June 20, 2013 – Young people with conduct problems and psychopathic traits such as callousness and remorselessness show less activity in the regions of the brain associated with empathy, according to a new study led by a Georgetown psychology professor.
Abigail Marsh, working with colleagues from the National Institutes of Health, the Center for Disease Control and Prevention and three other academics, recently published her research in the Journal of Child Psychology and Psychiatry.
Violence Not Inevitable
The researchers used functional MRI to measure brain activity in adolescents with psychopathic traits as well as conduct disorder or oppositional defiant disorder and then compared the results with that of a control group of the same age.
The study showed that regions in the brain associated with empathic pain responses – the amygdala and a part of the anterior cingulate cortex – were less active in the adolescents with psychopathic traits and conduct problems when they observed photos of people with pain-inducing injuries.
“Some kinds of violent behavior result from symptoms of mental illness,” the professor notes. “And these problems deserve treatment like any other mental illness. If we can start to understand the brain processes that underlie violent behavior we may one day be able to prevent a lot of suffering.”
More Than Symptoms
Her next research project hopes to disambiguate the groups of young people with different kinds of aggression issues.
“One of the problems right now is that that they all get lumped together as conduct disorder or oppositional defiant disorder,” Marsh says. “But those diagnoses are just lists of behaviors – that doesn’t tell us much about what’s going on psychologically. Among kids who have conduct problems, some of them have too little responsiveness in regions such as the amygdala and others have too much and it seems to lead to different patterns of aggression.”
She says that in young people who have too little emotional activity, the low amygdala response may be what underlies what’s called proactive aggression, or aggression aimed at achieving a goal.
“That is really consistent with what we see in people with low empathy,” she says. “And that’s in contrast to reactive aggression, which produces big emotional outbursts but is not closely linked to low empathy.”
A number of factors influenced Marsh’s research interests and eventually led to her obtaining a Ph.D. in psychology from Harvard.
When she was only 20, a stranger saved her life after a freeway accident in her hometown of Tacoma, Washington. Three years later, on New Year’s Eve in Las Vegas, a stranger punched her in the face and broke her nose, an experience she described in a 2012 article in Slate.
“I was thrown by the incident, because you’d like to think that there are not that many people in the world who would do that,” she says. “But then you literally have come face-to-face with someone who does and have to rethink assumptions. I think my interest in understanding the roots of aggression owes a lot to that encounter.”
In her Slate article, she also wrote about a man who had rage attacks but was later found to have a tumor pressing on his hypothalamus, a part of the brain known to be involved in aggression.
When the tumor was removed, the rage attacks stopped.
“That’s very clear, right? It was the tumor, not the man,” she says. “But then you have this really interesting question about people who maybe have genetic problems that lead to dysfunction in these same structures. And it creates this very blurry line between blame and blamelessness for aggression. It’s a puzzle.”
It’s a conundrum that Marsh hopes to one day help unravel.
“I will continue to use brain imaging, genetic and behavioral research paradigms in healthy adults and adolescents as well as adolescents with conduct problems to try to understand the origins of empathy, aggression, and altruism,” she explains.