Effects of acute tiagabine administration on aggressive responses of adult male parolees

Directional Deep Brain Stimulation of the Posteromedial Hypothalamus for Refractory Intermittent Explosive Disorder: A Case Series Using a Novel Neurostimulation Device and Intraoperative Microdialysis

BACKGROUND

Intermittent explosive disorder (IED) is a psychiatric disorder characterized by recurrent outbursts of aggressive behavior. Deep brain stimulation (DBS) in the posteromedial nucleus of the hypothalamus (pHyp) is an alternative therapy for extreme cases and shows promising results. Intraoperative microdialysis can help elucidate the neurobiological mechanism of pHyp-DBS. We sought to evaluate efficacy and safety of pHyp-DBS using 8-contact directional leads in patients with refractory IED (rIED) and the accompanying changes in neurotransmitters.

METHODS

This was a prospective study in which patients with a diagnosis of rIED were treated with pHyp-DBS for symptom alleviation. Bilateral pHyp-DBS was performed with 8-contact directional electrodes. Follow-up was performed at 3, 6, and 12 months after surgery.

RESULTS

Four patients (3 men, mean age 27 ± 2.8 years) were included. All patients were diagnosed with rIED and severe intellectual disability. Two patients had congenital rubella, one had a co-diagnosis of infantile autism, and the fourth presented with drug-resistant epilepsy. There was a marked increase in the levels of gamma-aminobutyric acid and glycine during intraoperative stimulation. The average improvement in aggressive behavior in the last follow-up was 6 points (Δ: 50%, P = 0.003) while also documenting an important improvement of the Short Form Health Survey in all domains except bodily pain. No adverse events associated with pHyp-DBS were observed.

CONCLUSIONS

This is the first study to show the safety and beneficial effect of directional lead pHyp-DBS in patients with rIED and to demonstrate the corresponding mechanism of action through increases in gamma-aminobutyric acid and glycine concentration in the pHyp.

Cortical control of aggression: GABA signalling in the anterior cingulate cortex

Reduced top-down control by cortical areas is assumed to underlie pathological forms of aggression. While the precise underlying molecular mechanisms are still elusive, it seems that balancing the excitatory and inhibitory tones of cortical brain areas has a role in aggression control. The molecular mechanisms underpinning aggression control were examined in the BALB/cJ mouse model. First, these mice were extensively phenotyped for aggression and anxiety in comparison to BALB/cByJ controls. Microarray data was then used to construct a molecular landscape, based on the mRNAs that were differentially expressed in the brains of BALB/cJ mice. Subsequently, we provided corroborating evidence for the key findings from the landscape through ¹H-magnetic resonance imaging and quantitative polymerase chain reactions, specifically in the anterior cingulate cortex (ACC). The molecular landscape predicted that altered GABA signalling may underlie the observed increased aggression and anxiety in BALB/cJ mice. This was supported by a 40% reduction of ¹H-MRS GABA levels and a 20-fold increase of the GABA-degrading enzyme Abat in the ventral ACC. As a possible compensation, Kcc2, a potassium-chloride channel involved in GABA-A receptor signalling, was found increased. Moreover, we observed aggressive behaviour that could be linked to altered expression of neuroligin-2, a membrane-bound cell adhesion protein that mediates synaptogenesis of mainly inhibitory synapses. In conclusion, Abat and Kcc2 seem to be involved in modulating aggressive and anxious behaviours observed in BALB/cJ mice through affecting GABA signalling in the ACC.

Aggression Toward Sexualized Women Is Mediated by Decreased Perceptions of Humanness

Researchers have argued that the regulation of female sexuality is a major catalyst for women's intrasexual aggression. The present research examined whether women behave more aggressively toward a sexualized woman and whether this is explained by lower ratings of the target's humanness. Results showed that women rated another woman lower on uniquely human personality traits when she was dressed in a sexualized (vs. conventional) manner. Lower humanness ratings subsequently predicted increased aggression toward her in a behavioral measure of aggression. This effect was moderated by trait intrasexual competitiveness; lower humanness ratings translated into more aggression, but only for women scoring relatively high on intrasexual competition. Follow-up studies revealed that the effect of sexualized appearance on perceived humanness was not due to the atypicality of the clothing in a university setting. The current project reveals a novel psychological mechanism through which interacting with a sexualized woman promotes aggressive behavior toward her.

The Point Subtraction Aggression Paradigm as a laboratory tool for investigating the neuroendocrinology of aggression and competition

A contribution to a special issue on Hormones and Human Competition.The ease of measuring steroids in saliva has led to an increase in investigating their role in competition and aggression in laboratory settings and using behavioral measures of aggression. We review here the Point-Subtraction-Aggression-Paradigm (PSAP) as a measure of costly aggression and we compare and contrast the PSAP to other aggression measures. We describe our use of the PSAP, highlighting how it can be modified to investigate a broad array of experimental questions. We review studies that have investigated neuroendocrine function and the PSAP, and we conclude that across studies the relationship between fluctuations in testosterone and PSAP aggression scores are directionally positive, and are likely specific to men. Investigations of other neuroendocrine measures and the PSAP are fewer, limiting conclusions that can be drawn for other hormones. We provide two versions of the PSAP that can be used with E-PRIME® software for researchers interested in this measure for their laboratories.

Threatening Men's Mate Value Influences Aggression Toward an Intrasexual Rival: The Moderating Role of Narcissism

Correlational research has linked low mate value (MV)--one's worth as a mating partner to members of the opposite sex--with aggression in men. In 2 experiments, we examined the effects of self-perceived MV on men's reported willingness to aggress directly toward a hypothetical mate poacher (Experiment 1, N = 60) and observable aggression toward a same-sex rival in a laboratory paradigm (Experiment 2, N = 54). In both experiments, the roles of narcissism in moderating the effect of MV condition on subsequent aggression were examined. Results of Experiment 1 indicated that men randomly assigned to the low MV condition were significantly more willing to report aggressive intention than men in the high MV condition. This relationship was moderated by narcissism such that men in the low MV condition who were also high in narcissism were the most likely to aggress. Results of Experiment 2 similarly showed that men in the low MV condition relative to the high MV condition aggressed more toward a same-sex rival when they were high in narcissism. These findings support evolutionary hypotheses surrounding the importance of self-perceived MV in directing aggressive mating efforts, as situated in the framework of threatened egotism.

Synthesis and pharmacological properties of new GABA uptake inhibitors

BACKGROUND

γ-Aminobutanoic acid (GABA) is the principal inhibitory neurotransmitter in the mammalian central nervous system. The identification and subsequent development of the GABA transport inhibitors which enhance the GABA-ergic transmission has shown the important role that GABA transporters play in the control of numerous functions of the nervous system. Compounds which inhibit GABA uptake are used as antiepileptic drugs (tiagabine - a selective GAT1 inhibitor), they are also being investigated for other indications, including treatment of psychosis, general anxiety, sleep disorders, drug addiction or acute and chronic pain.

METHODS

In this paper, the synthesis of 2-substituted-4-(1,3-dioxoisoindolin-2-ylo)-butanamides and 2-substituted-4-aminobutanoic acids derivatives is described. These compounds were tested in vitro for their ability to inhibit GABA uptake. The inhibitory potency towards murine plasma membrane GABA transporters (mGAT1-4) was performed as [(3)H]GABA uptake assay based on stably transfected HEK cells. Compound 18, which demonstrated the highest affinity for mGAT1-4 (pIC(50) ranged from 4.42 for mGAT1 to 5.07 for mGAT3), was additionally investigated in several behavioral tests in mice.

RESULTS

Compound 18 increased the locomotor activity (14-38%) and had anxiolytic-like properties in the four-plate test (ED(50) = 9.3 mg/kg). It did not show analgesic activity in acute pain model, namely the hot plate test, however, it was antinociceptive in the acetic acid-induced writhing test (ED(50) = 15.3 mg/kg) and in the formalin model of tonic pain. In the latter assay, it diminished nocifensive behavior in both phases and in the first (neurogenic) phase of this test the obtained ED(50) value (5.3 mg/kg) was similar to morphine (3.0 mg/kg).

CONCLUSION

Compound 18 exhibited significant anxiolytic-like properties and was antinociceptive in some models of pain in mice. Moreover, it did not impair animals' motor coordination in the chimney test. Some of the described pharmacological activities of compound 18 can be partly explained based on its affinity for plasma membrane GABA transporters.

Chronic tiagabine administration and aggressive responding in individuals with a history of substance abuse and antisocial behavior

Anticonvulsants, notably those which modulate GABA activity, have shown efficacy in reducing aggressive behavior. Previously, we found dose-related decreases in human aggressive responding following acute tiagabine administration. Here, we examined the effects of chronic tiagabine over a 5-week period. Twelve individuals at increased risk for aggressive and violent behavior (currently on parole/probation with personality and/or substance use disorders) were randomly assigned to placebo (n = 6) or an escalating dose sequence of placebo, 4 mg, 8 mg, 12 mg, placebo (n = 6). Data were analyzed using both frequentist and Bayesian mixed models, evaluating aggressive behavior as a function of time, dose condition, and their interaction. For aggressive responding, there was a significant interaction of drug condition and time. Aggression in the tiagabine condition decreased for each additional week in the study, while participants in the placebo condition failed to demonstrate similar change over time. For monetary-reinforced responding, no drug or drug by time interactions were observed, suggesting specificity of drug effects on aggression. The small number of subjects limits the generality of the findings, and previous studies with tiagabine are limited to acute dosing and case report investigations. However, the present data provide an indication that tiagabine merits further examination as an agent for management of impulsive aggression.

The psychopharmacology of aggressive behavior: a translational approach: part 1: neurobiology

Patients with mental disorders are at an elevated risk for developing aggressive behavior. In the last 19 years, the psychopharmacological treatment of aggression has changed dramatically because of the introduction of atypical antipsychotics into the market and the increased use of anticonvulsants and lithium in the treatment of aggressive patients.Using a translational medicine approach, this review (part 1 of 2) examines the neurobiology of aggression, discussing the major neurotransmitter systems implicated in its pathogenesis, namely, serotonin, glutamate, norepinephrine, dopamine, and γ-aminobutyric acid, and also their respective receptors. The preclinical and clinical pharmacological studies concerning the role of these neurotransmitters have been reviewed, as well as research using transgenic animal models. The complex interaction among these neurotransmitters occurs at the level of brain areas and neural circuits such as the orbitoprefrontal cortex, anterior cortex, amygdala, hippocampus, periaqueductal gray, and septal nuclei, where the receptors of these neurotransmitters are expressed. The neurobiological mechanism of aggression is important to understand the rationale for using atypical antipsychotics, anticonvulsants, and lithium in treating aggressive behavior. Further research is necessary to establish how these neurotransmitter systems interact with brain circuits to control aggressive behavior at the intracellular level.

Pharmacologic treatment of impulsive aggression with antiepileptic drugs

Aggressive behavior is a major concern in mental health and criminal justice settings. Although pharmacotherapy is often used in the treatment of the violent individual, no medication is presently approved by the US Food and Drug Administration specifically for such use. In recent years, antiepileptic drugs (AEDs) have become increasingly popular for the management of impulsive (reactive) aggressive behavior. The research literature has implicated several neurobiologic deficits associated with impulsive aggression, including reduced central serotonergic functioning, executive dysfunction, and prefrontal deficits. It has been suggested that the neurobiologic deficits specific to impulsive aggressive behavior may serve as indicators of an ineffective behavioral control system. A review of the literature finds that AEDs, particularly those that block sodium channels and/or have GABA-related mechanisms of action, are effective in reducing the frequency and intensity of impulsive aggressive outbursts both when used as the primary agent of treatment and as an adjunct to ongoing pharmacotherapy. Strong evidence for efficacy in impulsive aggression exists from randomized controlled trials for most of the common AEDs (phenytoin, carbamazepine, oxcarbazepine, lamotrigine, valproate/divalproex sodium, topiramate). Additional controlled studies are needed for tiagabine and gabapentin. Of the common AEDs, only levetiracetam has been shown to be ineffective in the treatment of impulsive aggression. It is important to note that the anti-aggressive effects seen with the AEDs appear to be specific to the impulsive form of aggression. Individuals who display premeditated aggression do not seem to benefit from this type of treatment. Clinically, we recommend phenytoin (initial dose 100 mg three times daily) as the AED of first choice for the treatment of impulsive aggressive outbursts. This recommendation is based on this drug's limited side effect profile (compared with the other AEDs) and the large amount of empiric data supporting its clinical efficacy in impulsive aggression. In the event that the impulsive aggressive individual does not respond to pharmacotherapy with phenytoin, carbamazepine (initial dose 150 mg three times daily) and valproate/divalproex sodium (initial dose 250 mg three times daily) have both proved to be effective secondary options.

A prospective study of lipids and serotonin as risk markers of violence and self-harm in acute psychiatric patients

Cross-sectional studies have reported an association between lipids and serotonin levels and aggression, but a literature search revealed a paucity of prospective studies. Subjects of the present naturalistic study were 254 of all (489) involuntary and voluntary acutely admitted patients to a psychiatric hospital during 1year. Serum lipids and platelet serotonin at admission were prospectively compared with recorded intra-institutional and 1-year post-discharge violence and self-harm. Total cholesterol had a significant negative relationship to inpatient suicidal behaviour and inpatient violent behaviour and to 3-month post-discharge violent behaviour. Triglycerides were a significant marker of inpatient self-mutilation and of self-mutilation in combination with suicidal behaviour at 3 and 12 months of follow-up. High-density lipoprotein (HDL) had a significant negative relationship to violence at 12-months, and to repeated violence in seven patients with two or more admissions. The post-discharge relationships between total cholesterol and violence and between triglycerides and self-harm remained significant even when controlling for other possible explanatory variables in a multivariate model. Results did not change after controlling for current medication at admission. There was no association between platelet serotonin and violence or self-harm. Future research may examine if lipid measurements add incremental validity to established clinical risk assessment procedures of violent and self-harm behaviour.

Neuropsychiatry of aggression

Aggression is a serious medical problem that can place both the patient and the health care provider at risk. Aggression can result from medical, neurologic, and/or psychiatric disorders. A comprehensive patient evaluation is needed. Treatment options include pharmacotherapy as well as nonpharmacologic interventions, both of which need to be individualized to the patient.

The Use of Antiepileptic Drugs (AEDs) for the Treatment of Pediatric Aggression and Mood Disorders

Aggressive symptomatology presents across multiple psychiatric, developmental, neurological and behavioral disorders, complicating the diagnosis and treatment of the underlying pathology. Anti-Epileptic Drugs (AEDs) have become an appealing alternative in the treatment of aggression, mood lability and impulsivity in adult and pediatric populations, although few controlled trials have explored their efficacy in treating pediatric populations. This review of the literature synthesizes the available data on ten AEDs - valproate, carbamazepine, oxcarbazepine, phenytoin, lamotrigine, topiramate, levetiracetam, zonisamide, gabapentin and tiagabine - in an attempt to assess evidence for the efficacy of AEDs in the treatment of aggression in pediatric populations. Our review revealed modest evidence that some of the AEDs produced improvement in pediatric aggression, but controlled trials in pediatric bipolar disorder have not been promising. Valproate is the best supported AED for aggression and should be considered as a first line of treatment. When monotherapy is insufficient, combining an AED with either lithium or an atypical anti-psychotic can result in better efficacy. Additionally, our review indicates that medications with predominately GABA-ergic mechanisms of action are not effective in treating aggression, and medications which decrease glutaminergic transmission tended to have more cognitive adverse effects. Agents with multiple mechanisms of action may be more effective.

Translational research in behavior analysis: historical traditions and imperative for the future

"Pure basic" science can become detached from the natural world that it is supposed to explain. "Pure applied" work can become detached from fundamental processes that shape the world it is supposed to improve. Neither demands the intellectual support of a broad scholarly community or the material support of society. Translational research can do better by seeking innovation in theory or practice through the synthesis of basic and applied questions, literatures, and methods. Although translational thinking has always occurred in behavior analysis, progress often has been constrained by a functional separation of basic and applied communities. A review of translational traditions in behavior analysis suggests that innovation is most likely when individuals with basic and applied expertise collaborate. Such innovation may have to accelerate for behavior analysis to be taken seriously as a general-purpose science of behavior. We discuss the need for better coordination between the basic and applied sectors, and argue that such coordination compromises neither while benefiting both.

Acute topiramate differentially affects human aggressive responding at low vs. moderate doses in subjects with histories of substance abuse and antisocial behavior

Anticonvulsant drugs have demonstrated efficacy in the management of irritability and aggression in a variety of psychiatric populations. We examined the acute effects of topiramate on aggression using a laboratory model of human aggression (PSAP) in individuals at high risk for aggressive and violent behavior.Twelve subjects, on parole/probation and with an Axis-II personality disorder and/or a substance use disorder, received 100, 200, 300, and 400 mg in an ascending sequence, with intervening placebo doses.Subjects participated 2-3 days per week over 4-6 weeks. Due to cognitive side effects at 300 mg, two subjects only completed through the 200 mg dose. Topiramate produced an inverted U-shaped dose response curve, with increases in aggression peaking at 200 mg and a modest decrease at 400 mg. Statistical analysis revealed a polynomial trend for dose (p=0.001). The observed inverted U-shaped function in aggressive responding is consistent with non-human aggression studies of GABA-A modulators. Acute topiramate doses >400 mg may have anti-aggressive effects, but dose levels in the 200-300 mg range may produce increases in aggression and side effects.

Neurobiology of aggression and violence

Acts of violence account for an estimated 1.43 million deaths worldwide annually. While violence can occur in many contexts, individual acts of aggression account for the majority of instances. In some individuals, repetitive acts of aggression are grounded in an underlying neurobiological susceptibility that is just beginning to be understood. The failure of "top-down" control systems in the prefrontal cortex to modulate aggressive acts that are triggered by anger provoking stimuli appears to play an important role. An imbalance between prefrontal regulatory influences and hyper-responsivity of the amygdala and other limbic regions involved in affective evaluation are implicated. Insufficient serotonergic facilitation of "top-down" control, excessive catecholaminergic stimulation, and subcortical imbalances of glutamatergic/gabaminergic systems as well as pathology in neuropeptide systems involved in the regulation of affiliative behavior may contribute to abnormalities in this circuitry. Thus, pharmacological interventions such as mood stabilizers, which dampen limbic irritability, or selective serotonin reuptake inhibitors (SSRIs), which may enhance "top-down" control, as well as psychosocial interventions to develop alternative coping skills and reinforce reflective delays may be therapeutic.