Teen brains hyper-wired for rewards

Teens are notorious for taking more risks than adults, and a new imaging study suggests it's because the adolescent brain is hyper-motivated when it comes to receiving rewards.

A study published online in Proceedings of the National Academy of Sciences suggests that teen brains showed more activity in a specific pleasure centre of the brain compared to adults when they were rewarded during gambling games where money was at stake.

"Anticipating or receiving a financial reward produced strong activity in a brain region called the ventral striatum, especially in adolescents," said study author Adriana Galvan, an assistant professor of psychology, behavioural neuro-science and developmental psychology at the University of California, Los Angeles.

Read: Heavy dagga use 'shrinks' teen brains

Betting games

For the study, Galvan and her colleagues examined brain cell activity in the brains of 19 adults and 22 teens using functional magnetic resonance imaging (fMRI) while the study participants played betting games that included modest monetary rewards – final wins never tallied more than $40.

The teenagers were 13 to 17 years old, and the average age of the adults was 28. Each performed gambling tasks. In each trial, the participants decided whether or not to accept or reject a bet that had a 50% chance of resulting in a win or a 50% chance of ending in a loss – so the trials were completely based on chance, not skill.

The fMRI images monitored brain activity during the betting, and the authors reported that the ventral striatum showed greater activity in teenagers than in adults during the betting. Galvan said the increased brain activity in the teens showed they valued the anticipated payoff more than the adults did, even during the trials in which both age groups accepted the same bets.

Unique developmental changes

The reward-sensitive brain regions in the teens were hyperactive compared to the adult brains. There are unique developmental changes going on in their neural circuits, the researchers explained.

Read: Brain activity may predict teens' heavy drinking

"We don't see this in studies of younger kids either," said Galvan. "In a previous study we published of younger children, they didn't have the same neuro-sensitivity to rewards that we see in adolescents."

Galvan also noted that the greater activation in the teen brains, when it came to reward-earning, was associated with making better choices in the game.

"The adolescents were better able to pick up on the risks that were beneficial – that were worth taking. We don't know why. They were just more responsive to the rewards," the author said.

Not always without logic

Galvan said the research may help begin to change the way parents and other adults view teens' risk-taking choices. Maybe those choices, while dicey at times, may not always be without logic, she said.

"What we hope these data do is start to change the conversation about the fact that being hypersensitive to rewards during adolescence is not necessarily negative," said Galvan.

Read: Why some teenagers start smoking or experimenting with drugs – while others don't

"Sometimes that gets spun – that being sensitive to rewards at this time in life may lead to bad outcomes, like use of drugs," she noted. "But if the rewards go the other way – helping to volunteer, getting a thrill from a soccer game – that's something that can be advantageous to helping them become well-adjusted adults."

Wolf said it's early yet, though, to offer parenting advice based on these results. "At this point, such studies don't have strong implications for parenting advice. I think that what parents already know about teenagers has not been superseded, but studies like this could help down the line," he said.

Read more:

Obesity impairs brain function in teens

Teen marijuana use harms brain

Booze and dope damage teen brain

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