Aggression, and some related psychological constructs (anger, hostility, and impulsivity); some comments from a research project

COMT but not serotonin-related genes modulates the influence of childhood abuse on anger traits

Anger-related traits are regulated by genes as well as early environmental factors. Both childhood maltreatment and genes underlie vulnerability to suicidal behaviors, possibly by affecting the constitution of intermediate phenotypes such as anger traits. The aim of this study was to test the interaction between nine candidate genes and childhood maltreatment in modulating anger-related traits in 875 adult suicide attempters. The State-Trait Anger Expression Inventory and the Childhood Trauma Questionnaire were used to examine anger traits and traumatic childhood experiences, respectively. The functional polymorphism of the catecholamine-O-methyl-transferase (COMT) gene Val158Met significantly modulated the association between sexual abuse and anger-trait level (P = 0.001). In the presence of sexual abuse, individuals carrying the Val high-activity allele displayed greater disposition toward anger than individuals homozygous for the Met allele (P = 0.0003). Notably, none of the serotonin-related genes influenced the effect of childhood abuse on anger traits. The results of the present study suggest that anger-trait level is influenced by the interaction between childhood abuse and functional polymorphism in the COMT gene. This study was carried out in a population with a high frequency of childhood abuse and a high disposition toward anger, and replication in healthy subjects is needed.

Validation of the Australian Propensity for Angry Driving Scale (Aus-PADS)

The present study used a university sample to assess the test-retest reliability and validity of the Australian Propensity for Angry Driving Scale (Aus-PADS). The scale has stability over time, and convergent validity was established, as Aus-PADS scores correlated significantly with established anger and impulsivity measures. Discriminant validity was also established, as Aus-PADS scores did not correlate with Venturesomeness scores. The Aus-PADS has demonstrated criterion validity, as scores were correlated with behavioural measures, such as yelling at other drivers, gesturing at other drivers, and feeling angry but not doing anything. Aus-PADS scores reliably predicted the frequency of these behaviours over and above other study variables. No significant relationship between aggressive driving and crash involvement was observed. It was concluded that the Aus-PADS is a reliable and valid tool appropriate for use in Australian research, and that the potential relationship between aggressive driving and crash involvement warrants further investigation with a more representative (and diverse) driver sample.

Citalopram intervention for hostility: results of a randomized clinical trial

Hostility is associated with an increased risk for cardiovascular disease (CVD). Because central serotonin may modulate aggression, we might expect selective serotonin reuptake inhibitors (SSRIs) to be effective in reducing hostility. Such effects have never been examined in individuals scoring high on hostility who are otherwise free from major Axis I psychopathology according to criteria in the Diagnostic and Statistical Manual of Mental Disorders (4th ed., Text Revision; American Psychiatric Association, 2000). A total of 159 participants (ages 30?50 years, 50% female) scoring high on 2 measures of hostility and with no current major Axis I diagnosis were randomly assigned to 2 months of citalopram (40 mg, fixed-flexible dose) or placebo. Adherence was assessed by electronic measurement and by drug exposure assessment. Treated participants showed larger reductions in state anger (Condition x Time; p = .01), hostile affect (p = 02), and, among women only, physical and verbal aggression (p = .005) relative to placebo controls. Treatment was also associated with relative increases in perceived social support (p = .04). The findings have implications for understanding the central nervous system correlates of hostility, its associations with other psychosocial risk factors for CVD, and, potentially, the design of effective interventions.

Disentangling impulsiveness, aggressiveness and impulsive aggression: an empirical approach using self-report measures

There is confusion in the literature concerning the concept of impulsive aggression. Based on previous research, we hypothesize that impulsivity and aggression may be related, though not as closely as to consider them the same construct. So, our aim was to provide empirical evidence of the relationship between the impulsivity and aggressiveness constructs when considered as traits. Two widely used questionnaires [Barratt's Impulsiveness Scale (BIS) and Aggression Questionnaire-Refined (AQ-R)] were administered to 768 healthy respondents. Product-moment and canonical correlations were then calculated. In addition, a principal components analysis was conducted to explore whether impulsive aggression can be defined phenotypically as the expression of a single trait. The common variance between impulsivity and aggressiveness was never higher than 42%. The principal components analysis reveals that one component is not enough to represent all the variables. In conclusion, our results show that impulsivity and aggressiveness are two separate, although related constructs. This is particularly important in view of the misconceptions in the literature.

Adolescents with childhood ADHD and comorbid disruptive behavior disorders: aggression, anger, and hostility

This study examined the self-reported expression of overt aggressive behaviors and covert emotional and cognitive processes in adolescents diagnosed with ADHD and comorbid disruptive behavior disorders (DBDs) during childhood.

METHODS

Participants were a clinically referred sample of 85 individuals diagnosed with ADHD, initially recruited in the early to mid 1990s when they were 7-11 years of age. At that time, 44 (52%) met criteria for a comorbid diagnosis of ODD and an additional 22 (26%) met criteria for a comorbid diagnosis of CD. Approximately 10 years later, these youth, along with an age-matched comparison sample (n=83), were re-evaluated to assess a wide array of outcomes including physical and verbal aggression, anger, and hostility.

RESULTS

Individuals diagnosed with ADHD + CD in childhood reported elevated levels of physical aggression when compared to Controls and the ADHD-only group. Individuals diagnosed with ADHD + ODD had elevated levels of verbal aggression compared to Controls. Additionally, both comorbid groups experienced significantly greater amounts of anger, but not hostility, as compared to Controls. Importantly, the persistence of ADHD symptoms into adolescence accounted for most group differences in verbal aggression and anger at follow-up, but not physical aggression, which was accounted for by childhood CD.

CONCLUSION

Adolescents diagnosed with ADHD and comorbid disruptive behavior disorders during childhood report high levels of aggression associated with increased emotionality in the form of anger, but not hostile cognitions. These findings suggest that in addition to inattention and hyperactivity/impulsivity, emotional dysregulation may be an important component of ADHD, particularly as it presents in adolescence.

Anger and Associated Experiences of Sadness, Fear, Valence, Arousal, and Dominance Evoked by Visual Scenes

Anger is a basic emotion experienced in several aversive situations. In this study, the relation between Anger, Fear, and Sadness, as well as the dimensions of Valence, Arousal, and Dominance, were examined. It was hypothesized that pictures showing an Intention to Harm would evoke not only Anger, but also Fear and Sadness, and that this would be correlated with low Valence, high Arousal, and high Dominance. To this end, 45 healthy volunteers (25 women and 20 men; M age = 27.2 yr., SD = 9.5) recorded appraisals for each of these emotional experience while viewing 120 pictures selected from the International Affective Picture System. Data were analyzed with a linear mixed model and a hierarchical classes approach to identify differences and correlations between emotional categories. Results indicate that those pictures showing Intention to Harm generate higher Anger and Fear, while pictures representing Frustration of Goals leads to higher Sadness. In addition, high Anger, Fear, and Sadness are associated with low Valence, moderate Arousal, and high Dominance. Same sex differences in emotional responses were also found. These findings suggest that the experience of Anger requires the inference of the other's mental and physical state and need the regulation of cognitive and affective systems acting together. The study of this emotion should consider both categorical and dimensional approaches in order to define its coherent features.

Examining the role of static and dynamic risk factors in the prediction of inpatient violence: variable- and person-focused analyses

Although the construct of psychopathy is related to community violence and recidivism in various populations, empirical evidence suggests that its association with institutional aggression is weak at best. The current study examined, via both variable-level and group-level analyses, the relationship between standard violence risk instruments, which included a measure of psychopathy, and institutional violence. Additionally, the incremental validity of dynamic risk factors also was examined. The results suggest that PCL-R was only weakly related to institutional aggression and only then when the behavioral (Factor 2) aspects of the construct were examined. The clinical and risk management scales on the HCR-20, impulsivity, anger, and psychiatric symptoms all were useful in identifying patients at risk for exhibiting institutional aggression. These data suggest that factors other than psychopathy, including dynamic risk factors, may be most useful in identifying forensic patients at higher risk for exhibiting aggression.

Aggressiveness, anger, and hostility in eating disorders

OBJECTIVE

Despite evidence of a link between the behavioral and cognitive dimensions of aggressiveness and eating disorders, only few studies have tested this relation empirically.

METHODS

A total of 112 female patients with anorexia nervosa (n = 61) or bulimia nervosa (n = 51) and 631 young girls attending 7 high schools in the same health district as the patients (northeast Italy) were invited to fill in a set of self-report instruments including the Eating Attitudes Test, the Bulimic Investigatory Test of Edinburgh, the Body Attitudes Test, and the Buss-Perry Aggression Questionnaire (AQ).

RESULTS

In both healthy controls and patients, scores on the measures of eating disorder symptoms were positively related to the scores on the AQ: the strength of the association did not differ between healthy controls and patients. However, patients diagnosed with eating disorders were not more likely to disclose a propensity to aggression than the healthy controls drawn from the community: patients with anorexia nervosa scored lower than controls on the physical aggression and on the verbal aggression subscales of the AQ (P < .05). On the other hand, patients with bulimia nervosa scored higher than controls on the anger subscale of the AQ (P < .05) but did not differ from them on the other subscales of the questionnaire.

CONCLUSIONS

The results confirm the higher propensity to anger in patients with bulimia nervosa; in patients with anorexia nervosa, difficulties in expressing anger and outward-directed aggressiveness can be a prevailing feature. The younger age of controls and exclusive reliance on self-report measures might have concealed some differences between patients and community subjects.

Attention-deficit/hyperactivity disorder and callous-unemotional traits as moderators of conduct problems when examining impairment and aggression in elementary school children

Examined whether attention-deficit/hyperactivity disorder (ADHD) and callous-unemotional (CU) traits moderate the association between conduct problems (CPs) and impairment and aggression. Participants were 214 children who were rated by their elementary school classroom teachers. Results indicated that the association between CP and impairment and aggressive outcomes is almost always moderated by ADHD and/or CU. Moreover, in many instances, the association between CP and outcomes was moderated by both ADHD and CU such that the moderating effects of CU on CP were more pronounced at lower levels of ADHD. Results are discussed with respect to developmental taxonomies and trajectories of the disruptive behavior disorders.

Sex, aggression and impulse control: an integrative account

There is evidence that the male sex and a personality style characterized by low self-control/high impulsivity and a propensity for negative emotionality increase the risk for impulsive aggressive, antisocial and criminal behavior. This article aims at identifying neurobiological factors underlying this association. It is concluded that the neurobiological correlates of impulsive aggression act through their effects on the ability to modulate impulsive expression more generally, and that sex-related differences in the neurobiological correlates of impulse control and emotion regulation mediate sex differences in direct aggression. A model is proposed that relates impulse control and its neurobiological correlates to sex differences in direct aggression.

MODERATE AND SEVERE AGGRESSION JUSTIFICATION INSTRUMENTAL AND REACTIVE CONTEXTS

The main goal of this study was to analyze the justification of interpersonal aggression various situations or contexts. For this purpose, a self-report instrument was employed that measures different kinds of aggressive behaviors in situations in which it may be considered justified: the Cuestionario de Actitudes Morales sobre Agresión (CAMA; Ramirez, 1991), a reliable and valid test to measure the different degrees to which youth and adolescents may justify interpersonal aggression (Ramirez & Andreu, 2006). A large sample (N = 735) of participants from various educational centers of Madrid was utilized. Results revealed that normative beliefs vary as a function of age, sex, and the instrumental-reactive context. Reactive situations elicited higher levels of justification than instrumental situations and higher levels in the justifying beliefs about severe aggression were found among men than among women and in adolescents than in young adults. There were no significant differences in the justifying beliefs about moderate aggression.

Catechol-O-methyltransferase polymorphism (COMT) in suicide attempters: a possible gender effect on anger traits

Anger-related personality traits are considered contributory risk factors for suicidal behavior. According to twin studies, they are partially under genetic control and their various clinical expressions have been associated with serotonergic and catecholaminergic activities. A functional polymorphism on the human catechol-O-methyltransferase (COMT) gene, which codes for the catecholamines inactivating enzyme COMT, has been shown to influence aggressive and anger-related traits in various clinical populations. The aim of the present study was to investigate the association between anger traits (as characterized by the State-Trait Anger Expression Inventory, STAXI) and COMT Val158Met polymorphism in suicide attempters (n = 427) and control subjects (n = 185). Results showed that the high activity genotype (Val/Val) was more frequent in suicide attempters than in normal controls. Moreover, the Val/Val genotype markedly affected the scores on two STAXI subscales--Trait Anger and Anger Control--in female suicide attempters, thus suggesting a possible gender effect of the COMT genotype on a stable personality trait. These results are discussed in the light of recently published data on the effect of COMT Val158Met polymorphism on different cognitive and behavioral traits.

Individual differences in offensive aggression in golden hamsters: a model of reactive and impulsive aggression?

In humans, reactive aggression is associated with impulsivity. The purpose of this study is to relate reactive and impulsive aggression in humans with offensive aggression in animals and identify neurobiological correlates associated with certain forms of the behavior. We predicted that individual differences in offensive aggression are associated with individual differences in impulsivity. Adult male hamsters were repeatedly tested for offensive responses and divided into High-Aggression or Low-Aggression groups. They were then trained and tested under a delay-discounting paradigm to assess impulsivity. High-Aggression animals consistently attacked and bit more frequently and faster, and showed highly repetitive behavior, indicated by repeated attacks per contact bout. In addition, these animals engaged in more fragmented and shorter contact bouts. During impulsivity testing, High-Aggression animals preferred immediate smaller rewards over delayed larger rewards. Furthermore, 5-HT and vasopressin (AVP) innervation was compared between the groups. High-Aggression animals showed decreased 5-HT varicosities in several key brain areas involved in aggressive and/or impulsive behavior and decreased AVP fibers in the anterior hypothalamus. Together, these data show a convergence of behavioral phenotypes through individual differences in offensive aggression and impulsivity. As such, this association provides support for an animal model of reactive and impulsive aggression. Furthermore, this behavioral convergence is supported by a concurrent reduction in 5-HT innervation of brain areas controlling aggression and impulsivity, providing a common neural mechanism for this phenotype.

Differential role of the 5-HT1A receptor in aggressive and non-aggressive mice: An across-strain comparison

Differential role of the 5-HT(1A) receptor in aggressive and non-aggressive mice: an across-strain comparison. PHYSIOL BEHAV 00(0) 000-000, 2006. According to the serotonin (5-HT)-deficiency hypothesis of aggression, highly aggressive individuals are characterized by low brain 5-HT neurotransmission. Key regulatory mechanisms acting on the serotonergic neuron involve the activation of the somatodendritic inhibitory 5-HT(1A) autoreceptor (short feedback loop) and/or the activation of postsynaptic 5-HT(1A) receptors expressed on neurons in cortico-limbic areas (long feedback loop). In this study, we examined whether low serotonin neurotransmission is associated with enhanced 5-HT(1A) (auto)receptor activity in highly aggressive animals. Male mice (SAL-LAL, TA-TNA, NC900-NC100) obtained through different artificial-selection breeding programs for aggression were observed in a resident-intruder test. The prefrontal cortex level of 5-HT and its metabolite 5-HIAA were determined by means of HPLC. The activity of the 5-HT(1A) receptors was assessed by means of the hypothermic response to the selective 5-HT(1A) agonists S-15535 (preferential autoreceptor agonist) and 8-OHDPAT (full pre- and postsynaptic receptor agonist). Highly aggressive mice had lower serotonin levels in the prefrontal cortex and two out of three aggressive strains had higher 5-HT(1A) (auto)receptor sensitivity. The results strengthen the validity of the serotonin-deficiency hypothesis of aggression and suggest that chronic exaggerated activity of the 5-HT(1A) receptor may be a causative link in the neural cascade of events leading to 5-HT hypofunction in aggressive individuals.

Plasma serotonin levels in young violent offenders: Aggressive responding and personality correlates

70 young male violent offenders and 30 normal controls in Hunan, China were interviewed and assessed by the Minnesota Multiphasic Personality Inventory (MMPI), Point Subtraction Aggression Paradigm (PSAP) and plasma serotonin (5-HT) level. Compared to the normal controls, the violent offenders had significantly higher plasma 5-HT levels; higher scores on the MMPI subscale Pd (P < 0.01), Pa (P < 0.05); and higher PSAP-B responding and lower PSAP-C responding (P < 0.05). There was a positive correlation between the MMPI Pd score and the PSAP B response, but no significant correlation was found between Pd score and plasma 5-HT level, or between PSAP B response and plasma 5-HT level. Our data suggest that the young violent offenders are more aggressive than the normal control. But this study did not demonstrate that the plasma 5-HT level had a correlation with the PSAP aggressive response. The relationship between the aggressiveness and impulsivity in the violent behavior needs further study.