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Your teenage son looks like a grown man. He’s inches taller than his father, and his voice has turned deep. But his behavior is another matter. He makes hasty decisions, drives cars too fast and tends to make his parents annoyed.
That’s because his brain is developing more slowly than the rest of his body. Researchers at the National Institute of Mental Health and UCLA conducted a decade-long study of normal brain development. They found that the frontal lobe, the area responsible for understanding future consequences, making wise decisions and controlling impulses（冲动）, has not become mature （成熟的）until the early 20s.
Immature brains have fast-growing synapses （突触）and sections that remain unconnected. As a result, they're easily influenced by the environment and susceptible to unexpected behavior.
This may explain the puzzling contradiction of adolescence. Teens are at their physical prime. Yet their death rates rise sharply. Study shows that rates of death by injury for people between the ages of 15 and 19 are six times those seen in kids ages 10 to 14. The Insurance Institute for Highway Safety reports that teens are four times more likely than older drivers to be involved in a car crash and three times more likely to die in one.
Adolescents also are more susceptible to the effects of drugs and alcohol. Rates of drug and alcohol abuse are high when compared with other age groups. Frances Jensen and David Urion, doctors at Children’s Hospital Boston and Harvard Medical School, discovered that adult brain cells recovered more quickly from alcohol exposure than younger brain cells. Jensen said in Harvard Magazine: “For a teenager, what he drank on the weekend is still with him during that test on Thursday.”
The implications for parents are clear. Teens aren’t making trouble on purpose. They desire independence, but they are still tender. They’re still forming into the adults they’ll eventually be. And, of course, they won’t be this age forever. Finally, they will grow up and become rational and wise adults.