Substance use escalates between adolescence and young adulthood, and most experimentation occurs among peers. To understand underlying mechanisms, research has focused on neural response during relevant psychological processes. Functional magnetic resonance imaging (fMRI) research provides a wealth of information about brain activity when processing monetary rewards; however, most studies have used tasks devoid of social stimuli. Given that adolescent neurodevelopment is sculpted by the push-and-pull of peers and emotions, identifying neural substrates is important for intervention. We systematically reviewed 28 fMRI studies examining substance use and neural responses to stimuli including social reward, emotional faces, social influence, and social stressors. We found substance use was positively associated with social-reward activity (e.g., in the ventral striatum), and negatively with social-stress activity (e.g., in the amygdala). For emotion, findings were mixed with more use linked to heightened response (e.g., in amygdala), but also with decreased response (e.g., in insula). For social influence, evidence supported both positive (e.g., cannabis and nucleus accumbens during conformity) and negative (e.g., polydrug and ventromedial PFC during peers\' choices) relations between activity and use. Based on the literature, we offer recommendations for future research on the neural processing of social information to better identify risks for substance use.

Adolescence is a developmental period marked by changes in cognition, emotion, and social relations. For example, sensitivity to social feedback increases as peer relationships become more important yet less stable, leaving adolescents vulnerable to experiences of peer victimization and rejection. Given that prefrontal brain regions responsible for regulatory abilities continue to mature during adolescence, the brain is especially susceptible to environmental influences. As such, exposure to adverse peer experiences may undermine emotion regulation development. Thus, the present review sought to elucidate the association between adverse peer experiences and emotion regulation in adolescence (i.e. age 12-17 years). Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review of the literature assessing adverse peer experiences (victimization and rejection) and emotion regulation (including neurobiological, behavioral, cognitive levels of analysis) was conducted (Narticles included = 27). Results demonstrate that adverse peer experiences are negatively associated with emotion regulation processes, behaviorally and neurally. Although variability in definitions and measurement of constructs make nuanced comparisons between studies difficult, the present systematic review organizes this body of literature and discusses how promising theoretical perspectives, including the cognitive control of emotion model and social information processing theory, may help to explain this association. Finally, recommendations for future work to expand our understanding of these processes, and for intervention and prevention efforts (e.g., school-based violence prevention and socio-emotional learning programs, parenting practices) that may serve to ameliorate outcomes for youths facing adverse peer experiences and emotion dysregulation, are discussed.

During adolescence, peer relationships take precedence and there is a normative increase in social anxiety. Although prospective studies have suggested peer functioning and social anxiety can influence each other, their findings have not been examined systematically. We performed a systematic review and meta-analysis of prospective studies to examine the bidirectional relationship between peer functioning and social anxiety in adolescence.
EMBASE, PsycINFO, Medline, and PubMed were searched to identify relevant articles. Meta-analysis was conducted to examine the mean effect sizes of prospective associations between social anxiety and four dimensions of peer functioning. Moderator analysis was performed, with age, gender, time interval between baseline and follow-up assessment, and publication year as moderators.
Meta-analyses of 23 studies showed that friendship quality (r =-.11), peer rejection (r =-.06), and peer victimization (r =.23) were each associated with later social anxiety, but peer acceptance was not (r =-.11). Social anxiety at baseline was associated with prospective levels of friendship quality (r =-.11), peer rejection (r=.09), and peer victimization (r =.17), but not peer acceptance (r =-.14). Age moderated the association between friendship quality and prospective social anxiety. Other moderator effects were statistically non-significant.
Limitations include different classifications of peer functioning, the use of self-report measures, heterogeneity between studies, and underrepresentation of clinical samples.
A significant bidirectional association was found with social anxiety across three dimensions of peer functioning. Psychological prevention and intervention targeting peer functioning and social anxiety are indicated.