Regulating violence: response inhibition is differentially related to instrumental and reactive aggression

Abstract

Response inhibition is the termination or prevention of impulsive motor responses. Impaired response inhibition has been primarily related to disorders with pronounced impulsivity. The current review proposes that response inhibition performance is also central to the symptomatology of aggressive disorders. Importantly, it is proposed that response inhibition performance is related to increased instrumental aggression (or goal-directed aggression), but decreased reactive aggression (or aggression in response to frustration/threat). This is because response inhibition is implicated in emotional and behavioral regulation. Reactive aggression is related to impaired emotional and behavioral regulation, while instrumental aggression requires strong emotional and behavioral regulation. The purpose of this review is to explore this hypothesis by focusing on the relationship of response inhibition with disorders related to of impulsivity and aggression. Strong evidence in favor of the hypothesized relationship will be presented by focusing on studies showing that aggressive disorders hallmarked by instrumental aggression are related to improved response inhibition, while disorders with pronounced reactive aggression are related to impaired response inhibition. Furthermore, the current review aims to explore possible neurobiological mechanisms underlying this relationship. Recently the dual-hormone serotonergic (DHS) hypothesis of aggression has been proposed. This states that high testosterone/cortisol ratios predispose to increased general aggression, after which 5-HT (or serotonin) levels affect the balance between instrumental and reactive aggression by mediating impulsivity. The current review will propose that response inhibition mediates the relationship of 5-HT with instrumental and reactive aggression.