Prior research suggests that increased adolescent risk-taking in the presence of peers may be linked to the influence of peers on the valuation and processing of rewards during decision-making. The current study explores this idea by examining how peer observation impacts the processing of rewards when such processing is isolated from other facets of risky decision-making (e.g. risk-perception and preference, inhibitory processing, etc.). In an fMRI paradigm, a sample of adolescents (ages 14–19) and adults (ages 25–35) completed a modified High/Low Card Guessing Task that included rewarded and un-rewarded trials. Social context was manipulated by having participants complete the task both alone and while being observed by two, same-age, same-sex peers. Results indicated an interaction of age and social context on the activation of reward circuitry during the receipt of reward; when observed by peers adolescents exhibited greater ventral striatal activation than adults, but no age-related differences were evinced when the task was completed alone. These findings suggest that, during adolescence, peers influence recruitment of reward-related regions even when they are engaged outside of the context of risk-taking. Implications for engagement in prosocial, as well as risky, behaviors during adolescence are discussed.

These findings provide support for negative urgency as a unique mediator of the associations between childhood maltreatment and both alcohol and cannabis problems, suggesting that future work on mechanisms in these associations should focus on mood-based impulsivity.

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Individual differences in acute alcohol effects on cognitive control and subjective responses—and acute tolerance to these effects—are implicated in the risk for heavy drinking and alcohol-related harms. Few studies have examined these effects in drinkers under age 21. Additionally, studies of acute tolerance typically involve bolus oral alcohol administration, such that estimates of tolerance are confounded with blood alcohol concentration (BAC) limb. The current study examined cognitive control and subjective responses in young heavy drinkers (n = 88, M = 19.8 years old [SD = 0.8]) during a single-session alcohol clamp protocol. Participants completed an intravenous alcohol session comprising an ascending limb (0 to 80mg% in 20 minutes) and a BAC plateau (80mg% for 80 minutes). Serial assessments included a cued go/no-go task and measures of stimulation, sedation and craving. Relevant individual difference factors (ADHD symptoms and sensation seeking) were examined as moderators. Multi-level modeling demonstrated that response inhibition worsened following initial rise in BAC and showed increasing impairment during the BAC plateau. ADHD symptoms and sensation seeking moderated this effect. Significant within-person associations between stimulation and craving were evident on the ascending limb only. Participants with higher ADHD symptoms reported steeper increases in stimulation during the ascending limb. These findings provide initial information about subjective and behavioral responses during pseudo-constant BAC, and potential moderators of these outcomes, in late adolescence. Additional studies with placebo-controlled designs are necessary to confirm these findings.