Multimodal microglial and kynurenine pathway alterations across the affective-psychosis spectrum: a systematic review of patterns, heterogeneity, and dimensional implications.

The decision to take a risk is not straightforward and often uncertain. Individuals must weigh the potential consequences of their actions, but they often lack complete information about the possible outcomes. For example, when deciding to drive a scooter without a helmet, one must consider the likelihood and/or magnitude of possible injuries against the potential benefits. Given the inherent uncertainty of risky decisions, people might turn to others for information. In particular, adolescents’ tendency to take or avoid risks seems dependent on social signals from their peers; cautious peers can stimulate more safe choices, while peers with a riskier attitude can sway adolescents to make more risky choices (Braams et al., ; Cascio et al., ; Knoll, Leung, Foulkes & Blakemore, ). However, not all peers exert the same influence due to their social relationships; some may have higher social status, such as popular peers, while others may share more similarities, like best friends. In addition to the ambiguity in risk-decisions that stimulates adolescents to seek guidance from peers (Slagter et al., ), many risk-behaviours occur when peers are present. In these situations, risk-taking might not always be rational, driven by one’s risk assessment, but rather guided by what is socially accepted or what benefits one’s social status. To understand how adolescents’ risk behavior is influenced by their peers, it is essential to identify and understand which peers serve as a source of influence in a private and public context. This understanding is especially important for behavior change interventions that focus on adolescents’ social networks (Paluck et al., ; Veenstra & Laninga-Wijnen, ). This study therefore examined how two different peer sources within adolescents’ school-based social networks influence adolescents’ risky choices. Specifically, it investigated these influences in contexts where adolescents’ choices were either visible or not visible to their peers. Previous literature has identified two major sources that impact adolescent risk-taking: friends and popular peers. For example, adolescents’ perceptions of their popular peers’ substance use at high school predicted steeper increases in adolescents’ own substance use over a 2-year period (Helms et al., ), and exposure to anti-alcohol messages from peers with a high social status was shown to reduce adolescents’ willingness to drink (Teunissen et al., ). However, the impact of popular peers is mixed and not consistently observed (Field et al., ; Field & Prinstein, , but also see: Slagter, Gradassi, van Duijvenvoorde et al., ; Lansu et al., ). Furthermore, the impact of popular peers has been primarily established in comparisons to low-status peers only (e.g. Cohen & Prinstein, ; Teunissen et al., ). Remarkably, only a few studies have simultaneously examined the relative impact of friends and popular peers. For example, a longitudinal study showed that the injunctive norm of popular peers (i.e., adolescents’ perceptions of their peers’ attitudes regarding substance use) did not predict adolescents’ onset of substance use over time beyond the injunctive norm of friends (Field, ). In addition, an information sampling study showed that adolescents were mainly interested in receiving information from their friends but not from peers perceived as popular (Slagter et al., ). Thus, these studies suggest that the impact of friends may be larger than that of popular peers. As adolescents are exposed to both friends and popular peers in their daily lives, it will be important to directly assess the relative influence of friends and popular peers within the same study. The influence of friends and popular peers may vary depending on whether decisions are made in private settings, such as scrolling through Instagram at home, where choices remain confidential, or in public contexts, like being in the school canteen surrounded by classmates, where peers can observe and evaluate one’s choices. In these different contexts, different motives for behavioral conformity may be at play (Deutsch & Gerard, ; Cialdini & Goldstein, ).