Venturing inside the teenage brain

If you’ve ever tried to warn teenagers of the consequences of risky behavior — only to have them sigh and roll their eyes — don’t blame them.

Blame their brain anatomy.

Sociologists and psychologists have long known that teen brains are predisposed to downplay risk, act impulsively and be undaunted by the threat of punishment. But now scientists are beginning to understand why.

"I think teenage behavior is probably the most misunderstood of any age group — not only by parents but by teenagers themselves," says Pradeep Bhide, a Florida State University College of Medicine neuroscientist and director of the Center for Brain Repair.

"It’s a critical time in life, and a very stressful one, when they are going through so many changes at the same time that their brains are changing. The teen years are actually a very busy time for brain development."

During the past year, Bhide brought together some of the world’s foremost brain researchers in a quest to explain why teenagers — and male teens in particular — often behave erratically. He and two Cornell University colleagues examined 20 of the leading research projects from brain experts around the world and recently published their findings in a special volume of the scientific journal Developmental Neuroscience.

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Food commercials excite teen brains

Watching TV commercials of people munching on hot, crispy French fries or sugar-laden cereal resonates more with teens than advertisements about cell phone plans or the latest car.

A new University of Michigan study found that regardless of body weight, teens had high brain activity during food commercials compared to nonfood commercials.

"It appears that food advertising is better at getting into the mind and memory of kids," said Ashley Gearhardt, U-M assistant professor of psychology and the study’s lead author. "This makes sense because our brains are hard-wired to get excited in response to delicious foods."

Children see thousands of commercials each year designed to increase their desire for foods high in sugar, fat and salt. Researchers from U-M, the Oregon Research Institute and Yale University analyzed how the advertising onslaught affects the brain.

Thirty teenagers (ages 14-17) ranging from normal weight to obese watched a television show with commercial breaks. Their brain activity was measured with a functional magnetic resonance imaging scanner.

The video showed 20 food commercials and 20 nonfood commercials featuring major brands such as McDonald’s, Cheerios, AT&T and Allstate Insurance. Study participants were asked to list five commercials they saw and to rate how much they liked the product or company featured in the ads.

Regions of the brain linked to attention, reward and taste were active for all participants, especially when food commercials aired. Overall, they recalled and liked food commercials better than nonfood commercials.

Teens whose weight was considered normal had greater reward-related brain activity when viewing the food commercials compared to obese adolescents. Gearhardt said this suggests that all teenagers, even those who are not currently overweight, are affected by food advertising and that exposure could lead to future weight gain in normal weight youth.

The study concluded that obese participants may attempt to control their response to food commercials, which might alter the way their brain responds. But if these teens are bombarded with frequent food cues, their self-control might falter—especially if they feel stressed, hungry or depressed.

Gearhardt said brain regions that are more responsive in lean adolescents during food commercials have been linked with future weight gain. These findings, which appear in the current issue of Social Cognitive and Affective Neuroscience, may inform the current debates about the impact of food advertising on minors.

Research reveals why some teenagers more prone to binge drinking

New research helps explain why some teenagers are more prone to drinking alcohol than others. 

The study, led by King’s College London’s Institute of Psychiatry (IoP) and published in Proceedings of National Academy of Sciences (PNAS)* provides the most detailed understanding yet of the brain processes involved in teenage alcohol abuse.

Alcohol and other addictive drugs activate the dopamine system in the brain which is responsible for feelings of pleasure and reward. Recent studies from King’s IoP found that the RASGRF2 gene is a risk gene for alcohol abuse, however, the exact mechanism involved in this process has, until now, remained unknown.

Professor Gunter Schumann, from the Department of Social, Genetic and Developmental Psychiatry (SGDP) at King’s Institute of Psychiatry and lead author of the study says: “People seek out situations which fulfill their sense of reward and make them happy, so if your brain is wired to find alcohol rewarding, you will seek it out. We now understand the chain of action: how our genes shape this function in our brains and how that, in turn, leads to human behaviour. We found that the RASGRF-2 gene plays a crucial role in controlling how alcohol stimulates the brain to release dopamine, and hence trigger the feeling of reward. So, if people have a genetic variation of the RASGRF-2 gene, alcohol gives them a stronger sense of reward, making them more likely to be heavy drinkers.”

*Paper reference:  Stacey, D. et al. ‘RASGRF-2 regulates alcohol-induced reinforcement by influencing mesolimbic dopamine neurone activity and dopamine release’ Proceedings of the National Academy of Sciences (PNAS)  2012