People are often forced to make decisions under stress. This is particularly true during adolescence, a developmental period with significant social, emotional and stressful changes. Increases in adolescent life stressors are paralleled by compromised decision-making and impulse control, both of which are subserved by brain regions that undergo significant maturation during this developmental window. With support from the National Science Foundation, Dr. Adriana Galvan is investigating the effects of daily stress on cognition and brain function in adolescents and an adult comparison group. Daily stress is monitored via a personal digital device that adolescents carry. It provides daily measures of stress over two weeks. On a day when adolescents report a high level of stress, and on a separate day when they report a low level of stress, they visit the laboratory to receive a functional magnetic resonance imaging (fMRI) brain scan. While receiving the brain scan, they perform computer games that are designed to measure decision-making and impulse control behavior. In addition, their stress hormone levels related to brain function are measured. By taking this multi-method approach, Dr. Galvan is learning how daily stress influences cognitive neurodevelopment in adolescents. She predicts that stress will result in worse decision-making and impulse control in both adolescents and adults. However, this effect is exaggerated in adolescents, who are even more susceptible to the effects of high stress days.
This research can have significant implications beyond providing evidence for the effects of stress on neurodevelopment. It can provide a broader conceptualization of why adolescents respond differently to their environment, and how this difference eventually influences the poor decision-making that is characteristic of adolescence. The field is in critical need of an integrated approach to brain-environment interactions. Further, this work will be the first of its kind to merge daily monitoring tools together with functional brain imaging and can, therefore, serve as a methodological template for other areas of cognitive neuroscience, beyond developmental work. The understanding of neural correlates of decision-making in development also provides an important baseline for understanding impairments in this very basic cognitive process, as manifested in a broad range of poor developmental outcomes and psychiatric disorders, including drug addiction, attention deficit hyperactivity disorder, anxiety, and schizophrenia, all of which have frequent onset in adolescence. In addition, understanding the teenage brain will undoubtedly contribute to social policy decisions that hinge on age and maturation, including the juvenile justice system, driving laws, teenage pregnancy, and educational policies. As such, this project has broad health and societal implications. Finally, this research project provides training opportunities for students at the undergraduate, graduate, and post-doctoral levels, and is committed to advancing the training of students from underrepresented groups.
The teenage years are characterized by exploratory behavior, risky decisions and strong emotions. It is also during this time that the brain experiences significant changes in brain regions that process decision-making, stress and emotions. In this study, our goal was to determine whether emotional stress that arises from daily activities differentially influences risky decisions, biological reactivity to stress and brain functioning in teenagers versus adults. Research participants were asked to visit the laboratory on two separate visits: once when they were feeling high levels of stress and once when they were feeling low levels of stress. At the laboratory, they provided ratings of stress and performed computerized games designed to test risky choices and behavioral regulation. Findings show that both teenagers and adults show higher levels of stress hormones on high versus low stress days. However, only teenagers madee riskier choices on high-stress days. Further, brain activation was not different in the adults on high versus low-stress days but was significantly different in teenagers: there was less engagement of the prefrontal cortex, a region critical for optimal decision-making, on high-stress versus low-stress days. Teenagers also showed variable brain activation in emotion and reward regions on high versus low-stress days. Collectively, this study shows that normative, daily stress has a stronger influence in teens relative to adults, by biasing them towards riskier choices and perturbing brain activation. This type of research will help inform society about how context, arousal and environmental circumstances alter optimal brain functioning in teenagers.
