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January 4, 2011

Risky Teen Brains

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Adolescence brings more freedom and with it, more opportunities for risky behaviors. But as this ScienCentral News video reveals, mental health researchers say teen risk-taking is also a natural response to changes in their brains.

Risks vs. Rewards

Plenty of adolescent behaviors are annoying, but others can be dangerous or even potentially deadly-- like substance abuse and unprotected sex. Brain researcher Monique Ernst points out that teenagers' propensity for thrill-seeking doesn't just come from having more independence, exposure to risky behaviors, or peer pressure.

"This behavior doesn't come from the environment only," she says. "It is actually very much governed by changes that happen in the brain as the adolescents grow."

Ernst, a researcher and clinician in the National Institute of Mental Health's (NIMH) Mood and Anxiety Disorders Program Branch, says in spite of teens generally being at their peak of health, they have a disproportionately high rate of injury and death.

"Their speed of reaction time is really high, their cognitive function, or their thinking, is pretty good, their athletic ability is great," Ernst says. "So they're really healthy, and at the same time, their rate of being sick or impaired and their rate of [injury and death] is really high.

"It's 100 percent higher than children or even adults," she says. "And the main reason for that is their risk-taking behavior."

Monique Ernst with her Wheel of Fortune test.
To understand why teens tend to make risky choices, Ernst and her colleagues have imaged the brains of teens and adults who were asked to play a gambling game that the researchers have dubbed "the wheel of fortune." Volunteers chose whether to bet in a situation with low odds of winning a larger amount of money, and another situation with good odds of winning a small amount of money. The scientists took functional MRI brain scans during the task, and also questioned the volunteers about their emotional reactions to betting, winning and losing.

Ernst says they were interested in three brain regions that they thought might differ among adolescents and adults.

"There are some systems that respond principally to reward, so you approach a reward. There is another system that responds specifically to avoidance, so you avoid something that can be dangerous," she explains. "And you have a system on top of it that modulates your preference… that we call the modulatory or regulatory system. And so there is this kind of triumvirate of brain networks that need to be in balance. And the hypothesis is that this balance is different in adolescents than in adults or even in kids."

As expected, teens bet more often than adults did when the payoff was bigger but the risk of losing was high. As the researchers wrote in the journal Neuropsychologia, they did observe differences in teenagers versus adults.

"The adolescents were using the reward system more than the adults when they were receiving rewards, and they were using less the avoidance system than the adults when they were receiving losses," says Ernst.

Functional MRI scans show brain activity.
They also found that adults seemed to make better use of their regulatory system. "The prefrontal cortex or the thinking region is less active when there is a choice to make in adolescents, than in adults," she says.
Ernst says the research lays the groundwork for further studies because understanding normal adolescent brain development is important for studying mental illnesses, many of which begin during youth.

And understanding how risk-taking behavior is a part of normal brain development will help to develop better ways of preventing teens from making dangerous choices.

"This is a model that can help us designing other experiments to go further into understanding the maturation
of the brain function in humans, particularly through the period of adolescence," she says. "It's important because if we understand that, maybe we can do something about it."

Ernst says it makes evolutionary sense for teen brains to seek out novelty in preparation for leaving the nest. But she says to protect teens from costly risks, it's important to channel their enthusiasm towards worthwhile goals.

And Ernst isn't just a brain researcher, she's also a mother of teens. She says her research can help parents to understand that risk-seeking is actually a part of normal adolescent behavior. "I think it's a wonderful period, and the energy and the enthusiasm and the ideas that they can have, which kind of die slowly with age, is wonderful," she laughs.

Publication: Neuropsychologia, March 2007

Research funded by: National Institute of Mental Health (NIHM) and NIH

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