Teenagers gamble. Whether it’s a bet they’ll win a class election or they won’t get caught if they drink underage, adolescents take risks more often than other age groups.
“Scientists have studied this question for decades, and we still don’t know why some adolescents choose to make risky decisions that negatively impact their health,” said Nina Lauharatanahirun, a psychology graduate student from Los Angeles who carries out her research at the Virginia Tech Carilion Research Institute (VTCRI) in the laboratory of Brooks King-Casas, an associate professor.
The National Institute on Drug Abuse (NIDA), one of the National Institutes of Health, awarded Lauharatanahirun a competitive F31 individual predoctoral National Research Service Award to investigate the neurobehavioral mechanisms of risky decision-making in adolescents. Lauharatanahirun’s study under the mentorship of King-Casas, who is also an associate professor of psychology in the College of Science and co-leads an ongoing study on risky behaviors in teenagers with Jungmeen Kim-Spoon, a professor of psychology at Virginia Tech.
The years between 13 and 17 are critical in an adolescent’s brain development, as sensitivity to high-reward stimuli increases. The brain’s prefrontal regions, which should help inhibit impulsive behavior, are still developing. Problems in development of the region or in the learning and valuation process can translate into risky behaviors.
Lauharatanahirun is specifically focusing her study on risky behavior with unclear outcomes, building on King-Casas and Kim-Spoon’s study of why adolescents engage with risks with well-defined outcomes. Lauharatanahirun is also studying, as King-Casas does, how the valuation and learning processes might play a role in modifying such behavior.
“The ultimate goal is to figure out whether we can identify important predictors of risky behaviors in adolescents,” said Lauharatanahirun, noting that teens’ hazardous choices are actually a public health issue. “If you look at the leading causes of disease and death in adolescents, almost all of them are preventable and most of them are linked to engaging in risky behaviors.”
According the Centers for Disease Control, the top three causes of death in people aged 10 to 14 years old are accidents, suicide, and cancer. In the next age group, of 15- to 19-year-olds, homicide moves up to the third most common cause of death, knocking cancer down to fourth place.
Most risky decisions are made when the outcomes are partially to completely unknown, according to Lauharatanahirun. For instance, teenagers who drive under the influence might guess that they have about a 70 percent chance of getting pulled over, but they don’t actually know their true chances.
It’s called ambiguous uncertainty, and adolescents have a higher tolerance for it than other age groups.
There is a growing body of research that suggests risky behavior may stem from the slower development of the brain areas important for executive functioning, such as the prefrontal cortex. In comparison, the earlier developing subcortical areas, such as the amygdala and insula, control, among other things, aggression, arousal, and fear responses. These areas also house the pleasure part of the brain and learn to link specific behaviors to certain rewards, which can lead to addiction.
The prefrontal cortex, which doesn’t fully develop until a person’s mid-20s, is responsible for higher-level thinking, with a focus on future goals. It is thought to curb subcortical urges and weighs the potential outcomes before acting.
“Our goal is to better understand how the adolescent brain processes ambiguous probability information when making risky decisions” Lauharatanahirun said.
To study this, Lauharatanahirun uses functional magnetic resonance imaging, known as fMRI, to reveal the neural networks underlying ambiguity processing.
Study participants select between monetary gambles, sometimes with known probabilities and sometimes without. Based on the participant’s choices and their brain activity during the task, a computational model estimates the participant’s willingness to take risks for valued rewards.
“In adults, risk and reward can be separated from one another. They have separable but overlapping neural correlates,” Lauharatanahirun said. “This project should help us begin to understand if reward and risk information are processed the same way in adolescents.”
Next, participants estimate the likelihood of a potential consequence of a real-world scenario, such as the chance of getting injured while playing a sport. Once participants give their estimation, which can range from zero to 100 percent, they’re given the actual likelihood.
“Most of the outreach aimed at reducing risky behavior focuses on educating adolescents about the negative consequences that are likely to occur,” Lauharatanahirun said. “But we don’t know how kids most likely to engage in substance abuse behaviors process this information.”
From the real-world scenario trials, Lauharatanahirun measures the adolescents’ estimation error – how likely they are to overestimate or underestimate an outcome.
“We’re also interested in understanding how positive risks, such as speaking up in class or standing up for their beliefs, are processed compared to risky behaviors with unhealthy consequences, such as drinking or substance abuse,” Lauharatanahirun said, explaining that it may be that different types of risks are processed by separate brain areas.
Lauharatanahirun plans to complete this project by the end of 2017. She hopes the results will increase understanding of how the adolescent brain makes decisions in risky situations, and, ultimately, contribute to the development of prevention and intervention strategies for identifying and treating adolescents at risk for negative health outcomes, such as addiction.