Inside the Teen Brain
Behavior can be baffling when young minds are taking shape
One day, your child is a beautiful, charming 12-year-old, a kid who pops out of bed full of good cheer, clears the table without being asked, and brings home good grades from school. The next day, your child bursts into tears when you ask for the salt and listens to electronic music at maximum volume for hours on end. Chores? Forget it. Homework? There's little time, after talking to friends on the phone for five hours every night. Mornings? Your bluebird of happiness is flown, replaced by a groaning lump that can scarcely be roused for school. In short, your home is now inhabited by a teenager.
The shootings in Littleton, Colo., focused the nation's attention on aberrant adolescent behavior, but most teens never come close to committing violent acts. Still, even the most easygoing teenagers often confound their elders with behavior that seems odd by adult standards.
For most of this century, the assumption has been that teenage sturm und drang, the insolence and the rages, are all directed at parents. Teens turn against authority figures, went the conventional wisdom, in an effort to define who they are and to assert their independence--a view that spawned the teenage rebel, that quintessential American icon. The alternative explanation was that hormones, those glandular bringers of sexual stirrings and pimples, were to blame.
The true source of teenage behavior lies north of the gonads. It's that 3-pound blob of gray and white matter known as the brain.
Yes, teenagers do have brains, but theirs don't yet function like an adult's. With the advent of technologies such as magnetic resonance imaging, neuroscientists have discovered that the adolescent brain is far from mature. "The teenage brain is a work in progress," says Sandra Witelson, a neuroscientist at McMaster University in Ontario, and it's a work that develops in fits and starts.
Until the past decade, neuroscientists believed that the brain was fully developed by the time a child reached puberty and that the 100 billion neurons, or nerves, inside an adult's skull--the hardware of the brain--were already in place by the time pimples began to sprout. The supposition was that a teenager could think like an adult if only he or she would cram in the necessary software--a little algebra here, some Civil War history there, capped by proficiency in balancing a checkbook. But the neural circuitry, or hardware, it turns out, isn't completely installed in most people until their early 20s.
And just as a teenager is all legs one day and all nose and ears the next, different regions of his brain are developing on different timetables. For instance, one of the last parts to mature is in charge of making sound judgments and calming unruly emotions. And the emotional centers in the teenage brain have already been revving up, probably under the influence of sex hormones.
This imbalance may explain why your intelligent 16-year-old doesn't think twice about getting into a car driven by a friend who is drunk, or why your formerly equable 13-year-old can be hugging you one minute and then flying off the handle the next.