Testosterone, cortisol, and serotonin as key regulators of social aggression: A review and theoretical perspective

In human and non-human animals the steroid hormones cortisol and testosterone are involved in social aggression and recent
studies suggest that these steroids might jointly regulate this behavior. It has been hypothesized that the imbalance between
cortisol and testosterone levels is predictive for aggressive psychopathology, with high testosterone to cortisol ratio predisposing
to a socially aggressive behavioral style. In this review, we focus on the effects of cortisol and testosterone on human social
aggression, as well as on how they might modulate the aggression circuitry of the human brain. Recently, serotonin is hypothesized
to differentiate between impulsive and instrumental aggression, and we will briefly review evidence on this hypothesis. The
aim of this article is to provide a theoretical framework for the role of steroids and serotonin in impulsive social aggression
in humans.