Gender Differences in Reactive and Proactive ... - Springer Link

Gender Differences in Reactive and Proactive Aggression Daniel F. Connor, MD Ronald J. Steingard, MD University of Massachusetts Medical School

Jennifer J. Anderson, RNc Devereux School

Richard H. Melloni Jr., PhD Northeastern University

ABSTRACT: The purpose of our investigation was to study gender differences in proactive and reactive aggression in a sample of 323 clinically referred children and adolescents (68 females and 255 males). Proactive aggression and reactive aggression were assessed using the Proactive/Reactive Aggression Scale. Demographic, historical, family, diagnostic, and treatment variables were entered into stepwise regression analyses to determine correlates of proactive and reactive aggression in males and females. Results reveal high rates of aggression in both males and females in the sample. Self reported drug use, expressed hostility, and experiences of maladaptive parenting were correlated with proactive aggression for both genders. Hyperactive/impulsive behaviors were correlated with male reactive aggression. An early age of traumatic stress and a low verbal IQ were correlated with female proactive aggression. Gender differences in correlates of proactive and reactive aggression may provide possible targets for research, prevention, and treatment efforts focused on reducing maladaptive aggression in clinically referred youth. KEY WORDS: proactive aggression; reactive aggression; children; adolescents.

Gender differences related to the presence of aggressive behavior are not well studied in clinically referred populations of children and adolescents (hereby referred to as children). Studies of aggression in The authors would like to thank Lang Lin, MS, for statistical assistance and the Devereux School, Rutland, MA, for support of this research. This work was supported in part by a Devereux Institute for Clinical Training and Research grant award to Dr. Connor and by an RSDF grant award from Northeastern University to Dr. Melloni. Address correspondence to Daniel F. Connor, MD, Department of Psychiatry-7th Floor, Room S7-802, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655; e-mail: [email protected]. Child Psychiatry and Human Development, Vol. 33(4), Summer 2003 © 2003 Human Sciences Press, Inc.

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clinical samples have largely focused on the psychiatric diagnosis of conduct disorder, which is more prevalent in males than females.1–3 Studies of female aggression have largely focused on relational aggression as investigated in non-referred community samples of school children.4,5 Two types of aggression that are receiving research attention are proactive aggression and reactive aggression.6 Reactive aggression has its theoretical roots in the frustration-aggression model,7 which states that reactive aggression is an angry, defensive response to threat, frustration, or provocation. Proactive aggression has its theoretical roots in social learning theory.8 Proactive aggression is a deliberate coercive behavior that is controlled by external reinforcements and is used as a means of obtaining a desired goal. These two types of aggression have been largely studied in nonreferred community samples.9 Studies have established a reliable and valid method of measurement for these two aggression types,6 with adequate construct validity10 [even controlling for comorbid ADHD, CD, and ODD11], as assessed by teachers in community school classrooms, in play groups, and in adjudicated adolescents.12,13 Proactive aggression and reactive aggression have been shown to predict different social-information processing mechanisms,14 different outcomes in violence potential and conduct problems,15,16 and different developmental histories and concurrent adjustment.17 Although proactive and reactive aggression are intercorrelated, confirmatory factor analysis has shown that a two-factor model better fits the data than a single factor model.10 Thus, proactive aggression and reactive aggression are distinct from one another. Research has identified a number of correlates associated with aggression in community, juvenile justice, and clinical samples. These correlates have been studied more thoroughly in delinquent, aggressive, and conduct disordered youngsters, than in proactive and reactive aggression. Demographic variables associated with aggression include gender and IQ. Males are generally found to be more aggressive than females.3 Neuropsychological studies of antisocial youth have consistently documented a global IQ deficit of about one-half standard deviation, compared to non-antisocial youngsters.18 There also exists evidence of a more specific Verbal IQ deficit in antisocial youngsters. For over 60 years, neuropsychologists have consistently noted that Performance IQ test scores are generally greater than Verbal IQ scores in delinquent and antisocial youth.3,18,19 Since language func-

D. F. Connor, R. J. Steingard, J. J. Anderson, and R. H. Melloni

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tions are primarily sub served by the left brain hemisphere in almost all individuals, this Performance > Verbal score finding has been taken as evidence of language-based deficits in aggressive and antisocial youths. The existence of such deficits is further supported by findings of increased rates of reading and spelling learning disabilities in children with conduct problems, even after controls for global intelligence and socio-economic status.20 For these reasons we chose to study Verbal IQ in our clinically referred sample. Other variables associated with risk for aggression and conduct problems include individual factors such as substance abuse, alcohol abuse, and hostile perceptions.3 Family factors include parental psychopathology (e.g., substance abuse, violence) and traumatic stress such as child abuse (e.g., physical and/or sexual abuse).21 Psychiatric disorders such as the disruptive behavioral disorders (e.g., attentiondeficit/hyperactivity disorder, conduct disorder, oppositional defiant disorder) are closely associated with aggressive behavior in youngsters.22 In referred samples of seriously emotionally disturbed youths treatment variables such as the number and type of psychiatric medications prescribed have been associated with aggressive behavior independent of psychiatric diagnosis.23 Since some youngsters referred to mental health treatment may have associated neurological problems affecting the CNS and medical difficulties such as asthma, we wished to ascertain if these conditions explained variance in proactive/ reactive aggression. Because these correlates have received little attention in proactive/reactive aggression research we chose to study them. We investigated proactive and reactive aggression because these two types of aggression are emerging as important areas of study as researchers attempt to characterize maladaptive aggressive behavior in clinically referred youths.3 No studies have examined gender differences relative to the presence of proactive or reactive aggression in seriously emotionally disturbed children referred for mental health treatment. The aims of our study were to (1) identify gender differences with regards to the prevalence of proactive and reactive aggression and, (2) identify correlates of proactive aggression and reactive aggression in males and females from a convenience sample of clinically referred children and adolescents. Based on previous research we hypothesized that males and females would demonstrate some partially overlapping, and also some distinct associations with demographic, historical, familial, and psychiatric treatment correlates.

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Methodology Subjects Male and female subjects were ascertained from unsolicited consecutive referrals to a residential treatment center (RTC)(inpatients, N = 253), and a pediatric psychopharmacology clinic serving a tertiary hospital and medical school (outpatients, N = 70). Subjects were unselected for any psychiatric diagnosis, subject characteristic, or treatment. Overall, 91.5% of eligible subjects (323 of 353 children) consented to participate in the study. The RTC serves seriously emotionally disturbed (SED) children generally referred from their respective school systems, juvenile justice, or state protective services agencies. The psychopharmacology clinic serves as a major regional referral site for primary care clinicians, pediatric subspecialty clinicians, and mental health clinicians. All subjects and legal guardians gave consent. The Institutional Review Boards of both the RTC and the medical school approved this study.

Procedures Children were systematically assessed at evaluation. A board-certified or board-eligible child psychiatrist clinically evaluated all children. Parents, legal-guardians, and/or staff workers [who worked closely with inpatient children] were interviewed about the child. Low verbal IQ, the frequent presence of language-based learning disabilities, and the frequent absence of parent/ guardians familiar with inpatient children precluded using structured diagnostic interviewing. Clinical diagnoses were assigned using DSM-IV criteria.1 Rating scales were completed by parents at the time of evaluation for outpatients and completed by clinical staff within four months of admission to RTC. Historical variables were assessed by interviewing patients and parent/ guardians, and by record review. This method of assessment has been used in previously published research.23,24

Assessments Demographic variables included age and verbal IQ. Psychiatric diagnoses including alcohol and substance abuse were obtained on subjects. Historical variables assessed included the presence of physical or sexual abuse, age at first abuse, perpetrator type (adult versus child), parental alcohol/substance abuse, and parental violence. Treatment variables included number and type of medications prescribed at evaluation. Proactive aggression and reactive aggression were assessed using the Proactive/Reactive Rating Scale.6,12 This rating scale consists of 3 questions assessing reactive aggression and 3 questions assessing proactive aggression. An example of a reactive aggression question is “When this child has been teased or threatened, he or she gets angry easily and strikes back.” An example of a proactive aggression statement is “This child uses physical force in


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order to dominate other kids.” The statements are written so that the respondent can use a 1- to 5-point scale, ranging from never to almost always, to indicate how frequently the statement applied to an individual child. For each aggression type the responses to each of the three questions were summed and then divided by three, yielding an average score. Children scoring an average of ≥ 3 (sometimes true, usually true, or almost always true) on either set of proactive/reactive statements were considered to demonstrate that type of aggression. The Proactive/Reactive aggression scale demonstrates adequate internal consistency, reliability and validity in children. For example, internal consistency for the Proactive/Reactive aggression scale is α = .91, inter-rater reliability for reactive aggression is K = .74, and for proactive aggression is K = .60.6,12 Separate behavioral profiles were obtained for boys displaying proactive versus reactive aggression in community elementary school samples partially supporting the validity of the Proactive/Reactive aggression scale.6 To assess overall aggression frequency and severity in the sample the Overt Aggression Scale modified to assess the frequency and severity of aggression over the month previous to rating, the Modified Overt Aggression Scale (MOAS), was used. The MOAS yields a total score ranging between 0 and 240.25,26 This scale has adequate reliability, validity, and is a standard aggression rating scale used in clinical aggression research with children.27 For example, the average Intraclass Correlation Coefficient (ICC) of reliability for physically aggressive behaviors (as scored by the scale for each individual incident) in samples of child and adult psychiatric patients is .88 supporting the scale’s reliability.26 For the Modified Overt Aggression Scale assessing behaviors over the previous month, the internal consistency of the scale α = .75, and the median inter-rater reliability coefficient is 0.96.25 Parents completed scales for outpatients and staff for inpatients. Children were asked to self-report drug and alcohol abuse. For the 70 outpatient children, not in a highly structured treatment setting, parental reports were used to supplement youth self-reports. Youth self-reports of substance use may be valid in highly structured psychiatric treatment settings where honest reporting is encouraged. For example, in a study of 87 substance abusing adolescents and 85 controls youth’s self-reports significantly discriminated patients from controls on DSM-IV substance abuse disorders, and did not discriminate between other diagnoses such as ADHD and depression.28 In another study of substance abusing adolescents, self-reports of substance abuse were compared with supervised urine drug samples for 55 subjects. Only 4.7% of cases involved subjects not reporting substance use detected by urine drug screens.29 This research supports the validity of self-report substance abuse data. In our sample at evaluation, the inter-rater agreement was good to excellent for self-reported drug use (K = .73) and self-reported alcohol use (K = .76). We assessed child self-report hostile attributions with the child version of the Buss Durkee Hostility Inventory.30 This self-report true/false scale yields an expressed hostility factor (score 0 to 7), an experienced hostility factor (score 0 to 6), as well as a total hostility rating (score 0 to 13). For children with a reading level of less than the third grade the questions were read aloud by the parent/staff worker completing the scale. The convergent and discrimi-

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nant validity of this scale has been supported.30,31 In child samples the scale test-retest reliability is 0.57.32 Classroom teachers assessed child hyperactive/impulsive behaviors by using the 10-item Conners Teacher Questionnaire (CTQ), yielding a total score between 0 and 30. Inter-rater reliability for the CTQ is r = .55. Test-retest factor reliabilities for the CTQ range from .70 to .90.33,34 All raters were blind to study aims and hypotheses. Inter-rater reliability was completed on diagnostic, historical, treatment, and chart review variables between a board-eligible and a board-certified child psychiatrist on 40 subjects (12%) for this study as follows: primary psychiatric diagnosis (K = .75), affective disorders (K = .87), disruptive behavior disorders (K = .92), psychotic disorders (K = .53), neurological diagnosis (K = .73), parental history of alcohol/substance (K = .99), parental history of violence (K = .99), parental arrest history (K = .99), history of physical abuse (K = .85), history of sexual abuse (K = .93), and number of medications at evaluation (ICC = .97). The mean Kappa was .84 on diagnostic, historical, and chart review variables for this data set.

Statistical Analysis The sample (N = 323) was divided and variables compared by gender. Differences in continuous variables were assessed using one-way ANOVA. To ascertain correlates of proactive or reactive aggression by gender, four stepwise regression analyses were conducted. Variables were entered into a stepwise regression model with proactive aggression (male or female) or reactive aggression (male or female) as the dependent measure. Variables with p ≤ .10 were entered into the regression analyses. Missing data resulted in an evaluable sample size of 313 for regression analyses. Significance was set at p < .05 for all tests.

Results Subjects The sample consists of 68 females and 255 males. For the total sample combined 74% were Caucasian American, 10% Hispanic American, 13% African American, 1% Asian American, and 2% Other. Additional sample characteristics are described in Table 1. Aggression differences between outpatients and inpatients were investigated. Inpatients had higher proactive aggression scores (F1,318 = 4.21, p = .04) than outpatients. However, no differences were found between inpatients and outpatients on MOAS severity and frequency (F1,318 = .172, p = .68) or reactive aggression (F1,318 = 1.08, p = .30).


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Table 1 Characteristics of the Sample by Gender (N = 323)

Characteristic Age Verbal IQ Physical Abuse Sexual Abuse Number of Subjects with ≥ 2 Placements Psychiatric Diagnosis Psychotic Affective DBD Alcohol Abuse Drug Abuse No. Comorbid Dx Number of Psych Meds Reactive Aggressors Proactive Aggressors Total MOAS Score Expressed Hostility Score Experienced Hostility Score Total Hostility Score Hyperactivity/Impulsivity CTQ Score Number of Subjects With Primary Caregiver Bio/Adop Parental History SUDs Parental History Violence

Male (N = 255)

Female (N = 68)

(N,%) or (X ± SD) (range)

(N,%) or (X ± SD) (range)

12.9 ± 2.9 (5 to 18) 92.6 ± 13.9 97 (38.2) 53 (20.9) 199 (78.3)

13.5 ± 2.7 (7 to 18) 93.7 ± 15.7 32 (47.1) 31 (45.6) 51 (75.0)

29 (11.4) 146 (57.3) 212 (83.1) 51 (20.1) 59 (23.2) 2.6 ± 0.9 (1 to 5) 2.0 ± 1.6 (0 to 8) 148 (58.7) 48 (19.0) 28.4 ± 29.1 (0 to 164) 4.4 ± 1.7 (0 to 7) 3.3 ± 1.3 (0 to 6) 7.7 ± 2.5 (1 to 13) 13.3 ± 7.9 (0 to 30) 188 (74.0)

8 (11.8) 58 (85.3) 46 (67.6) 24 (35.3) 24 (35.3) 2.9 ± 0.9 (1 to 5) 1.8 ± 1.5 (0 to 5) 38 (55.9) 14 (20.6) 36.3 ± 34.1 (0 to 182) 4.4 ± 1.7 (0 to 7) 4.0 ± 1.1 (0 to 6) 8.4 ± 2.3 (2 to 13) 10.9 ± 8.5 (0 to 30) 50 (73.5)

148 (58.3) 153 (60.2)

41 (60.3) 39 (57.4)

SUDs = substance use disorders, Bio/Adop = biological or adoptive primary caregiver.

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Aggression Prevalence In our sample, proactive aggression was identified in 48 males (19%) and 14 females (20.6%). Reactive aggression was identified in 148 males (58.7%) and 38 females (55.9%)(Table 1). Females were equally as likely as males to be rated as proactive aggressors (F1,318 = 2.068, p = .15) and reactive aggressors (F1,318 = .021, p = .88) in our clinical sample. Comparing males and females on the MOAS, no gender differences in aggression frequency or severity were found in our sample (F1,318 = 3.623, p = .06). However, this latter result must be accepted cautiously. With a larger sample size and diminished risk for Type II statistical error, this no difference finding might indeed become significant. Regression Analyses Male Proactive Aggression (Table 2). Correlates of male proactive aggression included self-reported drug use, high expressed hostility, having a disruptive behavior diagnosis (DBD, including attention deficit hyperactivity disorder, oppositional defiant disorder, and/or conduct disorder), a parental history of violence, and hyperactive/impulsive behavior as assessed by the CTQ. Together, these five variables explained 24.9% of the variance in male proactive aggression. Self reported drug use, expressed hostility, and exposure to maladaptive parenting such as parental violence accounted for 19.8% of the total variance, while hyperactive/impulsive behaviors and a psychiatric diagnosis of DBD explained an additional 5.1% of the variance (see Table 3). Thus, variables other than hyperactive/impulsivity and DBD account for the majority of the variance in male proactive aggression. Male Reactive Aggression (Table 2). Seven variables were associated with male reactive aggression, accounting for 34.7% of the variance. Unlike male proactive aggression, variables measuring hyperactive/ impulsive behaviors (CTQ and DBD) accounted for a large proportion of the explained variance in male reactive aggression (20%) (see Table 3). In contrast, other variables including drug use (accounting for 1.3%), total hostility (7.9%), and victimization by an adult perpetrator (2.1%) explained less of the variance in male reactive aggression. Thus, variables assessing hyperactive/impulsive behaviors appear more important in explaining male reactive, compared to proactive, aggression. Having a medical illness such as asthma or neurological


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Table 2 Regression Analyses. Proactive and Reactive Aggression by Gender R

R2

∆R2

β*

Fchange

df1,2

p

.326 .412 .456 .486 .499

.106 .170 .207 .236 .249

.106 .063 .038 .029 .013

.334 .163 .184 .163 .123

28.89 18.49 11.50 8.99 4.07

1,243 1,242 1,241 1,240 1,239

.000 .000 .001 .003 .045

.427 .511 .533 .552 .569 .580 .589

.182 .261 .284 .305 .323 .336 .347

.182 .079 .023 .021 .018 .013 .011

.268 .278 −.132 .171 .144 .115 −.105

54.03 25.87 7.88 7.14 6.46 4.66 3.91

1,243 1,242 1,241 1,240 1,239 1,238 1,237

.000 .000 .005 .008 .012 .032 .049

.471 .570 .615 .662 .691

.221 .325 .378 .439 .477

.221 .104 .053 .060 .039

.222 .330 .393 .318 .209

18.76 10.02 5.44 6.77 4.61

1,66 1,65 1,64 1,63 1,62

.000 .002 .023 .012 .036

.293 .425 .481

.086 .181 .232

.086 .095 .051

−.324 −.325 .226

6.19 7.56 4.21

1,66 1,65 1,64

.015 .008 .044

Variable Male (N = 245) Proactive Aggression Drug Use Expressed Hostility DBD Parent Violence CTQ Score Reactive Aggression CTQ Score Total Hostility Neurological Problems Adult Perpetrator DBD Drug Use Asthma Female (N = 68) Proactive Aggression Drug Use Expressed Hostility DBD Parental SUDs Psychotic Disorder Reactive Aggression Age at First Abuse Verbal IQ Stimulant Use

β* = Standardized coefficient.

disorders inversely correlated with the presence of reactive aggression in males, accounting for 3.4% of the variance. Female Proactive Aggression (Table 2). Correlates of female proactive aggression included self-reported drug use, expressed hostility, having a DBD or a psychotic disorder, and experiencing upbringing with parental substance use problems. These five variables explained 47.7% of the variance in female proactive aggression in our sample. A large amount of the explained variance in female proactive aggression was accounted for by drug use, expressed hostility, and exposure to maladaptive parenting such as parental substance abuse (38.5%),

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which are very similar to the variables that explain most of the variance in male proactive aggression (see Table 2). Similarly to male proactive aggression, only 5.3% of the variance was explained by variables assessing the presence of disruptive behavior disorders (DBD). Thus, correlates of proactive aggression are largely similar across gender in our clinical sample, and include variables other than hyperactivity/impulsivity and DBD. Female Reactive Aggression (Table 2). Three variables including younger age at first abuse experience, lower verbal IQ, and being treated with stimulant medications explained 23.2% of the variance in female reactive aggression. Correlates of female reactive aggression appear different than correlates of male reactive aggression in our sample. For males, a large amount of the explained variance in reactive aggression appears to be mediated through variables assessing the presence of hyperactive/impulsive behaviors. Although variables assessing hyperactive/impulsive behaviors (treated with a stimulant medication, presumably for ADHD symptoms), explained 5.1% of the variance, an early trauma history coupled with a low verbal IQ explained 18.1% of the variance in female reactive aggression. Thus unlike proactive aggression, correlates of reactive aggression appear different for males and females in our sample. Discussion We studied gender differences in proactive and reactive aggression in a heterogeneous sample of clinically referred children and adolescents. High rates of proactive and reactive aggression, and aggression frequency and severity were found in our sample. Unlike studies of proactive and reactive aggression assessed in non-referred children that report higher rates of both proactive and reactive aggression for boys compared with girls,35 we found no gender differences in proactive or reactive aggression in our clinical sample. There exists a trend in the data set (p = .06) for aggression severity and intensity to be higher for boys compared with girls, although this finding did not reach statistical significance in our analysis. This suggests that in clinically ascertained samples of seriously emotionally disturbed youth gender differences in aggression may disappear and girls may be equally as proactive and reactive in their aggression, as boys. Many similarities in correlates associated with proactive aggression


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were found for both males and females in our clinical sample. Selfreported drug use, expressed hostility, having a disruptive behavior diagnosis, and experiencing maladaptive parenting (either parental violence or substance abuse) were remarkably similar for both males and females in explaining variance in proactive aggression. These results suggest that in samples of clinically referred children few gender differences in the correlates of proactive aggression may exist. This is unlike studies of conduct disorder in clinically referred samples of children which show differences in correlates across gender (i.e., higher rates of somatization in conduct disordered females and more physical aggression in conduct disordered males),2,36 and suggest that previously reported gender differences in referred aggressive children may depend in part on how aggression is defined or in what population aggression is sampled. Previous research has reported a robust association between substance use disorders and conduct disorder, especially for adolescents. Children with substance use disorders are found to be more aggressive than children without substance use disorders.37 Children with earlyonset aggression are more at risk for later substance use disorders than adolescents with later-onset aggression.38 Results from our sample suggest that the associations between substance use disorders and conduct disorder/aggression in clinically referred children may be mediated by the proactive type of aggression in contrast to reactive aggression, hold for self-reported drug use as opposed to alcohol use, and occur irrespective of gender. Thus, research examining the relationships between conduct problems, delinquency, aggression, and substance use disorders in clinically referred samples may wish to specifically evaluate proactive aggression in future studies. Expressed hostility also appears related to both male and female proactive aggression in our sample. Previous research in non-referred community samples has reported that reactive aggression, but not proactive aggression, is associated with hostile attributions.14 Because a large percentage of children in our sample experienced maladaptive parenting in their development and because proactive aggression is related to learning for children, they may be more hostile than nonreferred samples, and more ready to see positive outcomes from aggression. Our results support a relationship between proactive aggression and hostility for both males and females in clinical samples. Gender differences in reactive aggression were apparent in our sample. While variables assessing attention deficit hyperactivity disorder symptoms (stimulant use), and disruptive behavior disorder diagnoses

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accounted for some variance in both male and female reactive aggression, our results suggest the importance of hyperactive/impulsive behaviors in male reactive aggression. Hyperactivity/impulsive behaviors explained more of the variance in male reactive aggression than any other variable. Our results are in agreement with previous research reporting a relationship between attention deficits/hyperactivity and conduct problems/aggression in child psychopathology,22 and suggest that this relationship may be most robust for reactive types of aggression in clinically referred males. Reactive aggression in females was largely accounted for by variables other than those assessing hyperactivity/impulsivity. Early traumatic stress coupled with a low verbal IQ is related to female reactive aggression in our clinical sample. Our results are in agreement with previous studies documenting a relationship between early traumatic stress and aggression in clinically referred children,39 and suggest that this association may be important for clinically referred females who exhibit reactive types of aggression. The inability to modulate behaviors and feelings with words because of low verbal IQ is another risk factor for reactive aggression in previously abused and clinically referred females. Clinical Implications Systematically identifying types of aggression in the clinical setting in ways other than the DSM-IV diagnosis of conduct disorder or oppositional defiant disorder may prove helpful to the clinician. Our results suggest the importance of hyperactive-impulsive behavior to reactive aggression in clinically referred males. Clinically referred boys with high reactive aggression should be assessed for the presence of associated hyperactive-impulsive and ADHD behaviors. Since hyperactive-impulsive and ADHD behavior is robustly responsive to pharmacological interventions,40 stimulant therapy may be a helpful intervention for aggressive individuals with ADHD.41 Correlations between self-reported hostility and proactive and reactive aggression suggest that clinical interventions targeting selfreported attributes such as hostility may prove useful in decreasing aggression in clinically referred males and females. Cognitive behavioral therapy (CBT) interventions that target cognitive perceptions and appraisals of environmental events that serve to govern individual response may be useful in diminishing aggression in clinically referred youths.42


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Results underscore the importance of family assessment focused on evaluating the possibility of maladaptive parenting (e.g., parental violence, parental SUDs, abuse) in the etiology of aggression in referred males and females. Interventions to promote adaptive parenting may be an anti-aggression strategy for the violent child. Early intervention efforts directed towards at risk families to help prevent physical and sexual abuse may diminish vulnerability to reactive aggression in atrisk females. Clinicians need to be aware of the association between proactive aggression and substance abuse disorders in both genders. Highly proactively aggressive males and females should be assessed for the possibility of concomitant substance use disorders. Conversely, substance-abusing youngsters need clinical assessment for the presence of proactively aggressive behaviors. Limitations Limitations of our research must be considered. Our methodology was cross-sectional in design and so causality cannot be inferred from the results. The majority of subjects were seriously emotionally disturbed, with a history of multiple psychiatric treatment failures. The sample was heterogeneous in composition. Thus, results may not generalize to non-referred community samples or referred children with more mild mental health difficulties. The broad age range of our sample may have obscured more age-specific developmental correlates of proactive and reactive aggression in males and females. There were many fewer females than males in our sample. The stability of findings for females should be accepted cautiously until further studies can replicate our findings in samples with a larger number of females. A lack of structured diagnostic interviewing precluded a more precise assessment of the relationship between specific psychiatric diagnoses and aggression subtype. However, our sample size was large and aggression was highly prevalent in our subjects providing an adequate population with which to investigate proactive and reactive aggression in clinically referred males and females. Summary In summary, high rates of proactive and reactive aggression were found in our sample of clinically referred children. Females were equally as likely as males to meet our criteria for proactive aggression

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