Some scholars have proposed that lack of empathy and empathic concern (callous disregard for the welfare of others) is an important risk factor for conduct disorder.
Developmental psychologists and social neuroscientists have hypothesized that empathy and sympathetic concern for others are essential factors inhibiting aggression toward others. The propensity for aggressive behavior has been hypothesized to reflect a blunted empathic response to the suffering of others. Such a lack of empathy in aggressive individuals may be a consequence of a failure to be aroused by the distress of others. Similarly, it has been suggested that aggressive behavior arises from abnormal processing of affective information, resulting in a deficiency in experiencing fear, empathy, and guilt, which in normally developing individuals inhibits the acting out of violent impulses.
Recently, a functional magnetic resonance imaging (fMRI) study conducted by neuroscientist Jean Decety and colleagues at the University of Chicago reported that youth with aggressive conduct disorder (who have psychopathic tendencies) have a different hemodynamic brain response when confronted with empathy-eliciting stimuli. In the study, researchers compared 16- to 18-year-old boys with aggressive conduct disorder to a control group of adolescent boys with no unusual signs of aggression. The youth with the conduct disorder had exhibited disruptive behavior such as starting a fight, using a weapon and stealing after confronting a victim. The youth were tested with fMRI while looking at video clips in which people endured pain accidentally, such as when a heavy bowl was dropped on their hands, and intentionally, such as when a person stepped on another's foot. Results show that the aggressive youth activated the neural circuits underpinning pain processing to the same extent, and in some cases, even more so than the control participants without conduct disorder. However, aggressive adolescents showed a specific and very strong activation of the amygdala and ventral striatum (an area that responds to feeling rewarded) when watching pain inflicted on others, which suggested that they enjoyed watching pain. Unlike the control group, the youth with conduct disorder did not activate the areas of the brain involved in understanding social interaction and moral reasoning (i.e., the paracingulate cortex and temporoparietal junction).