Unlocking The Teenage Brain (page 2)
Adolescence is a wild ride for everybody—parents, teachers, and kids. There are fast-moving rapid and dramatic changes in biology, cognition, emotion, and interpersonal relationships. Just about everything that could change, does change. A good metaphor for puberty and the teen years is "starting the engine of a race car with an unskilled driver." The teen brain itself is different, and the teen skill set is different from what the same individuals had as preteens. This has been the recent focus of so many neuroscientific investigators that I can't begin to share all the latest discoveries with you here. We'll focus on just a few of the critical ones.
Many areas of the brain are under major construction during adolescence. In fact, the changes are as dramatic as those happening in an infant's brain. It's safe to call the teen years a "sensitive period" for human brain development. The parietal lobes undergo major changes from ages twelve to seventeen. Certain sub-areas may double or triple in size. The frontal lobes, a big chunk of "gray matter," are the last area to mature, undergoing dramatic changes. Gray matter (brain cells) thickens first (between ages eleven to thirteen) and later thins (reduces 7 to 10 percent) between the ages of thirteen and twenty. In 1999, Jay Giedd and colleagues demonstrated a growth spurt of gray matter in the teen brain.34 As the child spends more time learning, the brain's dendrites continue to make more connections.
This is followed by massive pruning, in which about 1 percent of gray matter is pared down each year during the teen years, while the total volume of white matter ramps up. Gray matter is overall brain tissue, white matter is the fatty coating on the axons called myelin that speeds up connectivity. It's a bit like the insulating rubber coating on electrical cords that protects raw wires from exposure. MRI results suggest that the thickening of gray matter is due to massive changes in synaptic reorganization, meaning more usage and more connections.35 These cells become highly receptive to new information. But they're not excited for the long term—the teen brain is not ready for that yet. Larger delayed rewards are valued less than smaller immediate rewards in impulsive individuals. Adolescents' sensitivity to rewards is stronger than that of adults. As a result, kids seek higher levels of novelty and stimulation to achieve the same feeling of pleasure. Risk, rewards, and fun are driving their brains. Keep that in mind with teens; they're terrible at risk management. In fact, their peers make too many decisions ("group think") because, collectively, no one can make up his or her mind except, often, the more impulsive ones. It's almost as if mother nature wanted teens to explore risky things and make babies.
But while this nearly exploding brain has more choices, it is often paralyzed by inefficiency. Just as with infants, it's the thinning back of synapses that creates more efficient decision making. Think of the metaphor of traveling through a dense forest; it's more efficient with a wide, paved road than with a machete, clearing underbrush on foot. Typically, the myelination process pushes back maturing until somewhere between ages sixteen and twenty, and often this extends into the late twenties. Elizabeth Sowell's work at UCLA suggests that the frontal lobes of girls mature faster than those of boys during puberty.36 But both genders are generally poor at reading and interpreting emotions. Their frontal lobes are still too immature to damp down impulsive responses to the emotions, usually generated from the emotional "smoke detector" we call the amygdala.
Generally, girls "connect the dots" earlier than boys in both emotional and cognitive functions. While most brains become physically mature between the ages of eighteen and thirty, it takes boys until about age twenty-four to catch up to girls' brain development. Using the frontal lobes for self-regulation, teens slowly (way too slowly for most adults who live and work with them) learn about interrupting a risky behavior, thinking before acting, and choosing among different courses of action. Unfortunately, the much-needed maturation of neural networks governing self-regulation hasn't happened in adolescence. These processes suggest that the "under construction brain" areas may be highly unstable, volatile, and unpredictable. The result is that they have a very high risk rate for accidents and injuries.
The differences are dramatic; all these changes mean that a teen's brain needs more sleep time to learn, organize, and store new learning.37 One metaphor to consider is that teen brains resemble blueprints and roughly framed buildings more than a finished home. Instead of thinking about a teenage mind as an empty house that needs furnishings, educators and parents would do better to understand it as the rough framing of a house that still needs wiring, plumbing, flooring, and windows. Avoid treating teenagers like adults; they're not. They have the highest accident rate in cars of any age group. Teens are in a developmental fog and often make decisions even a nine-year-old would call stupid. They have sound biological reasons for the following patterns:
- Susceptibility: Teens are particularly susceptible to the risky extremes of novelty. Novelty juices up their unstable systems with brain chemicals such as dopamine and noradrenaline. They choose short-lasting, immediate rewards over larger, delayed rewards. Their undeveloped frontal lobes play a significant role in reckless behaviors.
- Lack of planning: Teens have trouble anticipating the consequences of their behavior because they rely on their immature frontal lobes. They don't see options very well. They get confused easily under stress and rarely plan more than one move ahead.
- Emotional stew: Emotions are essential to learning, and teens are still learning how to understand and manage emotions. They are poor at reading emotions and weak at selecting the right friends and getting their minds outside their own world of feelings.38
- Crowd morality: Teenagers will climb the moral ladder only as their frontal lobes develop. To develop a clear moral and ethical compass, one needs real-life experiences, mediated by thoughtful adults. But teens spend an average of twenty-eight hours a week interfacing with digital technology (computers, cell phones, videogames, and television). This time is all unsupervised, most of it alone. To balance this, they often seek friendly (even if it's negative) peer clustering. But they're more likely to engage in risky behaviors when they are in groups than alone.
- Difficulty in self-regulation: Teens face a huge risk of chemical imbalances for behavioral and personality disorders such as anxiety, depression, stress, eating disorders, and shifts in sleep habits. Teens are more vulnerable to all of these than adults and have few coping skills.
- Risk taking: Teens are extremely vulnerable to addiction, and compared with adults they are less cognizant of the effects of drug use and abuse, and their addictions are harder to break. They see drugs as harmless, for the most part, and tend to believe that they can survive anything.
Does all this chaos and change suggest that the teen brain is too big of a cauldron for positive change? No, in fact, it's quite the opposite. For good or ill, the teen brain is highly vulnerable, and that's both a curse and an opportunity. The bottom line is that they have a tough time predicting the future. Figure 4.6 illustrates how teens struggle in being able to predict the likelihood of relatively straightforward risks.
The brain's wild ride means that multiple systems and structures are undergoing massive changes. That affects the very core of our strongest success strategy in life, predictability. Jeff Hawkins has argued persuasively, in On Intelligence, that understanding, developing, and enhancing our capacity to predict is what gives us our intelligence.39 In general, teens are very poor at prediction skills, and that's one reason they struggle so much. Their brains are just not done maturing. For more on the importance of prediction to our daily lives, the lay reader might enjoy Hawkins's book. It's a good, upbeat, well-researched primer.
Brain Maximizer: The natural tendency of the teenage brain is to explore, take risks, and socialize. The parent's role is mediation. Manage the risks, stay highly involved in their lives, ask questions, and reduce opportunities for dangerous activities. Ideally, parents will offer safer alternatives to teens for risk taking, such as camping, sports, school theater, wilderness treks, the use of helmets, and padding for activities such as skateboarding. Remember, their brains are not adult yet, and they will not make mature, measured decisions. For the teenage brain to be maximized, it should be guided carefully through this dangerous time with focus, love, and involvement.
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