human aggression is a continuum of traits, ranging from normal to pathological phenomena. However, the individual differences in serotonergic neurotransmission and their relationships with aggression traits in healthy individuals remain unclear. In this study, we explored the relationship between 5-HT2A receptor availability in vivo and aggression traits in healthy participants. Thirty-three healthy participants underwent 3-Tesla magnetic resonance imaging and positron emission tomography (PET) with [11C]MDL100907, a selective radioligand for 5-HT2A receptors. To quantify 5-HT2A receptor availability, the binding potential (BPND) was derived using the basis function implementation of the simplified reference tissue model, with the cerebellum as the reference region. The participants' aggression levels were assessed using the Buss-Perry Aggression Questionnaire. The voxel-based correlation analysis with age and sex as covariates revealed that the total aggression score was significantly positively correlated with [11C]MDL100907 BPND in the right middle temporal gyrus (MTG) pole, left fusiform gyrus (FUSI), right parahippocampal gyrus, and right hippocampus. The physical aggression subscale score had significant positive correlations with [11C]MDL100907 BPND in the left olfactory cortex, left orbital superior frontal gyrus (SFG), right anterior cingulate and paracingulate gyri, left orbitomedial SFG, left gyrus rectus, left MTG, left inferior temporal gyrus, and left angular gyrus. The verbal aggression subscale score showed significant positive correlations with [11C]MDL100907 BPND in the bilateral SFG, right medial SFG, left FUSI, and right MTG pole. Overall, our findings suggest the possibility of positive correlations between aggression traits and in vivo 5-HT2A receptor availability in healthy individuals. Future research should incorporate multimodal neuroimaging to investigate the downstream effects of 5-HT2A receptor-mediated signaling and integrate molecular and systems-level information in relation to aggression traits.

Neural correlates of aggression in personality disorders from the perspective of DSM-5 maladaptive traits: a systematic review

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published in 2013, includes an alternative model of personality disorders (AMPD) focusing on a maladaptive trait model utilized to diagnose several personality disorders. Borderline personality disorder (BPD) and antisocial personality disorder (ASPD) are two conditions categorized by AMPD that exhibit high rates of violence and aggression. Several of the traits outlined in the AMPD, including hostility, impulsivity, risk-taking, and callousness, have been previously linked to aggression in BPD and ASPD. However, to the best of our knowledge, there has never been a synthesis of neuroimaging studies that have investigated links between these traits and aggression in BPD and ASPD. To overcome this gap, we conducted a systematic review under the PRISMA framework to locate neuroimaging articles published since the release of AMPD linking trait anger/hostility, impulsivity, risk-taking, and callousness to aggression in BPD and ASPD. Key findings included the following: i) anger/hostility, associated with alterations in the interplay between prefrontal and subcortical regions (primarily the amygdala), may be a common factor explaining aggressive reactions to response to interpersonal threat or provocation; ii) alterations of fronto-temporal-limbic regions and serotonergic and endocannabinoid signaling systems may link impulsivity to aggression in BPD and ASPD; iii) weaker cortico-striatal connectivity could relate to greater risk taking and greater proclivity for violence. Insufficient evidence from neuroimaging articles was discerned to describe a relationship between callousness and aggression. Overall, results of this review reveal a relative paucity of neuroimaging studies examining AMPD traits relevant to aggression in BPD and ASPD. In addition to encouraging further investigation of neuroimaging markers of AMPD traits linked to aggression, we recommend multi-methodological designs, including the incorporation of other biomarkers, such as hormones and indices of physiological arousal, to fully expand our understanding of aggression in BPD and ASPD.

Prelimbic area to lateral hypothalamus circuit drives social aggression

Controlling aggression is a vital skill in social species such as rodents and humans and has been associated with the medial prefrontal cortex (mPFC). In this study, we showed that during aggressive behavior, the activity of GABAergic neurons in the prelimbic area (PL) of the mPFC was significantly suppressed. Specific activation of GABAergic PL neurons significantly curbed male-to-male aggression and inhibited conditioned place preference (CPP) for aggression-paired contexts, whereas specific inhibition of GABAergic PL neurons brought about the opposite effect. Moreover, GABAergic projections from PL neurons to the lateral hypothalamus (LH) orexinergic neurons mediated aggressive behavior. Finally, directly modulated LH-orexinergic neurons influence aggressive behavior. These results suggest that GABAergic PL-orexinergic LH projection is an important control circuit for intermale aggressive behavior, both of which could be targets for curbing aggression.

Mediating effect of amygdala activity on response to fear vs. happiness in youth with significant levels of irritability and disruptive mood and behavior disorders

Introduction

Irritability, characterized by a tendency to exhibit increased anger, is a common clinical problem in youth. Irritability is a significant clinical issue in youth with various psychiatric diagnoses, especially disruptive behavior, and mood disorders (Attention-Deficit/Hyperactivity Disorder, Oppositional Defiant Disorder, Conduct Disorder, and Disruptive Mood Dysregulation Disorder). Although there have been previous studies focusing on functional alteration in the amygdala related to irritability, there is no comprehensive model between emotional, neuronal, and behavioral characteristics.

Methods

Using an functional magnetic resonance imaging (fMRI) procedure, we investigated the relationships between behavioral irritability, selective impairments in processing facial emotions and the amygdala neural response in youth with increased irritability. Fifty-nine youth with disruptive mood and behavior disorder completed a facial expression processing task with an event-related fMRI paradigm. The severity of irritability was evaluated using the Affective Reactivity Index.

Results

In the result of behavioral data, irritability, and reaction time (RT) differences between interpreting negative (fear) and positive (happiness) facial expressions were positively correlated. In the fMRI result, youth showed higher activation in the right cingulate gyrus, bilateral cerebellum, right amygdala, right precuneus, right superior frontal gyrus, right middle occipital gyrus, and middle temporal gyrus, during the happiness condition vs. fear condition. No brain region exhibited greater activation in the fear than in the happiness conditions. In the result of the mediator analysis, increased irritability was associated with a longer RT toward positive vs. negative facial expressions. Irritability was also positively associated with the difference in amygdala blood oxygen level-dependent responses between the two emotional conditions (happiness > fear). This difference in amygdala activity mediated the interaction between irritability and the RT difference between negative and positive facial expressions.

Discussion

We suggest that impairment in the implicit processing of facial emotional expressions with different valences causes distinct patterns of amygdala response, which correlate with the level of irritability. These results broaden our understanding of the biological mechanism of irritability at the neural level and provide information for the future direction of the study.

Administration of α-lipoic acid and silymarin attenuates aggression by modulating endocrine, oxidative stress and inflammatory pathways in mice

Aggression, a highly prevalent behavior among all the psychological disorders having strong association with psychiatric imbalance, neuroendocrine changes and neurological disturbances (including oxidative stress & neuroinflammation) require both pharmacological and non-pharmacological treatments. Focusing the preclinical neuroendocrine determinants of aggression, this interventional study was designed to elucidate the curative effect of antioxidants on aggression in male mice. Adult albino male mice (n = 140) randomly divided into two main treatment groups for α-lipoic acid (ALA) and silymarin with 5 subgroups (n = 10) for each curative study, namely control, disease (aggression-induced), standard (diazepam, 2.5 mg/kg), low dose (100 mg/kg) and high dose (200 mg/kg) treatment groups of selected antioxidants. Resident-intruder paradigm and levodopa (L-dopa 375 mg/kg, p.o.) induced models were used for aggression. Effect of antioxidant treatment (i.e., 21 days bid) on aggression was assessed by evaluating the changes in aggressive behavior, oxidative stress biomarkers superoxide dismutase, catalase, glutathione, nitrite and malondialdehyde (SOD, CAT, GSH, nitrite & MDA), neurotransmitters (dopamine, nor-adrenaline and serotonin), pro-inflammatory cytokines tumor necrosis factor-α and interleukin- 6 (TNF-α & IL-6) along with serum testosterone examination. This study showed potential ameliorative effect on aggressive behavior with both low (100 mg/kg) and high (200 mg/kg) doses of antioxidants (ALA & silymarin). Resident-intruder or L-dopa induced aggression in male mice was more significantly tuned with ALA treatment than silymarin via down regulating both oxidative stress and inflammatory biomarkers. ALA also exhibited notable effects in managing aggression-induced disturbances on plasma testosterone levels. In conclusion, ALA is more effective than silymarin in attenuating aggression in mice.

Anger: an underappreciated destructive force in healthcare

Anger is an emotional state that occurs when unexpected things happen to or around oneself and is "an emotional state that varies in intensity from mild irritation to intense fury and rage." It is defined as "a strong feeling of displeasure and usually of antagonism," an emotion characterized by tension and hostility arising from frustration, real or imagined injury by another, or perceived injustice. It can manifest itself in behaviors designed to remove the object of the anger (e.g., determined action) or behaviors designed merely to express the emotion. For the Roman philosopher Seneca anger is not an uncontrollable, impulsive, or instinctive reaction. It is, rather, the cognitive assent that such initial reactions to the offending action or words are in fact unjustified. It is, rather, the cognitive assent that such initial reactions to the offending action or words are in fact unjustified. It seems that the year 2022 was a year when many Americans were plainly angry. "Why is everyone so angry?" the New York Times asked in the article "The Year We Lost It." We believe that Seneca is correct in that anger is unacceptable. Anger is a negative emotion that must be controlled, and Seneca provides us with the tools to avoid and destroy anger. Health care professionals will be more effective, content, and happier if they learn more about Seneca's writings about anger and implement his wisdom on anger from over 2000 years ago.

Self-reported traumatic brain injury in a sample of impulsive violent offenders: neuropsychiatric correlates and possible "dose effects"

Background

Traumatic brain injury (TBI) is a major public health problem that may be associated with numerous behavioral problems, including impulsivity, aggression and violence. Rates of self-reported TBI are high within offender populations, but the extent to which TBI is causally implicated in causing illegal behavior is unclear. This study examined the psychological and functional correlates of histories of traumatic brain injury in a sample of impulsive violent offenders.

Methods

Study participants, all men, had been recruited to participate in a randomized controlled trial of sertraline to reduce recidivism. Study entry criteria were an age of at least 18 years, a documented history of two or more violent offenses and a score of 70 or above on the Barratt Impulsiveness Scale. An extensive list of standardized questionnaires was administered to obtain information on previous TBI and other neuropsychiatric conditions or symptoms.

Results

In the sample of 693 men, 66% were aged between 18 and 35 years old, and 55% gave a history of TBI ("TBI+"). Overall, 55% of study participants reported at least one TBI. High levels of neuropsychiatric symptomatology were reported. In 75% of TBI+ individuals, their most severe TBI (by self-report) was associated with loss of consciousness (LOC) < 30 min. Compared to TBI- (those without history of TBI) participants, TBI+ individuals were more impulsive (Eysenck Impulsivity), irritable, angry, and reported higher levels of assaultive behavior, depressive symptomology, alcohol use disorder, suicidal ideation, suicide attempts, and lower quality of life. Potential "dose effects" of TBI severity and frequency in terms of neuropsychiatric symptomatology were identified.

Conclusion

Like other studies of offender populations, single and multiple TBIs were very common. The associations of TBI, TBI severity, and TBI frequency (i.e., TBI "burden") with adverse neuropsychiatric phenomena suggest TBI contributes importantly to offender morbidity but the select nature of the sample and cross-sectional study design constrain the interpretation of these findings.

Effects of childhood trauma on aggressive behaviors and hippocampal function: the modulation of COMT haplotypes

Background

Aggression is a commonly hostile behavior linked to the hippocampal activity. Childhood trauma (CT) exposure has been associated with altered sensitization of the hypothalamic-pituitary-adrenal (HPA) axis and hippocampal volume，which could increase violent aggressive behaviors. Additionally, Catechol-O-methyltransferase (COMT), the major dopamine metabolism enzyme, is implicated in stress responsivity, including aggression. Hence, CT exposure may affect aggression through the effect on the hippocampal function, which might also be modulated by the COMT variations.

Objectives

This study examined whether both CT and haplotypes of COMT moderate hippocampal function and thus affect human aggressive behavior.

Methods

We obtained bilateral hippocampal functional connectivity maps using resting state functional magnetic resonance imaging (MRI) data. COMT haplotype estimation was performed using Haploview 4.2 and PHASE 2.1. Then we constructed a moderated mediation model to study the effect of the CTQ × COMT on aggressive behavior.

Results

Three major haplotypes were generated from thirteen single nucleotide polymorphisms (SNPs) within the COMT gene and formed three haplotypes corresponding to high, medium, and low enzymatic activity of COMT. The results showed interactive relationships between the Childhood Trauma Questionnaire (CTQ) and COMT with respect to the functional connectivity (FC) of the bilateral hippocampus (HIP)-orbital frontal cortex (OFC). Specifically, CT experience predicted lower negative HIP-OFC coupling in the APS and HPS haplotypes corresponding to the medium and high enzymatic activity of COMT, but greater FC in the LPS haplotypes corresponding to the low enzymatic activity. We also observed a conditional mediation effect of the right HIP-OFC coupling in the link between COMT and aggressive behavior that was moderated by CT experience.

Conclusions

These results suggest that CT and COMT have a combined effect on aggressive behavior through hippocampal function. This mediation analysis sheds light on the influence of childhood experience on aggressive behavior in different genetic backgrounds.

Efficacy of increasing levels of exposure therapy in the treatment of maladaptive behaviors and anxiety

The present study examined the effectiveness of increasing levels of exposure therapy, which is applied for the treatment of maladaptive behaviors and anxiety. A total of 16 sessions were applied to the study group in the experimental group three times a week for 10 weeks. Patients aged ≥18 years whom the referring clinician evaluated as meeting the criteria for the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-V-TR) Generalized Anxiety Disorder were included in the study. For the control group, demographic characteristics and Spielberger's State-Trait Anxiety Inventory were applied in the first session, followed by Spielberger's State-Trait Anxiety Inventory as a post-test and follow-up. Electroencephalography (EEG) recordings of the study group were obtained at the cortical level. Electrodes for EEG measurements were recorded using the International 10/20 Electrode Placement System. EEG data were obtained using the EEG Analysis Program software. Following the data collection phase, all data were entered into cells based on items using SPSS 25 software. When the findings obtained in the study were examined, it was determined that the increasing levels of exposure and behavioral therapy applied for maladaptive anxiety decreased the anxiety levels compared to those before therapy. This finding can be interpreted as that the cortical function-oriented application method for anxiety effectively reduced the anxiety levels of the study group. However, EEG asymmetry revealed a change in the data before and after the application. These findings demonstrate that the application affects the EEG asymmetry changes at the cortical level.

Innovative Reports on the Effects of Anabolic Androgenic Steroid Abuse-How to Lose Your Mind for the Love of Sport

Anabolic-androgenic steroids (anabolic-androgenic steroids, AAS) are testosterone-derived compounds whose popularity and use are constantly growing. Chronic use of AAS leads to many hormonal and metabolic disorders in the human body, which often lead to permanent health damage. Changes affect the following systems: cardiovascular, musculoskeletal, reproductive, digestive, and nervous. We decided to collect the existing knowledge in the literature and enrich it with the latest research reports in the field of degenerative effects of AAS on the nervous system. The work aimed to increase public awareness of the dangers and consequences of AAS use and improve it with the latest research on the neurodegenerative effects of AAS. We hope that our work will contribute to raising public awareness and reducing the use of AAS.

Dopamine transporter blockade during adolescence increases adult dopamine function, impulsivity, and aggression

Sensitive developmental periods shape neural circuits and enable adaptation. However, they also engender vulnerability to factors that can perturb developmental trajectories. An understanding of sensitive period phenomena and mechanisms separate from sensory system development is still lacking, yet critical to understanding disease etiology and risk. The dopamine system is pivotal in controlling and shaping adolescent behaviors, and it undergoes heightened plasticity during that time, such that interference with dopamine signaling can have long-lasting behavioral consequences. Here we sought to gain mechanistic insight into this dopamine-sensitive period and its impact on behavior. In mice, dopamine transporter (DAT) blockade from postnatal (P) day 22 to 41 increases aggression and sensitivity to amphetamine (AMPH) behavioral stimulation in adulthood. Here, we refined this sensitive window to P32-41 and identified increased firing of dopaminergic neurons in vitro and in vivo as a neural correlate to altered adult behavior. Aggression can result from enhanced impulsivity and cognitive dysfunction, and dopamine regulates working memory and motivated behavior. Hence, we assessed these behavioral domains and found that P32-41 DAT blockade increases impulsivity but has no effect on cognition, working memory, or motivation in adulthood. Lastly, using optogenetics to drive dopamine neurons, we find that increased VTA but not SNc dopaminergic activity mimics the increase in impulsive behavior in the Go/NoGo task observed after adolescent DAT blockade. Together our data provide insight into the developmental origins of aggression and impulsivity that may ultimately improve diagnosis, prevention, and treatment strategies for related neuropsychiatric disorders.

Association Between Aggression and Differential Functional Activity of Neural Regions Implicated in Retaliation

OBJECTIVE

The goal of the current study was to determine the extent to which atypical neural responsiveness during retaliation is associated with observed aggression in youth in residential care.

METHOD

This functional magnetic resonance imaging study involved 83 adolescents (56 male and 27 female; mean age, 16.18 years) in residential care performing a retaliation task. Of the 83 adolescents, 42 displayed aggressive behavior within the first 3 months of residential care, whereas 41 did not. During the retaliation task, participants were offered either fair or unfair divisions of $20 pots (allocation phase) and could either accept the offer or reject it, and, by spending $1, $2, or $3, punish the partner (retaliation phase).

RESULTS

The study's main findings were that aggressive adolescent showed the following: reduced down-regulation of activity within regions involved in representing the expected value of choice options (left ventromedial prefrontal cortex and left posterior cingulate cortex) as a function of offer unfairness and retaliation level; and reduced recruitment of regions implicated in response control (right inferior frontal gyrus and bilateral anterior insular cortex) and associated fronto-parietal regions as a function of retaliation level. The aggressive adolescents were also significantly more likely to have been aggressive prior to residential care and showed a strong trend for increased retaliation on the task.

CONCLUSION

We suggest that individuals with a greater propensity for aggression show reduced representation of the negative consequences of retaliation and associated reduced recruitment of regions potentially involved in over-ruling these negative consequences to engage in retaliation.

DIVERSITY & INCLUSION STATEMENT

We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. We worked to ensure sex balance in the selection of non-human subjects. We actively worked to promote sex and gender balance in our author group. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work. While citing references scientifically relevant for this work, we also actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our reference list. While citing references scientifically relevant for this work, we also actively worked to promote sex and gender balance in our reference list. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group.

Deep brain stimulation may be a viable option for resistant to treatment aggression in children with intellectual disability

INTRODUCTION

Deep brain stimulation (DBS) is a surgical technique used to manage aggression in patients who do not improve despite the use of appropriate drug treatment.

OBJECTIVE

The objective of this study is to assess the impact of DBS on aggressive behavior refractory to the pharmacological and behavioral treatment of patients with Intellectual Disabilities (ID).

METHODS

A follow-up was conducted on a cohort of 12 patients with severe ID, undergoing DBS in posteromedial hypothalamic nuclei; evaluated with the Overt Aggression Scale (OAS), before the intervention, at 6, 12, and 18 months of medical follow-up.

RESULTS

After the surgical procedure, there was a significant reduction in the aggressiveness of patients in the follow-up medical evaluation at 6 months (t = 10.14; p < 0.01), 12 months (t = 14.06; p < 0.01), and 18 months (t = 15.34; p < 0.01), respect to the initial measurement; with a very large effect size (6 months: d = 2.71; 12 months: d = 3.75; 18 months: d = 4.10). From 12 months onward, emotional control stabilized and is sustained at 18 months (t = 1.24; p > 0.05).

CONCLUSION

DBS in posteromedial hypothalamic nuclei may be an effective treatment for the management of aggression in patients with ID refractory to pharmacological treatment.

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.

Reduction of aggressive behaviour following hypothalamic deep brain stimulation: Involvement of 5-HT1A and testosterone

BACKGROUND

Aggressive behaviour (AB) may occur in patients with different neuropsychiatric disorders. Although most patients respond to conventional treatments, a small percentage continue to experience AB despite optimized pharmacological management and are considered to be treatment-refractory. For these patients, hypothalamic deep brain stimulation (pHyp-DBS) has been investigated. The hypothalamus is a key structure in the neurocircuitry of AB. An imbalance between serotonin (5-HT) and steroid hormones seems to exacerbate AB.

OBJECTIVES

To test whether pHyp-DBS reduces aggressive behaviour in mice through mechanisms involving testosterone and 5-HT.

METHODS

Male mice were housed with females for two weeks. These resident animals tend to become territorial and aggressive towards intruder mice placed in their cages. Residents had electrodes implanted in the pHyp. DBS was administered for 5 h/day for 8 consecutive days prior to daily encounters with the intruder. After testing, blood and brains were recovered for measuring testosterone and 5-HT receptor density, respectively. In a second experiment, residents received WAY-100635 (5-HT_1A antagonist) or saline injections prior to pHyp-DBS. After the first 4 encounters, the injection allocation was crossed, and animals received the alternative treatment during the next 4 days.

RESULTS

DBS-treated mice showed reduced AB that was correlated with testosterone levels and an increase in 5-HT1_A receptor density in the orbitofrontal cortex and amygdala. Pre-treatment with WAY-100635 blocked the anti-aggressive effect of pHyp-DBS.

CONCLUSIONS

This study shows that pHyp-DBS reduces AB in mice via changes in testosterone and 5-HT1_A mechanisms.