Testosterone and cortisol modulate the effects of empathy on aggression in children.

This study aimed to analyze the potential moderating role of circulating testosterone, cortisol and estradiol levels on the attenuating effect of empathy on aggression in children. Participants were 139 children (80 boys and 59 girls) from the 3rd year of primary school (age 8). Their aggressive behavior was measured by the Direct and Indirect Aggression Scale, an instrument which uses peer rating; empathy was measured using the Empathy Quotient-Child Version. Hormone levels (testosterone, cortisol and estradiol) were analyzed using an enzymoimmunoassay technique in saliva samples. A regression analysis revealed an interaction effect of empathy x testosterone in girls, with higher levels of empathy corresponding to lower levels of aggression at both moderate and low testosterone levels. In boys, an interaction effect of empathy x cortisol was observed, with lower levels of empathy corresponding to higher aggression levels at moderate and high cortisol levels, and higher levels of empathy corresponding to lower aggression levels again at moderate and high cortisol levels. Our results indicate the importance of taking the interaction of psychological and biological factors into account in order to gain greater insight into the complex mechanisms underlying aggressive behavior.