Neural mechanisms of anger regulation as a function of genetic risk for violence.

Genetic risk may predispose individuals to compromised anger regulation, potentially through modulation of brain responses to emotionally evocative stimuli. Emphatically expressed, the emotional word No can prohibit behavior through conditioning. In a recent functional magnetic resonance imaging study, the authors showed that healthy males attribute negative valence to No while showing a lateral orbitofrontal response that correlated with their self-reported anger control. Here, the authors examined the influence of the monoamine oxidase A (MAOA) gene (low vs. high transcription variants) on brain response to No and in relationship to trait anger reactivity and control. The orbitofrontal response did not differ as a function of the genotype. Instead, carriers of the low-MAOA genotype had reduced left middle frontal gyrus activation to No compared with the high variant. Furthermore, only for carriers of the up low-MAOA genotype, left amygdala and posterior thalamic activation to No increased with anger reactivity. Thus, vulnerability to aggression in carriers of the low-MAOA genotype is supported by decreased middle frontal response to No and the unique amygdala/thalamus association pattern in this group with anger reactivity but not anger control.