Risk-taking and social exclusion in adolescence: Neural mechanisms underlying peer influences on decision-making

•Adolescents completed a driving risk task before and after social exclusion by peers.•Teens with low resistance to peer influence (RPI) took more risks after exclusion.•Low RPI teens showed increased neural activity in regions of mentalizing during risk.•Signal in temporoparietal junction mediated the effect of RPI on post-exclusion risk.•Thinking about evaluation by peers may affect risk decisions for susceptible teens.

Social exclusion and risk-taking are both common experiences of concern in adolescence, yet little is known about how the two may be related at behavioral or neural levels. In this fMRI study, adolescents (N = 27, 14 male, 14-17 years-old) completed a series of tasks in the scanner assessing risky decision-making before and after an episode of social exclusion. In this particular context, exclusion was associated with greater behavioral risk-taking among adolescents with low self-reported resistance to peer influence (RPI). When making risky decisions after social exclusion, adolescents who had lower RPI exhibited higher levels of activity in the right temporoparietal junction (rTPJ), and this response in rTPJ was a significant mediator of the relationship between RPI and greater risk-taking after social exclusion. Lower RPI was also associated with lower levels of activity in lPFC during crashes following social exclusion, but unlike rTPJ this response in lPFC was not a significant mediator of the relationship between RPI and greater risk-taking after social exclusion. The results suggest that mentalizing and/or attentional mechanisms have a unique direct effect on adolescents' vulnerability to peer influence on risk-taking.