Baseline Aggression Research Articles

Longitudinal associations between popularity, peer acceptance, and academic performance in adolescents

Longitudinal associations between popularity, peer acceptance, and academic performance were examined in Chinese 7th ( n = 880; 400 girls; Mage = 13.33, SD = .64) and 10th grade ( n = 646; 342 girls; Mage = 16.76, SD = .75) adolescents across three academic years. Growth curve analysis revealed parallel changes in popularity and academic performance in both middle- and high-school students whereas a positive association between the trajectories of peer acceptance and academic performance was found only in high school. Random-intercept cross-lagged panel analysis revealed that popular students increased their academic performance 1 year later, and that improved academic performance positively predicted subsequent popularity. Changes in peer acceptance were not associated with longitudinal changes in academic performance nor did baseline aggression moderate the effect of initial popularity on the trajectory of academic performance. The positive between-person associations of academic performance with popularity and peer acceptance were greater in middle- than in high-school adolescents. These results have implications for understanding the positive and negative effects of peer status on academic adjustment.

A systematic review with meta-analysis of cognitive bias modification interventions for anger and aggression

Aggression and anger are associated with interpretation and attention biases. Such biases have become treatment targets for anger and aggressive behavior in cognitive bias modification (CBM) interventions. Several studies have evaluated the efficacy of CBM for the treatment of anger and aggressive behavior, with inconsistent results. The present study meta-analytically analyzed 29 randomized controlled trial studies (N = 2334) published in EBSCOhost and PubMed between March 2013 and March 2023 assessing the efficacy of CBM for anger and/or aggression. Included studies delivered CBMs that addressed either attention biases, interpretation biases, or both. Risk of publication bias and potential moderating effects of several participant-, treatment- and study-related factors were assessed. CBM significantly outperformed control conditions in the treatment of aggression (Hedge's G = −0.23, 95% CI [-0.35, −0.11], p < .001) and anger (Hedge's G = −0.18, 95% CI [-0.28, −0.07], p = .001) independent of treatment dose, participant demographic characteristics, and study quality, though overall effects were small. Follow-up analyses demonstrated that only CBMs targeting interpretation bias were efficacious for aggression outcomes, but not when baseline aggression was accounted for. Findings suggest that CBM demonstrates efficacy for the treatment aggressive behavior and to a lesser extent, anger.

Stimulation of medial amygdala GABA neurons with kinetically different channelrhodopsins yields opposite behavioral outcomes.

The medial amygdala (MeA) receives pheromone information about conspecifics and has crucial functions in social behaviors. A previous study showed that activation of GABA neurons in the postero-dorsal MeA (MeApd) with channelrhodopsin-2H134R (ChR2) stimulates inter-male aggression. When performing these experiments using the faster channelrhodopsinH134R,E123T (ChETA), we find the opposite behavioral outcome. A systematic comparison between the two channelrhodopsin variants reveals that optogenetic activation of MeApd GABA neurons with ChETA suppresses aggression, whereas activation under ChR2 increases aggression. Although the mechanism for this paradoxical difference is not understood, we observe that activation of MeApd GABA neurons with ChR2 causes larger plateau depolarizations, smaller action potentials, and larger local inhibition than with ChETA. Thus, the channelrhodopsin variant used for invivo optogenetic experiments can radically influence the behavioral outcome. Future work should continue to study the role of specific sub-populations of MeApd GABA neurons in aggression control.

Cigarette Smoking and Schizophrenia: Etiology, Clinical, Pharmacological, and Treatment Implications.

Recent data suggests that the prevalence of smoking in schizophrenia remains high. While reports suggest that smoking increases the risk of developing schizophrenia, the potential causative role of smoking in this relationship needs further investigation. Smokers with schizophrenia are more likely to have more intense positive symptoms and lower cognitive function, but diminished intensity of extrapyramidal side effects than nonsmoking patients with schizophrenia. They were also more likely to exhibit aggressive behaviour compared to nonsmokers, which could suggest higher levels of baseline aggression. The significant cost associated with regular tobacco expenditure can detract from investment in key domains. Large-scale trials have shown that pharmacotherapy for smoking cessation is effective and does not worsen the risk of developing neuropsychiatric symptoms compared to placebo. Electronic cigarette use among schizophrenia patients is high, and there is emerging evidence supportive of its efficacy. Future improvements include large-scale trials assessing the utility, efficacy, and safety of electronic cigarettes in schizophrenia patients.

Dopamine promotes aggression in mice via ventral tegmental area to lateral septum projections

Septal-hypothalamic neuronal activity centrally mediates aggressive behavior and dopamine system hyperactivity is associated with elevated aggression. However, the causal role of dopamine in aggression and its target circuit mechanisms are largely unknown. To address this knowledge gap, we studied the modulatory role of the population- and projection-specific dopamine function in a murine model of aggressive behavior. We find that terminal activity of ventral tegmental area (VTA) dopaminergic neurons selectively projecting to the lateral septum (LS) is sufficient for promoting aggression and necessary for establishing baseline aggression. Within the LS, dopamine acts on D2-receptors to inhibit GABAergic neurons, and septal D2-signaling is necessary for VTA dopaminergic activity to promote aggression. Collectively, our data reveal a powerful modulatory influence of dopaminergic synaptic input on LS function and aggression, effectively linking the clinically pertinent hyper-dopaminergic model of aggression with the classic septal-hypothalamic aggression axis.

Prevalence and Cumulative Incidence of Caregiver-Reported Aggression in Advanced Parkinson Disease and Related Disorders.

To estimate the point prevalence and cumulative incidence of caregiver-reported aggressive behaviors among people living with advanced Parkinson disease and related disorders (PDRDs) and secondarily examine variables associated with aggression. Caregivers from a clinical trial of outpatient palliative care for PDRD were surveyed about patient aggression at baseline and every 3 months over 12 months. Baseline responses were used for point prevalence. Cumulative incidence was calculated using responses from caregivers with no reported baseline aggression and available data at all other time points. Measures of disease severity, quality of life, mood, and caregiver burden were included in correlation and relative risk models, adjusting for age, sex, and diagnosis. Of 170 caregivers, 31 (18.2%) reported physical aggression, and 18 (10.6%) reported sexual aggression. Twelve-month cumulative incidence for physical and sexual aggression was 21.1% (23/109) and 16.0% (19/119), respectively. Physical aggression cumulative incidence was associated with patient depression (r = 0.37), patient-perceived quality of life (r = -0.26), caregiver burden (r = 0.26), caregiver-perceived patient quality of life (r = -0.26), and caregiver anxiety (r = 0.20). Age, sex, cognitive impairment, and dementia were not associated with aggression. No variables were associated with cumulative sexual aggression. There was a high prevalence and incidence of aggression in our PDRD cohort. This is an understudied issue in PDRD, and our findings highlight the need for increased awareness among neurologists. Providers should consider assessing for aggression when discussing neuropsychiatric symptoms or screening for caregiver burden. Future research should examine the relationship between aggression and patient and caregiver health outcomes. Clinical trial registration number: NCT02533921.

A mechanism-based group-psychotherapy approach to aggressive behaviour in borderline personality disorder: findings from a cluster-randomised controlled trial.

Aggressive behaviour is a prevalent and harmful phenomenon in patients with borderline personality disorder (BPD). However, no short-term, low-cost programme exists that specifically focuses on aggression. Attuning therapy modules to pathogenetic mechanisms that underlie reactive aggression in BPD, we composed a 6 week mechanism-based anti-aggression psychotherapy (MAAP) approach for the group setting, which we tested against a non-specific supportive psychotherapy (NSSP). A cluster-randomised two-arm parallel-group phase II trial of N = 59 patients with BPD and overt aggressive behaviour was performed (German Registry for Clinical Trials, DRKS00009445). The primary outcome was the externally directed overt aggression score of the Modified Overt Aggression Scale (M-OAS) post-treatment (adjusted for pre-treatment overt aggression). Secondary outcomes were M-OAS irritability, M-OAS response rate and ecological momentary assessment of anger post-treatment and at 6 month follow-up, as well as M-OAS overt aggression score at follow-up. Although no significant difference in M-OAS overt aggression between treatments was found post-treatment (adjusted difference in mean 3.49 (95% CI -5.32 to 12.31, P = 0.22), the MAAP group showed a clinically relevant decrease in aggressive behaviour of 65% on average (versus 33% in the NSSP group), with particularly strong improvement among those with the highest baseline aggression. Most notably, significant differences in reduction in overt aggression between MAAP and NSSP were found at follow-up. Patients with BPD and aggressive behaviour benefited from a short group psychotherapy, with improvements particularly visible at 6 month follow-up. Further studies are required to show whether these effects are specific to MAAP.

Longitudinal Associations Linking Elementary and Middle School Contexts with Student Aggression in Early Adolescence.

Growing up in poverty increases youth risk for developing aggressive behavior problems, which, in turn, are associated with a host of problematic outcomes, including school drop-out, substance use, mental health problems, and delinquency. In part, this may be due to exposure to adverse school contexts that create socialization influences supporting aggression. In the current study, 356 children from low-income families (58% White, 17% Latinx, 25% Black; 54% girls) were followed from preschool through seventh grade. Longitudinal data included measures of the school-level contexts experienced by study participants during their elementary and middle school years, including school levels of poverty (percentage of students receiving free or reduced-price lunch) and academic achievement (percentage of students scoring below the basic proficiency level on state achievement tests). Regression analyses suggested little impact of these school-level contexts on teacher or parent ratings of aggression in fifth grade, controlling for child baseline aggression and demographics. In contrast, school-level contexts had significant effects on child aggression in seventh grade with unique contributions by school-level achievement, controlling for child fifth grade aggression and elementary school contexts along with baseline covariates. These effects were robust across teacher and parent ratings. Findings are discussed in terms of understanding the school-based socialization of aggressive behavior and implications for educational policy and prevention programming.

Honey bee aggression: evaluating causal links to disease-resistance traits and infection

Aggression is a context-dependent behavior that often represents an adaptive trade-off with other energetically demanding phenotypes. Diseases can impose strong selection pressures on an organism, impacting the expression of aggression if the behavior is physiologically or genetically linked to disease resistance traits. However, aggression is also often a “sickness behavior” modulated directly by infection to conserve energy. Here we examine the cause-effect relationships between aggression and infection in the honey bee (Apis mellifera), a species with a heavy disease burden in which aggression has been correlated with diverse positive health outcomes. We induced infection in individual worker bees that differ in baseline aggression levels as a function of their colony-of-origin. We evaluated whether baseline aggression alters the response to infection, including the expression of disease-resistance behaviors and immune genes (defensin-1, hymenoptaecin, and vitellogenin). We found limited impact of baseline aggression on immune gene expression and the behavioral response to infection, but showed that infection can cause a change in aggression, at least in some cases. Though we cannot rule out the idea that high aggression is protective against infection, we find greater support for the idea that low aggression may be an energy-conserving “sickness behavior.” Future work concerning the evolutionary ecology of aggression and disease resistance in honey bees should consider the bidirectional relationship between these phenotypes, as well as the range of possible genetic and physiological mechanisms that connect them. Genetic and physiological relationships between disease resistance traits and other behavioral phenotypes like aggression may impact how both traits are expressed in a particular ecological context, and ultimately, how these traits evolve. These relationships are particularly complex in social species, where social interactions both modulate aggressive behaviors and are involved in the response to infection. In honey bees, where pathogen loads and other stressors are prevalent, high aggression predicts health resilience. Here we show that high aggression co-occurs with some behavioral traits that improve the outcome of infection like grooming behaviors. Infection also causes a change in immune function and to an extent aggression, suggesting low aggression that is to some degree an energy conservation measure in sick honey bees.

Effects of a universal classroom management teacher training program on elementary children with aggressive behaviors.

The purpose of this study was to examine the treatment effects of the Incredible Years Teacher Classroom Management (IY TCM), a universal classroom management intervention, on the outcomes of children with aggressive behavior in elementary school. Classroom management has been demonstrated as a factor in either escalating children's aggressive behavior or decreasing those problematic behaviors. Participants included 1,817 students (Grade K to 3) and 105 teachers from nine elementary schools in a large urban Midwestern school district. Teachers were randomly assigned to receive IY TCM or to a wait-list comparison group. The hypotheses were that baseline levels of aggression would moderate the relationship between intervention status and outcomes. Findings indicated the hypothesized moderation effect on several outcome variables; specifically, children with baseline aggression problems who were in IY TCM classrooms had significantly improved math achievement, emotional regulation, prosocial behaviors, and observed aggression in comparison to similar peers in the control classrooms. Implications for practice and future research based on the findings are discussed. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Metaanalysis of the relationship between violent video game play and physical aggression over time

To clarify and quantify the influence of video game violence (VGV) on aggressive behavior, we conducted a metaanalysis of all prospective studies to date that assessed the relation between exposure to VGV and subsequent overt physical aggression. The search strategy identified 24 studies with over 17,000 participants and time lags ranging from 3 months to 4 years. The samples comprised various nationalities and ethnicities with mean ages from 9 to 19 years. For each study we obtained the standardized regression coefficient for the prospective effect of VGV on subsequent aggression, controlling for baseline aggression. VGV was related to aggression using both fixed [β = 0.113, 95% CI = (0.098, 0.128)] and random effects models [β = 0.106 (0.078, 0.134)]. When all available covariates were included, the size of the effect remained significant for both models [β = 0.080 (0.065, 0.094) and β = 0.078 (0.053, 0.102), respectively]. No evidence of publication bias was found. Ethnicity was a statistically significant moderator for the fixed-effects models (P ≤ 0.011) but not for the random-effects models. Stratified analyses indicated the effect was largest among Whites, intermediate among Asians, and nonsignificant among Hispanics. Discussion focuses on the implications of such findings for current debates regarding the effects of violent video games on physical aggression.

Searching for neural and behavioral parameters that predict anti-aggressive effects of chronic SSRI treatment in rats

RationaleOnly a subset of impulsive aggressive patients benefits from selective serotonin reuptake inhibitor (SSRI) treatment, confirming contradictory results about the association between serotonin (5-hydroxytryptamine, 5-HT) and aggression. This shows the need to define behavioral characteristics within this subgroup to move towards individualized pharmacological treatment of impulsive aggression. MethodsHere we submitted an outbred strain of Long Evans rats to a crossover design treatment regimen with the SSRI citalopram, to test its anti-aggressive effect. Behavioral characteristics were baseline aggression, anxiety parameters as measured in the elevated plus maze and open field and cue responsivity as indicated by sign vs. goal tracking behavior. 5-HT1A receptor densities as measured by ex vivo [18F]MPPF binding were determined in the dorsal raphe nucleus, dentate gyrus, orbitofrontal cortex, infralimbic cortex and prelimbic cortex, because of the receptors’ involvement in the therapeutic delay of SSRIs and aggression. ResultsWe found statistically significant increased variance in aggressive behavior after citalopram treatment. However, none of the selected parameters predicted the citalopram treatment effect. ConclusionSince aggression after citalopram treatment decreased in a subgroup of animals and increased in the other, future research should focus on other possible predictors to support treatment strategies in aggressive patients.

Longitudinal trends and year-to-year fluctuations in student–teacher conflict and closeness: Associations with aggressive behavior problems

Longitudinal research suggests that student–teacher relationships characterized by elevated (or increasing) conflict and low (or decreasing) closeness promote heightened aggression in elementary school. However, prior research has not explored fluctuations in the quality of student–teacher relationships across school years, which may also impact students. This study applied a new methodology to determine whether year-to-year fluctuations in student–teacher conflict or closeness also predicted increased student aggression. 154 children were followed from Head Start preschools through elementary school. Early elementary teachers (kindergarten through third grade) rated the quality of conflict and closeness with students. Fifth grade teachers rated student aggression. Regression analyses revealed that year-to-year fluctuations in student–teacher conflict, along with mean levels of student–teacher conflict, each made unique contributions to fifth grade aggression, controlling for baseline aggression. In addition, for students with low aggression at kindergarten entry, year-to-year fluctuations in student–teacher closeness predicted increased aggression. Possible mechanisms accounting for the detrimental effects of fluctuations in student–teacher relationship quality are discussed, along with implications for practice.

Bidirectional Regulation of Aggression in Mice by Hippocampal Alpha-7 Nicotinic Acetylcholine Receptors.

Humans with 15q13.3 microdeletion syndrome (15q13.3DS) are typically hemizygous for CHRNA7, the gene coding for the α7 nicotinic acetylcholine receptor (nAChR), and manifest a variable neuropsychiatric phenotype that frequently includes persistent aggression. In mice, nAChR activation by nicotine is anti-aggressive, or 'serenic,' an effect which requires α7 nAChRs and is recapitulated by GTS-21, an α7 nAChR partial agonist. Pharmacotherapies potentiating α7 nAChR signaling have also been shown to reduce aggression in human 15q13.3DS. These findings identify the α7 nAChR as an important regulator of aggressive behavior, but the underlying neurobiological substrates remain to be determined. We therefore investigated the brain regions and potential neural circuits in which α7 nAChRs regulate aggressive behavior in male mice. As in 15q13.3DS, mice heterozygous for Chrna7 were significantly more aggressive compared to wild-type controls in the resident-intruder test. We subsequently examined the hippocampus, where α7 nAChRs are highly expressed, particularly in GABAergic interneurons. Resident-intruder interactions strongly activated granule cells in the dentate gyrus (DG). In contrast, GTS-21, which reduces aggression in mice, reduced DG granule cell activity during resident-intruder interactions. Short hairpin RNA knockdown of Chrna7 in the DG enhanced baseline aggression and eliminated the serenic effects of both nicotine and GTS-21 on attack latency. These data further implicate α7 nAChRs in regulation of aggression, and demonstrate that hippocampal α7 nAChR signaling is necessary and sufficient to limit aggression. These findings suggest that nAChR-mediated regulation of hippocampal excitatory-inhibitory balance could be a promising therapeutic intervention for aggression arising in certain forms of neuropsychiatric disease.

A Two-Week Psychosocial Intervention Reduces Future Aggression and Incarceration in Clinically Aggressive Juvenile Offenders

There is a largely unmet need for evidence-based interventions that reduce future aggression and incarceration in clinically aggressive juvenile offenders serving probation. We addressed this gap using a group randomized controlled trial. Offenders both with andwithout clinical aggression were included, enabling comparison of intervention effects. Juveniles 13 to 17 years old (N= 310, mean=16 years, 90% African-American, 66% male) on probation were assigned to a 2-week intervention targeting psychosocial factors implicated in risky behavior (e.g., learning strategies to manage "hot" emotions that prompt risk taking) or to an equally intensive health promotion control. Participants completed aggression measures at baseline, 6-, and 12-month follow-up and reported on incarceration at 12 months. Spline regression tested symptom change. Among clinically aggressive offenders (n= 71), the intervention arm showed significantly greater reductions in aggression over the first 6 months compared with controls. Juveniles from the intervention no longer met clinical criteria, on average, but clinically significant symptoms persisted in the control group. By 12 months, participants from the intervention appeared to maintain treatment gains, but their symptom levels no longer differed significantly from those in the control. However, the intervention group was nearly 4 times less likely than controls to report incarceration. Intervention effects were significantly stronger for offenders with clinical than with nonclinical (n= 239) baseline aggression. A 2-week intervention expedited improvements in aggression and reduced incarceration in clinically aggressive juvenile offenders. The findings underscore the importance of directing intervention resources to the most aggressive youth. Clinical trial registration information-PHAT Life: Preventing HIV/AIDS Among Teens in Juvenile Justice (PHAT Life); http://clinicaltrials.gov/; NCT02647710.

Behavioral Differences among Eastern Bluebird Populations Could Be a Consequence of Tree Swallow Presence: A Pilot Study

Aggressive interference competition for limited resources is frequently observed among animals. However, these behavioral interactions within (intraspecific) and between (interspecific) species are costly as they can be energetically expensive and cause injury or death. To avoid these agonistic interactions, numerous species alter their behaviors and resource requirements. Spatial variation in nest site competition allows for investigation of concurrent variation in territorial defense behavior. Further, among species with bi-parental nest defense, behavioral similarity in territorial defense may benefit pairs. Here, we studied territorial aggression between two eastern bluebird (Sialia sialis) populations (North Carolina and Alabama, USA) that differ in avian community structure; those in North Carolina have recently begun to experience strong interspecific competition for nesting cavities by tree swallows (Tachycineta bicolor), a competitive pressure that is relatively new for North Carolina bluebirds (~35-40 years) and is absent in Alabama populations. We found that bluebirds in North Carolina are more aggressive to simulated territorial intrusions compared to their Alabama counterparts. Behavioral similarity (here, in aggression) between partners is strong and similar in both populations. These results suggest that bluebirds in North Carolina may have to maintain higher baseline aggression during territory establishment and nest construction to co-occur with highly aggressive tree swallows, but that, in both populations, behavioral similarity between partners may be adaptive. Finally, we acknowledge the preliminary nature of this study and the need for expanding the behavioral studies to other sites in the southeastern United States. Greater regional coverage would exclude the possibility of alternative drivers of the observed behavioral differences between the North Carolina and Alabama populations.

Prozac impacts lateralization of aggression in male Siamese fighting fish

Previous studies have shown that Siamese fighting fish, Betta splendens, preferentially use right-eye during the aggressive displays. However, administration of antidepressant drugs may disrupt eye-use preference in association with a reduction in aggression; a phenomena that has not been explored in fish. The objective of the current study was to examine the effects of exposure to the antidepressant drug, fluoxetine, on lateralization in eye-use during aggressive displays in male Siamese fighting fish. Baseline aggression and lateralization in eye use of thirty fish were assessed toward live conspecifics, following which experimental subjects (n=15) were then exposed to fluoxetine (540ng/L) in a static renewal water system. Behavior was quantified again after 9 days of exposure. All of the subjects preferentially used the right-eye during aggressive responses before the exposure experiments. Fluoxetine exposed subjects showed a reduction in the time spent gill flaring as has previously been reported, indicative of a reduction in the level of aggression. Fluoxetine also had a significant effect on the lateralization in preferred eye-use while looking at their opponent. Fish exposed to fluoxetine switched from a preferential use of the right-eye during aggressive encounters prior to exposure to using their left-eye after exposure to fluoxetine. The results are discussed with regard to asymmetrical distribution of serotonin between the two brain hemispheres.

Aggression in Psychiatric Wards: Effect of the Use of a Structured Risk Assessment

Health care workers are often exposed to violence and aggression in psychiatric settings. Short-term risk assessments, such as the Brøset Violence Checklist (BVC), are strong predictors of such aggression and may enable staff to take preventive measures against aggression. This study evaluated whether the routine use of the BVC could reduce the frequency of patient aggression. We conducted a study with a semi-random regression discontinuity design in 15 psychiatric wards. Baseline aggression risk was assessed using the Aggression Observation Short Form (AOS) over three months. The BVC was implemented in seven intervention wards, and the risk of aggressive incidents over three months of follow-up was compared with the risk in eight control wards. The analysis was conducted at the ward level because each ward was allocated to the intervention and control groups. At baseline, the risk of aggression varied between wards, from one aggressive incident per patient per 1,000 shifts to 147 aggressive incidents per patient per 1,000 shifts. The regression discontinuity analysis found a 45% reduction in the risk of aggression (Odds Ratio (OR) = 0.55, 95% confidence interval: 0.21–1.43). The study did not find a significant reduction in the risk of aggression after implementing a systematic short-term risk assessment with the BVC. Although our findings suggest that use of the BVC may reduce the risk of aggression, the results need to be confirmed in studies with more statistical power.

Uric acid excretion predicts increased aggression in urban adolescents

Elevated levels of uric acid have been linked with impulsive and disinhibited behavior in clinical and community populations of adults, but no studies have examined uric acid in relation to adolescent aggression. This study examined the prospective role of uric acid in aggressive behavior among urban, low income adolescents, and whether this relationship varies by gender. A total of 84 adolescents (M age 13.36years; 50% male; 95% African American) self-reported on their physical aggression at baseline and 1.5years later. At baseline, the youth also completed a 12-h (overnight) urine collection at home which was used to measure uric acid excretion. After adjusting for baseline aggression and age, greater uric acid excretion predicted more frequent aggressive behavior at follow up, with no significant gender differences. The results suggest that lowering uric acid levels may help reduce youth aggression.

Aggression among adolescent victims of school bullying: Protective roles of family and school connectedness.

OBJECTIVES: To examine cross-sectional and 2-year longitudinal associations between school victimization and aggression among middle and high school students. Drawing on resilience theory, family and school connectedness were examined as compensatory or protective factors. METHOD: We sampled 373 students (Grades 7-10, 54% girls, 53% White/Caucasian, 26% Hispanic/Latino, and 56% economically disadvantaged), who completed up to 3 annual surveys. RESULTS: Aggression declined over the 3 waves. Victimization predicted higher initial levels of and steeper decline in aggression. Family connectedness was protective; baseline aggression was lower and declined more steeply for youth who reported more family connectedness. School connectedness played a complex role, potentially contributing to students' vulnerability over time. CONCLUSIONS: The steeper declines in aggression among victimized youth suggest a resilience process. High family connectedness and school belonging were linked to lower level of aggression regardless of victimization. Efforts to provide family support may be effective in reducing risk for aggression among victimized youth. Promoting students' sense of school belonging may compensate for negative effects of victimization on aggression in the short term; however, broader efforts directed at establishing a safe and supportive school climate and setting social norms that discourage school violence may be necessary to reduce the incidence of victimization and subsequent aggressive behavior. ©2016 American Psychological Association Language: en