Stress Induction and Cortisol Collection

An adapted version of the Trier Social Stress Test-Child (TSST-C;Buske-Kirschbaum, Jobst, Wustmans, Kirschbaum, Rauh & Hellhammer, 1997; Stroud, Foster, Papandonatos, Handwerger, Granger, Kivlighan & Niaura 2009) was administered. Participants first completed a 20-minute baseline period in which they watched G-rated movies and television shows, followed by three stressors. The stressors included a speech (5 minutes preparation plus a 5 minute speech), a mental arithmetic task (5 minutes), and a mirror-tracing task (5 minutes) performed in front of a “stern” two-member audience. Following the stress tasks, participants engaged in a 60 minute recovery period in which they watched G-rated movies and television shows, as well as completed questionnaires. During the TSST-C, saliva samples were collected from each participant by passive drool (Granger, Kivlighan, Fortunato, Harmon, Hibel, Schwartz & Whembolua 2007). In order to control for variability in cortisol levels due to conditions outside of the TSST-C, we asked study participants not to eat or drink 2 hours prior to the session, consume caffeine 24 hours prior, exercise 24 hours prior, or use alcohol or medications 48 hours prior. To optimize timing for assessment of cortisol response to the stress tasks, participant saliva was taken 15-20 minutes after each period of interest for a total of nine saliva samples (2 during the baseline period, 1 after the speech preparation to assess anticipatory stress, 1 after the speech, 1 after the mental arithmetic problems, 1 after the mirror-tracing task, and 3 throughout recovery period). After collection, the samples were frozen at −80 degrees Celsius until they were shipped on dry ice to the laboratory of Clemens Kirschbaum, Ph.D. (Dresden University of Technology), where cortisol measurements were assessed using a chemiluminescence-immuno-assay (CLIA) with high sensitivity (0.16 ng/ml; IBL, Hamburg, Germany). Both intra- and inter-assay coefficients for cortisol were below 8%.