The interactive effects of peers and alcohol on functional brain connectivity in young adults.

Alcohol and peer influence are known to have independent effects on risky decision making. We investigated combined influences of peers and alcohol on functional brain connectivity and behavior. Young adults underwent fMRI while completing response inhibition (Go/No-Go) and risky driving (Stoplight) tasks. Intoxicated participants made more mistakes on Go/No-Go, and showed diminished connectivity between the anterior insular cortex (AIC) and regions implicated in executive function (e.g., dorsal anterior cingulate). During the Stoplight game, peer observation was associated with increased connectivity between the AIC and regions implicated in social cognition (e.g., ventromedial prefrontal cortex). Alcohol and peers also exerted interactive influences, such that some connectivity changes only occurred when participants were observed by peers and under the influence of alcohol. These findings suggest that brain systems underlying decision making function differently under the combined influence of alcohol and peers, and highlight mechanisms through which this combination of factors is particularly risky for youth.

Peers influence adolescent reward processing, but not response inhibition.

Most adolescent risk taking occurs in the presence of peers. Prior research suggests that peers alter adolescents' decision making by increasing reward sensitivity and the engagement of regions involved in the processing of rewards, primarily the striatum. However, the potential influence of peers on the capacity for impulse control, and the associated recruitment of the brain's control circuitry, has not yet been adequately examined. In the current study, adolescents underwent functional neuroimaging while they completed interleaved rounds of risk-taking and response-inhibition tasks. Social context was manipulated such that the participants believed they were either playing alone and unobserved, or watched by an anonymous peer. Compared to those who completed the tasks alone, adolescents in the peer condition took more risks during the risk-taking task and exhibited relatively heightened activation of the striatum. Activity within this striatal region also predicted individual differences in overall risk taking. In contrast, the presence of peers had no effect on behavioral response inhibition and had minimal impact on the engagement of typical cognitive control regions. In a subregion of the anterior insula engaged mutually by both tasks, activity was again found to be sensitive to social context during the risk-taking task, but not during the response-inhibition task. These findings extend the evidence that the presence of peers biases adolescents towards risk taking by increasing reward sensitivity rather than disrupting cognitive control.

Working Memory Training in Adolescents Decreases Laboratory Risk Taking in the Presence of Peers.

Adolescence is a period of heightened risk-taking relative to both adulthood and childhood, due in part to peers' increased influence on adolescent decision making. Because adolescents' choices have harmful consequences, there is great interest in specific interventions that might attenuate risk taking. We hypothesized that it might be possible to reduce adolescent risk taking through an intervention targeting the ability/tendency to engage cognitive control processes. While some studies of Working Memory Training (WMT) have indicated subsequent enhancement of adults' cognitive control abilities, potential impacts on adolescent cognitive control have not been explored. Accordingly, we tested whether four weeks of WMT (relative to Active Control Training, ACT) might increase performance on cognitive control measures and decrease risk-taking in adolescents. Adolescents receiving WMT, compared to those receiving ACT, exhibited some evidence of improved short-term memory performance following the 4-week training period. Improvements did not significantly transfer to performance on basic cognitive control measures. However, on two risk-taking tasks administered at post-training either with or without an anonymous peer audience, adolescents who received WMT evinced suppressed levels of risk taking when observed by peers, an effect not seen in ACT. Further work is needed to more fully characterize the potential of WMT interventions in stemming risk behavior within adolescent samples.