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THE TEEN BRAIN
Brain Immaturity Could Explain Teen Crash Rate
Risky Behavior Diminishes At Age 25, NIH Study Finds
By Elizabeth Williamson, Washington Post Staff Writer, Tuesday, February 1, 2005; Page A01
By most physical measures, teenagers should be the world's best drivers. Their muscles are supple, their reflexes quick, their senses at a lifetime peak. Yet car crashes kill more of them than any other cause -- a problem, some researchers believe, that is rooted in the adolescent brain.
A National Institutes of Health study suggests that the region of the brain that inhibits risky behavior is not fully formed until age 25, a finding with implications for a host of policies, including the nation's driving laws.
"We'd thought the highest levels of physical and brain maturity were reached by age 18, maybe earlier -- so this threw us," said Jay Giedd, a pediatric psychiatrist leading the study, which released its first results in April. That makes adolescence "a dangerous time, when it should be the best."
Last month, Sen. William C. Mims (R-Loudoun) cited brain development research in proposing a Virginia bill that would ban cell phone use in vehicles by drivers younger than 18. It passed Friday.
In Maryland, Dels. Adrienne A. Mandel and William A. Bronrott said the research could bolster three bills the Montgomery County Democrats submitted to the legislature Friday. The bills would expand training and restrict passenger numbers and cell phone use for certain teenage drivers.
The measures also are supported by crash statistics and a soon-to-be-released study from Temple University, which used a driving-style test to show that young people consistently take greater risks when their friends are watching.
"This goes toward supporting evidence that the judgment of teens further deteriorates with distractions. These crashes are preventable," Mandel said. "I would welcome [researchers'] testimony at our bill hearings."
The research has implications beyond driving: Attorneys cited brain development studies as the U.S. Supreme Court considered whether juvenile offenders should be eligible for the death penalty. The court is expected to reach a decision by midyear.
Critics of brain-imaging research -- and Giedd himself -- emphasize that there is no proven correlation between brain changes and behavior. Giedd, however, said the duration and depth of the study mean "it's time to bring neuroscience to the table" in the teen driving debate.
"We can determine what is the relationship between brain development and driving ability and what we can do to make it better," Giedd said.
At Temple University in Philadelphia, psychology professor and researcher Laurence Steinberg plans a new study: scanning teenagers' brains while they perform a task that simulates driving decisions, in an effort to understand the biological underpinnings of risk-taking among young people.
Giedd intends to pursue similar studies with his subjects, focusing on ways to give young people, and those responsible for them, more tools for beating the odds.
Teenagers are four times as likely as older drivers to be involved in a crash and three times as likely to die in one, according to the Insurance Institute for Highway Safety.
"Right now our first subjects are reaching driving age," Giedd said. "What better application could there be than saving their lives?"
Lily and Zoe Ulrich, 15-year-old identical twins from Frederick, have been part of Giedd's study at NIH for two years. When they signed up, they answered questions about their diet, athletics, social habits, peer pressure, language skills and intellectual achievements.
The blond, 5-foot-4 sisters wear glasses, earn straight A's and often finish each other's sentences. They will receive their learner's permits this month. "I'm excited . . . it's really cool," Lily said. "I'm a little more nervous," said Zoe. "We think the same a lot of the time but not always."
Giedd would like to know why.
Sitting in his closet-size office in NIH's sprawling Building 10, he turns to his laptop, where the fruit of 13 years' work appears. It's an eight-second, time-lapse image of the brain, swept by a vivid blue wave symbolizing maturing gray matter. The color engulfs the frontal lobes and ends in "a direct hit," Giedd said, with the dorsal-lateral prefrontal cortex, just behind the brow.
About as thick and wide as a silver dollar, this region distinguishes humans from other animals. From it, scientists believe, come judgments and values, long-term goals, the weighing of risks and consequences -- what parents call wisdom or common sense and what science calls "executive functions."
While society and tradition have placed the point of intellectual maturity, the "age of reason," years earlier, the study -- an international effort led by NIH's Institute of Mental Health and UCLA's Laboratory of Neuro Imaging -- shows it comes at about age 25.
The process is generally completed a year or two earlier in women but varies greatly from person to person. Why that is, Giedd said, "we still don't know."
"We have to find out what matters. Diet? Education, video games? Medicine, parenting, music? Is the biggest factor whether you're a musician or a jock or the amount of sleep you get?"
As important, Giedd said, is the study's finding that the brain matures in a series of fits and starts. While it remains to be proved, he said, this "may be a key to when the brain is most receptive" to learning certain skills, such as driving.
The study, which is ongoing, involves scanning the brains of 2,000 people ages 4 through 26 using magnetic resonance imaging, a radiation-free tool that permits researchers to view the organs of healthy people in minute detail.
Every two years, study participants come to the Bethesda-based National Institute of Mental Health, where they are scanned and interviewed. Half the children are healthy, and half have brain-related disorders. In the next phase, researchers plan to focus almost solely on twins, hoping to expand beyond the 180 pairs participating now, to measure the impact of environmental factors on the maturing brain.
Giedd said he's been bashed by teenagers who said the study suggests they're brain-damaged. On the contrary, he said: "Teenagers' brains are not broken; they're just still under construction."
The pattern probably serves an evolutionary purpose, he said, perhaps preparing youths to leave their families and fend for themselves, without wasting energy worrying about it.
The findings imply that many life choices -- college and career, marriage and military service -- often are made before the brain's decision-making center comes fully online. But for young adults, "dying on a highway is the biggest risk out there," Giedd said. "What if we could predict earlier in life what could happen later?"
A 'Period of Recklessness'
Temple's Steinberg said the NIH/UCLA research supports his theory that teen recklessness is partly the result of a critical gap in time -- starting with the thrill-seeking that comes in puberty and ending when the brain learns to temper such behavior. Since children today reach puberty earlier than previously, about age 13, and the brain's reasoning center doesn't reach maturity until the mid-twenties, Steinberg said, "this period of recklessness has never been as long as it is now."
In a study to be published this year, Temple researcher Margo Gardner and Steinberg illustrated the impact of peer pressure on risk-taking. Volunteers in three age groups -- 13 to 16, 18 to 22 and 24 and older -- were told to bring two friends to the study, which involved an arcade-style driving game.
To "win," participants guided a car through a course as quickly as possible. Periodically, a yellow warning light flashed, and some time later a "wall" popped up. If players hit it, they lost all their "points."
Participants took the test alone and with their friends in the room. Researchers found that those in the two younger groups consistently took more chances with friends present. Those 24 and older behaved equally cautiously, regardless of whether friends were watching.
The results help show why teenagers are more likely to drink, take drugs or commit crimes in groups, he said. They're also reflected in auto crash statistics.
According to the Arlington-based Insurance Institute for Highway Safety, the chances of a crash by a 16- or 17-year-old driver are doubled with two peers in the vehicle and quadrupled with three or more. "Every passenger you add increases the risk," said Alan Williams, chief scientist at the institute. The brain and behavior studies, he said, "certainly tie in with what we know."
After a spate of teen driving deaths across the Washington region in the fall, Maryland is attempting to join Virginia and the District in limiting the number of unrelated passengers in cars with young drivers. In addition to cell phone restrictions that the Maryland and Virginia legislatures are considering, Maryland Gov. Robert L. Ehrlich Jr. (R) is backing a measure that would revoke the licenses of convicted drunk drivers under age 21, for as long as five years.
Steinberg said he agrees with such approaches. "We have to limit the harm adolescents [encounter], rather than to try and change them."
The best way to do that, he added, "is by passing laws."
Staff writer David Snyder contributed to this report.
The Teen Brain
Surprise: It grows long past childhood. So chalk up some of that baffling behavior to neurobiology, not hormones.
By Tim Wendel USA Today
Until scientists began to employ MRI imaging a few years ago, the teenage brain was thought to be largely finished. After all, brain size usually doesn't change that much after childhood. Many assumed it only required fine-tuning in preparation for adulthood. "Now we're finding out how wrong we were," says Richard Restak, a neuropsychiatrist and author of "The Secret Life of the Brain". "The teenage brain is a work in progress that we're only beginning to understand." From the thickening and then thinning of gray matter to the development of the all-important frontal lobes, the brain undergoes dramatic change during adolescence. What parents once blamed on hormones is actually "a grand upheaval of the brain," says Barbara Strauch, a medical science editor and author of "The Primal Teen: What the New Discoveries About the Teenage Brain Tell Us About Our Kids".
This upheaval affects everything from schoolwork and sleep patterns to teens' propensity for taking risks.
Risk-taking: Blame immature frontal lobes
All parents want their children to explore the world. But what if the family curfew has become a joke? What if a teenager exhibits behavior that not only worries an adult but also can be dangerous to the kid? Ron Dahl, a pediatrician and child psychiatric researcher at the University of Pittsburgh Medical Center, says a desire for thrills and taking risks is a building block of adolescence. The frontal lobes help put the brakes on such behavior, but they're also one of the last areas of the brain to develop fully. Located right behind the forehead, the frontal lobes actually grow larger than adult size in puberty. But the process is far from complete; refinement of the frontal lobes can continue into the early 20s.
"This is a crucial stage of development," says Mel Levine, director of the University of North Carolina's clinical center for the study of development and learning, "because the frontal lobes enable a person to know where they're heading as opposed to having no idea of what the consequences will be."
In calm situations, teenagers can rationalize almost as well as adults. But stress can hijack what Dahl calls "hot cognition" and decision-making. The frontal lobes cannot cope. Dahl points out that studies are far from complete, but he and other experts contend that higher levels of the neurotransmitter dopamine make teens hungry for stimulation, including risky behavior.
Academics: "Wow! It suddenly makes sense"
Besides the frontal lobes, other key areas of the brain are transformed during adolescence. The corpus callosum, a thick bundle of nerve fibers that connects the left and right hemispheres of the brain, enlarges. The anterior cingulate gyrus, which helps us stay focused, matures, as do key areas in the cerebral cortex that recently have been linked to language development and spatial reasoning. Such development may explain why things will suddenly click for a struggling geometry student: The brain finally can make sense of the subject material. Several experts contend that music, math and sports can help structure the brain faster and better than simply hanging out or watching television. "The adolescent brain exhibits a tremendous plasticity," Restak says. "Indeed, the adolescent's choices determine the quality of his brain."
Time: Teens really do need extra sleep
But even the best choices, inside or outside of the classroom, will do little good if a teen is too tired. Levine recommends that parents set up a daily schedule at home and stick to it. Instead of telling a teen he can watch television after he does his homework, try saying, "First, spend two hours every evening on brain work. After that, you can watch TV." Early research indicates that too many timed deadlines, at school or at home, reward impulsive behavior and do little to accentuate the frontal lobes and develop other crucial areas of the teen brain.
Melatonin, an important brain chemical, can wreak havoc in an adolescent's world. Melatonin helps make us drowsy, and in teens it's secreted later at night. Sleep specialist Mary Carskadon, professor of psychiatry and human behavior at Brown University, says such changes in melatonin production push teens to stay up later. Her surveys and field studies show that teens average 7 1/2 hours of sleep a night. She maintains that for brain development, nine hours should be the goal. "Most teens are very sleep-deprived," Carskadon says. "That's when problems in the development of the frontal cortex and many of those synapses emerge. We are only now learning about the [effect] of sleep on learning and memory. And what's more important during adolescence than learning and memory?"
Parents: You can help new brain cells connect
In childhood, brain cells grow quickly, like new stalks on a plant. As adolescence accelerates, there's an overabundance of new connections in the brain. As teens mature, some connections are pruned away, increasing the brain's efficiency. The chance to help shape this pruning makes parents more crucial, not less. "This is a sensitive time, when feelings are becoming linked with rational thought," Dahl says. "The stakes are very high, and parents need to feel that it's OK to be monitoring what their adolescents are doing." When Strauch was researching her book, Primal Teen, she often brought her two teens along. As a result, she found herself more empathic. "There's so much going in the brain, and it should give us hope," she says. "We should not really give up on any kid. They may be sitting in a lump and sleeping until noon and have pink hair, but there are all kinds of changes going on under that pink hair.”
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