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Since the heyday of research on aggression in the late 1960s, developments in several varied areas had enabled us to take a new look at this important though difficult topic. Recent findings and sophisticated new techniques in behavior genetic analysis at the time had made it possible not only to enhance our understanding of the genetic mechanisms underlying aggressive behavior, but also to provide some reasonable suggestions as to the role of aggression in evolution. Originally published in 1983, there had been significant advances in genetic and neural research and a much more sophisticated and heuristic approach to the measurement and conceptualization of aggressive behavior had developed. The ten chapters in this volume provide a thorough overview of these new approaches and methodologies. There are also suggestions regarding the scope of future research on aggressive behavior, since much of what is presented describes the ongoing research activities of the contributors. This book is divided into four sections: The first provides a systematic foundation for research on aggression, and a description of some of the newer strategies for research in this area; the second concerns quantitative genetic analyses, selection data from both wild and laboratory populations, and situational determinants of aggressive behavior; the third section details new and exciting findings in neurochemical and neuropharmacological effects; and the last section contains a chapter that provides a summary and synthesis of all that has come before.

This study provides a comprehensive overview of the materials and methods used to evaluate the effectiveness of the use of biofeedback in the treatment of aggressive episodes in children and adolescents. Aggressive episodes are common in various disorders and are associated with deficits in emotional processing and impulse control, primarily due to dysfunctions in the amygdala and prefrontal cortex (PFC). These brain regions also regulate physiological arousal, influencing heart rate and other autonomic functions even before aggression manifests. These early signals can be shown to the person (biofeedback) reinforcing therapeutic skills to enhance emotional regulation and reduce aggression. A total of 70 participants will be recruited for a randomized controlled trial (RCT). All participants will receive therapy, although only the intervention group will incorporate biofeedback. The experimental study will be split into three blocks: (1) Home Monitoring: Physiological signals will be recorded using a smartwatch, and aggressive episodes will be captured with a camera; (2) Laboratory Assessment: Participants will attend three sessions, where therapists will induce aggressive reactions, using the video clips recorded at home. Simultaneously, real-time physiological signals will be measured. These sessions will also include relaxation periods before and after the provoked outburst; (3) Therapeutic Intervention: Similar to the laboratory assessment block, therapists will induce aggressive responses in three sessions; however, in this block, participants will receive therapy. Additionally, participants who belong to the intervention group, will include biofeedack in the therapy. Biofeedback is focused on heart rate (HR), heart rate variability (HRV), and skin conductance level (SCL). The CACIA, the Stroop, and other pre- and post-experimental tests. will be used to assess the differences between the control and intervention groups. Emotions play a fundamental role in decision-making, social interactions, and mental health. Emotional dysregulation often leads to aggression, irritability, and anxiety. Showing physiological responses to patients, such as heart rate variability and skin conductance, may improve emotional awareness and regulation. This study aims to verify the effectiveness of including biofeedback in such therapy.

Sexual and aggressive behaviors are fundamental to animal survival and reproduction. The medial preoptic nucleus (MPN) and ventrolateral part of the ventromedial hypothalamus (VMHvl) are essential regions for male sexual and aggressive behaviors, respectively. While key inhibitory inputs to the VMHvl and MPN have been identified, the extrahypothalamic excitatory inputs essential for social behaviors remain elusive. Here we identify estrogen receptor alpha (Esr1)-expressing cells in the posterior amygdala (PA) as a main source of excitatory inputs to the hypothalamus and key mediators for mating and fighting in male mice. We find two largely distinct PA subpopulations that differ in connectivity, gene expression, in vivo responses and social behavior relevance. MPN-projecting PAEsr1+ cells are activated during mating and are necessary and sufficient for male sexual behaviors, while VMHvl-projecting PAEsr1+ cells are excited during intermale aggression and promote attacks. These findings place the PA as a key node in both male aggression and reproduction circuits.Yamaguchi et al. identify a little-known amygdalar region, the posterior amygdala, as a key node in male mouse social behaviors. Two largely non-overlapping subpopulations in the posterior amygdala form parallel projections to distinct hypothalamic regions to regulate mating and fighting.

Heightened aggression is characteristic of multiple neuropsychiatric disorders and can have various negative effects on patients, their families and the public. Recent studies in humans and animals have implicated brain reward circuits in aggression and suggest that, in subsets of aggressive individuals, domination of subordinate social targets is reinforcing. In this study, we showed that, in male mice, orexin neurons in the lateral hypothalamus activated a small population of glutamic acid decarboxylase 2 (GAD2)-expressing neurons in the lateral habenula (LHb) via orexin receptor 2 (OxR2) and that activation of these GAD2 neurons promoted male–male aggression and conditioned place preference for aggression-paired contexts. Moreover, LHb GAD2 neurons were inhibitory within the LHb and dampened the activity of the LHb as a whole. These results suggest that the orexin system is important for the regulation of inter-male aggressive behavior and provide the first functional evidence of a local inhibitory circuit within the LHb.Flanigan et al. show that activation of inhibitory neurons in the lateral habenula by the neuropeptide orexin (hypocretin) promotes both inter-male aggression and conditioned place preference for contexts associated with winning aggressive contests.

Previous research on aggression in martial arts and combat sports (MA&CS) has shown mixed results. Some studies showed that MA&CS training lowers aggression levels, while other studies found it increases aggression or has no effect. To explain better this inconsistency, this study used latent class analysis to identify distinct subgroups of MA&CS practitioners based on aggression levels and related demographic and sports factors. Previous research predominantly employed a variable-centered approach to investigate the relationships between variables and their impact on outcomes. This study adopts a person-centered approach to identify subgroups that exhibit similar patterns of aggression, thereby enhancing the understanding of individual differences through variable configurations. A cross-sectional study was conducted with 367 participants aged between 16 and 57 years old ( M  = 27.28, SD  = 9.52), including 23% of women, and 76% MA&CS athletes in such disciplines as Brazilian jiu-jitsu (BJJ), karate Kyokushin (KK), mixed martial arts (MMA), and wrestling. Participants completed paper-and-pencil self-report psychological questionnaires, including the Buss-Perry Aggression Questionnaire and provided demographic information. Latent class analysis was performed using aggression scores, age, gender, education, economic status, MA&CS training experience, and discipline. Three latent classes were identified: MA&CS Experts ( n  = 182), MA&CS Newbies ( n  = 95), and Non-Athletes ( n  = 90). Among MA&CS Experts were more women [χ 2 (2) = 14.55, p  < 0.001], older participants [H(2) = 236.42, p  < 0.001], more experienced [H(2) = 8.31, p  = 0.004], those with higher education [χ 2 (10) = 572.93, p  < 0.001] and economic status [χ 2 (8) = 60.67, p  < 0.001], and lower aggression scores [ F (2, 161) = 10.443, p  < 0.001], compared to MA&CS Newbies. MA&CS Newbies had higher physical aggression than Non-Athletes ( p  < 0.001). BJJ was overrepresented in the MA&CS Experts class, while KK and MMA were underrepresented [χ 2 (8) = 396.69, p  < 0.001]. The MA&CS Newbies included athletes representing all four MA&CS disciplines in a similar proportion. The results highlight the role of long-term MA&CS training in potentially reducing aggression, particularly hostility, physical aggression, and verbal aggression. Demographic factors like age, gender, education, and economic status were also important in distinguishing the latent classes. The findings suggest aggression in MA&CS is a complex phenomenon influenced by multiple socio-cultural factors. Both the type of MA&CS and socio-demographic factors should be controlled by researchers and sports coaches if the goal of training is to reduce aggression in martial arts athletes.

DNA methylation profiles of aggressive behavior may capture lifetime cumulative effects of genetic, stochastic, and environmental influences associated with aggression. Here, we report the first large meta-analysis of epigenome-wide association studies (EWAS) of aggressive behavior (N = 15,324 participants). In peripheral blood samples of 14,434 participants from 18 cohorts with mean ages ranging from 7 to 68 years, 13 methylation sites were significantly associated with aggression (alpha = 1.2 × 10−7; Bonferroni correction). In cord blood samples of 2425 children from five cohorts with aggression assessed at mean ages ranging from 4 to 7 years, 83% of these sites showed the same direction of association with childhood aggression (r = 0.74, p = 0.006) but no epigenome-wide significant sites were found. Top-sites (48 at a false discovery rate of 5% in the peripheral blood meta-analysis or in a combined meta-analysis of peripheral blood and cord blood) have been associated with chemical exposures, smoking, cognition, metabolic traits, and genetic variation (mQTLs). Three genes whose expression levels were associated with top-sites were previously linked to schizophrenia and general risk tolerance. At six CpGs, DNA methylation variation in blood mirrors variation in the brain. On average 44% (range = 3–82%) of the aggression–methylation association was explained by current and former smoking and BMI. These findings point at loci that are sensitive to chemical exposures with potential implications for neuronal functions. We hope these results to be a starting point for studies leading to applications as peripheral biomarkers and to reveal causal relationships with aggression and related traits.

This study provides a comprehensive overview of the materials and methods used to evaluate the effectiveness of the use of biofeedback in the treatment of aggressive episodes in children and adolescents. Aggressive episodes are common in various disorders and are associated with deficits in emotional processing and impulse control, primarily due to dysfunctions in the amygdala and prefrontal cortex (PFC). These brain regions also regulate physiological arousal, influencing heart rate and other autonomic functions even before aggression manifests. These early signals can be shown to the person (biofeedback) reinforcing therapeutic skills to enhance emotional regulation and reduce aggression. A total of 70 participants will be recruited for a randomized controlled trial (RCT). All participants will receive therapy, although only the intervention group will incorporate biofeedback. The experimental study will be split into three blocks: (1) Home Monitoring: Physiological signals will be recorded using a smartwatch, and aggressive episodes will be captured with a camera; (2) Laboratory Assessment: Participants will attend three sessions, where therapists will induce aggressive reactions, using the video clips recorded at home. Simultaneously, real-time physiological signals will be measured. These sessions will also include relaxation periods before and after the provoked outburst; (3) Therapeutic Intervention: Similar to the laboratory assessment block, therapists will induce aggressive responses in three sessions; however, in this block, participants will receive therapy. Additionally, participants who belong to the intervention group, will include biofeedack in the therapy. Biofeedback is focused on heart rate (HR), heart rate variability (HRV), and skin conductance level (SCL). The CACIA, the Stroop, and other pre- and post-experimental tests. will be used to assess the differences between the control and intervention groups. Emotions play a fundamental role in decision-making, social interactions, and mental health. Emotional dysregulation often leads to aggression, irritability, and anxiety. Showing physiological responses to patients, such as heart rate variability and skin conductance, may improve emotional awareness and regulation. This study aims to verify the effectiveness of including biofeedback in such therapy.

Background The purpose of this study was to investigate the relationship between anxiety proneness and aggressive behavior in adolescents. Methods A quantitative, large scale cross-sectional study was conducted in Korea. The survey questionnaire included general health behavior and scales for assessing anxiety (Revised Children’s Manifest Anxiety Scale; RCMAS) and aggressive behavior (The Aggression Questionnaire; AQ) in adolescents. Results A total of 2432 students participated in the survey, and 1933 individuals completed the questionnaire, indicating a response rate of 79.5%. Based on RCMAS, 163 (8.4%) subjects were classified as the anxiety group. Aggressive behavior was significantly associated with higher anxiety scores. In particular, among four subdomains of aggression, anger and hostility had a stronger relationship with anxiety than did physical and verbal aggression. Multivariate analysis demonstrated that anxiety was independently associated with gender, age, headache, constipation, asthma, and aggression score. Adolescents with total aggression scores of 69 or higher showed a 9-fold (AOR = 9.00, CI = 6.33–13.51) higher risk of anxiety compared to those with under 69. Conclusion Aggression and anxiety are important aspects of mental health in adolescents. Our results demonstrated that higher risk of anxiety was associated with total aggression scores. In particular, indirect aggression (i.e. anger and hostility) was more closely associated with anxiety than direct aggression.

For international students coming to China, the process of learning Chinese is very difficult. At the same time, chronic academic underachievement can lead to aggressive behavior (AB). Although physical activity (PA) has been shown to improve learning performance and psychological well-being, its effectiveness in Chinese language learning and AB has not been clarified. Therefore, the present study examined PA as the main variable and explored its dosage profile in Chinese learning and alleviation of AB. A total of 964 international students from different countries from 8 universities in Beijing were selected as the study population and were assessed using the International Physical Activity Questionnaire (IPAQ), Buss-Perry Aggression Questionnaire (BPAQ) and Hanyu Shuiping Kaoshi (HSK) for 3 longitudinal follow-ups. Analyses of variance, correlations and path models were performed using ANOVA, Pearson and cross-lagged panel model (CLPM). High PA level accounted for 18%, moderate PA level for 35%, and light PA level for 47%. PA was significantly elevated on AB and all sub-indicators except HSK (F = 1.58-4.38, η² = 0.03-0.05, P < 0.05), and was decreasingly related to physical aggression, verbal aggression, and angry (F = 4.38, η² = 0.03,; F = 3.24, η² = 0.04,; F = 2.37, η² = 0.04; P < 0.01). In terms of correlation, cross-sectional comparison showed that AB was significantly negatively correlated with both HSK and PA (r = -0.41, P < 0.01; 1 = -0.44, P < 0.01). The longitudinal results showed a decreasing trend of negative correlation between AB and PA under T1-T3 stages (r = -0.29, r = -0.44, P < 0.01), and no significant change in the degree of negative correlation with HSK (r = -0.28, r = -0.35, P < 0.01). The positive correlation between HSK and PA did not change significantly (r = 0.15, r = 0.18, P < 0.01). The positive correlation of PA itself decreased over time (r = 0.83, r = 0.76, P < 0.01). The CLPM results show that under T1 phase, PA negatively affects AB in T1 and T2 phases (β = -0.42, β = -0.18) and positively affects HSK in T2 phase (β = 0.24). AB negatively affects T1 and T2 phase HSK (β = -0.25, β = -0.26). HSK negatively affects AB in T2 phase (β = -0.11). Under T2 phase, PA negatively affects T3 phase AB (β = -0.07) and positively affects T3 phase HSK (β = 0.22). AB negatively affects T3 stage HSK (β = -0.10). HSK negatively influences T3 stage AB (β = -0.08). (1) PA may have beneficial effects on both Chinese L2 learning efficacy and the reduction of AB. (2) Higher levels of PA are likely to strengthen these effects. (3) Establishing daily PA habits may serve as an effective strategy to enhance L2 learning outcomes while simultaneously reducing AB in learners.

The present study aimed to investigate the longitudinal influence of physical education classes, extracurricular sports activities, and leisure satisfaction on aggressive behavior among South Korean adolescents. Data were drawn from the Korea Youth Panel Survey. We used latent growth curve modeling to explain the growth trajectory of adolescent aggressive behaviors and a multi-group analysis to investigate gender differences in aggressive behavior. The results indicated that adolescents' aggressive behavior significantly changed with age. There were significant gender-based differences in the level of and changes in aggressive behavior over time. Both extracurricular sports activities and leisure satisfaction had significant influences on the changes in adolescents' aggressive behavior with age, whereas physical education classes did not.