Procedure

After recruitment, participants and their legal guardians will be provided with written information on background, aim, study procedure, risks and advantages of participation, data collection and privacy policy (T0, see Fig. 1). After obtaining informed and written consent by the children and adolescents and their legal guardians, participants will be screened for eligibility with semi-structured diagnostic interviews (see Psychological Measures) (T1, see Fig. 1). In a second appointment, the assessment of salivary hormone concentrations under stress conditions will take place (T2, see Fig. 1). Each appointment will last approximately 2.5 h. The TSST [33] (T2b, see Fig. 1) will be conducted in order to induce a psychological and physiological stress response in children (see Physiological Measures). See Fig. 1 for an overview of the trial procedure.

Schedule of Enrolment, Interventions and Assessments—Trial Procedure. TSST Trier Social Stress Test, WISC-V Wechsler Intelligence Scale for Children—V, WAIS-IV Wechsler Adult Intelligence Scale—Fourth Edition, M.I.N.I-KID 6.0 Mini-international Neuropsychiatric Interview for children and adolescents, SCARED-D Screen for Child Anxiety Related Emotional Disorders—German Version, SPAIK Social Phobia and Anxiety Inventory for Children, BAI Beck Anxiety Inventory, BDI-II Beck Depression Inventory-II, STAI State-Trait Anxiety Inventory, PDS Pubertal Development Scale, ECR-RC Experiences in Close Relationships Scale—Revised Child version, VAS Visual Analogue Scale for perceived stress, anxiety, insecurity, tension, OXT Oxytocin, CORT Cortisol, T2a Time previous to TSST, T2b TSST, T2c Time after TSST

All children and adolescents will receive a 50 € gift voucher for participating. In case a participant and legal guardian withdraw their consent from participating at any given time, the data already obtained will be destroyed or only considered if written permission is obtained.