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PubMed2006

Trait modulation of alcohol-induced laboratory aggression.

Modest alcohol and aggressive trait effects on laboratory-induced aggression among men have been reported with some consistency in the literature. Relationships between aggressive personality traits and laboratory-induced aggression appear to become less consistent under the influence of alcohol. Several research teams have found suggestions that the effects of alcohol on laboratory aggression may be reduced or even reversed among individuals with aggressive personality traits. This study examined the effects of alcohol on the aggressive responding on the Point Subtraction Aggression Paradigm (PSAP) of eight undergraduate men who generated evidence on the Million Clinical Multiaxial Inventory-II (MCMI-II) of sadistic-aggressive personality disorder features. This sample was compared with a group of 18 undergraduate male peers without MCMI-II elevations described in a previous study. Neither alcohol ingestion (0.8 ml/kg) nor aggressive personality traits predicted laboratory behavior in isolation, but alcohol was found to selectively attenuate (d = 0.75) PSAP responding for the sadistic-aggressive as opposed to the control subjects (i.e., a significant aggressive trait by alcohol interaction). The possible value of this counterintuitive response tendency in identifying men at elevated risk for alcohol-related aggression was discussed. Large, immediate reductions in laboratory-based aggressive responding while under the influence of alcohol might provide a paradoxical high risk indicator that has not been previously identified.

Adult↗
PubMed2003

Neurosteroids, GABAA receptors, and escalated aggressive behavior.

Aggressive behavior can serve important adaptive functions in social species. However, if it exceeds the species-typical pattern, it may become maladaptive. Very high or escalated levels of aggressive behavior can be induced in laboratory rodents by pharmacological (alcohol-heightened aggression), environmental (social instigation), or behavioral (frustration-induced aggression) means. These various forms of escalated aggressive behavior may be useful in further elucidating the neurochemical control over aggression and violence. One neurochemical system most consistently linked with escalated aggression is the GABAergic system, in conjunction with other amines and peptides. Although direct stimulation of GABA receptors generally suppresses aggression, a number of studies have found that positive allosteric modulators of GABAA receptors can cause increases in aggressive behavior. For example, alcohol, benzodiazepines, and many neurosteroids are all positive modulators of the GABAA receptor and all can cause increased levels of aggressive behavior. These effects are dose-dependent and higher doses of these compounds generally shift from heightening aggressive behavior to being sedative and anti-aggressive. In addition, these modulators interact with each other and can have additive effects on the GABAA receptor and on behavior, including aggression. The GABAA receptor is a heteropentameric protein that can be constituted from various subunits. It has been shown that subunit composition can affect sensitivity of the receptor to some modulators and that subunit composition differentially affects the sedative vs anxiolytic actions of benzodiazepines. Initial studies targeting alpha subunits of the GABAA receptor point to their significant role in the aggression-heightening effects of alcohol, benzodiazepines, and neurosteroids.

Aggression↗
PubMed2005

The role of alcohol and steroid hormones in human aggression.

The association between alcohol and aggressive behavior is well established although a direct causal relationship has proven hard to demonstrate. There are, however, indications that alcohol facilitates aggression in individuals who already have a predisposition to behave aggressively. Aggressive personality disorders have in turn been explained by elevated testosterone level. A one-to-one relation between increased levels of testosterone and aggression has been, nevertheless, difficult to reveal. Two metabolites of testosterone, estradiol and 5alpha-dihydrotestosterone (DHT), have been studied much less in human aggressive behavior. Estradiol might reduce androgenic effects and have a counterbalancing influence on aggression. DHT, again, has a much higher affinity than testosterone to androgen receptors, and there are indications that some of the effects of testosterone-mediating aggressive behavior occur after aromatization. Disregard of seasonal and circadian fluctuations in male testosterone production might be responsible for some of the inconclusive testosterone-aggression results. In addition, increasing age decreases both aggressive behavior and testosterone production in males. Cortisol has yielded conflicting results as a mediator in aggressive behavior. Both higher and lower levels have been reported in aggressive and abusive men. Finally, the acute and chronic effects of alcohol influence the steroid hormone levels in various ways. The present understanding of the etiology of aggression is still vague. It is clear that a multidimensional approach, combining both biological and psychosocial factors, will be necessary for the development of a more general concept of human aggression in the future.

Adolescent↗
PubMed1987

Social-information-processing factors in reactive and proactive aggression in children's peer groups.

We examined social-information-processing mechanisms (e.g., hostile attributional biases and intention-cue detection deficits) in chronic reactive and proactive aggressive behavior in children's peer groups. In Study 1, a teacher-rating instrument was developed to assess these behaviors in elementary school children (N = 259). Reactive and proactive scales were found to be internally consistent, and factor analyses partially supported convergent and discriminant validities. In Study 2, behavioral correlates of these forms of aggression were examined through assessments by peers (N = 339). Both types of aggression related to social rejection, but only proactively aggressive boys were also viewed as leaders and as having a sense of humor. In Study 3, we hypothesized that reactive aggression (but not proactive aggression) would occur as a function of hostile attributional biases and intention-cue detection deficits. Four groups of socially rejected boys (reactive aggressive, proactive aggressive, reactive-proactive aggressive, and nonaggressive) and a group of average boys were presented with a series of hypothetical videorecorded vignettes depicting provocations by peers and were asked to interpret the intentions of the provocateur (N = 117). Only the two reactive-aggressive groups displayed biases and deficits in interpretations. In Study 4, attributional biases and deficits were found to be positively correlated with the rate of reactive aggression (but not proactive aggression) displayed in free play with peers (N = 127). These studies supported the hypothesis that attributional biases and deficits are related to reactive aggression but not to proactive aggression.

Aggression↗
PubMed2003

Aggression involving alcohol: relationship to drinking patterns and social context.

AIMS: The present study examines the relationships between: (1) alcohol involvement/perceived intoxication level of participants and aggression severity; (2) respondent drinking patterns and involvement in alcohol-related aggression; and (3) social context and alcohol-related aggression. DESIGN: Random digit dialing (RDD) with computer assisted telephone interviewing (CATI) was used to obtain a random sample of Ontario adults aged 18-60 (response rate of 67%). PARTICIPANTS: Respondents who reported that they had been involved personally in physical aggression in the past 12 months were the focus of the present study. MEASUREMENTS: Questions were asked regarding the most recent incident of physical aggression, including whether the respondent and opponent drank alcohol prior to aggression, perceived intoxication levels at the time, number of participants, relationship to opponent, social context of aggression, time of day and day of week. Three items were used to assess aggression severity: injury to respondent, use of threats by respondent or opponent and police involvement. FINDINGS: (1) Injury to respondent and threats by respondent were not associated with alcohol involvement per se, but were significantly related to perceived level of alcohol intoxication; (2) drinking pattern of respondent was significantly associated with alcohol-related aggression but unrelated to aggression that did not involve alcohol; and (3) a number of contextual factors (e.g. gender, number of participants, time of day) were found to be associated with alcohol involvement in aggression. CONCLUSIONS: The results suggest that both drinking pattern and contextual factors are important in distinguishing between alcohol-related aggression and non-alcohol-related aggression. As well, alcohol intoxication may be an important predictor of aggression severity.

Adolescent↗
PubMed1997

Effects of serotonin reuptake inhibitors on aggressive behavior in psychiatrically hospitalized adolescents: results of an open trial.

Low concentrations of the neurotransmitter serotonin and its 5-hydroxyindoleacetic acid metabolite in the central nervous system have been associated with increased aggressive behavior in animals and humans. Controlled clinical trials of serotonin agonists in depressed adults have suggested that aggressive behavior is less likely during treatment with these medications than with placebo, but there have been no previous studies of selective serotonin reuptake inhibitors (SSRIs) and aggression in children. We prospectively followed the course of aggressive behavior in 19 psychiatrically hospitalized adolescents (not selected for aggressiveness) who received open clinical trials of fluoxetine, paroxetine, or sertraline. The patients received standard doses (equivalent to fluoxetine 10-40 mg daily) for a minimum of 5 weeks. The starting dose was 15 +/- 5 mg, and dosages were raised at a mean rate of 5 mg every 4 days up to a mean dose of 25 +/- 10 mg daily. Results from trials of the three SSRIs were clustered because the sample sizes were not sufficient for separate analyses. Overall, there were no statistically meaningful improvements in the level of aggressive behavior, as measured on a modified version of the Overt Aggression Scale, over the course of these patients' SSRI trials. Symptoms of physical aggression toward others or self were manifest in 12 of the 19 patients while on SSRIs. Of the 19 patients, 13 were assessed both on and off SSRIs: verbal aggression (p = 0.04), physical aggression toward objects (p = 0.05), and physical aggression toward self (p < 0.02) occurred significantly more frequently on SSRIs than off; no increase was observed in physical aggression toward others. Patients with the highest baseline aggressivity scores did not show greater improvement during SSRI treatment. Further research is warranted, particularly to explore whether SSRIs may have therapeutic effects on aggression at higher (or lower) doses than were administered in this open trial.

1-Naphthylamine↗
PubMed1997

The effects of phenytoin on impulsive and premeditated aggression: a controlled study.

Studies of the effects of phenytoin on aggression have produced equivocal results primarily because of a lack of (1) common objective criterion measures of aggressive acts across studies; (2) rigorous inclusion and exclusion criteria for selecting subjects; and (3) a nosologic basis for classifying different types of aggression. The current study was designed to remedy these deficiencies. Aggression was defined using a nosology that defines three types of aggression: (1) medically related; (2) premeditated; and (3) impulsive. The purpose of this study was to test the hypothesis that phenytoin will decrease impulsive aggressive acts but not have a significant influence on premeditated aggressive acts. Sixty inmates were divided into two groups on the basis of committing primarily impulsive aggressive acts or premeditated aggressive acts while in prison. Medical aggression was ruled-out by subject selection. The study used a double-blind, placebo-controlled, crossover design. As hypothesized, phenytoin (200 mg a.m. and 100 mg p.m.) significantly reduced impulsive aggressive acts but not premeditated aggressive acts. Event-related potentials (ERPs) measured information processing in the cortex during drug/placebo conditions. The amplitudes of P300 ERP waveforms among impulsive aggressive subjects were increased significantly during the phenytoin condition but not during the placebo condition. There were no significant changes in P300 ERP waveforms between drug/placebo conditions among nonimpulsive aggressive subjects.

Adult↗
PubMed2006

Bad nights or bad bars? Multi-level analysis of environmental predictors of aggression in late-night large-capacity bars and clubs.

AIMS: To clarify environmental predictors of bar-room aggression by differentiating relationships due to nightly variations versus across bar variations, frequency versus severity of aggression and patron versus staff aggression. DESIGN, SETTING AND PARTICIPANTS: Male-female pairs of researcher-observers conducted 1334 observations in 118 large capacity (> 300) bars and clubs in Toronto, Canada. MEASUREMENTS: Observers independently rated aspects of the environment (e.g. crowding) at every visit and wrote detailed narratives of each incident of aggression that occurred. Measures of severity of aggression for the visit were calculated by aggregating ratings for each person in aggressive incidents. FINDINGS: Although bivariate analyses confirmed the significance of most environmental predictors of aggression identified in previous research, multivariate analyses identified the following key visit-level predictors (controlling for bar-level relationships): rowdiness/permissive environment and people hanging around after closing predicted both frequency and severity of aggression; sexual activity, contact and competition and people with two or more drinks at closing predicted frequency but not severity of aggression; lack of staff monitoring predicted more severe patron aggression, while having more and better coordinated staff predicted more severe staff aggression. Intoxication of patrons was significantly associated with more frequent and severe patron aggression at the bar level (but not at the visit level) in the multivariate analyses and negatively associated with severity of staff aggression at the visit level. CONCLUSIONS: The results demonstrate clearly the importance of the immediate environment (not just the type of bar or characteristics of usual patrons) and the importance of specific environmental factors, including staff behaviour, in predicting both frequency and severity of aggression.

Aggression↗
PubMed2006

Influence of subjective intoxication, breath alcohol concentration, and expectancies on the alcohol-aggression relation.

BACKGROUND: The purpose of this study was to investigate the influence of subjective intoxication, alcohol-aggression expectancies, and breath alcohol concentration (BrAC) on intoxicated aggression in men and women while controlling for dispositional aggressivity. METHODS: Subjects were 328 (163 men and 165 women) healthy social drinkers between 21 and 35 years of age. Following the consumption of either an alcohol or an active placebo beverage, subjects were tested on a modified version of the Taylor Aggression Paradigm in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Levels of subjective intoxication and BrAC were measured immediately before subjects began the aggression task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. RESULTS: Subjective intoxication ratings were not related to aggressive behavior for either men or women. Alcohol-aggression expectancies were related to aggression for men, but this effect was rendered nonsignificant when controlling for dispositional aggressivity, which in turn, was significantly related to the dependent variables for both men and women. Finally, BrAC was also related to aggression above and beyond the effects of dispositional aggressivity, yet only for men. CONCLUSIONS: Taken as a whole, this study suggests that intoxicated aggression is primarily the result of alcohol's pharmacological properties in conjunction with an aggressive disposition.

Adult↗
PubMed2004

Escalated aggressive behavior: new pharmacotherapeutic approaches and opportunities.

Psychopharmacologic studies of aggressive behavior in animals under controlled laboratory conditions have been instrumental in developing and evaluating specific and effective novel drug treatments that reduce aggressive behavior. An initial contribution of this research is to create experimental conditions that enable the display of aggressive and defensive acts and postures in species that engage in either dominance or territorial or maternal aggression. Quantitative ethological analyses allow the precise delineation of the sequential organization of aggressive bursts, providing a benchmark for assessing excessive or pathological forms of aggressive behavior. A second contribution of preclinical research is the development of experimental models of escalated forms of aggressive behavior, such as focusing on genetic predispositions or social provocations and frustrative experiences. A critical role of preclinical research is in the pharmacological and neurochemical analysis of aggressive behavior; for example, a host of undesirable side effects prompted a shift from classic dopaminergic neuroleptic compounds to the more recently developed atypical neuroleptics with effective and more specific anti-aggressive effects. The long-established role of brain serotonin in impulsive and escalated forms of aggressive behavior continues to be a focus of preclinical studies. New evidence differentiates dynamic state changes in corticolimbic serotonergic neurons during the termination of aggressive behavior from the deficient-serotonin trait in violence-prone individuals. It can be anticipated that currently developed tools for targeting the genes that code for specific subtypes of serotonin receptors will offer new therapeutic options for reducing aggressive behavior, and the 5-HT(1B) receptor appears to be a promising target. The modulation of GABA and GABA(A) receptors by 5-HT in corticolimbic neurons promises to be particularly relevant for specific forms of escalated aggressive behavior such as alcohol-heightened aggression.

Aggression↗
PubMed2000

Alcohol-related aggression in the general population.

OBJECTIVE: This study estimates the relationships between drinking in the event and drinking patterns and different levels of aggression severity. METHOD: A telephone survey of 1,001 adults (542 women) age 18 and over was conducted (response rate of 67%) using computer assisted telephone interviewing (CATI). Respondents were asked whether they had been personally involved in a serious argument, an incident involving threat, or physical aggression in the past year and whether anyone had been drinking alcohol in the most recent incident. Respondents also reported their typical alcohol consumption patterns. RESULTS: The proportion of respondents reporting involvement in serious arguments, threats or physical aggression was 19.8%, 11.8% and 12.0%, respectively. Someone in the incident had been drinking in 38.1% of serious arguments, 56.5% of threats and 67.9% of incidents of physical aggression. When gender, age, education, marital status and employment status were controlled for, high quantity drinking (as measured by the largest number of drinks consumed on one drinking occasion in the past year), overall estimated annual volume of alcohol consumed, and frequency of consuming five drinks per occasion were significantly greater for physical aggression, compared with arguments and no aggression. However, drinker status (abstainer/drinker) and frequency of drinking were not significantly associated with involvement in aggression. In a logistic regression analysis controlling for demographic variables, a composite measure of alcohol consumption was highly significant for physical aggression versus no aggression and for physical versus verbal aggression. Physical aggression was also associated with being younger, separated/ divorced and a student. CONCLUSIONS: The results suggest that alcohol intoxication, rather than mere alcohol consumption, is associated with aggression. Moreover, alcohol intoxication is more strongly associated with physical aggression than with verbal aggression.

Adolescent↗
PubMed2004

A study on aggressive behavior among nursing home residents with cognitive impairment.

PURPOSE: With a sample of cognitively impaired nursing home residents and nursing staff, the following were examined 1) the proportion and nature of aggressive behavior, 2) the frequency and types of aggressive behavior, 3) the difference between the residents who demonstrate aggressive behavior and those who do not demonstrate aggressive behavior (age, mental status, functional status, and pain, length of nursing home stay), and 4) nursing staff responses to aggressive behavior by residents. METHODS: A cross-sectional descriptive study design was used. Data were collected from cognitively impaired nursing home residents (N=205) and nursing staff (N=60) at two nursing homes using Ryden Aggression Scale I and II, Mini-Mental State Exam, Modified Barthel Index, Verbal Descriptor Scale, and aggressive behavior management questionnaire. Data were analyzed using descriptive statistics including t-test. RESULTS: About 62.9% residents were found to be aggressive and 38.5% were both physically and verbally aggressive. Pushing, making threatening gestures, hitting, slapping, cursing/obscene/vulgar languages, making verbal threats were occurred frequently. Aggressive residents were significantly older, had more cognitive impairment, had more pain, and stayed longer in the nursing home when compared with non-aggressive residents. Considerable proportion of nursing staff responded to aggressive behaviors inadequately. CONCLUSION: Aggressive behavior among cognitively impaired nursing home residents is prevalent thus needs to be prevented and reduced. Along with environmental modification, educational programs for nursing staff and family caregivers need to be developed and implemented so that they can have extensive knowledge and skills to manage aggressive behaviors.

Aged↗
PubMed1986

Cognitive social learning mediators of aggression.

This research explored links between aggression in elementary school children and 2 classes of social cognitions that might influence children's decisions about whether to behave aggressively. Aggressive and nonaggressive children (mean age 11.3 years) responded to 2 questionnaires. One questionnaire measured children's perceptions of their abilities to perform aggression and related behaviors (perceptions of self-efficacy), and the other measured children's beliefs about the reinforcing and punishing consequences of aggression (response-outcome expectancies). Compared to nonaggressive children, aggressive subjects reported that it is easier to perform aggression and more difficult to inhibit aggressive impulses. Aggressive children also were more confident that aggression would produce tangible rewards and would reduce aversive treatment by others. There were negligible sex differences in perceived self-efficacy for aggression but large sex differences in anticipated social and personal consequences for aggression, with girls expecting aggression to cause more suffering in the victim and to be punished more severely by the peer group and by the self. It was concluded that children's knowledge of their capabilities and children's knowledge of the consequences of their actions are factors that need to be taken into account by cognitive models of aggression.

Aggression↗
PubMed1979

Aggression during competition: effects of age, sex, and amount and type of provocation.

Three experiments were designed to examine the expression of instrumental and hostile aggression by 6- to 10-year-old children during a competitive game. The rate at which a child pressed a button which allegedly interfered with his opponent's progress on the task was the measure of instrumental aggression. Pressing a second button presumably caused one's opponent to hear an aversive noise and served as the measure of hostile aggression. The task was designed in an attempt to isolate (a) frustration from attack as the instigator of aggression and (b) instrumental from hostile aggression as the desired outcome. In all three experiments the measures of instrumental and hostile aggression were generally highly correlated except under provocation conditions during which the number of attacks exceeded the number of frustrations. This suggested that the task was successful in tapping two different classes of aggressive responding. In Experiment 1 older children (N = 161 males and females) expressed more of both instrumental and hostile aggression than did younger children, and males were more aggressive than females on both measures. However, neither measure of aggression varied as a function of level of provocation. This finding was discrepant from the authors' previous research which had focused solely on instrumental aggression. Apparently, the introduction of attack and the opportunity for hostile responding changed the experimental situation. In order to focus more directly on this issue, Experiments 2 (N = 60 males) and 3 (N = 56 males) used various combinations of attack and frustration with 9- and 10-year-old males. Attack, prior to frustration, elicited the greatest amount of hostile aggression. Frustration, with no attack, resulted in the highest level of instrumental aggression. The complex relationship between these sources of provocation and instrumental and hostile aggression was discussed.

Age Factors↗
PubMed1979

Sex differences in children's expression and control of fantasy and overt aggression.

The present study explored sex differences in children's expression and control of fantasy and overt aggression. Fifth-grade boys and girls were presented a TAT-like projective test to measure fantasy aggression and controls over aggression. Overt peer-oriented aggression was measured by peer and teacher ratings. Results indicated that boys were rated more physically and verbally aggressive than girls but not more indirectly aggressive. Boys also produced more physical aggression in fantasy than girls, although the opposite trend was found for indirect aggression; no sex difference was found for verbal fantasy aggression. Finally, girls had a higher ratio of aggression control per total fantasy aggression than boys. The results support the position that while boys, in contrast to girls, are socialized in a way that encourage direct expression of aggression, girls are just as likely to be aggressive as boys when the aggression is indirect. The results are discussed further from the perspective of social learning theory and Maccoby and Jacklin's biological position.

Aggression↗
PubMed1996

Aggressive boys' hostile perceptual and response biases: the role of attention and impulsivity.

The present study addressed whether (1) aggressive boys show hostile biases or general deficits in social perception, (2) aggressive boys' social perceptual difficulties also characterize isolate and isolate-aggressive children, (3) aggressive, isolate, and isolate-aggressive boys' social perceptual difficulties are attributable to inattention and impulsivity, and (4) aggressive and nonaggressive boys differ in the links between social perception and proposed behavioral responses. Aggressive boys demonstrated hostile biases, but not general deficits, in intention-cue detection relative to average-status boys. Isolate-aggressive boys resembled aggressive boys in social perception, whereas isolate boys showed mild deficits relative to average-status boys. Although isolates' general deficits were predominantly accounted for by inattention and impulsivity, aggressives' and isolate-aggressives' hostile biases remained after these problems were statistically controlled. The aggressive groups proposed aggressive responses much more frequently than the nonaggressive groups following intentions perceived as nonhostile. Measures corresponding to several stages of Dodge's social information processing model discriminated the aggressive from nonaggressive groups, thus providing support for this model.

Aggression↗
PubMed2003

p53 mutations in human aggressive and nonaggressive basal and squamous cell carcinomas.

PURPOSE: The purpose is to investigate whether aggressive basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) differ from nonaggressive BCC and SCC with respect to the p53 mutation spectrum and whether specific mutations can serve as prognostic indicators of tumor aggressiveness. EXPERIMENTAL DESIGN: We analyzed 342 tissues from patients with aggressive and nonaggressive BCCs and SCCs for p53 mutations by single-strand conformation polymorphism and nucleotide sequencing. RESULTS: p53 mutations were detected in 33 of 50 aggressive BCCs (66%), 37 of 98 nonaggressive BCCs (38%), 28 of 80 aggressive SCCs (35%), 28 of 56 nonaggressive SCCs (50%), and 3 of 29 samples of sun-exposed skin (10%). About 71% of the p53 mutations detected in aggressive and nonaggressive BCCs and SCCs were UV signature mutations. The frequency of CC to TT mutations in aggressive (36%) and nonaggressive SCCs (39%) was 2-fold higher than in aggressive (18%) and nonaggressive (14%) BCCs. In contrast, aggressive BCCs had a higher frequency (24%) of transversions than nonaggressive BCCs (8%) and aggressive (14%) and nonaggressive (11%) SCCs did. CONCLUSIONS: Our results indicate that UV radiation is responsible for the induction of p53 mutations and perhaps for the initiation of both aggressive and nonaggressive BCCs and SCCs. Although some differences in p53 mutation frequency, types of mutation, and hot spots were seen between aggressive and nonaggressive BCCs and SCCs, these factors do not constitute as clear-cut diagnostic or prognostic indicators of tumor aggressiveness. Tumor aggressiveness may be attributable to other genetic changes or events that occur during tumor progression.

Adult↗
PubMed2001

Effects of reducing children's television and video game use on aggressive behavior: a randomized controlled trial.

CONTEXT: The relationship between exposure to aggression in the media and children's aggressive behavior is well documented. However, few potential solutions have been evaluated. OBJECTIVE: To assess the effects of reducing television, videotape, and video game use on aggressive behavior and perceptions of a mean and scary world. DESIGN: Randomized, controlled, school-based trial. SETTING: Two sociodemographically and scholastically matched public elementary schools in San Jose, Calif. PARTICIPANTS: Third- and fourth-grade students (mean age, 8.9 years) and their parents or guardians. INTERVENTION: Children in one elementary school received an 18-lesson, 6-month classroom curriculum to reduce television, videotape, and video game use. MAIN OUTCOME MEASURES: In September (preintervention) and April (postintervention) of a single school year, children rated their peers' aggressive behavior and reported their perceptions of the world as a mean and scary place. A 60% random sample of children were observed for physical and verbal aggression on the playground. Parents were interviewed by telephone and reported aggressive and delinquent behaviors on the child behavior checklist. The primary outcome measure was peer ratings of aggressive behavior. RESULTS: Compared with controls, children in the intervention group had statistically significant decreases in peer ratings of aggression (adjusted mean difference, -2.4%; 95% confidence interval [CI], -4.6 to -0.2; P =.03) and observed verbal aggression (adjusted mean difference, -0.10 act per minute per child; 95% CI, -0.18 to -0.03; P =.01). Differences in observed physical aggression, parent reports of aggressive behavior, and perceptions of a mean and scary world were not statistically significant but favored the intervention group. CONCLUSIONS: An intervention to reduce television, videotape, and video game use decreases aggressive behavior in elementary schoolchildren. These findings support the causal influences of these media on aggression and the potential benefits of reducing children's media use.

Aggression↗