Effects of clorazepate, diazepam, and oxazepam on a laboratory measurement of aggression in men

Behavioral restriction, lorazepam, and escitalopram uniquely influence the expression of naturalistic stereotypy in deer mice: perspectives on anxiety- and compulsive-like behavior

Introduction: Stereotypical expression in laboratory-housed rodents can be explained by different motivational, coping, and motor dysfunction theories. Here, we aimed to explore the neurocognitive underpinnings of high stereotypical (HS) expression in deer mice (Peromyscus maniculatus bairdii), previously proposed as a model system of compulsive-like behavioral persistence. Specifically, we aimed to establish whether HS behavior is related to an underlying escape-related trigger. Methods: One-hundred and sixteen deer mice were classified as either non-stereotypical (NS) or HS. Mice of each cohort were further subdivided and exposed to either sub-acute (3-day) or chronic (25-day) behavioral restriction (R), and high-dose escitalopram (ESC), lorazepam (LOR), alone and in combination with R (ESC+R and LOR+R, respectively). Mice were reassessed for stereotypical behavior at both time points. Results: Our results indicate that HS behavior is likely not temporally and functionally related to an anxiogenic trigger, i.e., R, but rather that HS is associated with parallel changes in anxiogenic feedback processing. We also show that chronic R alone significantly decreased the time spent in expressing HS behavior in animals of the HS, but not NS phenotype. Discussion: This points to the possibility that HS-expressing mice represent a subgroup of P. maniculatus bairdii in which unique interactions between neurobiology and processes of gradual behavioral organization, may contribute to the expression of the typical behaviors observed in this cohort. Collectively, our findings highlight the value of the deer mouse model system to investigate the potential neurocognitive mechanisms that may underlie the development of persistent phenotypes that can likely not be explained entirely by current theories.

Association between homicide injury severity and benzodiazepine influence

There are case reports of offenders inflicting excessive injuries on their victims when under the influence of benzodiazepines. However, the potential association between benzodiazepine influence on the offender and victim injury severity in a general homicide population has not been studied. We investigated associations between offender positive testing for benzodiazepines or z-drugs (zolpidem, zopiclone and zaleplon) and victim injury severity. Data were drawn from 95 Swedish homicide cases from 2007–2009 in which offenders had known toxicology. There were no significant differences in injury severity between cases in which the offender tested positive vs. negative for benzodiazepines/z-drugs. Thus, the findings do not support the hypothesis that there is an association between benzodiazepine influence on the offender and victim injury severity in a general homicide population.

Key points

Some previous studies have linked benzodiazepines to aggression, violence and excessive homicide injuries.

The present study analysed the association between homicide injury severity and benzodiazepine status of the offender.

Offenders who tested positive for benzodiazepines did not inflict more severe injuries on their victims.

These findings do not support the hypothesis that benzodiazepine influence generally causes offenders to inflict more severe injuries on homicide victims.

A Conceptual Review of Lab-Based Aggression Paradigms

Aggression is often defined as a behavior that is done with the intent to harm an individual who is believed to want avoid being harmed (e.g., Baron & Richardson, 1994). Accordingly, social scientists have developed several tasks to study aggression in laboratory settings; tasks that we refer to as “lab-based aggression paradigms.” However, because of the legal, ethical, and practical issues inherent in provoking aggression within the confines of a laboratory setting, it is feasible to study only very mildly harmful aggression. The current conceptual review examines the criteria that are necessary to study aggression in a laboratory setting, discusses the strengths and weaknesses of several new and/or commonly-used lab-based aggression paradigms, and offers recommendations for the future of lab-based aggression research. Collectively, we hope the current discussion helps researchers to describe the contributions and limitations of lab-based aggression research and, ultimately, helps to improve the informativeness of lab-based aggression research.

Benzodiazepines and disinhibition: a review

AIMS AND METHODS

To describe and attempt to quantify the incidence of disinhibitory reactions to benzodiazepines and to identify those at risk. Medline search, 1966–January 2002.

Results

The overall incidence of disinhibitory reactions is small, but those with impulse control problems, neurological disorders, learning disabilities, the under 18s and the over 65s are at significant risk.

Clinical Implications

It is important to be aware of the ability of benzodiazepines to cause behavioural disinhibition and to maintain a high degree of vigilance when these drugs are administered to patients known to be at risk. In patients who have experienced behavioural disinhibition with benzodiazepines, antipsychotic drugs should be used to modify behaviour in any future emergencies.

Considerations on nonclinical approaches to modeling risk factors of suicidal ideation and behavior

Given the serious nature of suicidal ideation and behavior (SIB) and the possibility of treatment-emergent SIB, pharmaceutical companies are now applying more proactive approaches in clinical trials and are considering the value of nonclinical models to predict SIB. The current review summarizes nonclinical approaches to modeling three common risk factors associated with SIB: aggression, impulsivity, and anhedonia. For each risk factor, a general description, advantages and disadvantages, species considerations, nonclinical to clinical translation, and pharmacological validation with respect to treatments associated with SIB are summarized. From this review, several gaps were identified that need to be addressed before use of these nonclinical models can be considered a viable option to predict the relative risk for SIB. Other future directions that may compliment these nonclinical approaches, including the use of selectively-bred or genetically-modified rodent models, transgenic models, gene expression profiling, and biomarker analysis, are discussed. This article was developed with the support of the DruSafe Leadership Group of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ, www.iqconsortium.org).

Is Medicine Use for Nervousness Associated with Adolescent At-Risk or Problem Gambling?

OBJECTIVE

To examine the association between adolescent at-risk or problem gambling (ARPG) and medicine used to treat nervousness in a large-scale nationally representative sample of Italian adolescents.

STUDY DESIGN

Data from the 2013/2014 Health Behaviour in School-aged Children Survey was used for cross-sectional analyses (a sample of 20,791 15-year-old students). Self-administered questionnaires were completed by a representative sample of high-school students. Respondents' ARPG, use of medicine for nervousness and potential confounding factors were assessed. Multilevel logistic regression analyses were used to test the association between medicine use to treat nervousness and ARPG.

RESULTS

The overall prevalence of adolescents reporting medicine use for nervousness in the last month was 6.3%. The odds of ARPG were 3 times higher among adolescents who used medicine for nervousness compared to that among adolescents who did not take such medicine (OR 2.96, 95% CI 2.07-4.25). Importantly, the association between medicine used to treat nervousness and ARPG did not vary significantly when viewed in light of psychological symptoms.

CONCLUSIONS

Medicine use to treat nervousness is associated with increased risk of gambling-related harm.

α2-containing GABA(A) receptors: a requirement for midazolam-escalated aggression and social approach in mice

RATIONALE

Benzodiazepines (BZDs) are prescribed to reduce anxiety, agitation, and muscle spasms and for their sedative-hypnotic and anticonvulsant effects. Under specific conditions, BZDs escalate aggression in some individuals. Specific effects of BZDs have been linked to the α-subunit subtype composition of GABAA receptors.

OBJECTIVES

Point-mutated mice rendered selectively insensitive to BZDs at α1-, α2-, or α3-containing GABAA receptors were used to determine which α-subunit subtypes are necessary for BZDs to escalate aggression and social approach and to reduce fear-motivated behavior.

METHODS

During resident-intruder confrontations, male wild-type (WT) and point-mutated α1(H101R), α2(H101R), and α3(H126R) mice were treated with midazolam (0-1.7 mg/kg, i.p.) and evaluated for aggression in an unfamiliar environment. Separate midazolam-treated WT and point-mutated mice were assessed for social approach toward a female or investigated in a 6-day fear-potentiated startle procedure.

RESULTS

Moderate doses of midazolam (0.3-0.56 mg/kg, i.p.) escalated aggression in WT and α3(H126R) mutants and increased social approach in WT and α1(H101R) mice. The highest dose of midazolam (1.0 mg/kg) reduced fear-potentiated startle responding. All mice were sensitive to the sedative effect of midazolam (1.7 mg/kg) except α1(H101R) mutants.

CONCLUSIONS

Midazolam requires BZD-sensitive α1- and α2-containing GABAA receptors in order to escalate aggression and α2- and α3-containing receptors to reduce social anxiety-like behavior. GABAA receptors containing the α1-subunit are crucial for BZD-induced sedation, while α2-containing GABAA receptors may be a shared site of action for the pro-aggressive and anxiolytic effects of BZDs.

Substance use and violence among youth: a daily calendar analysis

BACKGROUND

While researchers have identified factors that contribute to youth violence, less is known about the details of violent incidents. In addition, substance use has been linked to youth violence; however, little is known about actual substance use on days in which violence occurs.

OBJECTIVE

This study examined reasons for peer violence and the association between substance use and violence using daily calendar-based analyses among at-risk urban youth.

METHODS

Data were collected from Emergency Department (ED) patients (ages 14-24; n = 599; 59% male, 65% African American) who screened positive for substance use in the past 6 months. Daily data regarding past 30-day substance use and violence and reasons for violent incidents were obtained via semi-structured interviews. Multi-level multinomial regression models were conducted to test the associations between substance use and peer violence incidents (i.e., none, moderate and severe).

RESULTS

Conflict over 'personal belongings' was a common reason for violence among males; 'jealousy'/'rumors' were common reasons among females. Moderate victimization was more likely to be reported on days in which participants reported alcohol and cocaine use. Severe victimization was more likely to be reported on days in which participants reported alcohol use. Moderate or severe aggression was more likely to be reported on days in which participants reported alcohol and non-medical sedative use.

CONCLUSIONS

RESULTS suggest that youth violence prevention that addresses differential reasons for violence among males and females as well as substance use would be beneficial.

Benzodiazepine use and aggressive behaviour: a systematic review

CONTEXT

The relationship between benzodiazepine consumption and subsequent increases in aggressive behaviour in humans is not well understood.

OBJECTIVES

The current study aimed to identify, via a systematic review, whether there is an association between benzodiazepine consumption and aggressive responding in adults.

METHOD

A systematic review was conducted and reported in line with the PRISMA statement. English articles within MEDLINE, PsycARTICLES, PsycINFO, Academic Search Complete, and Psychology and Behavioural Sciences Collection databases were searched. Additional studies were identified by searching reference lists of reviewed articles. Only articles that explicitly investigated the relationship between benzodiazepine consumption and subsequent aggressive behaviour, or a lack thereof, in human adults were included.

RESULTS

Forty-six studies met the inclusion criteria. It was not possible to conduct a meta-analysis due to the heterogeneity of study design and benzodiazepine type and dose. An association between benzodiazepine use and subsequent aggressive behaviour was found in the majority of the more rigorous studies, although there is a paucity of high-quality research with clinical or forensic populations. Diazepam and alprazolam have received the most attention. Dose-related findings are inconsistent: therapeutic doses may be more likely to be associated with aggressive responding when administered as a once-off, whereas higher doses may be more risky following repeated administration. Trait levels of anxiety and hostility may indicate a vulnerability to the experience of benzodiazepine-related aggression.

CONCLUSIONS

There appears to be a moderate association between some benzodiazepines and subsequent aggressive behaviour in humans. The circumstances under which aggressive responding may be more likely to follow benzodiazepine use remain unclear, although some evidence suggests dose and/or personality factors may influence this effect.

A daily calendar analysis of substance use and dating violence among high risk urban youth

BACKGROUND

Dating violence (DV) among youth is an important public health problem. This study examined reasons for physical DV and the association between substance use and youth DV using daily calendar-based analyses among at-risk urban youth.

METHODS

Patients (aged 14-24) presenting to an urban Emergency Department (ED) for a violent injury and a proportionally selected comparison sample of non-violently injured youth who screened positive for substance use in the past 6 months (n=599) were enrolled in this study. Multi-level, multinomial regressions were conducted using daily-level substance use data from Time Line Follow Back (TLFB) responses and physical DV data that were obtained by coding Time Line Follow Back - Aggression Module responses for the 30 days prior to visiting the ED.

RESULTS

The two most commonly reported reasons for physical dating aggression and victimization, across sexes, were "jealousy/rumors" or "angry/bad mood." Multi-level multinomial regression models, adjusting for clustering within individual participants, showed that among females, cocaine use and sedative/opiate use were associated with severe dating victimization and alcohol use was associated with severe dating aggression.

CONCLUSIONS

Use of TLFB data offers a unique opportunity to understand daily-level factors associated with specific incidents of DV in more detail. This study provides novel data regarding reasons for DV and the relationship between daily substance use and DV among urban youth, with alcohol, cocaine, and sedative/opiate use being associated with various types of DV. ED based DV interventions should be tailored to address youths' reasons for DV as well as reducing their substance use.

Irritability in Huntington's disease

Irritability is a frequent neuropsychiatric symptom in patients with Huntington's disease (HD). The Irritability Scale (IS) and the irritability factor of the Problem Behaviours Assessment (PBA) was used to assess irritability among 130 HD mutation carriers and 43 verified non-carriers. The IS was tested using receiver operating characteristic analysis against different cut-offs of the PBA irritability factor. A robust IS cut-off score of ≥14 points was found indicating that 45 (35%) of the 130 mutation carriers were irritable vs. 4 (9%) of the 43 non-carriers (P=0.001). The level of agreement between self-report and informant-report IS was of moderate strength (intraclass correlation=0.61). Using univariate and multivariate regression analyses, independent correlates of irritability were being married/living together (P=0.02), CAG repeat length (P=0.01), and use of benzodiazepines (P=0.008). Using the same model with the informant's irritability score, use of benzodiazepines was the only significant independent correlate of irritability (P=0.005). Irritability is a prominent symptom of HD and can be reliably assessed with the IS using a cut-off score ≥14 points. Although it is unclear whether benzodiazepine use causes irritability, or irritability leads to the prescription of benzodiazepines, clinical evaluation with respect to the use of benzodiazepines in HD warrants attention.

Flunitrazepam intake in male offenders

The abuse of flunitrazepam (FZ) compounds is worldwide, and several studies have reflected on the consequences with regard to violence, aggression and criminal lifestyle of FZ users. Criminals take high doses of FZ or some other benzodiazepines to "calm down" before the planned crime. There is support from earlier studies that most likely, all benzodiazepines may increase aggression in vulnerable males. Chronic intake of high doses of FZ increases aggression in male rats. Because psychopathy involves aggression, we have examined whether psychopathy as well as any of the four facets of the Psychopathy Checklist-Revised (PCL-R) (Interpersonal, Affective, Lifestyle and Antisocial) are related to different substance use disorders, with the focus on FZ. We have also examined the relationship between each PCL-R item and FZ use. Participants were 114 male offenders aged 14-35 years, all of whom were convicted for severe, predominantly violent, offences. Substance use, including FZ, was not more common in those who scored high in psychopathy. Use of FZ was more common in offenders who scored high in Facet 4 (Antisocial) of the PCL-R (odds ratio = 4.30, 95% CI 1.86-9.94). Only one of the PCL-R items, "Criminal versatility", was significantly associated with FZ use (odds ratio = 3.7). It may be concluded that intake of FZ has a specific relationship to only one of the facets and not to psychopathy per se. The findings have also important theoretical implications because Facet 4 is not a key factor of the construct of psychopathy. Clinical implications of the article: We have used the new two-factor and four-facet theoretical model of psychopathy in the young offender population, many of them with one or more substance use disorders. The present results suggest that antisocial behavior defined by Facet 4 (poor behavioral control, early behavior problems, juvenile delinquency, revocation of conditional release and criminal versatility) in the studied subjects is more typical for FZ users than it is for non-FZ users. This may have implications for assessment and treatment. Clinicians should be aware that criminals with high scores on Facet 4 have a more than fourfold odds of being a FZ user. This conclusion has an important clinical implication because FZ abuse is very common and is not always the focus of a forensic psychiatric assessment.

The psychopharmacology of aggressive behavior: a translational approach: part 2: clinical studies using atypical antipsychotics, anticonvulsants, and lithium

Patients experiencing mental disorders are at an elevated risk for developing aggressive behavior. In the past 10 years, the psychopharmacological treatment of aggression has changed dramatically owing to the introduction of atypical antipsychotics on the market and the increased use of anticonvulsants and lithium in the treatment of aggressive patients.This review (second of 2 parts) uses a translational medicine approach to examine the neurobiology of aggression, discussing the major neurotransmitter systems implicated in its pathogenesis (serotonin, glutamate, norepinephrine, dopamine, and γ-aminobutyric acid) and the neuropharmacological rationale for using atypical antipsychotics, anticonvulsants, and lithium in the therapeutics of aggressive behavior. A critical review of all clinical trials using atypical antipsychotics (aripiprazole, clozapine, loxapine, olanzapine, quetiapine, risperidone, ziprasidone, and amisulpride), anticonvulsants (topiramate, valproate, lamotrigine, and gabapentin), and lithium are presented. Given the complex, multifaceted nature of aggression, a multifunctional combined therapy, targeting different receptors, seems to be the best strategy for treating aggressive behavior. This therapeutic strategy is supported by translational studies and a few human studies, even if additional randomized, double-blind, clinical trials are needed to confirm the clinical efficacy of this framework.

Baseline trajectories of drinking moderate acamprosate and naltrexone effects in the COMBINE study

BACKGROUND

The COMBINE study evaluated the effects of acamprosate, naltrexone, and the Combined Behavioral Intervention (CBI). In secondary analyses, our goals were to identify trajectories of any drinking prior to randomization, to characterize subjects in these trajectories, and to assess whether prerandomization trajectories predict drinking outcomes and moderate treatment response.

METHODS

We analyzed daily indicators of any drinking in 90 days prior to randomization using a trajectory-based approach. General linear models and generalized logistic regression assessed main and interactive effects of prerandomization drinking trajectories and treatment on summary drinking measures during active treatment.

RESULTS

We identified five trajectories of any drinking prior to randomization: "T1: frequent drinkers", "T2: very frequent drinkers", "T3: nearly daily drinkers", "T4: consistent daily drinkers", and "T5: daily drinkers stopping early". During treatment, "T3: nearly daily drinkers" and "T4: consistent daily drinkers" had significantly worse drinking outcomes than "T1: frequent drinkers", while "T5: daily drinkers stopping early" had comparable drinking outcomes to "T1: frequent drinkers". Acamprosate significantly increased the chance of abstinence from heavy drinking for the "T2: very frequent drinking" trajectory but decreased the chance of abstinence from heavy drinking for "T5: daily drinkers stopping early". Naltrexone differentially improved rates of continuous abstinence for very frequent drinkers.

CONCLUSIONS

Acamprosate benefited very frequent drinkers and contrary to expectations was associated with poorer response compared to placebo for consistent daily drinkers who had longer durations of pretreatment abstinence (e.g., ≥14 days). Baseline drinking trajectories also moderated naltrexone effects. These findings may help clinicians identify patients for whom acamprosate and naltrexone may be most beneficial.

GABA(A) receptors in the dorsal raphé nucleus of mice: escalation of aggression after alcohol consumption

RATIONALE

The dorsal raphé nucleus (DRN), the origin for serotonin (5-HT) in forebrain areas, has been implicated in the neural control of escalated aggression. Gamma aminobutyric acid type-A (GABA(A)) and type-B (GABA(B)) receptors are expressed in the DRN and modulate 5-HT neuronal activity, and both play a role in the behavioral effect of alcohol.

OBJECTIVE

The purpose of this study is to examine the interaction between drugs acting on GABA receptors in the DRN and alcohol in their effects on aggressive behaviors.

METHOD

Male CFW mice, housed with a female, were trained to self-administer ethanol (1.0 g/kg) or water via an operant conditioning panel in their home cage. Immediately after they drank either ethanol or water, the animals were microinfused with a GABAergic drug into the DRN, and their aggressive behaviors were assessed 10 min later. Muscimol (0.006 nmol), a GABA(A) receptor agonist, escalated alcohol-heightened aggression but had no effect in the absence of ethanol. This effect of muscimol was prominent in the animals that showed alcohol-heightened aggression, but not the animals that reduced or did not change aggressive behavior after ethanol infusion compared to water. On the other hand, the GABA(B) agonist baclofen (0.06 nmol) increased aggressive behavior similarly in both water and ethanol conditions. Antagonists of the GABA(A) and GABA(B) receptors, bicuculline (0.006 nmol) and phaclofen (0.3 nmol) respectively, did not suppress heightened-aggressive behavior induced by ethanol self-administration.

CONCLUSION

GABA(A) receptors in the DRN are one of the neurobiological targets of alcohol-heightened aggression. Activation of the GABA(B) receptors in the DRN also produced escalated aggression, but that is independent of the effect of alcohol.

Drug use and intimate partner violence among college students: an in-depth exploration

College students experience an extremely high level of violence among intimate partners during their college careers, with prevalence rates ranging between 20% and 50%. Because intimate partner violence (IPV) among college students is such a widespread problem, it is important to understand the factors that contribute to this type of abuse. Studies using a variety of samples demonstrate that drug use is one such factor. However, research to date fails to identify specific types of drugs linked to college students' use of violence against intimates. In an attempt to fill this void, this exploratory study uses data from the Relationship Characteristics Study, which was conducted in 2001 and includes a sample of 1,938 college students, to provide a more comprehensive understanding of the relationship between college students' drug use and IPV perpetration than the current literature allows.

Cerebrospinal fluid GABA concentration: relationship with impulsivity and history of suicidal behavior, but not aggression, in human subjects

The objective of this study was to assess the relationship between cerebrospinal fluid concentrations of the neurotransmitter gamma-aminobutyric acid (GABA) and measures of impulsivity and related behaviors (aggression and suicidality) in healthy volunteer and personality disordered subjects. CSF GABA levels, and measures of impulsivity, aggression, and history of suicidal behavior were obtained by morning lumbar puncture in 57 healthy volunteer subjects and in subjects with personality disorder. CSF GABA levels were not found to correlate with measures of aggression but were found to correlate directly with measures of impulsivity; e.g., a composite measure of impulsivity in all subjects (r=0.35, df=46, P=0.015) and in personality disordered subjects examined separately (r=0.39, df=30, P=0.029). In the personality disorder group, CSF GABA levels were higher among subjects with a history of suicidal behavior compared with those without this history. These data suggest that central GABAergic function correlates directly with impulsiveness and history of suicidal behavior, but not aggressiveness, in personality disordered subjects. This may be consistent with observations that high doses of benzodiazepines can lead to "behavioral disinhibition" in human subjects. Further work assessing this and other aspects of the central GABA system in personality disordered subjects are warranted.

Heightened aggression after chronic flunitrazepam in male rats: potential links to cortical and caudate-putamen-binding sites

RATIONALE

Higher doses of benzodiazepines induce sedation. However, in low to moderate doses, benzodiazepines can increase aggressive behavior both after acute and chronic administration. The determinants for increasing aggression after chronic intake of flunitrazepam, a so-called date rape drug, in violence-prone individuals are incompletely understood.

OBJECTIVES

The aim of this study is to assess the effects of acute and chronic treatment with flunitrazepam on male aggression in resident rats. We also examined possible changes in binding to benzodiazepine receptors throughout the brain of rats that display aggressive behavior after repeated flunitrazepam treatment using quantitative receptor autoradiography.

MATERIALS AND METHODS

The behaviors of the male Wistar resident rats (n = 35) toward a male intruder were recorded for 10 min twice a week. The salient aggressive and non-aggressive elements in the resident rat's behavior were analyzed. Initially, the dose-dependent effects of flunitrazepam (0.01, 0.03, 0.1, 0.18, and 0.3 mg/kg) or vehicle were determined in all rats; subsequently, 0.3 mg/kg per day flunitrazepam was administered for 42 days (n = 15), and a parallel group was treated with vehicle (n = 20). After the chronic treatment, the flunitrazepam (0, 0.01, 0.03, 0.1, 0.18, and 0.3 mg/kg) effects were again assessed.

RESULTS

The most significant finding is the escalation of aggression after chronic treatment with flunitrazepam. A previously sedative 0.3 mg/kg dose of flunitrazepam engendered very high levels of attack bites, sideways threats, and aggressive postures (total aggression) after 6 weeks of daily administration. Individual differences emerged, and these were associated with decreased binding to benzodiazepine receptors, mainly in the limbic structures such as the cingulate cortex (cingulate areas 1 and 2) and caudate-putamen (posterior part) of aggressive animals, suggesting that these areas are pivotal in the control of emotional and aggressive behavior.

CONCLUSIONS

Chronic flunitrazepam produces changes in receptor binding in discrete areas of the cingulate cortex and caudate-putamen that are proposed to be part of the mechanisms for increased expression of aggressive behavior.

Forensic psychiatric aspects of inpatient violence

Inpatient aggression jeopardizes the safety of psychiatric clinicians and patients. A minority of psychiatric inpatients is responsible for most of inpatient assaults; this subset of repetitively assaultive patients warrants greater attention in the form of systematic study. In developing treatment approaches for assaultive inpatients, it is important to characterize the primary motivation driving aggressive behavior. There are many pharmacologic agents and psychotherapeutic approaches available to address inpatients who engage in impulsive and psychotic violence, but the treatment of inpatients with antisocial or psychopathy personality remain limited, and further study is needed. To protect the safety of patients and staff, criminal prosecution of inpatient assaults is clinically justified if an assailant continues to be aggressive despite appropriate clinical interventions or commits an act of planned aggression so egregious that prosecution is the only reasonable alternative.

Diazepam impairs behavioral inhibition but not delay discounting or risk taking in healthy adults

There are reports that diazepam can increase, decrease, or have no effect on measures of impulsive behavior, which may be related, in part, to differences among the tasks used to measure impulsivity. This study examined the effects of a relatively high dose of diazepam (20 mg) on 5 measures of impulsive behavior in healthy adult men and women. Volunteers (N = 18) participated in a 2-session double-blind randomized design in which they received 20 mg diazepam or placebo. One hour after ingesting the capsule, participants completed mood questionnaires and several impulsivity tasks to measure subtypes of impulsive behavior, including behavioral inhibition, delay and probability discounting, and risk taking. Diazepam impaired behavioral inhibition but had no effect on measures of discounting or risk taking. These results are discussed in the context of other recent findings suggesting that different behavioral indices of impulsivity are dissociable and governed by separate underlying mechanisms.

The role of alcohol and drugs in triggering criminal violence: a case-crossover study*

AIMS

To investigate the triggering effects of alcohol, illegal substances and major classes of prescribed psychotropic drugs on criminal violence.

DESIGN

A case-crossover design, using each subject as its own control.

SETTING AND PARTICIPANTS

A consecutive sample of 133 violent offenders was recruited from a forensic psychiatric evaluation unit and a national prison evaluation unit in Sweden during 2002-03. Measurements Offenders were assessed with structured interviews. Risk estimates were based on hazard periods of 24 hours. We used standard Mantel-Haenszel methods for statistical analyses.

FINDINGS

A 13.2-fold increase of risk of violence [95% confidence interval (CI): 8.2-21.2] was found within 24 hours of alcohol consumption. This increase in violence risk was similar among individuals combining alcohol with benzodiazepines [Relative risk (RR) = 13.2, 95% CI: 4.9-35.3]. Use of benzodiazepines alone in regular doses (RR = 0.4, 95% CI: 0.2-0.5) or antidepressants [selective serotonin reuptake inhibitors (SSRIs) or tricyclics] (RR = 0.4, 95% CI: 0.3-0.8) was associated with a lowered risk for violence.

CONCLUSIONS

This study confirmed that alcohol is a strong trigger of criminal violence. Benzodiazepines in combination with alcohol caused no further increase of violence risk. Benzodiazepines in regular doses and antidepressants may inhibit violence, but further studies are needed to verify causality. The case-crossover method can contribute to research on the proximal causes of criminal violence.

Escalated aggressive behavior: Dopamine, serotonin and GABA

The ethical dilemma in aggression research is how to reconcile two divergent objectives, namely to avoid harm and injury as much as possible and, at the same time, how to study behavioral phenomena that validly represent the essence of the neurobiology of aggression. Clinical and preclinical aggression research focuses on different types of aggression. Preclinical studies are usually stimulated by an ethological approach and focus on the phylogeny, ontogeny, survival value and neural mechanisms of ritualized displays and signals. On the other hand, clinical studies focus on violent individuals and pathologically excessive forms of aggressive behavior. This review emphasizes research on escalated forms of aggression in animals and humans and their pharmacotherapy. The current experimental models to generate escalated levels of aggressive behavior in laboratory rely on social instigation, frustrative non-reward and alcohol drinking. These types of aggression are modulated by canonical neurotransmitters like dopamine, serotonin (5-HT) and GABA. It continues to be a main goal of much neurobiological research to find potential targets of pharmacological agents that interact with dopaminergic, GABAergic and serotonergic systems and have high efficacy and selectivity to reduce excessive levels of aggressive and violent behaviors without side-effects. While the mesocorticolimbic dopamine system is implicated in the initiation, execution, termination and consequences of aggressive behavior, drugs with a high affinity for dopamine D2 receptors lack specificity for reducing aggressive behavior. Current investigations point to 5-HT(1B) receptor subtypes as particularly relevant. First, they are differentially expressed in aggression-prone individuals relative to those who are not excessively aggressive. Second, these and also other 5-HT receptor subtypes emerge to be significant targets for anti-aggressive interventions. Positive modulators of GABA(A) receptors with specific subunit configuration may be relevant for heightening aggression, and these sites may be targets for intervention. A prerequisite for rational pharmacotherapies will be adequate characterization of serotonergic and GABAergic receptor regulation in individuals exhibiting escalated aggression.

Escalated aggression as a reward: corticosterone and GABA(A) receptor positive modulators in mice

RATIONALE

Individuals seek out the opportunity to fight, but the mechanisms behind this positively reinforcing effect of aggression have yet to be understood.

OBJECTIVES

The aims of this study were to (1) describe behavioral and corticosterone elevations that occur in aggressive mice conditioned to respond for the opportunity to fight another mouse, (2) determine if corticosterone elevations are necessary for operant responding and escalated aggression, and (3) determine if corticosterone elevations alter the aggression-heightening effects of gamma-aminobutyric acid (GABA)(A) receptor positive modulators.

METHODS AND RESULTS

Aggressive male CFW mice were conditioned to respond under the control of a fixed-interval 10-min (FI10) schedule that reinforced their operant behavior by the presentation of an intruder mouse into their home cage. After the FI10, aggressive behavior was ca. 75% higher than the species-typical levels of fighting and plasma corticosterone was more than twice as high after briefly fighting and/or responding on the FI10 schedule. Inhibition of corticosterone synthesis by metyrapone (30-100 mg/kg) reduced both conditioned responding as well as the aggressive behavior after the FI. Although the benzodiazepine midazolam (0.3-3 mg/kg) heightened species-typical aggressive behavior, it did not increase the high level of aggression engendered by the FI schedule. However, midazolam (0.3 mg/kg) and the neurosteroid allopregnanolone (17 mg/kg) both heightened aggression when given after corticosterone synthesis inhibition by metyrapone (56 mg/kg).

CONCLUSIONS

These data suggest that corticosterone elevations are required for responding that is motivated by aggressive behavior and for escalated aggression that follows this responding. Corticosterone elevations also appear to inhibit the aggression heightening effect of GABA(A) receptor positive modulators.

Acute effects of lorazepam on laboratory measures of aggressive and escape responses of adult male parolees

Acute benzodiazepine administrations typically decrease aggressive responding, but increases in aggression have been reported in some studies. The benzodiazepine lorazepam has been studied less frequently than other benzodiazepines in aggression research, although it is often used to suppress violent aggression in patients. The present study was designed to investigate the effects of acute administrations of lorazepam on aggressive responding in adult humans on a laboratory aggression task. Eight adult males participated in experimental sessions on the Point Subtraction Aggression Paradigm (PSAP), which provided subjects with aggressive, escape and monetary-reinforced response options. Acute oral doses (1, 2 and 4 mg) of lorazepam decreased both aggressive responding and monetary-reinforced responding in seven of eight subjects. In one subject, lorazepam produced dose-dependent increases in aggressive responding. The effects of lorazepam on escape responding were the same as the effects on aggressive responding. The results are consistent with prior research using the PSAP and clinical data showing that benzodiazepines generally decrease aggression, and contrast with other studies that have shown that benzodiazepines can increase aggression. Since lorazepam affected both aggressive and escape responding, it is suggested that while lorazepam often produces sedation, it also modifies human aggressive responding, in part, by suppressing reactions to aversive stimuli.

Benzodiazepines and heightened aggressive behavior in rats: reduction by GABA(A)/alpha(1) receptor antagonists

RATIONALE

Positive modulators of the benzodiazepine/GABA(A) receptor complex can heighten aggressive behavior; the GABA(A)/alpha(1) subunit may play a critical role in benzodiazepine-modulated aggressive behavior.

OBJECTIVE

The carboline derivatives, beta-CCt and 3-PBC, antagonists with preferential action at the GABA(A) receptors with alpha(1) subunits, may antagonize benzodiazepine-heightened aggression, thus implicating the alpha(1) subunit in heightened aggression.

METHODS

The GABA(A) receptor agonist 4,5,6,7-tetrahydroisoxazolo[5,4c]-pyridin-3-ol (THIP) (0.01-3.0 mg/kg), and the benzodiazepine receptor agonists midazolam (0.3-3.0 mg/kg) and triazolam (0.003-3.0 mg/kg) were administered to adult male resident rats to assess the drugs' effects on their aggressive behavior toward an intruder. Then beta-CCt (0.3-10.0 mg/kg) and 3-PBC (0.3-17.0 mg/kg) were each administered in conjunction with midazolam. The salient elements of aggressive and non-aggressive behavior were measured by analyzing video recordings and encoding each behavioral act and posture in terms of its frequency and duration of occurrence.

RESULTS

Midazolam significantly increased the duration of aggressive behaviors at 1.0 and 1.7 mg/kg, and triazolam increased attack bite frequency at 0.03 mg/kg, both implicating GABA(A) receptors with benzodiazepine binding sites in aggressive behavior. In the present dose range, THIP did not affect any behaviors. The broad-spectrum benzodiazepine antagonist, flumazenil (1.0 mg/kg), antagonized the aggression-heightening effects of midazolam. beta-CCt (0.3-10.0 mg/kg) and 3-PBC (0.3-17.0 mg/kg) also antagonized the aggression-heightening effects of midazolam (1.0 mg/kg).

CONCLUSIONS

These results implicate both the GABA(A) gamma and alpha(1) subunits in benzodiazepine-heightened aggression.

The effects of diazepam on human self-aggressive behavior

RATIONALE

Diazepam, a benzodiazepine with a relatively rapid onset of clinical effects, has been associated with suicide and other self-aggressive acts. The evidence for this association, however, comes exclusively from retrospective non-experimental studies. Although suggestive, the results of these studies do not support a cause-and-effect relationship between benzodiazepine consumption and self-aggressive behavior.

OBJECTIVE

To experimentally examine the effect of diazepam on human self-aggressive behavior under controlled laboratory conditions.

METHOD

Forty-six healthy men and women were randomly assigned to receive placebo, or 5 mg or 10 mg diazepam in a double-blind, between-groups design. Participants were then provided the opportunity to self-administer electric shocks during a competitive reaction-time task (the self-aggression paradigm, SAP). Self-aggression was defined by the intensity of shock chosen.

RESULTS

Diazepam (10 mg) was associated with higher average shock self-administered than placebo. Subjects receiving 10 mg diazepam were also more likely to attempt to self-administer a shock that they were led to believe was "severe" and painful. Sedation effects were found, but diazepam consumption did not impair memory, attention, concentration, pain threshold, or reaction-time performance.

CONCLUSIONS

Clinically relevant diazepam doses may be associated with self-aggressive behaviors at levels that do not significantly impair basic cognitive processes or psychomotor performance.

Use of an analog task to study effects of diazepam on taste perception, consummatory behaviors, and risk taking in a social context

In the present study, the authors examined the effects of diazepam (Valium) on various physical, social, and emotional variables within the framework of a task designed to test risk-taking behavior. Participants received either 10 mg of diazepam or a placebo. After the participants tasted strong-flavored liquids, they were able to engage in a risky behavior (i.e., drinking from a confederate's "used" water bottle). Half the participants received additional verbal pressure to drink from the bottle. The authors expected that diazepam would increase health-risk behavior, but the results were inconsistent with that prediction. The second goal of the experiment was to explore diazepam's effects on arousal, mood, social anxiety, and taste. Diazepam users exhibited differences in taste perception and social anxiety, which might in part explain the health-risk results.

GABAA/alpha1 receptor agonists and antagonists: effects on species-typical and heightened aggressive behavior after alcohol self-administration in mice

RATIONALE

The positive modulation of gamma-aminobutyric acid type-A (GABAA) receptors is a putative mechanism via which alcohol escalates aggressive behavior. Broad-spectrum benzodiazepine antagonists block alcohol-heightened aggression in rats and monkeys. However, the degree to which GABAA subunit composition plays a role in heightened aggressive behavior induced by self-administration of a moderate alcohol dose remains unresolved.

OBJECTIVE

Beta-carboline-3-carboxylate-t-butyl ester (beta-CCt) and zolpidem act preferentially at GABAA receptors containing the alpha1 subunit as antagonist and agonist, respectively, and serve as useful tools to evaluate the role of GABAA receptor subtypes in self-administered alcohol on aggression.

METHODS

Male resident mice, housed in breeding pairs, were conditioned to nose-poke in a removable panel in their home cage, with each fifth poke being reinforced by the delivery of 0.05 ml of 6% ethanol (EtOH). After consuming EtOH, the resident mice were given the antagonists beta-CCt and flumazenil or agonists zolpidem and triazolam, and then confronted an intruder male in their home cage for a 5-min period.

RESULTS

Following self-administration of EtOH (1.0 g/kg, 1.7 g/kg), 14 of 37 resident mice displayed unusually large increases in the frequency of attack bites and sideways threats. Flumazenil or beta-CCt decreased alcohol-heightened and non-heightened aggression in a dose-dependent manner. Administration of 3 mg/kg beta-CCt lowered the aggression-heightening effects of 1 g/kg and 1.7 g/kg EtOH, but did not antagonize the sedative effects of 3.0 g/kg EtOH. Triazolam and zolpidem decreased alcohol-heightened and non-heightened aggressive behavior, and these antiaggressive effects were accompanied by reduced motor activity, indicating sedation.

CONCLUSIONS

Benzodiazepine antagonists, particularly those acting preferentially at GABAA/alpha1 subunit-containing receptors, decrease alcohol-heightened and species-typical aggressive behavior, but are ineffective in attenuating the sedative effects of alcohol.

Acute effects of gabapentin on laboratory measures of aggressive and escape responses of adult parolees with and without a history of conduct disorder

RATIONALE

The possible role of GABA in human aggression was evaluated by administering gabapentin to subjects with and without a history of conduct disorder and comparing the effects on laboratory measures of aggression and escape.

METHODS

Eighteen male and two female subjects with a history of criminal behavior participated in experimental sessions, which measured aggressive and escape responses. Ten subjects had a history of childhood conduct disorder (CD+) and ten subjects with no history (non-CD controls). Aggression was measured using the Point Subtraction Aggression Paradigm (PSAP), which provided subjects aggressive, escape and monetary reinforced response options.

RESULTS

Acute doses (200, 400 and 800 mg) of gabapentin had similar effects on aggressive responses among CD+ subjects compared to non-CD control subjects. Aggressive responses of CD+ and non-CD control subjects increased at lower gabapentin doses, and decreased at the highest 800 mg gabapentin dose. Gabapentin increased escape responses for both CD+ and non-CD controls CD- subjects at the lowest dose, but then produced dose-related decreases at the two higher doses in both groups. No changes in monetary reinforced responses were observed, indicative of no CNS stimulation or sedation.

CONCLUSIONS

Gabapentin produced similar bitonic effects upon aggressive and escape responses in subjects with and without a history of childhood conduct disorder. This is in marked contrast to prior differential effects of baclofen on aggressive responses between CD+ and non-CD control subjects in a previous study.

Drugs of abuse and the elicitation of human aggressive behavior

The drug-violence relationship exists for several reasons, some direct (drugs pharmacologically inducing violence) and some indirect (violence occurring in order to attain drugs). Moreover, the nature of that relationship is often complex, with intoxication, neurotoxic, and withdrawal effects often being confused and/or confounded. This paper reviews the existing literature regarding the extent to which various drugs of abuse may be directly associated with heightened interpersonal violence. Alcohol is clearly the drug with the most evidence to support a direct intoxication-violence relationship. The literatures concerning benzodiazepines, opiates, psychostimulants, and phencyclidine (PCP) are idiosyncratic but suggest that personality factors may be as (or more) important than pharmacological ones. Cannabis reduces likelihood of violence during intoxication, but mounting evidence associates withdrawal with aggressivity. The literature on the relationship between steroids and aggression is largely confounded, and between 3,4-methylenedioxymethamphetamine (MDMA) and aggression insufficient to draw any reasonable conclusions. Conclusions and policy implications are briefly discussed.

Neurosteroids, GABAA receptors, and escalated aggressive behavior

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

Effects of diazepam and flumazenil on food competition behavior in high- and low-aggression pigeons

The food competition interaction test performed with food-restricted pigeons with previously consolidated dominance is a useful tool for the study of offensive and defensive social aggression. In the present study, we examined the effect of GABA-A-benzodiazepine (BZD) receptor manipulation on aggression, emotion, feeder control, and eating behavior in high- and low-aggression female pigeons maintained at 80% of their normal weight and exposed to food competition interactions. The pigeons were divided into pairs by previously ranked high-aggression females (total time spent in aggression over 60 s/5 min; n=6 pairs) and low-aggression females (time spent in aggression less than 10 s/5 min; n=6 pairs). In Experiment 1, a pigeon in each pair of high- and low-aggression subjects were treated daily with an oral dose of diazepam (DZP, 0.6 mg/kg/0.3 ml) for 8 days. The other animal received the vehicle. On Day 8, food competition trials (10 min) were performed 30 min after treatments. In Experiment 2, pigeons were injected subcutaneously with flumazenil (FZL, 0.1 mg/kg/1 ml) or saline and exposed to a food competition trial 30 min after injections. In Experiment 3, one animal in each pair received DZP for 8 days. The other animal received the vehicle. On Day 8, the DZP-treated subjects were injected subcutaneously with FZL (0.1 mg/ kg/1 ml) 30 min before the oral dose of DZP. Trials were performed 30 min after DZP or vehicle administration. In Experiment 1, it was found that the DZP group of high-aggression pigeons showed lower scores of aggression (P<.05) and emotional responses (P<.05) than controls. The other group-scored behaviors were not affected. The DZP low-aggressions, however, showed scores of aggression eightfold higher than their controls (P<.05) but the other scored behaviors were not changed. In Experiment 2, FZL injection did not induce intrinsic effects on aggression either in the high- or in the low-aggression group. Experiment 3 showed that the emotional and aggressive responses to DZP were neutralized by FZL. This shows that GABA-A-BZD receptor mechanisms are implicated in the DZP responses in high- and low-aggression pigeons.

The effects of diazepam (valium) and aggressive disposition on human aggression: an experimental investigation

Sixty male subjects with self-reported high, moderate, and low aggressive dispositions were given the opportunity to aggress, by administering electric shocks, against an increasingly provocative fictitious opponent within the context of a competitive reaction time task. Subjects were randomly assigned to one of two conditions: (1) 10 mg of diazepam or (2) placebo. Results indicated that diazepam-intoxicated subjects aggressed by selecting the highest shock setting (10) more frequently than did nonintoxicated subjects. High hostile subjects were also more influenced by the aggression-enhancing effects of diazepam than moderate and low hostile subjects. Benzodiazepine-facilitated aggression is discussed in the context of individual differences and the importance for physicians to assess a patient's disposition prior to prescribing such medication.

Differential effect of Fyn tyrosine kinase deletion on offensive and defensive aggression

Fyn tyrosine kinase is highly expressed in the limbic system and mice lacking Fyn tyrosine kinase showed increased fearfulness in a variety of tests for anxiety-related behaviors. To investigate the possible role of Fyn tyrosine kinase in aggression, we assessed the aggressive behaviors of the mice lacking the Fyn tyrosine kinase using the resident-intruder and restraint-induced target biting paradigms. The percentage of Fyn-deficient mice that attacked an inanimate target in a restraint tube was higher than that of the control mice. On the contrary, in the resident-intruder paradigm, the percentage of Fyn-deficient mice that attacked the intruder was lower and the Fyn-deficient mice showed a longer latency to attack an intruder. These results suggest a distinct role of Fyn tyrosine kinase in enhancing the offensive aggression and decreasing the defensive aggression. A possible influence of anxiety-phenotype of the Fyn-deficient mice on their abnormal aggressive behavior was discussed.