The noradrenergic system and its involvement in aggressive behaviors

Although a multitude of variables are associated with the expression of aggression, it is imperative that accurate neurochemical vulnerabilities be understood. Norepinephrine is one neurochemical that has been linked to aggressive behavior displayed by nonhuman and human animals. The purpose of the present review was to interpret research findings regarding this relationship. The authors evaluated previous research in order to determine whether a reliable connection between norepinephrine and aggressive behavior exists. Moreover, the potential nature of the norepinephrine–aggressive behavior relationship is presented. In general, research has found a positive relationship between levels of norepinephrine and aggressive behavior among nonhuman animals and humans. However, multiple studies reporting contradictory results were also reviewed that suggest a nonlinear relationship. Norepinephrine's relationship with aggressive behavior may best be explained in terms of the stress–response system and the type of aggressive behavior elicited. Limitations of the previous studies and ideas for future research are discussed.