By Jeffrey Kluger Thursday, September 23, 2010
When it comes to raising civilized kids there are no hard rules, but there are two things on which most parents agree: Boys are generally wilder than girls, and adolescents are wilder than kids of any other age. If you’ve got an adolescent boy, you’re in the sweet spot for trouble. Now, a study shows how a glitch in the brains of the most difficult boys may be responsible for their behavior.
Psychiatrist Thomas Crowley of the University of Colorado at Boulder, along with his collaborators, recruited two sample groups of 20 adolescent boys each. One group had clearly been having its struggles: Nineteen of the 20 boys already had a diagnosis of conduct disorder; they had been on some kind of academic or legal probation for an average of 139 of the previous 180 days; and all of them had a history of substance abuse. All had also been abstinent for an average of five weeks before the test. The other group of 20 had none of these problems.
The scientists then conducted functional magnetic resonance imaging (fMRIs) of the boys’ brains while they played a simple computer game that involved risks and rewards. Every time the boys chose a non-risky option in the course of the game, they won a penny. Every time they chose a riskier one they either won five cents or lost 10. An understanding of risk, reward and possible future outcomes is, of course, a central pillar of mature and disciplined behavior, and watching how those processes play out in the brain is a pretty good way of understanding conduct.
The first surprise — actually the only true surprise — when the researchers analyzed their results was that the troubled boys and the untroubled ones chose the game’s risky option with about the same frequency. Kids who don’t have a clear sense of the potential consequences of their actions (which ought to include those with conduct disorder and a substance abuse history) would be expected to roll the dice on high-risk, big-payoff choices more than other kids, and yet the study didn’t show this.
What truly separated the subjects lay deeper in their brains. The fMRIs revealed that the boys with behavioral problems had significantly less activity in the anterior cingulate cortex — which monitors rewards and punishments — and the dorsolateral prefrontal cortex, which receives information from the anterior cingulate and governs the decision-making processes that result. They also had lower activity in a handful of other regions, including the amygdala, which plays a role in modulating emotions.
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