Corticolimbic function in impulsive aggressive behavior

Topological features of functional brain networks and subclinical impulsivity: an investigation in younger and older adults

Impulsive traits (i.e., the tendency to act without forethought regardless of negative outcomes) are frequently found in healthy populations. When exposed to risk factors, individuals may develop debilitating disorders of impulse control (addiction, substance abuse, gambling) characterized by behavioral and cognitive deficits, eventually leading to huge socioeconomic costs. With the far-reaching aim of preventing the onset of impulsive disorders, it is relevant to investigate the topological organization of functional brain networks associated with impulsivity in sub-clinical populations. Taking advantage of the open-source LEMON dataset, we investigated the topological features of resting-state functional brain networks associated with impulsivity in younger (n = 146, age: 20-35) and older (n = 61, age: 59-77) individuals, using a graph-theoretical approach. Specifically, we computed indices of segregation and integration at the level of specific circuits and nodes known to be involved in impulsivity (frontal, limbic, and striatal networks). In younger individuals, results revealed that impulsivity was associated with a more widespread, less clustered and less efficient functional organization, at all levels of analyses and in all selected networks. Conversely, impulsivity in older individuals was associated with reduced integration and increased segregation of striatal regions. Speculatively, such alterations of functional brain networks might underlie behavioral and cognitive abnormalities associated with impulsivity, a working hypothesis worth being tested in future research. Lastly, differences between younger and older individuals might reflect the implementation of age-specific adaptive strategies, possibly accounting for observed differences in behavioral manifestations. Potential interpretations, limitations and implications are discussed.

Peak alpha frequency and electroencephalographic microstates are correlated with aggression in schizophrenia

Large scale retrospective studies have shown an association between schizophrenia and risk of violence. Overall, this increase in risk is small and does not justify or support stigmatizing public perceptions or media depictions of people with schizophrenia. Nonetheless, in some situations, some symptoms of schizophrenia can increase the risk of violent behavior. Prediction of this behavior would allow high impact preventive interventions. However, to date the neurobiological correlates of violent behavior in schizophrenia are not well understood, precluding the development of prognostic biomarkers. We used electroencephalography to measure alpha activity and microstates from 31 patients with schizophrenia and 18 age matched controls. Participants also completed multiple assessments of current aggressive tendencies and their lifetime history of aggressive acts. We found that individual alpha peak frequency was negatively correlated with aggression scores in both patients and controls (largest Spearman's r = -0.45). Furthermore, this result could be replicated in data taken from a single frontal channel suggesting that this may be possible to obtain in routine clinical settings (largest Spearman's r = -0.40). We also found that transitions between microstates corresponding to auditory and visual networks were inversely correlated with aggression scores. Finally, we found that, within patients, aggression was correlated with the degree of randomness between microstate transitions. This suggests that aggression is related to inappropriate switching between large scale brain networks and subsequent failure to appropriately integrate complicated environmental and internal stimuli. By elucidating some of the electrophysiological correlates of aggression, these data facilitate the development of prognostic biomarkers.

Characterizing the role of impulsivity in costly, reactive aggression using a novel paradigm

A lack of self-control has long been theorized to predict an individual's likelihood to engage in antisocial behaviors. However, existing definitions of self-control encompass multiple psychological constructs and lab-based measures of aggression have not allowed for the examination of aggression upon provocation where self-control is needed most. We introduce two versions of a novel paradigm, the Retaliate or Carry-on: Reactive AGgression Experiment (RC-RAGE) to fill this methodological gap. Using large online samples of US adults (N = 354 and N = 366), we evaluate to what extent dispositional impulsivity, self-control, aggression, and state anger contribute to aggression upon provocation when there is a financial cost involved. Results showed that costly retaliation on this task was related to trait aggression and being in an angry emotional state, but not related to social desirability. Importantly, we show that the tendency to act impulsively is a better predictor of costly retaliation than other forms of self-control, such as the ability to delay gratification, resist temptation, or plan ahead. As a browser-based task, the RC-RAGE provides a tool for the future investigation of reactive aggression in a variety of experimental settings.

Neural correlates of aggression in personality disorders from the perspective of DSM-5 maladaptive traits: a systematic review

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published in 2013, includes an alternative model of personality disorders (AMPD) focusing on a maladaptive trait model utilized to diagnose several personality disorders. Borderline personality disorder (BPD) and antisocial personality disorder (ASPD) are two conditions categorized by AMPD that exhibit high rates of violence and aggression. Several of the traits outlined in the AMPD, including hostility, impulsivity, risk-taking, and callousness, have been previously linked to aggression in BPD and ASPD. However, to the best of our knowledge, there has never been a synthesis of neuroimaging studies that have investigated links between these traits and aggression in BPD and ASPD. To overcome this gap, we conducted a systematic review under the PRISMA framework to locate neuroimaging articles published since the release of AMPD linking trait anger/hostility, impulsivity, risk-taking, and callousness to aggression in BPD and ASPD. Key findings included the following: i) anger/hostility, associated with alterations in the interplay between prefrontal and subcortical regions (primarily the amygdala), may be a common factor explaining aggressive reactions to response to interpersonal threat or provocation; ii) alterations of fronto-temporal-limbic regions and serotonergic and endocannabinoid signaling systems may link impulsivity to aggression in BPD and ASPD; iii) weaker cortico-striatal connectivity could relate to greater risk taking and greater proclivity for violence. Insufficient evidence from neuroimaging articles was discerned to describe a relationship between callousness and aggression. Overall, results of this review reveal a relative paucity of neuroimaging studies examining AMPD traits relevant to aggression in BPD and ASPD. In addition to encouraging further investigation of neuroimaging markers of AMPD traits linked to aggression, we recommend multi-methodological designs, including the incorporation of other biomarkers, such as hormones and indices of physiological arousal, to fully expand our understanding of aggression in BPD and ASPD.

Anger and aggression research: A bibliometric analysis from 2012 to 2022

Anger and aggression are common sources of distress and impairment. There is, however, no available data on anger and aggression based on bibliometric analysis. This study uses bibliometric analysis to analyze research hotspots and trends in anger and aggression. Publications on anger and aggression within the last ten years were collected from the Web of Science Core Collection. Using descriptive bibliometrics, journals, countries, institutions, authors, references, and keywords in anger and aggression research were visually analyzed via CiteSpace. A total of 3114 articles were included, and studies on anger and aggression increased yearly. The publications are mainly from 106 countries led by the USA and 381 institutions led by Univ Penn. We identified 505 authors, where Emil F. Coccaro had the highest number of articles, while Buss A.H. was the most frequently co-cited author. AGGRESSIVE BEHAVIOR is the journal that bore most of the studies, while PLOS ONE was the most cited journal. Our analysis demonstrated that research on anger and aggression is flourishing. Behaviors of anger and aggression, risk factors, neural mechanisms, personality, and adolescence have been researched hotspots in the past ten years. Besides, victimization, drosophila melanogaster, psychopathic traits, and perpetration are emerging anger and aggression research trends.

Dopamine transporter blockade during adolescence increases adult dopamine function, impulsivity, and aggression

Sensitive developmental periods shape neural circuits and enable adaptation. However, they also engender vulnerability to factors that can perturb developmental trajectories. An understanding of sensitive period phenomena and mechanisms separate from sensory system development is still lacking, yet critical to understanding disease etiology and risk. The dopamine system is pivotal in controlling and shaping adolescent behaviors, and it undergoes heightened plasticity during that time, such that interference with dopamine signaling can have long-lasting behavioral consequences. Here we sought to gain mechanistic insight into this dopamine-sensitive period and its impact on behavior. In mice, dopamine transporter (DAT) blockade from postnatal (P) day 22 to 41 increases aggression and sensitivity to amphetamine (AMPH) behavioral stimulation in adulthood. Here, we refined this sensitive window to P32-41 and identified increased firing of dopaminergic neurons in vitro and in vivo as a neural correlate to altered adult behavior. Aggression can result from enhanced impulsivity and cognitive dysfunction, and dopamine regulates working memory and motivated behavior. Hence, we assessed these behavioral domains and found that P32-41 DAT blockade increases impulsivity but has no effect on cognition, working memory, or motivation in adulthood. Lastly, using optogenetics to drive dopamine neurons, we find that increased VTA but not SNc dopaminergic activity mimics the increase in impulsive behavior in the Go/NoGo task observed after adolescent DAT blockade. Together our data provide insight into the developmental origins of aggression and impulsivity that may ultimately improve diagnosis, prevention, and treatment strategies for related neuropsychiatric disorders.

Dissociation of behavioral and neural responses to provocation during reactive aggression in healthy adults with high versus low externalization

The externalizing spectrum describes a range of heterogeneous personality traits and behavioral patterns, primarily characterized by antisocial behavior, disinhibition, and substance (mis)use. In psychopathology, abnormalities in neural threat, reward responses and the impulse-control system may be responsible for these externalizing symptoms. Within the non-clinical range, mechanisms remain still unclear. In this fMRI-study, 61 healthy participants (31 men) from the higher versus lower range of the non-clinical variation in externalization (31 participants with high externalization) as assessed by the subscales disinhibition and meanness of the Triarchic-Psychopathy-Measure (TriPM) performed a monetary modified Taylor-Aggression-Paradigm (mTAP). This paradigm consisted of a mock competitive-reaction-time-task played against a fictional opponent with preprogrammed win- and lose-trials. In lose-trials, participants were provoked by subtraction of an amount of money between 0 and 90 cents. As a manipulation check, provocation induced a significant rise in behavioral aggression levels linked with an increased activation in the anterior cingulate cortex (ACC). High externalization predicted reduced ACC responses to provocation. However, high externalizing participants did not behave more aggressively than the low externalization group. Additionally, the high externalizing group showed a significantly lower positive affect while no group differences emerged for negative affect. In conclusion, high externalization in the non-clinical range was related to neural alterations in regions involved in affective decision-making as well as to changes in affect but did not lead to higher behavioral aggression levels in response to the mTAP. This is in line with previous findings suggesting that aberrations at multiple levels are essential for developing externalizing disorders.

Traffic costs of air pollution: the effect of PM2.5 on traffic violation

Although emerging studies have investigated the effect of air pollution on traffic crashes, it is unclear to scholars whether air pollution affects another road safety problem-traffic violations. To address this gap, the current paper constructs a data set from 1,390,221 traffic violation records of 640,971 drivers from the Wuhan Traffic Management Bureau between January 2018 and December 2018. An ordered logistic regression was conducted to verify our hypotheses. The result shows that PM_2.5 has no overall impact on the severity of traffic violations, but each 1% increase in the daily concentration of PM_2.5 leads to a 1.02-fold increase in the odds of serious inexperience-related violations and a 0.99-fold decrease in the odds of serious overconfidence-related violations. This effect is the strongest in PM_2.5, followed by NO₂, and has not been observed in CO and O₃. In addition, robustness tests indicate that the relationship between air pollution and traffic violations is consistent among the different subsets (e.g., clear weather, no rain and snow, and good visibility). We also provide valuable practical advice for drivers and traffic authorities.

Association between toxoplasmosis and bipolar disorder: A systematic review and meta-analysis

BACKGROUND

The relationship between toxoplasma gondii (T. gondii) infection and bipolar disorder (BD) is poorly understood. This review explores this relationship by estimating the strength of the association between the two conditions using data from published studies.

METHODS

Following PRISMA guidelines, we performed a review and meta-analysis of published articles obtained from a systematic search of PubMed, PsycINFO, EMBASE and the Cochrane library up to January 10th, 2021. We included observational studies that compared seroprevalence of IgG class antibodies against T. gondii in patients with a diagnosis of BD with healthy controls. We excluded studies that included <10 participants in each study arm and patients with a serious concomitant medical illness. Discrepancies between the two independent researchers were resolved by consulting a third experienced researcher. Summary data were extracted from published reports. Analysis was conducted using both fixed-effects and random-effects models. The study is registered with PROSPERO number CRD42021237809.

FINDINGS

The search yielded 23 independent studies with a total of 12690 participants (4021 with BD and 8669 controls). Persons with BD had a greater odd of seropositivity with toxoplasmosis than controls, both in the fixed-effects model (OR = 1.34 [95%CI: 1.19 to 1.51]) and the random-effects model (OR = 1.69 [95%CI: 1.21 to 2.36]). No publication bias was detected but reported results showed a high heterogeneity (I2 = 84% [95%CI:77%-89%]).

INTERPRETATION

The findings support the relationship between toxoplasmosis infection and BD and suggests a need for studies designed to explore possible causal relationship. Such studies may also improve our understanding of the pathophysiology of BD and open other avenues for its treatment.

FUNDING

P.O.R. Sardegna F.S.E. 2014-2020.

The Implication of 5-HT Receptor Family Members in Aggression, Depression and Suicide: Similarity and Difference

Being different multifactorial forms of psychopathology, aggression, depression and suicidal behavior, which is considered to be violent aggression directed against the self, have principal neurobiological links: preclinical and clinical evidence associates depression, aggression and suicidal behavior with dysregulation in central serotonergic (5-HT) neurotransmission. The implication of different types of 5-HT receptors in the genetic and epigenetic mechanisms of aggression, depression and suicidality has been well recognized. In this review, we consider and compare the orchestra of 5-HT receptors involved in these severe psychopathologies. Specifically, it concentrates on the role of 5-HT_1A, 5-HT_1B, 5-HT_2A, 5-HT_2B, 5-HT_2C, 5-HT₃ and 5-HT₇ receptors in the mechanisms underlying the predisposition to aggression, depression and suicidal behavior. The review provides converging lines of evidence that: (1) depression-related 5-HT receptors include those receptors with pro-depressive properties (5-HT_2A, 5-HT₃ and 5-HT₇) as well as those providing an antidepressant effect (5-HT_1A, 5-HT_1B, 5-HT_2C subtypes). (2) Aggression-related 5-HT receptors are identical to depression-related 5-HT receptors with the exception of 5-HT₇ receptors. Activation of 5-HT_1A, 5-HT_1B, 5-HT_2A, 5-HT_2C receptors attenuate aggressiveness, whereas agonists of 5-HT₃ intensify aggressive behavior.

Repetitive transcranial magnetic stimulation for post-traumatic stress disorder: Lights and shadows

We have read with interest the publication that describes the available data related to the use of neuromodulation strategies for the treatment of post-traumatic stress disorder (PTSD). Despite treatment advances, however, a substantial proportion of PTSD patients receiving psychological and/or pharmacological treatment do not reach an adequate clinical response. In their paper, the authors draw attention to the current understanding of the use of repetitive transcranial magnetic stimulation (rTMS) as a potential treatment for PTSD. Most of the previous studies indeed applied both inhibitory (1 Hz) and excitatory (> 1 Hz, up to 20 Hz) rTMS to the right and/or left dorsolateral prefrontal cortex. Despite larger therapeutic effects observed when high-frequency stimulation was applied, the question of which side and frequency of stimulation is the most successful is still debated. The authors also reported on the after-effect of rTMS related to neuroplasticity and identified the intermittent theta burst stimulation as a technique of particular interest because of it showed the most effective improvement on PTSD symptoms. However, although numerous studies have highlighted the possible beneficial use of rTMS protocols for PTSD, the exact mechanism of action remains unclear. In their conclusions, the authors stated that rTMS has been demonstrated to be effective for the treatment of PTSD symptoms. Nevertheless, we believe that further research with homogeneous samples, standardized protocols, and objective outcome measures is needed to identify specific therapeutic targets and to better define significant changes when active and sham stimulation procedures are compared.

Efficacy and tolerability of Brain Stimulation interventions in Borderline Personality Disorder: state of the art and future perspectives - A systematic review

Treating Borderline Personality Disorder (BPD) is a major challenge for psychiatrists. As Brain Stimulation represents an alternative approach to treat psychiatric disorders, our systematic review is the first to focus on both invasive and Non-Invasive Brain Stimulation (NIBS) interventions in people living with BPD, examining clinical effects over core features and comorbid conditions. Following PRISMA guidelines, out of 422 original records, 24 papers were included regarding Deep Brain Stimulation (n = 1), Electroconvulsive therapy (n = 5), Transcranial Magnetic Stimulation (n = 13) and transcranial Direct Current Stimulation (n = 5). According to impulsivity and emotional dysregulated domain improvements, NIBS in BPD appears to restore frontolimbic network deficiencies. NIBS seems also to modulate depressive features. Safety and tolerability profiles for each technique are discussed. Despite encouraging results, definitive recommendations on Brain Stimulation in BPD are mitigated by protocols heterogeneity, lack of randomized controlled trials and poor quality of included studies, including high risk of methodological biases. To serve as guide for future systematic investigations, protocols optimization proposals are provided, focusing on alternative stimulation sites and suggesting a NIBS symptom-based approach.

Non-invasive neuromodulation can reduce aggressive behaviors in humans: A critical perspective

Containing aggressive behavior is an ongoing challenge in modern society. Aggressiveness is a multi-level construct that can be driven by emotions (reactive aggression) or can be "cold-blooded" and goal-directed (proactive). Aggressive behavior could arise because of a misjudgment of others' intentions or can follow frontal brain lesions leading to a reduction of impulse control and emotion regulation. In the last few years, interventional and basic research studies adopting Non-Invasive Brain Stimulation (NIBS) have significantly risen. Those techniques have been used both in healthy people, to better understand the role of certain brain regions in psychological processes, and in aggressive subjects to improve their symptoms. From an overview of the literature, focusing on the paper that uses transcranial direct current stimulation (tDCS) to reduce aggressiveness, it emerges that tDCS can (i) enhance facial emotion expression recognition, (ii) improve impulses control, and (iii) affect approach/withdrawal motivation. The current work shows the strengths and weaknesses of tDCS intervention on aggressive individuals, suggesting that this instrument could be adopted on violent people, and paves the way for intervention in some applied settings such as prison.

Mapping the neurocircuitry of impulsive aggression through the pharmacologic review of anti-impulsive aggressive agents

Impulsive aggression, in contradistinction to premeditated aggression in humans or predatory aggression in animals, corresponds to defensive aggression in animal models. At the core of the neurocircuitry of impulsive aggression, from murine to feline to human species, it is the medial amygdala-mediobasal hypothalamus-dorsal periaqueductal gray pathway. Here, we update current knowledge on the neurocircuitry of impulsive aggression by placing the neurocircuitry and its neurophysiological substrates into the top-down/bottom-up hypothesis of impulsive aggression. We then reverse the neurotranslational approach, which applies neuroscience to developing therapeutic drugs, and apply current understanding of potential mechanisms of anti-impulsive aggression agents to further clarify, at least heuristically and hypothetically, the dynamic biochemical components of the neurocircuitry of impulsive aggression. To do this, we searched the medical literature for studies attempting to clarify the neurobiological and neurochemical effects of the five most widely studied anti-impulsive aggressive agents, particularly as they pertain to the top-down/bottom-up hypothesis. Multiple different mechanisms are discussed, all of which fitting in the hypothesis by way of either promoting the "top-down" part (i.e., enhancing inhibitory neurotransmitters), or suppressing the "bottom-up" part (i.e., decreasing excitatory neurotransmitters). The hypothesis appears consistent with the current psychopharmacological understanding of these agents, as well as to account for the likely multifactorial etiology of the condition. Limitations of the hypothesis and future directions are finally discussed.

Gene-environment interactions between CREB1 and childhood maltreatment on aggression among male Chinese adolescents

Both the genetic and environmental factors may affect aggression susceptibility. However, the conclusions of these associations remain discrepant. In addition, studies that explored the association between CREB1 and aggression were meager. The aim of our present study was to assess whether CREB1 polymorphisms were related to aggression and also to explore the interactive effects of CREB1 variants and childhood maltreatment on aggression. A total of 488 individuals with aggressive behavior and 488 controls were recruited. Aggression and childhood maltreatment were surveyed by standardized self-administered questionnaires. Buccal cells were also obtained and genotyping was conducted using SNPscan. Logistic regressions were applied to investigate both individual effects of CREB1 polymorphisms and the interactive influences with childhood maltreatment on aggression. We found that adolescents who carried the rs4675690 T allele in CREB1 showed a higher level of aggression compared with those who carried wildtype genotypes (CC) under the dominant model (OR = 1.67, 95% CI, 1.16–2.40) after controlling for age and childhood maltreatment. Moreover, we also found that rs4675690 T allele had a synergic additive interaction with childhood sexual abuse and emotional neglect on aggression. The significant interactive effects of CREB1 polymorphisms and childhood maltreatment on aggression were reported for the first time.

Repetitive transcranial magnetic stimulation in patients with borderline personality disorder: A systematic review

The literature on the application of repetitive transcranial magnetic stimulation (rTMS) in Borderline Personality Disorder (BPD) is unclear, even though its neuromodulatory effects on underlying neural circuitry involved in BPD symptoms suggest that it could be a potential treatment option. We sought to review the evidence on rTMS as a treatment option in BPD. PubMed (for Medline database), Google Scholar, and Scopus were systematically searched following the PRISMA guidelines for studies of any design examining the application of the rTMS treatment in adult patients with precise and primary diagnosis of BPD written in the English language. The systematic review has been registered on PROSPERO (CRD42020215927). Forty one records were screened, and eight fulfilled inclusion criteria (total of 63 patients). The existing studies suggest that rTMS is a well-tolerated treatment in patients with BPD. Double-blind randomized controlled studies are necessary to help elucidate the effects of rTMS in the different symptoms in BPD and establish efficacy and the best cortical targets and stimulation protocols. Longitudinal studies that combine evidenced based psychotherapy with rTMS may be a future line of investigation that could potentially improve outcomes for this population.

The Modulatory Role of Serotonin on Human Impulsive Aggression

The hypothesis of chronically low brain serotonin levels as pathophysiologically linked to impulsive aggression has been around for several decades. Whereas the theory was initially based on indirect methods to probe serotonin function, our understanding of the neural mechanisms involved in impulsive aggression has progressed with recent advances in neuroimaging. The review integrates evidence based on data from several neuroimaging domains in humans. In vivo molecular neuroimaging findings demonstrate associations between impulsive aggression and high serotonin 1B and serotonin 4 receptor binding, high serotonin transporter levels, and low monoamine oxidase A levels, suggesting that low interstitial serotonin levels are a neurobiological risk factor for impulsive aggressive behavior. Imaging genetics suggests that serotonergic-related genetic polymorphisms associate with antisocial behavior, and some evidence indicates that the low-expressing monoamine oxidase A genotype specifically predisposes to impulsive aggression, which may be mediated by effects on corticolimbic function. Interventions that (presumably) alter serotonin levels have effects on brain activity within brain regions involved in impulsive aggression, notably the amygdala, dorsal striatum, anterior cingulate, insula, and prefrontal cortex. Based on these findings, we propose a model for the modulatory role of serotonin in impulsive aggression. Future studies should ensure that clinical features unique for impulsive aggression are appropriately assessed, and we propose investigations of knowledge gaps that can help confirm, refute, or modify our proposed model of impulsive aggression.

Neural correlates of anger expression in patients with PTSD

Anger is a common and debilitating symptom of post-traumatic stress disorder (PTSD). Although studies have identified brain circuits underlying anger experience and expression in healthy individuals, how these circuits interact with trauma remains unclear. Here, we performed the first study examining the neural correlates of anger in patients with PTSD. Using a data-driven approach with resting-state fMRI, we identified two prefrontal regions whose overall functional connectivity was inversely associated with anger: the left anterior middle frontal gyrus (aMFG) and the right orbitofrontal cortex (OFC). We then used concurrent TMS-EEG to target the left aMFG parcel previously identified through fMRI, measuring its cortical excitability and causal connectivity to downstream areas. We found that low-anger PTSD patients exhibited enhanced excitability in the left aMFG and enhanced causal connectivity between this region and visual areas. Together, our results suggest that left aMFG activity may confer protection against the development of anger, and therefore may be an intriguing target for circuit-based interventions for anger in PTSD.

Voxel-based morphometry and cortical thickness in combat veterans suffering from impulsive aggression

BACKGROUND

Problems with impulsive aggression occur in many forms of psychiatric dysfunction, and are a common complaint among combat veterans. The present study sought to examine the neuroanatomical correlates of combat-related impulsive aggression.

METHODS

T1-weighted magnetic resonance images were acquired from 29 male veterans with impulsive aggression and 30 non-aggressive combat controls. Subcortical volumetry was conducted with the amygdala and hippocampus and their main constituent subdivisions as regions-of-interest (ROIs) (basolateral, centromedial amygdala; head, body, tail of hippocampus). Cortical thickness measurements were extracted for the dorsolateral prefrontal cortex, orbitofrontal cortex, and anterior cingulate cortex. Within-group correlations with psychometric measures were also explored.

RESULTS

No significant group differences in cortical thickness or subcortical grey matter volumes were observed for any of the ROIs. Also, no significant correlations with any of the psychometric measures were recorded. Exploratory whole-brain analysis of cortical thickness revealed a significant group × anxiety interaction effect in a cluster located in the left lingual gyrus.

CONCLUSIONS

The current findings indicate that problems with impulsive aggression may not be directly associated with alterations in cortical thickness or amygdalar/hippocampal (sub)volumes. The observed interplay between impulsive aggression problems and anxiety-related symptoms is consistent with prior work showing the two phenomena may share the same underlying (neural) mechanisms.

White matter microstructure in schizophrenia patients with a history of violence

Schizophrenia (SCZ) is associated with increased risk of violence compared to the general population. Neuroimaging research suggests SCZ to be a disorder of disrupted connectivity, with diffusion tensor imaging (DTI) indicating white matter (WM) abnormalities. It has been hypothesized that SCZ patients with a history of violence (SCZ-V) have brain abnormalities distinguishing them from SCZ patients with no history of violence (SCZ-NV). Yet, a thorough investigation of the neurobiological underpinnings of state and trait measures of violence and aggression in SCZ derived from DTI indices is lacking. Using tract-based spatial statistics, we compared DTI-derived microstructural indices: fractional anisotropy (FA), mean, axial (AD) and radial diffusivity across the brain; (1) between SCZ-V (history of murder, attempted murder, or severe assault towards other people, n = 24), SCZ-NV (n = 52) and healthy controls (HC, n = 94), and (2) associations with current aggression scores among both SCZ groups. Then, hypothesis-driven region of interest analyses of the uncinate fasciculus and clinical characteristics including medication use were performed. SCZ-V and SCZ-NV showed decreased FA and AD in widespread regions compared to HC. There were no significant differences on any DTI-based measures between SCZ-V and SCZ-NV, and no significant associations between state or trait measures of aggression and any of the DTI metrics in the ROI analyses. The DTI-derived WM differences between SCZ and HC are in line with previous findings, but the results do not support the hypothesis of specific brain WM microstructural correlates of violence or aggression in SCZ.

Low Competitive Status Elicits Aggression in Healthy Young Men: Behavioral and Neural Evidence

Winners are commonly assumed to compete more aggressively than losers. Here, we find overwhelming evidence for the opposite. We first demonstrate that low-ranking teams commit more fouls than they receive in top-tier soccer, ice hockey, and basketball men's leagues. We replicate this effect in the laboratory, showing that male participants deliver louder sound blasts to a rival when placed in a low-status position. Using neuroimaging, we characterize brain activity patterns that encode competitive status as well as those that facilitate status-dependent aggression in healthy young men. These analyses reveal three key findings. First, anterior hippocampus and striatum contain multivariate representations of competitive status. Second, interindividual differences in status-dependent aggression are linked with a sharper status differentiation in the striatum and with greater reactivity to status-enhancing victories in the dorsal anterior cingulate cortex. Third, activity in ventromedial, ventrolateral, and dorsolateral prefrontal cortex is associated with trial-wise increases in status-dependent aggressive behavior. Taken together, our results run counter to narratives glorifying aggression in competitive situations. Rather, we show that those in the lower ranks of skill-based hierarchies are more likely to behave aggressively and identify the potential neural basis of this phenomenon.

REVERSE phenotyping-Can the phenotype following constitutive Tph2 gene inactivation in mice be transferred to children and adolescents with and without adhd?

INTRODUCTION

Experimental models of neuropsychiatric disorders, for example, ADHD, are used to mimic specific phenotypic traits of a complex human disorder. However, it remains unresolved to what extent the animal phenotype reflects the specific human trait. The null mutant mouse of the serotonin-synthesizing tryptophan hydroxylase-2 (Tph2^-/- ) gene has been proposed as experimental model for ADHD with high face validity for impulsive, aggressive, and anxious behaviors. To validate this ADHD-like model, we examined the Tph2^-/- phenotype in humans when considering allelic variation of TPH2 function ("reverse phenotyping").

METHODS

58 participants (6 females, 8-18 years) were examined, of whom 32 were diagnosed with ADHD. All participants were phenotyped for impulsivity, aggression, and anxiety using questionnaires, behavioral tests, and MRI scanning while performing the 4-choice serial reaction time task. Additionally, participants were genotyped for the TPH2 G-703T (rs4570625) polymorphism. To analyze the relation between TPH2 G-703T variants and the impulsive/aggressive/anxious phenotype, mediation analyses were performed using behavioral and MRI data as potential mediators.

RESULTS

We found that the relation between TPH2 G-703T and aggression as part of the reverse Tph2^- /^- phenotype was mediated by structure and function of the right middle and inferior frontal gyrus.

CONCLUSION

At the example of trait aggression, our results support the assumption that the Tph2 null mutant mouse reflects the TPH2 G-703T-dependent phenotype in humans. Additionally, we conclude that "reverse phenotyping" is a promising method to validate experimental models and human findings for refined analysis of disease mechanisms.

Prevalence and psychiatric comorbidities of intermittent explosive disorders in Metropolitan São Paulo, Brazil

PURPOSE

To estimate the prevalence of intermittent explosive disorder (IED) in comorbidity with other psychiatric disorders and to describe the temporal sequencing of disorders in the São Paulo Metropolitan Area, Brazil.

METHODS

Data from the São Paulo Megacity Mental Health Survey, a population-based study of 5037 adult individuals, were analyzed. The World Health Organization Composite International Diagnostic Interview (CID 3.0) was used to assess lifetime DSM-IV disorders, including IED, with a response rate of 81.3%.

RESULTS

The majority (76.8%) of respondents with IED meet the criteria for at least one other psychiatric disorder, with a prevalence almost twice as high as that observed in individuals without IED. The prevalence of any anxiety, mood, impulse control or substance use disorders in respondents with IED was more than two times higher compared to those without IED, with prevalence ratios ranging from 2.1 (95% CI 1.74-2.48) to 2.9 (95% CI 2.12-4.06). The diagnosis of IED occurred earlier than most of the other mental disorders, except for those with usual onset in early childhood, as Specific and Social Phobias and Attention Deficit Disorder.

CONCLUSION

Considering that IED is a highly comorbid disorder and has an earlier onset than most other mental comorbidities in the Brazilian general population, these results may be useful in guiding governmental mental health actions.

Neuronal responses to adverse social threat in healthy human subjects

Social-emotional information processing (SEIP) is critical for appropriate human interaction. It is composed of processes that underlie how we behave towards others, especially in response to adverse social threat. We conducted a study in 26 healthy participants who completed a validated Video-SEIP (V-SEIP) task in the fMRI scanning environment. The V-SEIP phases studied included encoding (ENC) of socially relevant information, hostile attribution (HA) of motive, and the negative emotional response (NER) the participant would have in the context of the video vignettes. The ENC phase was associated with activation of amygdala, left ventrolateral prefrontal cortex, right middle temporal gyrus, and visual cortex, the HA phase associated with activation of several brain regions including frontal and temporal cortex as well as basal ganglia and cerebellum, while the NER phase was associated with activation in the midbrain with regions involving the periaqueductal gray, basal ganglia, and the cerebellum. We suggest that this V-SEIP task represents a novel neuro-biomarker for the study of SEIP and that it can be extended for use in a number of psychiatric conditions in which anger, irritability, and impulsive aggressive are prominent features.

Neural circuits and activity dynamics underlying sex-specific effects of chronic social isolation stress

Exposure to prolonged stress in critical developmental periods induces heightened vulnerability to psychiatric disorders, which may have sex-specific consequences. Here we investigate the neuronal circuits mediating behavioral changes in mice after chronic adolescent social isolation stress. Escalated aggression is exhibited in stressed males, while social withdrawal is shown in stressed females. In vivo multichannel recordings of free-moving animals indicate that pyramidal neurons in prefrontal cortex (PFC) from stressed males exhibit the significantly decreased spike activity during aggressive attacks, while PFC pyramidal neurons from stressed females show a blunted increase of discharge rates during sociability tests. Chemogenetic and electrophysiological evidence shows that PFC hypofunctioning and BLA principal neuron hyperactivity contribute to the elevated aggression in stressed males, while PFC hypofunctioning and VTA dopamine neuron hypoactivity contribute to the diminished sociability in stressed females. These results establish a framework for understanding the circuit and physiological mechanisms underlying sex-specific divergent effects of stress.

The neurobiology of human aggressive behavior: Neuroimaging, genetic, and neurochemical aspects

In modern societies, there is a strive to improve the quality of life related to risk of crimes which inevitably requires a better understanding of brain determinants and mediators of aggression. Neurobiology provides powerful tools to achieve this end. Pre-clinical and clinical studies show that changes in regional volumes, metabolism-function and connectivity within specific neural networks are related to aggression. Subregions of prefrontal cortex, insula, amygdala, basal ganglia and hippocampus play a major role within these circuits and have been consistently implicated in biology of aggression. Genetic variations in proteins regulating the synthesis, degradation, and transport of serotonin and dopamine as well as their signal transduction have been found to mediate behavioral variability observed in aggression. Gene-gene and gene-environment interactions represent additional important risk factors for aggressiveness. Considering the social burden of pathological forms of aggression, more basic and translational studies should be conducted to accelerate applications to clinical practice, justice courts, and policy making.

The personality dispositions and resting-state neural correlates associated with aggressive children

Despite aggression being detrimental to children's physical health, mental health and social development, the dispositional and neurological antecedents of aggression in the child are poorly understood. Here we examined the relationship between trait aggression as measured by Buss and Warren's Aggression Questionnaire and personality traits measured with Big Five Questionnaire for Children in 77 primary-school children and recorded resting-state brain activity (fractional amplitude of low-frequency fluctuations [fALFF]) and resting-state functional connectivity (rsFC) using functional magnetic resonance imaging. The present results showed that trait aggression was negatively correlated with agreeableness and positively correlated with neuroticism. The brain analyses showed that children with a higher propensity for aggression had a lower fALFF mainly in the left superior temporal gyrus, right parahippocampal gyrus and left supramarginal gyrus. Physical and total aggressions were negatively associated with rsFC between the right parahippocampal gyrus and the right putamen. Further analysis revealed that this rsFC could moderate the influence of neuroticism on total aggression. Moreover, the results suggest the presence of a sex difference in the neurodevelopmental mechanisms underlying aggression in middle childhood. Overall, our findings indicate that aggressive children have lower agreeableness and higher neuroticism, and the underlying neural systems are mainly implicated in social judgment and empathy.

Change in core symptoms of borderline personality disorder by tDCS: A pilot study

Borderline personality disorder (BPD) recognizes several psychopathological dimensions related to prefrontal cortex impairments. Transcranial Direct Current Stimulation (tDCS) targeting the right prefrontal dorsolateral cortex (DLPFC) positively influence cognitive functions related to impulsivity in healthy subjects. A randomized double-blind study was designed to investigate whether tDCS could modulate core dimensions (impulsivity, aggression, affective dysregulation) of BPD. Also effects on decision making process and substances craving was assessed. Patients were randomized to receive active-tDCS at 2 mA versus sham-tDCS, once a day for 15 sessions. Anode was placed on the right DLPFC (F4), cathode on the left DLPFC (F3). Impulsivity and aggression measures were significantly reduced only in patients treated with active-tDCS. Decision-making process was marginally influenced by the active current. Craving intensity was reduced only in the active-tDCS sample. Both groups showed improvements in the affective dysregulation dimension and anxious and depressive symptoms. The application of bilateral tDCS targeting right DLPFC with anodal stimulation seems to improve core dimensions of BPD (mainly impulsivity and aggression) probably by restoring prefrontal activity. tDCS might be a potential tool for preventing self-harming behaviors.

An overlapping pattern of cerebral cortical thinning is associated with both positive symptoms and aggression in schizophrenia via the ENIGMA consortium

BACKGROUND

Positive symptoms are a useful predictor of aggression in schizophrenia. Although a similar pattern of abnormal brain structures related to both positive symptoms and aggression has been reported, this observation has not yet been confirmed in a single sample.

METHOD

To study the association between positive symptoms and aggression in schizophrenia on a neurobiological level, a prospective meta-analytic approach was employed to analyze harmonized structural neuroimaging data from 10 research centers worldwide. We analyzed brain MRI scans from 902 individuals with a primary diagnosis of schizophrenia and 952 healthy controls.

RESULTS

The result identified a widespread cortical thickness reduction in schizophrenia compared to their controls. Two separate meta-regression analyses revealed that a common pattern of reduced cortical gray matter thickness within the left lateral temporal lobe and right midcingulate cortex was significantly associated with both positive symptoms and aggression.

CONCLUSION

These findings suggested that positive symptoms such as formal thought disorder and auditory misperception, combined with cognitive impairments reflecting difficulties in deploying an adaptive control toward perceived threats, could escalate the likelihood of aggression in schizophrenia.

Stress-induced aggression in heterozygous TPH2 mutant mice is associated with alterations in serotonin turnover and expression of 5-HT6 and AMPA subunit 2A receptors

BACKGROUND

The contribution of gene-environment interactions that lead to excessive aggression is poorly understood. Environmental stressors and mutations of the gene encoding tryptophan hydroxylase-2 (TPH2) are known to influence aggression. For example, TPH2 null mutant mice (Tph2-/-) are naturally highly aggressive, while heterozygous mice (Tph2+/-) lack a behavioral phenotype and are considered endophenotypically normal. Here we sought to discover whether an environmental stressor would affect the phenotype of the genetically 'susceptible' heterozygous mice (Tph2+/-).

METHODS

Tph2+/- male mice or Tph2+/+ controls were subjected to a five-day long rat exposure stress paradigm. Brain serotonin metabolism and the expression of selected genes encoding serotonin receptors, AMPA receptors, and stress markers were studied.

RESULTS

Stressed Tph2+/- mice displayed increased levels of aggression and social dominance, whereas Tph2+/+ animals became less aggressive and less dominant. Brain tissue concentrations of serotonin, its precursor hydroxytryptophan and its metabolite 5-hydroxyindoleacetic acid were significantly altered in all groups in the prefrontal cortex, striatum, amygdala, hippocampus and dorsal raphe after stress. Compared to non-stressed animals, the concentration of 5-hydroxytryptophan was elevated in the amygdala though decreased in the other brain structures. The overexpression of the AMPA receptor subunit, GluA2, and downregulation of 5-HT6 receptor, as well as overexpression of c-fos and glycogen-synthase-kinase-3β (GSK3-β), were found in most structures of the stressed Tph2+/- mice.

LIMITATIONS

Rescue experiments would help to verify causal relationships of reported changes.

CONCLUSIONS

The interaction of a partial TPH2 gene deficit with stress results in pathological aggression and molecular changes, and suggests that the presence of genetic susceptibility can augment aggression in seemingly resistant phenotypes.

The role of monoamine oxidase A in the neurobiology of aggressive, antisocial, and violent behavior: A tale of mice and men

Over the past two decades, research has revealed that genetic factors shape the propensity for aggressive, antisocial, and violent behavior. The best-documented gene implicated in aggression is MAOA (Monoamine oxidase A), which encodes the key enzyme for the degradation of serotonin and catecholamines. Congenital MAOA deficiency, as well as low-activity MAOA variants, has been associated with a higher risk for antisocial behavior (ASB) and violence, particularly in males with a history of child maltreatment. Indeed, the interplay between low MAOA genetic variants and early-life adversity is the best-documented gene × environment (G × E) interaction in the pathophysiology of aggression and ASB. Additional evidence indicates that low MAOA activity in the brain is strongly associated with a higher propensity for aggression; furthermore, MAOA inhibition may be one of the primary mechanisms whereby prenatal smoke exposure increases the risk of ASB. Complementary to these lines of evidence, mouse models of Maoa deficiency and G × E interactions exhibit striking similarities with clinical phenotypes, proving to be valuable tools to investigate the neurobiological mechanisms underlying antisocial and aggressive behavior. Here, we provide a comprehensive overview of the current state of the knowledge on the involvement of MAOA in aggression, as defined by preclinical and clinical evidence. In particular, we show how the convergence of human and animal research is proving helpful to our understanding of how MAOA influences antisocial and violent behavior and how it may assist in the development of preventative and therapeutic strategies for aggressive manifestations.

Testosterone administration in human social neuroendocrinology: Past, present, and future

Over the past 20 years, social neuroendocrinology researchers have developed pharmacological challenge paradigms to assess the extent to which testosterone plays a causal role in human psychological and behavioural processes. The current paper provides a brief summary of this research and offers recommendations for future research examining the neuroendocrine mechanisms underlying human behaviour.

Structural and functional abnormalities within sensori-motor and limbic networks underpin intermittent explosive symptoms in Tourette disorder

BACKGROUND

Intermittent explosive outbursts (IEO), manifesting as sudden episodes of verbal or physical aggression, are frequently present in patients with Tourette disorder (TD) and considered as one of the most disabling symptoms by patients and families. The neuronal correlates of these behaviours are poorly understood, and this was the primary objective of the present study.

METHODS

We assessed the presence of IEO in 55 patients with TD and then compared the subgroup of the patients with IEO to those without these manifestations using a multimodal neuroimaging approach.

RESULTS

47% of TD patients presented IEO, which was frequently associated with attention deficit hyperactivity disorder (ADHD). TD patients (without ADHD) with IEO compared to TD without IEO, showed structural changes in the right supplementary motor area as well as in the right hippocampus (increased fractional anisotropy), and in the left orbitofrontal cortex (decreased mean diffusivity). Using these three nodes as seeds for resting state functional connectivity, we showed a lower connectivity within the sensori-motor cortico-basal ganglia network, and an altered connectivity pattern among the orbito-frontal cortex, amygdala and hippocampus.

CONCLUSIONS

Overall, our results indicate that TD with IEO is associated with brain dysfunction related to a less efficient top-down control on action selection, and impairments related to emotional regulation, impulse control and aggressive behaviours.

Gray Matter Deficits and Dysfunction in the Insula Among Individuals With Intermittent Explosive Disorder

Although numerous neuroimaging studies have evaluated the characteristics of intermittent explosive disorder (IED), studies on the structural alterations and focal dysfunction in the brain in this condition are limited. This study aimed to identify gray matter deficits and functional alterations in individuals with IED using voxel-based morphometry (VBM) and functional magnetic resonance imaging (fMRI) analyses. Fifteen men with IED and 15 age- and sex-matched healthy controls participated in this study. Gray matter volume and brain activation while viewing the anger-inducing films were measured using 7T MRI. VBM results indicated that individuals with IED had significantly reduced gray matter volume in the insula, amygdala, and orbitofrontal area, relative to controls. Gray matter volume in the left insula was negatively correlated with composite aggression scores. fMRI results demonstrated that relative to healthy controls, individuals with IED showed greater activation in the insula, putamen, anterior cingulate cortex, and amygdala during anger processing. Left insular activity was positively correlated with composite aggression scores. Collectively, these findings suggest that structural and functional alterations in the left insula are linked to IED; this provides insight into the neural mechanisms underlying IED.

Protein-protein interactions underlying the behavioral and psychological symptoms of dementia (BPSD) and Alzheimer's disease

Alzheimer’s Disease (AD) is a devastating neurodegenerative disorder currently affecting 45 million people worldwide, ranking as the 6^th highest cause of death. Throughout the development and progression of AD, over 90% of patients display behavioral and psychological symptoms of dementia (BPSD), with some of these symptoms occurring before memory deficits and therefore serving as potential early predictors of AD-related cognitive decline. However, the biochemical links between AD and BPSD are not known. In this study, we explored the molecular interactions between AD and BPSD using protein-protein interaction (PPI) networks built from OMIM (Online Mendelian Inheritance in Man) genes that were related to AD and two distinct BPSD domains, the Affective Domain and the Hyperactivity, Impulsivity, Disinhibition, and Aggression (HIDA) Domain. Our results yielded 8 unique proteins for the Affective Domain (RHOA, GRB2, PIK3R1, HSPA4, HSP90AA1, GSK3beta, PRKCZ, and FYN), 5 unique proteins for the HIDA Domain (LRP1, EGFR, YWHAB, SUMO1, and EGR1), and 6 shared proteins between both BPSD domains (APP, UBC, ELAV1, YWHAZ, YWHAE, and SRC) and AD. These proteins might suggest specific targets and pathways that are involved in the pathogenesis of these BPSD domains in AD.

Violent Behavior Is Associated With Emotion Salience Network Dysconnectivity in Schizophrenia

Background: Despite individuals with schizophrenia being at an elevated risk of violence compared to the general population, limited efforts have been invested in investigating the neurobiological etiology explaining the increase. Among the few studies examining functional disruptions pertaining to violent schizophrenia patients using fMRI, only one study has considered functional connectivity. The current state of knowledge does not allow to infer deficits in functional connectivity specific to distinct cognitive/emotional states that have been associated with the emergence of violence in schizophrenia, such as negative emotion processing. This study sought to identify disrupted connectivity among men with schizophrenia and a history of violence (SCZ+V), compared to men with schizophrenia without a history of violence (SCZ-V) and healthy controls, during negative emotion processing using fMRI. Methods: Twenty SCZ+V, 19 SCZ-V, and 21 healthy men were scanned while viewing negative images. Results: Negative images elicited an increased connectivity between the dorsal anterior cingulate cortex (dACC) and the bilateral rostral prefrontal cortex (rPFC), as well as a decreased functional connectivity between the frontal regions (bilateral rPFC and dACC) and the putamen and hippocampus in SCZ+V men as compared to SCZ-V men and healthy controls. Concurrently, the centrality of the dACC within the network was reduced in SCV+V subjects. Conclusions: These results suggest an inefficient integration of the information by the dACC between frontal and limbic regions in SCZ+V men during negative emotion processing and highlight the importance of the ACC in the neurobiological bases of violent behavior in schizophrenia.

Amygdala GluN2B-NMDAR dysfunction is critical in abnormal aggression of neurodevelopmental origin induced by St8sia2 deficiency

Aggression is frequently observed in neurodevelopmental psychiatric disorders such as schizophrenia, autism, and bipolar disorder. Due to a lack of understanding of its underlying mechanisms, effective treatments for abnormal aggression are still missing. Recently, genetic variations in Sialyltransferase 2 (St8sia2) have been linked to these disorders and aggression. Here we identify abnormal aggressive behaviors and concomitant blunted fear learning in St8sia2 knockout (-/-) mice. It is worth noting that the amygdala of St8sia2-/- mice shows diminished threat-induced activation, as well as alterations in synaptic structure and function, including impaired GluN2B-containing NMDA receptor-mediated synaptic transmission and plasticity. Pharmacological rescue of NMDA receptor activity in the amygdala of St8sia2-/- mice with the partial agonist D-cycloserine restores synaptic plasticity and normalizes behavioral aberrations. Pathological aggression and associated traits were recapitulated by specific amygdala neonatal St8sia2 silencing. Our results establish a developmental link between St8sia2 deficiency and a pathological aggression syndrome, specify synaptic targets for therapeutic developments, and highlight D-cycloserine as a plausible treatment.

Volumetric Abnormalities in Violent Schizophrenia Patients on the General Psychiatric Ward

BACKGROUND

In recent years, neuroimaging has been used increasingly to explore the biological underpinnings of violence carried out by schizophrenia patients (SPs). Studies have focused mostly on patients with a history of carrying out severe physical assaults, or comorbid with substance abuse/personality disorder (SA/PD). As a result, participants were unrepresentative and the interpretation of brain-structure changes was confusing. Here, we concentrated on SPs on a general psychiatric ward with a history of relatively lower violence, and individuals comorbid with SA or PD were excluded. We expected to identify the characteristics of brain morphometry in this population, and to explore whether the morphometric changes were universal.

METHODS

Forty-eight violent schizophrenia patients (VSPs), twenty-seven non-VSPs (nVSPs) and 28 nonviolent healthy controls (HCs) were investigated. Voxel-based morphometry was used to evaluate the gray matter volume (GMV) of all study participants. Whole-brain analyses were used to reveal group effects and differences between any two groups. Correlation analyses were undertaken between significant brain regions and behavioral measurements in the VSP group.

RESULTS

Patients showed a significantly smaller GMV in widespread frontal, temporal, and limbic regions compared with HCs. No region was found in which the two patient groups had significantly larger volumes compared with that in HCs. A significant decrease in the GMV of the right fusiform gyrus was found in the VSP group compared with that in the nVSP group (p = 0.004), where the GMV of this region had a negative correlation with the Physical Aggression [subscale of the Modified Overt Aggression Scale (MOAS)] or Hostility score. The VSP group showed a trend of GMV decrease in the left middle temporal cortex compared with that in the nVSP group (p = 0.077). Negative correlation was also found between the GMV of left inferior temporal gyrus/left Superior frontal gyrus, medial and the Hostility score.

CONCLUSIONS

Our results provide initial evidence demonstrating the generalizability of GMV abnormalities in SPs engaged in varying levels of violence, even when SA or PD have not been implicated. GMV reduction was correlated with only the Physical Aggression subscale score of the MOAS, suggesting that this change in brain morphology may be dependent upon different types of violent actions.

Reduced Amygdala-Prefrontal Functional Connectivity in Children With Autism Spectrum Disorder and Co-occurring Disruptive Behavior

BACKGROUND

Disruptive behaviors are prevalent in children with autism spectrum disorder (ASD) and often cause substantial impairments. However, the underlying neural mechanisms of disruptive behaviors remain poorly understood in ASD. In children without ASD, disruptive behavior is associated with amygdala hyperactivity and reduced connectivity with the ventrolateral prefrontal cortex (vlPFC). This study examined amygdala reactivity and connectivity in children with ASD with and without co-occurring disruptive behavior disorders. We also investigated differential contributions of externalizing behaviors and callous-unemotional traits to variance in amygdala connectivity and reactivity.

METHODS

This cross-sectional study involved behavioral assessments and neuroimaging in three groups of children 8 to 16 years of age: 18 children had ASD and disruptive behavior, 20 children had ASD without disruptive behavior, and 19 children were typically developing control participants matched for age, gender, and IQ. During functional magnetic resonance imaging, participants completed an emotion perception task of fearful versus calm faces. Task-specific changes in amygdala reactivity and connectivity were examined using whole-brain, psychophysiological interaction, and multiple regression analyses.

RESULTS

Children with ASD and disruptive behavior showed reduced amygdala-vlPFC connectivity compared with children with ASD without disruptive behavior. Externalizing behaviors and callous-unemotional traits were associated with amygdala reactivity to fearful faces in children with ASD after controlling for suppressor effects.

CONCLUSIONS

Reduced amygdala-vlPFC connectivity during fear processing may differentiate children with ASD and disruptive behavior from children with ASD without disruptive behavior. The presence of callous-unemotional traits may have implications for identifying differential patterns of amygdala activity associated with increased risk of aggression in ASD. These findings suggest a neural mechanism of emotion dysregulation associated with disruptive behavior in children with ASD.

Understanding Chronic Aggression and Its Treatment in Children and Adolescents

PURPOSE OF REVIEW

Youth aggression is common and has a significant burden on individuals, families, and society. However, its treatment is often a challenge for clinicians. Thus, this review will examine the current understanding of youth aggression, conceptualize aggression as a symptom rather than its own disorder, and provide an overview of treatment strategies.

RECENT FINDINGS

Youth aggression is associated with complex genetic, neurobiological, and environmental risks. Prevention strategies are of the utmost importance for at-risk families and youth. Psychosocial interventions are the first line treatment. But if not fully effective, then pharmacologic interventions-including psychostimulants, alpha-2 agonists, atomoxetine, and risperidone-have shown benefits. Other medications, such as SSRIs, can be useful in certain scenarios. It is important to conceptualize youth aggression as being a trans-diagnostic symptom in psychopathology. Determining the underlying cause of aggression will help to guide treatment.

An investigation of the relationship between psychopathy and greater gray matter density in lateral prefrontal cortex

Psychopathic traits predispose individuals toward antisocial behavior. Such antagonistic acts often result in "unsuccessful" outcomes such as incarceration. What mechanisms allow some people with relatively high levels of psychopathic traits to live "successful", unincarcerated lives, in spite of their antisocial tendencies? Using neuroimaging, we investigated the possibility that "successful" psychopathic individuals exhibited greater development of neural structures that promote "successful" self-regulation, focusing on the ventrolateral prefrontal cortex (VLPFC). Across two structural magnetic resonance imaging studies of "successful" participants (Study 1: N = 80 individuals in long-term romantic relationships; Study 2: N = 64 undergraduates), we observed that gray matter density in the left and right VLPFC was positively associated with psychopathic traits. These preliminary results support a compensatory model of psychopathy, in which "successful" psychopathic individuals develop inhibitory mechanisms to compensate for their antisocial tendencies. Traditional models of psychopathy that emphasize deficits may be aided by such compensatory models that identify surfeits in neural and psychological processes.

The Hyperactivity-Impulsivity-Irritiability-Disinhibition-Aggression-Agitation Domain in Alzheimer's Disease: Current Management and Future Directions

Behavioral and psychological symptoms of dementia (BPSD) afflict the vast majority of patients with dementia, especially those with Alzheimer's disease (AD). In clinical settings, patients with BPSD most often do not present with just one symptom. Rather, clusters of symptoms commonly co-occur and can, thus, be grouped into behavioral domains that may ultimately be the result of disruptions in overarching neural circuits. One major BPSD domain routinely identified across patients with AD is the hyperactivity-impulsivity-irritiability-disinhibition-aggression-agitation (HIDA) domain. The HIDA domain represents one of the most difficult sets of symptoms to manage in AD and accounts for much of the burden for caregivers and hospital staff. Although many studies recommend non-pharmacological treatments for HIDA domain symptoms as first-line, they demonstrate little consensus as to what these treatments should be and are often difficult to implement clinically. Certain symptoms within the HIDA domain also do not respond adequately to these treatments, putting patients at risk and necessitating adjunct pharmacological intervention. In this review, we summarize the current literature regarding non-pharmacological and pharmacological interventions for the HIDA domain and provide suggestions for improving treatment. As epigenetic changes due to both aging and AD cause dysfunction in drug-targeted receptors, we propose that HIDA domain treatments could be enhanced by adjunct strategies that modify these epigenetic alterations and, thus, increase efficacy and reduce side effects. To improve the implementation of non-pharmacological approaches in clinical settings, we suggest that issues regarding inadequate resources and guidance for implementation should be addressed. Finally, we propose that increased monitoring of symptom and treatment progression via novel sensor technology and the "DICE" (describe, investigate, create, and evaluate) approach may enhance both pharmacological and non-pharmacological interventions for the HIDA domain.

Amygdala Resting State Connectivity Differences between Bipolar II and Borderline Personality Disorders

BACKGROUND

Borderline personality disorder (BPD) and bipolar II disorder (BD II) have significant clinical overlap, leaving the potential for diagnostic inaccuracies and inadequate treatment recommendations. However, few studies have probed for clinical and neurobiological differences between the two disorders. Clinically, some prior studies have linked BPD with greater impulsivity and more frequent negative affective shifts than BD II, whereas previous neuroimaging studies have highlighted both similar and distinct neural abnormalities in BPD and BD II. Notably, no prior study has specifically targeted cortico-limbic neural differences, which have been hypothesized to underlie these core clinical differences.

METHODS

Individuals with BPD (n = 14) and BD II (n = 15) completed various clinical measures and a resting state functional imaging scan at 3T. Whole-brain amygdala resting state functional connectivity (RSFC) was compared between the two groups.

RESULTS

Relative to the BD II group, BPD participants reported significantly higher levels of impulsivity, trait anxiety, more frequent negative affective shifts, greater interpersonally reactive affective instability, lower overall functioning, and were characterized by lower amygdala-middle frontal gyrus RSFC. Lower amygdala-middle frontal gyrus RSFC was associated with greater impulsivity, trait anxiety, affective shifts, interpersonal affective reactivity, and functional impairment.

LIMITATIONS

The current study consisted of small sample sizes and lacked a control group.

CONCLUSIONS

This preliminary study suggests that amygdala-frontal RSFC may distinguish BPD from BD II. These results may guide future work aimed at identifying neural markers that can help disentangle these two disorders, leading to greater diagnostic accuracy and appropriate treatment implementation.

Schizophrenia and bipolar disorders: The Toxoplasma connection

The infectious etiology of psychiatric illnesses has remained an unexplored area till recently. During the past two decades, numerous studies from multiple angles have tried to link chronic toxoplasmosis with schizophrenia and bipolar disorders, among others. Most of the evidence has come from serological studies in the patient population, but other facets have also been explored. This review examines the various areas from which a causal link has been deduced and includes: (a) serological studies, (b) effect of maternal toxoplasmosis on children, (c) neurotransmitter studies, (d) parasite localization in the brain, (e) role of cytokines, and (f) psychotherapy and its effect on Toxoplasma. However, multiple factors may play a role in the etiopathogenesis of psychiatric illnesses, and chronic Toxoplasma infection may be considered an important risk factor for the genesis and symptomatology of schizophrenia and bipolar disorders.

Neural correlates of early deliberate emotion regulation: Young children's responses to interpersonal scaffolding

Deliberate emotion regulation, the ability to willfully modulate emotional experiences, is shaped through interpersonal scaffolding and forecasts later functioning in multiple domains. However, nascent deliberate emotion regulation in early childhood is poorly understood due to a paucity of studies that simulate interpersonal scaffolding of this skill and measure its occurrence in multiple modalities. Our goal was to identify neural and behavioral components of early deliberate emotion regulation to identify patterns of competent and deficient responses. A novel probe was developed to assess deliberate emotion regulation in young children. Sixty children (age 4-6 years) were randomly assigned to deliberate emotion regulation or control conditions. Children completed a frustration task while lateral prefrontal cortex (LPFC) activation was recorded via functional near-infrared spectroscopy (fNIRS). Facial expressions were video recorded and children self-rated their emotions. Parents rated their child's temperamental emotion regulation. Deliberate emotion regulation interpersonal scaffolding predicted a significant increase in frustration-related LPFC activation not seen in controls. Better temperamental emotion regulation predicted larger LPFC activation increases post- scaffolding among children who engaged in deliberate emotion regulation interpersonal scaffolding. A capacity to increase LPFC activation in response to interpersonal scaffolding may be a crucial neural correlate of early deliberate emotion regulation.

Inferior frontal gyrus gray matter volume is associated with aggressive behavior in schizophrenia spectrum disorders

We aimed to assess potential gray matter (GM) alterations for aggressive patterns of behavior in a sample of in- and outpatients with schizophrenia spectrum disorders. Eighty-four patients previously participating in brain volumetric studies were included. Aggression was assessed using the Modified Overt Aggression Scales (MOAS) based upon review of clinical records of the hospital register. Multiple regression analyses for total MOAS and each MOAS subscale separately were conducted correcting for age, sex, history of addiction, chlorpromazine equivalents, illness duration, and total intracranial volume. Significant effects were reported in two cases; the total MOAS scores and MOAS verbal aggression scores were associated with GM volume in left inferior frontal gyrus. From the demographic/clinical characteristics, only the number of episodes correlated with the subscales and the total MOAS scores. Our results highlight the role of GM volume in left inferior frontal gyri in patients with history of aggression. This evidence ties in well with previous data reporting involvement of these regions in response control and semantic networks.

Trait and state patterns of basolateral amygdala connectivity at rest are related to endogenous testosterone and aggression in healthy young women

The steroid hormone testosterone (T) has been suggested to influence reactive aggression upon its action on the basolateral amygdala (BLA), a key brain region for threat detection. However, it is unclear whether T modulates resting-state functional connectivity (rsFC) of the BLA, and whether this predicts subsequent aggressive behavior. Aggressive interactions themselves, which often induce changes in T concentrations, could further alter BLA rsFC, but this too remains untested. Here we investigated the effect of endogenous T on rsFC of the BLA at baseline as well as after an aggressive encounter, and whether this was related to behavioral aggression in healthy young women (n = 39). Pre-scan T was negatively correlated with basal rsFC between BLA and left superior temporal gyrus (STG; p < .001, p < .05 Family-Wise Error [FWE] cluster-level corrected), which in turn was associated with increased aggression (r = .37, p = .020). BLA-STG coupling at rest might thus underlie hostile readiness in low-T women. In addition, connectivity between the BLA and the right superior parietal lobule (SPL), a brain region involved in higher-order perceptual processes, was reduced in aggressive participants (p < .001, p < .05 FWE cluster-level corrected). On the other hand, post-task increases in rsFC between BLA and medial orbitofrontal cortex (mOFC) were linked to reduced aggression (r = -.36, p = .023), consistent with the established notion that the mOFC regulates amygdala activity in order to curb aggressive impulses. Finally, competition-induced changes in T were associated with increased coupling between the BLA and the right lateral OFC (p < .001, p < .05 FWE cluster-level corrected), but this effect was unrelated to aggression. We thus identified connectivity patterns that prospectively predict aggression in women, and showed how aggressive interactions in turn impact these neural systems.