Cortisol and testosterone may influence how teens navigate trust in social situations

A new study has found that adolescents tend to trust their friends more than strangers, and this difference in trust is associated with variations in hormone levels, impulsivity, and social reasoning. The research highlights how biological and cognitive factors may relate to how adolescents navigate social relationships. The findings were published in Psychoneuroendocrinology.

Cortisol is a hormone released by the adrenal glands in response to stress. It follows a daily rhythm and helps regulate metabolism, immune function, and emotional responses. Higher or lower levels of cortisol can reflect how the body handles stress. Testosterone is a sex hormone associated with puberty, motivation for social dominance, and behavior regulation. While typically thought of as a male hormone, testosterone is present in both sexes and can affect behavior across a variety of contexts.

Both hormones increase during adolescence and are thought to influence how young people respond to social situations, including how they assess risk, interact with peers, and decide whether to trust others. But until now, few studies have looked at how these biological changes intersect with cognitive traits like impulsivity and theory of mind—the ability to understand others’ perspectives—to shape social behavior during early adolescence.

The research team, led by Rui Su and colleagues at Beijing Normal University, sought to understand how hormonal, cognitive, and social factors work together to influence trust in adolescents. Trust plays a key role in forming and maintaining social relationships, and adolescence is a time of heightened sensitivity to peer influence. Prior studies have shown that adolescents tend to trust friends more than strangers, but little was known about the biological and cognitive processes that support these decisions.

The researchers hypothesized that cortisol and testosterone would influence trust behavior both directly and indirectly, through their effects on impulsivity and theory of mind. They also believed that the degree of trust adolescents place in friends versus strangers would be shaped by these same variables.

The study included 142 typically developing adolescents, aged 10 to 14, from urban schools in Beijing. About 45% of the participants were girls. The study was conducted over two days. On the first day, participants collected saliva samples at home under parental supervision to measure cortisol levels. On the second day, the adolescents completed several tasks at school, including a trust game, a cartoon-based task to assess theory of mind, and a gambling task designed to measure impulsivity. Additional saliva samples were collected at school to assess testosterone levels.

In the trust game, each participant played the role of an investor who decided how many tokens to give to a friend or a stranger. The tokens given to the other player would triple in value, and the recipient could choose to return half or keep the full amount. The amount of tokens invested represented the level of trust, while the participants’ expectations of receiving a return were also recorded.

The theory of mind task asked participants to infer the intentions or feelings of characters in short cartoon stories. The impulsivity task required them to inflate virtual balloons to earn points, with the risk of losing everything if the balloon popped. More balloon explosions and risky pumps indicated higher impulsivity.

Adolescents invested more in friends than in strangers and believed their friends were more likely to reciprocate. These findings supported prior research showing that adolescents adjust their trust behavior based on social closeness.

Impulsivity was linked to a greater willingness to trust others in general, regardless of social distance. Adolescents who scored higher on impulsivity invested more tokens on average in both friends and strangers. However, this pattern did not extend to the difference between how much they trusted friends versus strangers. That distinction—called strategic trust—was instead related to theory of mind. Adolescents with stronger theory of mind were better at adjusting their trust depending on whether they were interacting with a friend or a stranger.

Cortisol was found to have a complex relationship with trust. Lower basal cortisol levels were linked to higher impulsivity, which in turn was associated with greater general trust. At the same time, lower cortisol levels were directly associated with reduced general trust, suggesting that cortisol affects trust through both impulsive and reflective pathways. These findings support the idea that adolescents with lower cortisol may be more impulsive and more inclined to trust based on gut feelings, but may also have less overall willingness to invest in social relationships.

Testosterone, on the other hand, was positively linked with theory of mind and with strategic trust. Adolescents with higher testosterone levels were better at adjusting their trust levels depending on who they were interacting with. This effect was most apparent among boys. For them, testosterone increased theory of mind, which in turn predicted more strategic trust—investing more in friends and less in strangers.

The researchers also explored how cortisol and testosterone worked together. They found that when testosterone levels were low or moderate, cortisol had an indirect effect on trust through impulsivity. But when testosterone levels were high, this relationship disappeared. This pattern supports the idea that the two hormone systems interact in opposing ways, with testosterone potentially reducing the impact of cortisol on behavior.

The study sheds light on how adolescent trust decisions are shaped by stress and sex hormones, impulsivity, and social reasoning. But there are some limitations. The findings were based on a single point in time, so the researchers could not track how hormone levels or trust behaviors changed as adolescents aged. A longitudinal study would be needed to capture developmental changes.

The sample size also was not large enough to support more complex statistical models that might reveal additional relationships among the variables. Including brain imaging in future studies could also help explain how these hormone-related differences are reflected in brain activity during trust decisions.

Nevertheless, the findings suggest that adolescents appear to rely more on impulsivity when making general trust decisions and more on theory of mind when making strategic ones. Cortisol affects trust both directly and through impulsivity, while testosterone supports more selective trust through its link to theory of mind, especially among boys. The interaction between these two hormone systems may help adolescents balance the desire to build relationships with the need to protect themselves from social risk.

The study, “Testosterone and cortisol jointly mediate and modulate trust behavior in early adolescence,” was authored by Rui Su, Xuting Jiang, Xiang Ma, Huagen Wang, and Chao Liu.