Neurobiology of Aggression and Violence

Abstract

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.Human aggression and violence are, unfortunately, ubiquitous phenomena with substantial costs to our society. The detrimental effects of aggression and violence are documented daily in the media. Aggression-defined as hostile, injurious, or destructive behavior often caused by frustration-can be collective or individual. The mental health professional is often called upon to evaluate pathological forms of individual aggression in the clinical, forensic, and school setting, yet the causes and treatment of pathological aggression and violence are poorly understood and understudied (1). While the underpinnings of human aggression are clearly multifactorial, including political, socioeconomic, cultural, medical, and psychological factors, it is also clear that some forms of pathological aggression, such as impulsive aggression (which occurs in the context of emotional arousal and provocation), have an underlying neurobiology that we are only beginning to understand. In this overview, after defining aggression, its prevalence, and its phenomenology, we will address the neurobiology of aggression, particularly pathological forms of impulsive aggression, by discussing the circuitry, both cortical and subcortical, as well as the role of neuromodulators in the initiation and suppression of aggression.Address correspondence and reprint requests to Dr. Siever, Department of Psychiatry (OOMH), 130 West Kingsbridge Rd., Bronx, NY 10468; Larry.Siever@va.gov. Dr. Siever reports no competing interests. NIH Public Access Definitions of AggressionAggression may be classified in a number of ways, for example, by the target of aggression (e.g., self-directed or other-directed), mode of aggression (e.g., physical or verbal, direct ...

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