Adolescents are infamous for engaging in more risky behavior as they mature from children to adults. This transition is notable for many changes, including a surge in testosterone for both boys and girls. The changing levels of testosterone, combined with the size of a frontal region of the brain, help to explain risk-taking in adolescence, according to new research.
“Together with my colleagues, we earlier demonstrated that pubertal hormone fluctuations are associated with adolescent brain development,” says Jiska Peper, a postdoctoral researcher at the Institute of Psychology at Leiden University. “That led us to investigate whether we could use these biological markers as a model to explain typical adolescent behavior, in this case increased risk-taking.” On the behavioral level, the idea is that increased testosterone production during puberty and adolescence might lead to reduced cognitive control and increased vulnerability to rewards.
Peper and colleagues, working with Eveline Crone in her lab, recruited 236 participants aged 8 to 25 years old, testing their hormone levels, neuroimaging their brains, and analyzing risk-taking behavior. They oversampled adolescents at age 12–13 years in girls and 13–14 years in boys to correspond to midpuberty in both sexes. “This selection allowed us to test for age versus puberty effect by including participants before, within, and after puberty, with most variation within puberty,” Peper says.
The researchers administered the computerized BART task, a traditional test of risk-taking. Participants click on a balloon pump to inflate a balloon. Every time the balloon is inflated, they earn money. Participants can stop inflating the balloon at any time and “cash out,” or they can keep inflating to try to collect more money. At random times, the balloon will explode, causing participants to lose their earned money. Peper’s team correlated the amount of money earned and balloon explosions in participants to their measured levels of testosterone and to brain scans of the orbitofrontal cortex (OFC), a region in the frontal lobes in the brain that is involved in value-based decision-making.
As published in the Journal of Cognitive Neuroscience, they found that in both boys and girls, higher testosterone levels led to more risk-taking; the researchers corrected for age relative to hormone levels in each age group. But the male participants with increased testosterone tended to explode more balloons, while the females with more testosterone earned more money. “In boys, higher testosterone may lead to more sensation seeking – the thrill of pumping the balloon further,” Peper says. “In girls, however, higher testosterone may lead to more long-term advantageous risk taking – more money earned.”
Another stark difference between the sexes was the size and role of the OFC brain region. In boys, having a larger OFC increased the link between high testosterone and more risk-taking, whereas in girls, a larger OFC reduced the link. “Compared to earlier brain developmental studies, this may suggest that a relatively mature OFC amplifies risk taking in boys, but a relatively mature OFC suppresses risk taking in girls” Peper says.
Differences aside, the researchers were quite surprised, Peper says, to find a similar mechanism of testosterone in girls. “It is not commonly known that girls also produce testosterone, albeit about 10 times less than boys,” she explains. “We did not expect that relatively low levels of testosterone in girls would be associated with increased risk-taking or development of the orbitofrontal cortex.”
The research not only increases understanding of the neural underpinnings of developmental changes in healthy adolescents but also could illuminate factors that influence pathological forms of risk taking, such as impulse regulation problems. Peper and colleagues have invited all the study’s participants back into the lab so that they can use a longitudinal approach to examine whether testosterone levels and OFC morphology early in adolescence can predict risk-taking a few years later.
-Lisa M.P. Munoz
The paper, “Development of Risk Taking: Contributions from Adolescent Testosterone and the Orbito-frontal Cortex,” Jiska S. Peper, P. Cédric M. P. Koolschijn, Eveline A. Crone, was published in the Journal of Cognitive Neuroscience online on July 16, 2013, and is forthcoming in print.
Media contact: Lisa M.P. Munoz, CNS Public Information Officer, cns.publicaffairs@gmail.com
