Unusually aggressive youth may actually enjoy inflicting pain on others, research using brain scans at the University of Chicago shows released on Friday showed.
Scans of the aggressive youth's brains showed that an area that is associated with rewards was highlighted when the youth watched a video clip of someone inflicting pain on another person. Youth without the unusually aggressive behavior did not have that response.
"This is the first time that fMRI scans have been used to study situations that could otherwise provoke empathy," said lead researcher Jean Decety. "This work will help us better understand ways to work with juveniles inclined to aggression and violence."
The new research shows that some aggressive youths' natural empathetic impulse may be disrupted in ways that increase aggression. The results are reported in the current issue of the journal Biological Psychology.
In the study, the researchers compared eight 16 to 18-year-old boys with aggressive conduct disorder to a control group of adolescent boys with no unusual signs of aggression. The boys 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.
"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," Decety said.
"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," he said. Unlike the control group, the youth with conduct disorder did not activate the area of the brain involved in self-regulation.