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PubMed1994

Psychomotor stimulant effects of d-amphetamine, MDMA and PCP: aggressive and schedule-controlled behavior in mice.

The objective of the present experiments was to characterize psychomotor stimulant effects of d-amphetamine, methylenedioxymethamphetamine (MDMA) and phencyclidine (PCP) on conditioned performance and on aggressive behavior in mice. In a novel protocol with alternating periods of schedule-controlled responding and aggressive behavior toward an intruder it was possible to assess a range of species-specific agonistic acts, postures, and motor activities as well as response rates and patterns engendered by a multiple Fixed Interval (FI) and Fixed Ratio (FR) schedule within the same animal. Initially, it was confirmed that d-amphetamine and, less reliably, MDMA and PCP, increased FI, but not FR responding in mice. In the next experiment, mice confronted an intruder at the midpoint of the 1-h daily session; following the display of aggressive behavior, the rate of FI responding showed an amphetamine-like increase, whereas only a transient change occurred after non-aggressive encounters. Thirdly, using this new protocol, PCP, d-amphetamine and MDMA altered FI and FR responding in a way that was closely similar to the first experiment. Low PCP and d-amphetamine doses increased aggressive behavior erratically in certain individuals, but not reliably for the group. MDMA dose-dependently decreased aggressive behavior, and all drugs disrupted aggressive behavior at higher doses. The characteristic increases in walking and decreases in rearing after higher doses of PCP and d-amphetamine were greatly attenuated when the intruder was present.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗
PubMed1996

Tryptophan depletion and aggressive responding in healthy males.

In order to study the effect of decreasing plasma tryptophan levels on aggressive responding in a controlled laboratory setting, we administered two doses (25 g and 100 g) of a tryptophan-free amino acid mixture to ten healthy male subjects after 24 h of a low tryptophan diet. Subjects were screened for current or past psychiatric, or non-psychiatric medical illness. Aggressive responding on a free-operant laboratory measure of aggression (the Point Subtraction Aggression Paradigm) and plasma tryptophan levels were measured before and after drinking the amino acid mixture. There was a significant increase in aggressive responding 5 h after the 100 g mixture and a significant increase in aggressive responding 6 h after the 25 g mixture compared to a baseline day when no drink was administered. There was also a significant decrease in plasma tryptophan at 5 hours after ingestion compared to baseline for both doses of amino acid mixture. This study supports the hypothesis that tryptophan depletion increases aggressive responding in healthy males in a laboratory setting, probably by decreasing brain serotonin.

Adult↗
PubMedDate not supplied

Thalamic modulation of aggression.

This experiment extends Pavlov's method of contrasts for 8 components of aggression were quantitatively evaluated in 11 freely moving adult cats. Aggression was elicited from the perifornix septohypothalamic areas by a series of progressively increasing and decreasing stimulation parameters. Three levels of thalamic stimulation (low, medium, and high) were combined with the perifornix stimulations. High level thalamic stimulation tended to facilitate the aggressive response elicited by low level perifornix stimulation. Thalamic lesions attenuated the aggression response, especially those elicited during high level perifornix stimulation. It was suggested that within the hypothalamic induced aggression circuitry the center median nucleus modulates the excitatory state of the system. The discussion concerns anatomic and physiologic pathways through which the center median nucleus may modulate the sensory, motor, and affective-autonomic subsystems into a well integrated aggressive state. These experimental findings are supported by the clinically established treatment of aggression by stereotaxic lesions placed in the center median nucleus.

Aggression↗
PubMed2001

Repeated alcohol: behavioral sensitization and alcohol-heightened aggression in mice.

RATIONALE: Repeated administration of psychomotor stimulants or opiates can induce behavioral sensitization, typically detected as progressive and long-lasting increases in the motor-activating effects of these drugs. This phenomenon may be relevant to seizure susceptibility, drug self-administration, and sexual behavior. Repeated administration of alcohol can also induce behavioral sensitization and may have consequences on how alcohol affects aggressive behavior. OBJECTIVES: To (1) determine the enduring nature of locomotor sensitization to alcohol; (2) examine subsequent changes to morphine and amphetamine effects on locomotor behavior; and (3) test whether behavioral sensitization to alcohol or morphine is relevant to alcohol-heightened aggression. METHODS AND RESULTS: In the first experiment, male CFW mice were given ten injections of alcohol (2.4 g/kg/day), morphine (30.0 mg/kg/day), or saline. Video tracking confirmed locomotor sensitization--an approximate 200% increase in the motor-stimulating effects of these drugs. Challenges with 2.0 g/kg alcohol revealed that locomotor sensitization to alcohol persisted for at least 2 months. Alcohol-sensitized mice showed evidence of cross-tolerance to the sedative effects of morphine (5 mg/kg) but showed no evidence of cross-sensitization to the stimulant effects of 30.0 mg/kg morphine or 1.0 mg/kg amphetamine. In the second experiment, under conditions resulting in species-typical aggressive behavior against a male intruder, there were no differences in the aggressive behavior relative to saline control mice following alcohol or morphine sensitization. However, in the mice sensitized to alcohol, but not to morphine, there was a vertical shift in the dose-effect curve for moderate doses of alcohol (0.6-1.7 g/kg, p.o.). In addition, twice as many alcohol-sensitized mice consistently showed alcohol-heightened aggression when compared with the saline control mice (74% vs 37%, respectively). CONCLUSIONS: Repeated administration of alcohol can sensitize locomotor stimulation and may also render mice more vulnerable to increased aggression after alcohol. Moreover, the results suggest that at least some of the neuroadaptations caused by repeated administration of alcohol are relevant to alcohol-heightened aggression.

Aggression↗
PubMed1999

Changes in aggressive behavior during withdrawal from long-term marijuana use.

RATIONALE: Even though marijuana is the most commonly abused illicit drug in the United States, it is still undetermined whether withdrawal after chronic use results in changes in aggressive behavior in humans. OBJECTIVE: The present study investigated the pattern and duration of changes in aggressive behavior in long-term marijuana users during a 28-day abstinence period verified by daily urines. METHOD: Chronic marijuana users who had smoked marijuana on at least 5000 occasions (the equivalent of smoking daily for approximately 14 years) and who were smoking regularly when recruited were studied on days 0 (when they were still smoking), 1 (during acute withdrawal), 3, 7 and 28 of a 28-day detoxification period. Aggressive behavior was measured using the Point Subtraction Aggression Paradigm. RESULTS: Compared to controls and to the pre-withdrawal data, chronic marijuana users displayed more aggressive behavior on days 3 and 7 of marijuana abstinence. These increases in aggressive responding returned to pre-withdrawal levels after 28 days and were paralleled by small, non-significant changes in depression and anxiety scores. CONCLUSIONS: Our findings confirm previous reports of an abstinence syndrome associated with chronic marijuana use and suggest that aggressive behavior should be an additional component of this syndrome.

Adult↗
PubMedDate not supplied

Acute and chronic effects of an aromatase inhibitor on territorial aggression in breeding and nonbreeding male song sparrows.

Many studies have demonstrated that male aggression is regulated by testosterone. The conversion of testosterone to estradiol by brain aromatase is also known to regulate male aggression in the breeding season. Male song sparrows (Melospiza melodia morphna) are territorial not only in the breeding season, but also in the nonbreeding season, when plasma testosterone and estradiol levels are basal. Castration has no effect on nonbreeding aggression. In contrast, chronic (10 day) aromatase inhibitor (fadrozole) treatment decreases nonbreeding aggression, indicating a role for estrogens. Here, we show that acute (1 day) fadrozole treatment decreases nonbreeding territoriality, suggesting relatively rapid estrogen effects. In spring, fadrozole decreases brain aromatase activity, but acute and chronic fadrozole treatments do not significantly decrease aggression, although trends for some behaviors approach significance. In gonadally intact birds, fadrozole may be less effective at reducing aggression in the spring. This might occur because fadrozole causes a large increase in plasma testosterone in intact breeding males. Alternatively, estradiol may be more important for territoriality in winter than spring. We hypothesize that sex steroids regulate male aggression in spring and winter, but the endocrine mechanisms vary seasonally.

Aggression↗
PubMed2002

Impulsivity and aggression as predictors of suicide attempts in alcoholics.

INTRODUCTION: The aim of this study was to assess the potential role of impulsive and aggressive behavior in the pathogenesis of suicide attempts in alcoholics. Impulsive and aggressive behavior as well as a psychiatric comorbidity with depressive conditions and personality disorders have been reported to be significant risk factors for suicide attempts in alcoholics. We hypothesized that alcoholics with a history of violent suicide attempts show an increased level of impulsive and aggressive behavior. Furthermore, the potential influence of concurrent personality disorders and depressive conditions were assessed. MATERIAL AND METHODS: 182 detoxified alcohol-dependent subjects were enrolled into the study. Impulsive and aggressive traits were assessed using the Buss-Durkee Hostility Inventory and the Brown-Goodwin Assessment for Lifetime History of Aggression, personality disorders using the SCID II. Characteristics of alcohol dependence and suicide attempts were evaluated using the Semi-Structured Assessment on Genetics in Alcoholism (SSAGA). RESULTS: Alcohol-dependent subjects with a history of suicidal behavior show a profile with higher impulsive and aggressive behavior. No significant association between these traits and concurrent borderline and antisocial personality disorder was found. Subjects with suicide attempts tended to have a significantly higher rate of depressive disorders. DISCUSSION: These results suggest that impulsive and aggressive traits might contribute significantly to the risk of suicide attempts in alcoholics.

Adult↗
PubMed2005

Characterizing aggressive and noncompliant behaviors in a children's psychiatric inpatient setting.

This study was conducted to evaluate aggression and noncompliance among child psychiatric inpatients in relation to demographic, clinical, and hospitalization characteristics, including the use of restraints and seclusion. Eighty six children (10.8+/-2.4 years old, 67% male) consecutively admitted to an inpatient psychiatric unit were rated weekly using the Modified Overt Aggression Scale (MOAS) and the Disruptive Behavior Rating Scale (DBRS) between November 1, 2002 and June 30, 2003. Moderate to high correlations were observed between the four types of aggression (verbal, and physical against self, others, or objects) and noncompliant behavior. In hierarchical regression analyses, only mental retardation emerged as a significant predictor of aggression and noncompliance. Aggression and noncompliance were associated with different characteristics of inpatient treatment. Aggressive behavior was significantly associated with the use of restraints and seclusion, and noncompliant behavior with length of hospitalization and number of psychiatric medications at time of discharge. Modifying milieu interventions for youths with mental retardation, and adapting behavioral interventions empirically proven to target noncompliance may be effective loci for reducing aggression in child psychiatric inpatient units.

Aggression↗
PubMed2006

Aggression and diagnosis in psychiatrically referred children.

We investigated correlations between measures of proactive and reactive aggression subtype, and the severity and frequency of overt aggression and psychiatric diagnosis in a clinically referred sample of children compared to a non-referred community comparison group free of psychiatric diagnosis. All measures of aggression were significantly correlated suggesting that there might be an underlying aggression construct that is manifested in distinct but correlated domains of aggression across diverse psychiatric diagnoses in referred children. Regression analysis revealed robust correlations between the number of lifetime psychiatric diagnoses adjusted for lifetime duration of illness and all measures of aggression. Our results support the need to consider the development of psychosocial and psychopharmacological treatment interventions specifically targeting excessive maladaptive aggression within and across multiple psychiatric diagnoses in children.

Adolescent↗
PubMed2005

A model of contagion through competition in the aggressive behaviors of elementary school students.

This article extends the work of Kellam, Ling, Merisca, Brown and Ialongo (1998) by applying a mathematical model of competition between children to peer contagion in the aggressive behaviors of elementary school students. Nonlinearity in the relationship between group aggression and individual aggression at 2-year follow-up is present. Consistent with the findings of Kellam et al. (1998), hierarchical linear modeling indicates that the relationship is statistically significant for those students whose initial parental ratings of aggressive behavior were above the sample median. In the context of competition between students, the behavior of initially aggressive students may be negatively reinforced. Lowering aggression in the school environment may therefore be the most effective way to lower the level of these students' aggressive behavior.

Aggression↗
PubMed2006

The development of aggression in 18 to 48 month old children of alcoholic parents.

This study examined the development of aggressive and oppositional behavior among alcoholic and nonalcoholic families using latent growth modeling. The sample consisted of 226 families assessed at 18, 24, 36, and 48 months of child age. Results indicated that children in families with nonalcoholic parents had the lowest levels of aggressive behavior at all time points compared to children with one or more alcoholic parents. Children in families with two alcoholic parents did not exhibit normative decreases in aggressive behavior from 3 to 4 years of age compared to nonalcoholic families. However, this association was no longer significant once a cumulative family risk score was added to the model. Children in families with high cumulative risk scores, reflective of high parental depression, antisocial behavior, negative affect during play, difficult child temperament, marital conflict, fathers' education, and hours spent in child care, had higher levels of aggression at 18 months than children in low risk families. These associations were moderated by child gender. Boys had higher levels of aggressive behavior at all ages than girls, regardless of group status. Cumulative risk was predictive of higher levels of initial aggressive behavior in both girls and boys. However, boys with two alcoholic parents had significantly less of a decline in aggression from 36 to 48 months compared to boys in the nonalcoholic group.

Adult↗
PubMed2006

Do early difficult temperament and harsh parenting differentially predict reactive and proactive aggression?

The goal of this study was to examine the links between difficult temperament (i.e., negative emotionality) and harsh parental discipline during toddlerhood, and reactive and proactive aggression in kindergarten. These links were assessed on a longitudinal population-based study of 1516 boys and girls followed longitudinally from the age of 17 months through the age of 72 months. Two possible models were tested to examine the interplay between negative emotionality and harsh parenting in predicting later reactive aggression compared to proactive aggression. The first was an additive model where both aspects make unique contributions in predicting later reactive aggression. The second model was an interactive model where harsh parenting exacerbates the link between negative emotionality and reactive aggression. Results showed a specific contribution of negative emotionality to reactive aggression. The results relative to harsh parenting are more mixed but nonetheless in line with developmental models stressing different pathways to reactive and proactive aggression.

Aggression↗
PubMed2007

"Accept me, or else...": disputed overestimation of social competence predicts increases in proactive aggression.

It has been proposed that aggressive behavior may result from unrealistically positive self-evaluations that are disputed by others (Baumeister, Smart, & Boden, 1996). The present three studies tested this proposition concurrently and longitudinally for the domain of self-perceived social competence (SPSC) in 3-6th grade children on two continents. Each study tested whether aggressive behavior is related to general overestimation of SPSC compared to competence as perceived by peers, or to disputed overestimation, that is, overestimation disputed through rejection by peers. Specificity of relations with reactively or proactively aggressive behavior patterns was assessed and the predictive value of overestimation to the development of these types of aggressive behavior was investigated. Concurrently, disputed overestimation explained more variance in aggressive behavior than general overestimation, and was uniquely related to proactive aggression. Longitudinally, disputed overestimation also uniquely predicted changes in proactive, not reactive aggression.

Aggression↗
PubMed1975

The inheritance of aggressiveness in the convict cichlid fish, Cichlasoma nigrofasciatum (Pisces: Cichlidae).

Intraspecific comparisons in aggression were made between X-irradiated (2 times 500 R) ancestors and untreated control animals. Bites delivered to sub-adult conspecifics were counted to measure aggressiveness. When compared with corresponding controls, a significant reduction in male aggressiveness was found in the post-irradiation F1 generation. A greater variation in bites delivered occurred among the F2 post-irradiation generations than among the control equivalents. Three distinct back-cross generations were obtained as follows. a single F1 female from the irradiated line was mated to (a) her high aggressive (I-A) and (b) her low aggressive (I-NA) F2 son; a F1 control female was mated to her low aggressive F2 son. In the back-cross generations, both I-A and C-NA males were more aggressive than I-NA males. No differences were found between I-A and C-NA back-cross males. The findings are discussed in terms of a two-factor model based on Mendelian laws.

Aggression↗
PubMed1976

Comparison of regional serotonin levels and turnover in the brain of naturally high and low aggressive rats.

Rats, matched by weight and goal approach, were tested for aggressiveness using a food-competition paradigm. Those winning and those losing all of their matches were designated as high and low aggressive, respectively. A third group of randomly selected rats never fought and were used as a control for the fighting experience. Half of the rats were used to determine serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels in discrete brain regions. The other half were used to estimate 5-HT turnover in the same brain regions. High and low aggressive rats did not differ with regard to 5-HT or 5-HIAA levels, but high aggressive rats showed faster 5-HT turnover than low aggressive rats. The turnover differences reached statistical significance in only two of the 3 brain regions examined: (a) all structures (minus olfactory bulbs) rostral to the level of the anterior commissure, and (b) the brain stem (hypothalamus-midbrain-medulla). The observed differences cannot be attributed to differing behavioral experiences since the high and low aggressive groups pooled did not differ from the no-fighting control. These findings are discussed with respect to the involvement of serotonin in rat intraspecies aggression.

Aggression↗
PubMed1986

Regional [3H]testosterone uptake in the brain of isolated non-aggressive mice.

Male mice which are housed individually develop a characteristic aggressive, 'fighting' behavior. A small percentage of mice so isolated fail to become aggressive and in fact, behaviorally are strikingly different in that they develop a 'timid' behavior. Isolation-induced aggression is an androgen-dependent behavior and androgen-sensitive neurons have been identified in mouse brain, mainly in the limbic system. When intact isolated aggressive mice and isolated and aggregated non-aggressive mice were injected with radioactive testosterone and sacrificed after 30 min no remarkable differences in uptake of radioactive testosterone occurred in various brain areas. However, in castrated animals the uptake of testosterone was greatly enhanced in the isolated non-fighters whereas testosterone uptake in the isolated fighters and aggregated non-fighters was in the range of the intact animals. This study represents, for the first time, a documented hormonal difference between isolated aggressive and non-aggressive animals.

Aggression↗
PubMed1983

Maternal aggression in hamsters: effects of stage of lactation, presence of pups, and repeated testing.

This study investigated maternal aggression in hamsters and examined the effects of early versus late lactation, presence or absence of the litters during the tests, and prior aggressive encounters. There was a total of six experimental groups. Two groups were tested in the presence of their litters on both Days 5 and 15 of lactation; two groups were presented with intruders after a 6-hr interval of mother-litter separation on Days 5 and 15 of lactation. The last two experimental groups were tested on Day 15 only in the presence of their litters or after a 6-hr separation from their litters. Estrous-cycling animals were also tested twice (10 days apart) or once to control for periods of social isolation. Animals were tested in their home cages for 10 min with weight-matched estrous-cycling intruders. Sexually receptive females were not used as controls or intruders. Measures of aggression included fights, attacks, chases, and intruder retreats. Lactating animals initiated significantly higher levels of all measures of aggression than cycling controls. There were no differences in aggression between Days 5 and 15 of lactation or between the groups tested in the presence or absence of their litters. Prior testing on Day 5 had little effect on aggressive responses on Day 15. The results are discussed in terms of comparisons to other species and the factors responsible for high levels of aggression during lactation.

Aggression↗
PubMed1986

Mice: progesterone stimulates aggression in pregnancy-terminated females.

Three experiments were conducted in order to assess the role of progesterone (P) in the aggressive behavior displayed by late pregnant Rockland-Swiss mice toward adult male intruders. In Experiment 1, hysterectomy on the 15th day of gestation reduced the aggressive behavior normally displayed by pregnant mice toward male intruders. In Experiment 2, Silastic implants of P stimulated aggression in hysterectomized mice but did not fully restore the behavior to the level of fighting normally observed in pregnant animals. In Experiment 3, aggressive behavior in P-treated hysterectomized animals was inhibited by simultaneous exposure to estradiol (E). Also, treatment with E alone did not stimulate aggression in hysterectomized mice. While pregnancy-induced aggression is promoted by P, other neuroendocrine factors may act in concert with the steroid to fully stimulate aggression in gravid mice.

Abortion, Induced↗