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PubMed2000

Ultradian corticosterone rhythm and the propensity to behave aggressively in male rats.

Ultradian fluctuations in plasma glucocorticoids have been demonstrated in a variety of species including humans. The significance of such rhythms is poorly known, although disorganized ultradian glucocorticoid rhythms have been associated with behavioural disorders. Here we report that ultradian glucocorticoid rhythms may establish the propensity to behave aggressively in male rats. Male rats were significantly more aggressive in the increasing phase of their corticosterone fluctuation when confronting a male intruder than counterparts in the decreasing phase of their corticosterone fluctuations facing such opponents. Corticosterone fluctuations were mimicked by a combination of treatments with the corticosterone synthesis inhibitor metyrapone and corticosterone. Again, males with increased plasma corticosterone levels were more aggressive than counterparts with a decreased plasma corticosterone concentration. These data suggest that the behavioural response to an aggressive challenge may vary in the same animal across the day due to the pulsating nature of corticosterone secretion. Aggressive behaviour is also episodic in humans; moreover, intermittent explosive behaviour is recognized as a psychological disorder. It can be hypothesized that a temporal coincidence between the occurrence of a challenge and a surge in plasma corticosterone concentration may be one of the factors that promote episodic aggressive outbursts.

Activity Cycles↗

PubMed2003

Aggressiveness is associated with genetic diversity in landlocked salmon (Salmo salar).

The amount of intraindividual genetic variation has often been found to have profound effects on life history traits. However, studies concerning the relationship between behaviour and genetic diversity are scarce. Aggressiveness is an important component of competitive ability in juvenile salmonids affecting their later performance and survival. In this study, we used an experimental approach to test the prediction that juveniles with low estimated genetic diversity should be less aggressive than juveniles with high estimated genetic diversity in fry from a highly endangered population of land-locked salmon (Salmo salar). This was achieved by using a method enabling the accurate estimation of offspring genetic diversity based on parental microsatellite genotype data. This allowed us to create two groups of offspring expected to have high or low genetic diversity in which aggressive behaviour could be compared. Salmon fry with low estimated genetic diversity were significantly less aggressive than fry with high estimated genetic diversity. Closer analysis of the data suggested that this difference was due to differences in more costly acts of aggression. Our result may reflect a direct effect of genetic variation on a fitness-related trait; however, we cannot rule out an alternative explanation of allele-specific phenotype matching, where lowered aggression is expressed towards genetically more similar individuals.

Aggression↗

PubMed2003

Hypocholesterolaemia in dogs with dominance aggression.

Serum lipids and lipoprotein concentrations have been associated with dominance aggression in humans. The aim of this study was to investigate the link between serum lipids, including cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC) to HDL-C ratio and dominance aggression in dogs. Levels of serum TC, triglyceride and HDL-C were significantly lower in dogs with dominance aggression compared with non-aggressive dogs (P < 0.001). These results suggest that a relationship exists between serum lipid profile and dominance aggression in dogs, and hypocholesterolaemia exists in dogs with dominance aggression.

Aggression↗

PubMed2003

The utility of Cox's Interaction Model to direct the assessment and prevention of adolescent aggression.

The current study of violence prevention is hampered by a lack of consensus on the definition of violence. There is, however, some agreement about the behavioral cues that may predict violent behavior such as aggression. Although it has been shown that individual-level variables (e.g., race, gender, and ethnicity) are correlated with aggressive behavior, it is clear that they alone are not explanatory of aggressive behavior. This article demonstrates how the Interaction Model of Client Health Behavior is an important health behavior framework for the assessment of aggression in adolescents, offering insight into the contextual nature of adolescent aggression. Victimization and witnessing of violence, frequently identified to be precursors of adolescent aggression in current epidemiologic studies, are examined within this framework. On the basis of the interactional nature of the phenomenon, necessary components for successful prevention programs are suggested. Finally, future research implications calling for a well-designed study that integrates individual and contextual variables with the use of this theory-driven explanatory framework are proposed.

Adolescent↗

PubMed2000

Pharmacologic approach to aggression in neuropsychiatric disorders.

Aggressive behavior has been associated with numerous neurologic conditions including traumatic brain injury, mental retardation, developmental disorders, Huntington disease, and several dementias. Preclinical and human studies suggest that dysfunction of neural systems involving the brainstem, hypothalamus, amygdala, or prefrontal cortex can give rise to aggression. Several neurochemicals are felt to be relevant to modulation of aggression, including serotonin, dopamine, norepinephrine, GABA, acetylcholine, and androgens. Pharmacologic intervention studies have targeted these systems but have been limited by inconsistent definitions of aggression and a relative paucity of controlled trials. This article briefly reviews studies of neural systems and medication trials relevant to aggression and propose a clinical approach to treatment of patients manifesting aggressive behavior.

Aggression↗

PubMed2000

Aggressive behaviour at a residential epilepsy centre.

There is an extensive literature on epilepsy and violence, but no study has addressed aggression (i.e. apparently intentional violence) in a residential-care population. We performed a retrospective study at the Chalfont Centre for Epilepsy (a residential-care facility in rural Buckinghamshire) in order to determine the frequency and character of episodes of aggression. This allowed us to identify a group of aggressive subjects who were compared with age- and sex-matched control subjects drawn from the remaining residents. We found the prevalence of aggression to be 27.2% in 1 year amongst long-term residents. The overall frequency was estimated at between 121 and 207 incidents per 100 persons per year. A few incidents (0.7%) were related to an acute psychosis but they were more likely to result in significant injury. Offenders were younger than non-aggressive residents. Gender, age of onset of epilepsy, history of psychosis, mobility, abnormality on MRI scan, learning disability and seizure frequency were not associated with aggressive conduct.

Adolescent↗

PubMed2003

[Emotional reactions of staff-members managing highly aggressive mentally ill patients].

Highly aggressive behaviour of psychiatric in-patients often provokes intense emotional reactions and countertransference-feelings in staff especially when it is necessary to control aggression in psychiatric emergency units. We investigated the emotional reactions immediately after the manifestation of a patient's aggressive behaviour in a group of 53 staff members. The amount of aggression was measured with the help of the "Modified Overt Aggression Scale" (MOAS). The type and intensity of the staff-emotions can be adequately described by using a special self-rating questionnaire: "Eigenschaftswörterliste" (EWL 60 S). Using principal component analysis, three factors were differentiated: experience of stress, experience of sovereignty and experience of calmness. Several independent variables were identified as selectively increasing the probability of priority of each emotional factor mentioned above. In addition, a subgroup of staff members who have a raised risk of stress experience compared to the other staff members was compiled by cluster analysis. Based on an aggressiveness sequence model, useful strategies were discussed which directly aim to improve the coping abilities of staff members dealing with their emotional over involvement.

Adaptation, Psychological↗

PubMed2004

[Ethnic minorities and aggressive behaviour in psychiatric in-patients: an investigation using a "Matched-Pair" design].

In a group of 105 mentally ill immigrants we investigated the intensity and the frequency of aggressive behaviour at the time of admission with the help of two standardized instruments: the "Social Dysfunction and Aggression Scale" (SDAS) and the "Modified Overt Aggression Scale" (MOAS). As many as possible collateral informants were contacted to gather all information available for the aggressiveness rating. The immigrant group was compared to a matched group of German patients. 416 German patients had to be investigated until 105 of them fulfilled the matching criteria. The matching variables were: age, gender, diagnosis (ICD-10), severity of mental illness (CGI) and social status. The physicians who carried out the matching process and who carried out the aggression-rating were "blind" to the aim of the investigation. We found out that there was no significant difference between immigrants and German patients when the sum-scores of the SDAS and the MOAS are compared (N = 210). When SDAS single variables were compared German patients had a higher severity and frequency of "physical violence towards other persons". We interpreted this finding as an increased level of disinhibition which may be correlated to a higher acceptance of aggressive behaviour in German culture compared to normative beliefs of Mediterranean immigrants.

Adolescent↗

PubMed2004

An aggression policy that works.

In 1999, a survey of the clinical staff in Royal Darwin Hospital showed that most instances of aggressive and abusive behaviour by patients or visitors occurring in the hospital went unreported because staff believed there would not be any follow-up investigation or action taken by management, Australia. In response, a hospital working party was formed to develop and implement an aggression management policy with practical effective strategies. The principal tool used was an Action Plan that delineated an immediate response to the aggression, as well as long-term strategies such as negotiated care and behaviour modification programs. An advocate is provided for the patient and debriefing for staff members. If the aggressive behaviour continues, early discharge of the patient could be initiated. The fundamental principle of the policy is to prevent fostering a culture of acceptance of aggressive behaviour through appropriate early intervention. In 2002, a follow-up survey showed that 82% of aggressive incidents were being reported and dealt with by management in a timely manner -- a significant improvement.

Aggression↗

PubMed2003

Progesterone receptors mediate male aggression toward infants.

Neuroendocrine mechanisms that mediate male aggression toward infants are poorly understood. Although testosterone is known to enhance aggression in other social contexts, evidence that it modulates aggression toward infants is equivocal. We have found that male progesterone receptor knockout (PRKO) mice exhibit no infanticidal behavior and little aggression toward young. Male PRKO mice also display significantly enhanced parental behaviors. In wild-type mice, blockade of PR induces a behavioral phenotype similar to that of the PRKO males, whereas progesterone exacerbates aggressive tendencies toward infants. Aggressive behaviors directed toward adult males, by contrast, are unaffected by progesterone, PR antagonism, or PR gene deletion. Previously thought to be of diminished importance in male animals, PRs play a critical and specific role in modulating infant-directed behaviors in male mice.

Aggression↗

PubMed2005

Changes in brain testosterone and allopregnanolone biosynthesis elicit aggressive behavior.

In addition to an action on metabolism, anabolic/androgenic steroids also increase sex drive and mental acuity. If abused, such steroids can cause irritability, impulsive aggression, and signs of major depression [Pearson, H. (2004) Nature 431, 500-501], but the mechanisms that produce these symptoms are unknown. The present study investigates behavioral and neurochemical alterations occurring in association with protracted (3-week) administration of testosterone propionate (TP) to socially isolated (SI) and group-housed male and female mice. Male but not female SI mice exhibit aggression that correlates with the down-regulation of brain neurosteroid biosynthesis. However, in female mice, long-term TP administration induces aggression associated with a decrease of brain allopregnanolone (Allo) content and a decrease (approximately 40%) of 5alpha-reductase type I mRNA expression. In spayed mice treated with TP, restitution experiments with progesterone and estrogen normalize brain Allo content and prevent aggression. Submicromolar doses of S-norfluoxetine (S-NFLX) that are insufficient to inhibit serotonin reuptake selectively increase brain Allo content and abolish TP-induced aggression. Our results support the view that TP-induced aggressive behavior is the result of a TP-mediated neurosteroid biosynthesis down-regulation that can be reversed by the S-NFLX-induced increase of brain Allo content.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed2001

Brain serotonin dysfunction accounts for aggression in male mice lacking neuronal nitric oxide synthase.

Genetically engineered mice with targeted disruption of the neuronal nitric oxide synthase (nNOS) gene established the inhibitory role of nitric oxide (NO) in male impulsive aggressive behavior. This was later confirmed by using selective nNOS inhibitors in male wild-type mice. The molecular mechanisms accounting for the aggressive behavior caused by the lack of neuronally derived NO is not known. Recent studies suggest that central serotonergic neuronal circuits and particularly 5-HT(1A) and 5-HT(1B) receptors play a prominent role in the regulation of aggression. Accordingly, we investigated whether the aggressiveness caused by the lack of nNOS might be because of alterations in serotonergic function. We now demonstrate that the excessive aggressiveness and impulsiveness of nNOS knockout mice is caused by selective decrements in serotonin (5-HT) turnover and deficient 5-HT(1A) and 5-HT(1B) receptor function in brain regions regulating emotion. These results indicate an important role for NO in normal brain 5-HT function and may have significant implications for the treatment of psychiatric disorders characterized by aggressiveness and impulsivity.

5-Hydroxytryptophan↗

PubMed1998

Alcohol-induced stimulation and sedation: relation to physical aggression.

The relation between the stimulating and the sedating effects of acute alcohol consumption on human physical aggression was examined. Sixty male social drinkers were assigned to either an alcohol or a sober group. Aggression was measured using a modified version of S. Taylor's (1967) aggression paradigm, in which electric shocks are received from and administered to a fictitious opponent during a competitive task. Aggression was operationalized as the intensity and the duration of the shocks selected. Stimulation and sedation were measured using a self-report inventory. Results demonstrated that stimulation was positively related to aggression, but only in the intoxicated state. Sedation was not related to aggression in either the intoxicated or the sober state.

Adult↗

PubMed2001

Aggression in toddlers: associations with parenting and marital relations.

This study examined the relation among parenting factors, marital relations, and toddler aggression. A structured questionnaire was administered to both parents of 254 2-year-olds. The authors used correlation and hierarchical multiple regression analyses to assess the extent to which certain personality traits, drug use, parenting style, and marital conflicts were related to the toddlers' aggressive behavior. Results showed that the maternal child-rearing and parental aggression domains had a direct effect on toddler aggression. The domain of maternal child rearing also served as a mediator for the domains of marital relations, paternal child rearing, parental aggression, and parental drug use. The findings indicated that maternal child-rearing practices, personality attributes, and drug use were more important than paternal attributes in relation to toddler aggression. Implications for prevention among families at risk are discussed.

Aggression↗

PubMed1998

Predictors of aggression in hospitalized adolescents.

Client records spanning a 14-month period were examined for an adolescent unit of a large state psychiatric hospital to identify client variables predictive of acts of physical aggression in hospitalized adolescents. Forty-two percent of the 43 girls and 55% of the 57 boys were classified as aggressive because they had committed at least one act of physical aggression during the data collection period. In logistic regression analyses, client characteristics were used to predict aggression classification and 79%, 81%, and 92% of the total sample, girls, and boys, respectively, were correctly classified. Aggression in the girls was associated with having a history of family violence, being of a minority race, and being on medication; for the boys, aggression was associated with a diagnosis of a conduct disorder, being on medication, and being previously hospitalized.

Adolescent↗

PubMed1997

A two-factor model of aggression.

This article synthesizes theoretical material from psychology research into a practical model for conceptualizing violence in psychiatric settings. Relevant research and theory are reviewed, focusing on two important behavioral models of aggressive behavior, hostile aggression and instrumental aggression. The concepts of reinforcement, anticipated rewards, specific and nonspecific stimulus-driven aggression, intermediary emotional states in aroused persons, and the aggression stimulus threshold are developed into a bimodal model applicable to the clinical management of violence. The model provides a broad framework for categorizing, understanding, and addressing aggressive behavior in clinical settings.

Adult↗

PubMed2001

Personality and neurocognitive correlates of impulsive aggression in long-term survivors of severe traumatic brain injury.

This study addresses a common outcome of severe traumatic brain injury (TBI), disinhibited aggressive behaviour. This behaviour has been classified in aggression literature as 'impulsive aggression' (IA). The purpose was to: (1) characterize those TBI patients who are likely to be an aggression risk, and (2) determine if TBI patients with IA demonstrate personality style and neurocognitive performance similar to that seen in other IA groups. Participants were 45 survivors of severe TBI (26 of whom had persisting problems with IA), who were clients of a residential brain injury treatment facility. IA participants had a higher incidence of pre-morbid aggressive behaviour, were younger, had a shorter tenure in the programine, and were more impulsive, irritable, and antisocial than the non-aggressive control participants. Unlike past research, no neurocognitive differences were found. The results are discussed in terms of the conceptualization, identification, and treatment of persisting IA in severe TBI.

Adult↗

PubMed2006

Evaluation of the Perception of Aggression Scale (POAS) in Swedish nurses.

Even though much is known about individual risk factors for institutional violence, large variations in frequency between institutions still remain unexplained. Staff attitudes have been pointed out as a possible important and explaining factor. The Perception of Aggression Scale (POAS) is a newly developed attitude inventory assessing nurses' attitudes toward aggressive patients. The aims of this study are to evaluate the factor structure of the Swedish version of the POAS and to evaluate its discriminatory capacity in different groups of nurses. The shortened POAS was handed out to 357 nurses at 12 different psychiatric wards in Sweden. Responses were analysed with exploratory principal component factor analysis. The emerging factors were correlated in a rank-transformed multiple regression analysis to individual characteristics of each nurse. The factor analyses revealed exactly the same factor structure in this Swedish sample of nurses as in previous German and Dutch studies. When expanding the factor analysis, a three-factor solution emerged. It was also found that the factor "Aggression as a protective measure" was correlated to age and experience of aggression management training while the factor "Aggression as dysfunctional/undesirable phenomenon" was sensitive for gender. The shortened 12-item POAS contains three discrete dimensions and thus seems to be a solid tool for evaluating attitudes towards violence. Of special interest is the possibility that the factor "Aggression as a protective measure" could be sensitive to training. Further studies should correlate dimensions of staff attitudes to the occurrence of inpatient violence.

Adult↗