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Researchers Explore the Brain for Clues to the Causes of Anti-Social Behavior

Is antisocial behavior rooted in genetics or is it something that is acquired? Answers to this perennial debate could do much to help shape interventions that mitigate or prevent such activities.

Researchers tried to shed light rather than heat on these issues at the AAAS Annual Meeting. While adding more pieces to the puzzle of understanding antisocial and criminal behavior on a population basis, they acknowledged that the picture is far less clear when one steps down a level to try to predict individual behavior.

“Brain differences are important in explaining why men commit more crimes than women,” said Adrian Raine a criminologist at the University of Pennsylvania, whose research focuses on the brain. He has identified several factors that are associated with increased likelihood of antisocial behavior.

The orbital frontal cortex in the brain regulates emotion. On average, women have a greater volume in this part of the brain than do than men, and persons of both sexes with a proportionately smaller volume in this area are more antisocial, he said.   

Emotion is thought to reside in the limbic system, the oldest, most primitive reptilian part of the brain. Raine has identified a marker [cavum septum pellucidum (CSP)] for maldevelopment of this region that occurs within the first six months of life.

“The seeds of sin are sown quite early on in life,” Raine offered. “Individuals with this neural abnormality are more psychopathic, they are more antisocial, they commit more crimes than individuals who lack this limbic abnormality.”   

What distinguishes psychopaths is that they “lack emotion, they lack remorse, fear, guilt. This is partly explained by a volume reduction in the amygdala, the seat of emotion in the [limbic portion of the] brain.” Raine has found an 18% reduction in the volume of the amygdala in adult psychopaths.

He has teased out another piece of evidence from a large and ongoing study that evaluated fear conditioning—the fear of impending punishment learned through negative experiences—in 1800 three-year-old children and followed them for 20 years. “We found that children with poor fear conditioning, or poor amygdala function at age 3, were much more likely to become criminal offenders 20 years later.”

For Raine, the breadth of these findings raises a question: “If the psychopath has an amygdala which is shrunken by 18%, which is functioning more poorly when they are making moral decisions, then how just is it for us to punish psychopaths as harshly as we do in the criminal justice system?”

Turning to spouse-abusers, Raine devised an experiment that showed them emotionally provocative images while scanning their brains (functional magnetic resonance imaging). He found much greater activation in the amygdala compared to normal persons.

“These spouse abusers, because their brains are wired up a little bit differently than the rest of us, they overly respond to mildly emotionally provocative stimuli, which could come from the spouse, the children, or further elements within the family.” He said that is not an excuse for their activity but it does help to better understand the nature of domestic violence.

White-collar criminals also have fallen under his gaze. In a study that has not yet been published, Raine compared these corporate felons with carefully matched control subjects. He found a handful of different measures by which these offenders “have biological brain advantages which give them a heads-up in perpetrating white collar criminal offenses.”

Nathalie M.G. Fontaine, an assistant professor of criminal justice at Indiana University-Bloomington, said 5-10% of children experience early-onset and persistent antisocial behavior. It is the most common reason why they are referred to mental health services.

Callous-unemotional (CU) traits—lack of emotion, guilt, and empathy—are factors associated with persistent antisocial behavior and potential risk for adult psychopathy. Her research team tracked and evaluated data on 9578 twins that was gathered in a family setting at age 4, as well as records of conduct problems in school settings at ages 7, 9, and 12. They also evaluated genetic factors associated with antisocial behavior.

She identified “early factors, at four years old, that could predict different pathways of these traits between 7 and 12. And then outcomes or potential consequences.”

High levels of CU traits invariably played out through conduct problems, and were associated with specific genetic factors. That was particularly for boys but less so for girls, suggesting that females are more reliant upon environmental rather than genetic factors to shape their social behavior. The reverse was not necessarily true; children with conduct problems did not necessarily possess CU traits. This suggests that there are alternative risk pathways to conduct problems.

Both researchers emphasized that their work only has validity at the group level. Applying it to individuals to predict who will or will not develop antisocial behavior is inexact and risky at this point.

“We can’t take individual markers…to really accurately predict in the future who is going to become a criminal offender and who is not,” said Raine. “There are enormous false positives” where an individual is wrongly labeled one way or the other. However, he believes markers such as these might become sufficiently better refined in the future to be able to use them predictively with individuals.

What is to be done with persons, particularly children, in which abnormal development in the amygdala is detected? Should they be prophylactically incarcerated to protect society? Few are suggesting that course of action. But there are attempts to modulate genetic and physical risk factors for antisocial behavior through environmental and other interventions.

Fontaine said her goal is to be able to identify children at risk “early enough so that we could help them as well as their families.” She believes intervention needs to be tailored to the individual. In some instances, punishment of bad behavior might be an effective tool but in others it might be more useful to reward or reinforce good behavior.

Raine is involved with a study using the supplement omega-3 fatty acid. Work in animals has shown that supplementation results in improved growth of brain cells. Two published randomized control studies have found that giving omega-3 to prisoners reduced serious offending in prison by 30-46%. He is conducting a similar study in 11 and 12-year-old children with aggressive behavior to see if it might reduce that behavior, and hopefully identify what areas of the brain might be affected by use of the supplement.



Bob Roehr

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