Salivary cortisol levels are associated with resource control in a competitive situation in 19month-old boys

Abstract: Glucocorticoids (GCs) have been related to social rank in many studies across species, a particular rank giving rise to a particular stress-related physiological profile. Our aim was to examine the hypothesis that GCs levels in toddlers would be related to social dominance in a competitive resource situation. Subjects were 376 toddlers from the Quebec Newborn Twin Study. At 19months of age, each subject was exposed to 2 unfamiliar situations known to be moderately stressful at that age. Saliva was collected before and after the unfamiliar situations, to assess pre-test and reactive cortisol. Then the toddler reaction to a competitive situation for a toy with an unfamiliar peer was assessed and we measured the proportion of time the child controlled the resource. In girls, no association between cortisol levels and the proportion of time the child got the toy was found. On the other hand, in boys, increased cortisol levels before the unfamiliar situation were significantly related to a decreased proportion of time they got the toy in the competitive situation (r 174 =−0.17, P =0.02). These results show that even in toddlers with limited social experience, association between GCs levels and social dominance can be found, an association that is specific to boys. [Copyright &y& Elsevier]