Social and neural determinants of aggressive behavior: pharmacotherapeutic targets at serotonin, dopamine and gamma-aminobutyric acid systems.

Aggressive outbursts that result in harm and injury present a major problem for the public health and criminal justice systems, but there are no adequate treatment options. Obstacles at the level of social policy, institutional regulation, and scientific strategy in developing animal models continue to impede the development of specific anti-aggressive agents for emergency and long-term treatments. To be more relevant to the clinical situation, preclinical aggression research has begun to focus on the neurobiological determinants of escalated aggressive behavior that exceeds species-typical patterns. It is the goal of this review to examine novel pharmacological and molecular tools that target the neural mechanisms for different kinds of aggressive behavior more selectively than previously possible and to outline potential pharmacotherapeutic options. (1) The preclinical focus on the behavioral characteristics and determinants of intense aggression promises to be most relevant to the clinical distinction between the proposed impulsive-reactive-hostile-affective subtypes of human aggression and the controlled-proactive-instrumental-predatory subtypes of aggression. The neural circuits for many types of human and animal aggression critically involve serotonin, dopamine and gamma-aminobutyric acid (GABA) and specific receptor subtypes. (2) The dynamic changes in frontal cortical serotonin that are triggered by engaging in aggressive behavior imply that serotonergic drug effects are largely determined by the functional state of the receptors at the time of drug treatment. Of the numerous 5-HT receptors currently identified, the 5-HT(1B) receptors offer a promising target for reducing impulsive aggressive behavior, particularly if the action can be limited to sites in the central nervous system. (3) Aggressive confrontations are salient stressors, both for the aggressor as well as the victim of aggression, that are accompanied by activation of the mesocorticolimbic but not the striatal dopamine system. Dopaminergic manipulations, particularly targeting the D(2) receptor family, can influence aggressive behavior in animals and human patients, suggesting that mesocorticolimbic dopamine may have important enabling or permissive functions. (4) GABA is critical in the neurochemical control of aggressive behavior as evidenced by studies that directly modify GABAergic neurotransmission and neurochemical studies that correlate GABA measurements with aggressive behavioral responses in several animal species. The GABA(A) receptor complex is a mechanism through which certain benzodiazepines and alcohol enhance and inhibit aggressive behaviors. Social and pharmacological experiences decisively determine the effects of GABAergic positive modulators on aggression.