February 25, 2008
Bratty Adolescents Have Bigger Amygdalas

A team of scientists at the University of Melbourne in Australia watched some 11 to 14 year old early adolescent children discuss points of disagreement with their parents and measured their reactions. Then the scientists measured the size of brain areas in each of the children. Well, the children more prone to tantrums and sulking had different sizes of various brain areas as compared to the more agreeable children. Is anyone surprised by this result?

Next the team scanned the children’s brains, focusing on three regions: the amygdala, which triggers impulsive reactions to emotional situations, and the anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) – pre-frontal parts of the brain involved in more thoughtful and reflective responses.

Children of both sexes who behaved more aggressively during the problem-solving tasks had bigger amygdalas, while boys who had smaller ACCs on the left side of the brain, compared with the right, stayed aggressive for longer. Also, boys with smaller OFCs on the left side were more likely to respond to a parent’s sulky behaviour with a sulk of their own.

Picture our genetically engineered future. I expect many prospective parents to opt to give their offspring genetic variations that will make their brains develop bigger anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) brain regions and to develop those regions sooner during adolescence. Just genetically engineer surliness and brattiness right out of kids. Why not?

From the abstract of the PNAS paper:

In a sample of 137 early adolescents, we investigated the relationship between aspects of the adolescents' brain structure and their affective behavior as assessed during observation of parent–child interactions. We found a significant positive association between volume of the amygdala and the duration of adolescent aggressive behavior during these interactions. We also found male-specific associations between the volume of prefrontal structures and affective behavior, with decreased leftward anterior paralimbic cortex volume asymmetry associated with increased duration of aggressive behavior, and decreased leftward orbitofrontal cortex volume asymmetry associated with increased reciprocity of dysphoric behavior. These findings suggest that adolescent brain structure is associated with affective behavior and its regulation in the context of family interactions, and that there may be gender differences in the neural mechanisms underlying affective and behavioral regulation during early adolescence. Particularly as adolescence marks a period of rapid brain maturation, our findings have implications for mental health outcomes that may be revealed later along the developmental trajectory.

For most kids the bratty punk surly rude inconsiderate phase won't last. But the behavior of some adults suggests that not all escape from this phase. These who get stuck in adolescence probably need brain gene therapy to push their brains along a sorely needed development path.

Team leader Nicholas Allen, a clinical psychologist with the University of Melbourne and the Orygen Research Centre, said: "The good news is that to a certain extent it's a phase. Parents do find it helpful to understand that some of the inexplicable behaviours teenagers come up with is part of a brain developmental phase."

What were you thinking?

Professor Allen said that the research also cast light on why teenagers who one day approached tasks with a maturity beyond their years could act with immaturity the next. “Your 6ft 2 son can manage some very complicated work yet still do these dumb things. ‘What were you thinking?’ has been asked by every parent of teenagers,” he said.

Also see my previous post Adolescence Is Tough On The Brain.

Share |      Randall Parker, 2008 February 25 10:36 PM  Brain Development

Kralizec said at March 2, 2008 2:17 PM:

Girl to boy: You've got so much attitude. I bet you have a big amygdala!
Boy to girl: D*mn right I do, b*tch! You think you can handle what I've got?

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