Rebellious Teen? A Brain Area May Hold the Key New research says the size of a key brain area may play a part in aggression.

Feb. 25, 2008 -- For many parents, raising a teen is an exercise in conflict management. And besides the usual battles over curfews, clothing choices and academic performance, some teens seem to seek out conflict with their parents more often than others.

For decades, researchers have tried to unravel the secrets behind parent-teen conflict. Now, child development experts are scrutinizing a new study that suggests the size of small, almond shaped structures in the center of the brain known as the amygdalae may hold the key to how aggressive teens behave toward their parents.

Scientists have already known that this area of the brain is heavily involved in emotional responses, and previous research has linked it to the fight-or-flight behaviors that typify our bodies' responses to emergency situations.

But researchers at the University of Melbourne's Orygen Research Center in Australia report that these areas of the brain may have a special link when it comes to teens who regularly fight with their parents.

The researchers looked at 137 teens and their parents who participated in a problem-solving task that was designed to cause conflict. After measuring the degree of fighting the teens experienced with their parents, the researchers had the adolescent volunteers undergo MRI brain scans to measure the size of their amygdalae.

What they found was that the larger their amygdalae, the more likely the kids were to fight with their folks.

"One of the things we found in our study was the children whose amygdalae were larger were more likely to spend a longer amount time being aggressive or angry with their parents during an interaction, so there was a relation to size of the amygdalae and how angry or aggressive the child was during the interaction," says lead study author Nick Allen, associate professor at the University of Melbourne's School of Behavioral Science.

Tiny Brain Structures Not the Big Picture

But the findings, which were released Monday in the journal Proceedings of the National Academy of Sciences, are already brewing debate among child development experts.

In particular, some are concerned that the research could lead to a conclusion that it is the large amygdalae of aggressive teens that necessarily fuels conflict, when a number of other biological and social factors may be to blame.

"The problem with this kind of research is that it is correlational and only demonstrates an association," says Merritt Schreiber of the UCLA National Center for Child Traumatic Stress.

"Even though not explicitly said, the underlying tendency is to assume this means causation -- in other words, that the structural changes cause aggression."

Others agree. "It says nothing about cause at all or interaction among factors leading to the results, which is likely extremely complex," says Daniel Kupper, assistant clinical professor of psychology and psychiatry at UCLA. "I'm not even certain there is much agreement as to what the size of the amygdala indicates, or how good the data is on normal amygdala size in adolescence."

Still, some child development experts say that the findings make sense, given what's already known about the amygdala.

"Amygdala overfunction creates a propensity to overreact to ... stressors and difficulty in disengaging in conflicts," says Kendall Johnson, a clinician in private practice in California and author of the books "Trauma in the Lives of Children" and "Dealing with Classroom Crisis."

"Like firefighters rushing into a burning building while the rest of us run out, teens with biologically based overreactivity tend to be attracted to conflict, exacerbate it, and not be able to think their way out of it," Johnson says. "Parents can learn to understand their children's violent behavior as a symptom of an underlying dysfunction rather than a sign of poor character or an indictment of bad parenting."

But Schreiber remains concerned that focusing too much on the size of one particular brain structure -- and not enough on a multitude of other biological and social factors -- would be tantamount to ignoring 40 years of research on other factors that could contribute to teen aggression. These factors, he says, include parenting practices and media influences.

Dr. Barbara Korsch, professor of pediatrics at the Keck School of Medicine of the University of Southern California, says ignoring these past findings could misdirect parents in dealing with their teens' problems with aggression.

"More and more malfunction is being attributed to ill-understood deviations in morphology and physiology," she says. "This may have one possible benefit -- to reduce parents' feelings of self-blame. But until we know a lot more, I think these are by far outweighed by the dangers in 'labeling' these adolescents as abnormal and doomed to conflict.

"We have so much established knowledge of the tremendous significance of family function, environmental pressures and education on these behaviors that I choose to stay with these explanations."

More Research on the Way

But even though it cannot yet be said for sure whether larger amygdalae can be blamed for aggression in teens, Allen says his current research aims to determine just that.

Specifically, he says that monitoring how the teens in this study fare over the years may help scientists draw a clearer picture of how, exactly, changes in the amygdalae and other biological factors fit in with teen aggression.

"We're certainly not saying this explains everything, or that this explains away bad behavior," Allen says. "Kids still need to be encouraged to have responsibility for their own behavior. But I think it's also good for parents to be realistic and to have an understanding that these kids are still growing.

"And the parts of the brain that are still developing and growing are the parts that control emotions and behavior, so when you see them behaving in ways that seem inexplicable -- that seem crazy -- at times, part of the explanation for that will be the biological changes the child is going through."

Cathy Becker contributed to this report.