Social buffering of the cortisol stress response during the Minnesota Imaging Stress Test in Children.

introductionTo understand neural underpinnings of individual differences in physiological stress responding, most notably of the hypothalamic-pituitaryadrenocortical system, but also of the autonomic system, it is essential to rely on an imaging task that reliably elevates cortisol and measures of the autonomic nervous system activity, such as salivary alpha amylase. When the question also involves neural activity related to social stress buffering, it requires a task that shows differential stress responses as a function of varying social buffering partners. The purpose of this study was to examine whether the Minnesota Imaging Stress Test in Children (MISTiC) with social buffering conditions fulfilled these requirements.

method180 children ages 11 through 15 years (92 female) had salivary cortisol and salivary alpha amylase (sAA) samples taken during the MISTiC, a socially evaluative stressor modeled after the Trier Social Stress Test. Participants were randomly assigned to one of three social buffering conditions: Alone-No Buffer, Parent-as-Buffer, and Researcher-as-Buffer. Buffers interacted briefly with participants audiovisually at multiple points. Saliva samples for cortisol determination were taken 3 times during the hour preceding the MISTiC with the last serving as the pretest (T0) sample. Saliva was then collected post MISTiC at 25, 35, 45, 55, and 65 min after T0. The T0, 25, and 35 samples were assayed for sAA.

results61 % of participants showed a significant increase in cortisol in response to the stressor (i.e., 115 % or greater) with roughly the same showing an increase in sAA. Change from T0 was analyzed for cortisol yielding a significant trials by condition interaction (p < .05). Post-hoc tests showed a significant difference between the Parent-as-Buffer and both the Alone-No Buffer and the Researcher-as-Buffer conditions, thus indicating that parents were still effective buffers for the cortisol response in this age range. The only significant effect for sAA was a trials effect, p < .001 with the same being true for self-ratings of stress, p < .001. Puberty (pre/early vs mid/late) did not moderate the response of social buffering condition on cortisol or sAA.

conclusionThe MISTiC is effective in elevating cortisol, sAA and perceived stress. For cortisol, the method used for buffering yielded significant differences by buffer type, suggesting that this paradigm is appropriate for assessing the neural systems underlying the social buffering of stress. Contrary to our prior work, pubertal stage did not moderate the effectiveness of the parent in buffering the child's cortisol response.