We all know the story of Romeo and Juliet: Two teenagers fall instantaneously and deeply in love despite their families’ being bitter enemies. Believing themselves to be “star-crossed lovers,” they seize the moment and secretly marry. Eventually they and their best friends die. The theme of the play is not only blind prejudices but also the consequences of immature passion.
But was it love that caused these two to act so recklessly, or merely a case of the radical changes taking place in the teenage brain? New scientific discoveries indicate that it’s not just those pesky hormones that are responsible for the departure from what we consider normal behavior in our teenagers, but incomplete brain development.
What’s Going On Inside That “Brain” Of Theirs
Ask most parents about their teen’s brain, and they’ll usually say, “What brain?” Then, after a moment, they’ll highlight the incredible spurts of real intellectual development they’ve briefly witnessed among the poor choices and boneheaded moves, moments when their kids finally seem to be grasping abstract ideas, concepts, or mathematical problems that had hitherto eluded them.
Both observations seem to be correct. There’s a lot of construction and restructuring going on inside the brains of our teens. Studies by Dr. Jay Giedd at the National Institute of Mental Health show that during puberty the cerebral cortex — the frontal lobe of the brain that functions as the chief executive or policeman of our brains, controlling impulsive behavior, planning, decision-making, and task organization — is undergoing dramatic changes. The gray matter, the outer layer of the brain, is both thickening—a process that scientists term exuberance, and refers to the rapid multiplying of branches of cells — and then swiftly and sharply thinning down.
These “exuberant” areas are thought to be advantageous in the acquiring of new skills. This area of growth in the frontal lobe peaks at puberty, usually about age 12. The pruning or fine-tuning doesn’t start until later, around age 13, when the brain needs to winnow down.
Giedd likens this process to Michelangelo’s David: “You start out with a huge block of granite at the peak [of] the puberty years. Then the art is created by removing pieces of the granite, and that is the way the brain also sculpts itself. Bigger isn’t necessarily better, or else the peak in brain function would occur at puberty.”
It’s important to remember that while the neurons are thinning down, the brain is honing in and conforming to the “use it or lose it” paradigm. Those connections that are reinforced will be strengthened, and those that are neglected will wither and die. So if a teenager is playing that violin or involved in sports or academics, those are the skills that will flourish and be hardwired into the brain, and if that same teenager is instead manically playing a video game — that skill will also flourish.
The malleable frontal cortex, where all the shapeshifting takes place in teenagers, doesn’t fully develop until age 20 or over. This is the area of our brains that has altered the most in human evolution and differentiates us from animals, allowing us to reason, have forethought and understand consequences. But it is not the only area of the brain that is undergoing development.
In the back of the brain, the cerebellum undergoes the most changes during the teen years and doesn’t finish growing until the early 20s. This area is involved in coordination of our muscles and mental processes. Giedd believes that an active involvement in sports and exercise helps not only our bodies to learn coordination, but our brains to learn to operate more smoothly, to navigate between work, social life, family, and even among academic subjects. “One of the tasks of the teenager,” Giedd says, “is to be fluid with social interactions and to get the subtle cues and even know when someone is joking. All these things scream cerebellum. And now it seems this area that regulates social behavior is the last to mature.”
In other societies around the world, teenagers may already be considered adults as young as age 12. “Such societies are more structured and ordered,” says Peter Jensen, the director of the Center for Advancement of Children’s Mental Health and himself a father of five. There isn’t the same wiggle room for risky adolescent behavior in these societies as there is in our own. Western culture is complex, full of stimuli and opportunities, both good and bad, less controlled and therefore less protected. In Western culture, adolescents’ brains need time to learn reason in order to make grown-up, wise choices.
But in our world, the risks are profuse and often dangerous — drugs, smoking, sex before maturity, reckless driving, skateboarding without a helmet, etc. Unfortunately, the adolescent brain, in the midst of synaptic rewiring, is primed and eager for new experiences.