The available literature suggests that deficient serotonergic activity in emotion regulation circuitry may be an important predisposing factor to impulsive aggression. In addition, serotonergic hypofunction may contribute to the hyperactivity of the dopaminergic system further promoting impulsive and aggressive behaviors. Since serotonin hypofunction in impulsive aggression has been reported often across the literature and has a heritable foundation, serotonin hypofunction may be a neurochemical vulnerability marker of impulsive aggression. Given the modulation of the serotonin system over dopaminergic activity, dopamine hyperactivity may secondarily contribute to impulsive aggression. Understanding the neural mechanisms of impulsive aggression and the identification of risk factors will advance the understanding of complex brain-behavior relations and provide insight into the etiology of impulsive aggression. This will help develop effective treatment strategies across impulsive aggression and its comorbid disorders. Impulsive aggression is a behavioral disposition characterized by the inability to regulate negative affect and impulses to harm oneself or others. Although the relationship between serotonin hypofunction and impulsive aggression is a consistent finding in clinical neuroscience, there are only a few studies that have examined the interaction between serotonergic and dopaminergic systems in individuals with impulsive aggression. References