Testosterone and cortisol jointly mediate and modulate trust behavior in early adolescence.

During early adolescence, individuals undergo significant changes in neuroendocrine systems, neurodevelopment, and social sensitivity. Placing trust in the appropriate person becomes especially crucial for adolescents, given their increased peer interaction and heightened susceptibility to peer influence during this period. Adolescents take social distance into account when making trust decisions. However, the biological and cognitive mechanisms involved in trust decision-making towards peers of different social distances remain unclear. The present study investigated the interactions among hormonal (basal cortisol and basal testosterone), cognitive (impulsivity and theory of mind), and contextual (friends and strange peers) factors underlying trust decision-making in a sample of 142 adolescents (45 % females, Mage = 12.32 years, SDage = 0.60). Using a balloon analog risk task, a cartoon story reasoning task, and a modified version of the trust game, we assessed adolescents' impulsivity, theory of mind, as well as trust investment and evaluation of return possibility towards their friends and strangers, separately. The results showed a unique hormonal-cognitive-contextual mechanism underlying trust investment, despite adolescents demonstrating a preference for trusting friends over strangers in both trust investment and trust evaluation. Cortisol predominantly influenced adolescents' general trust, directly and indirectly through impulsivity. Testosterone appeared to modulate the indirect effect of cortisol via impulsivity on general trust and impacted their strategic trust decisions through the theory of mind. These findings highlight the role of cortisol and testosterone in trust and its potential cognitive process and provide guidance for tailored interventions for promoting healthy social development.