Adults' Stress Response to Unexpected Oral and Arithmetic Tasks in Supine Position

To study the autonomic nervous system (ANS) and hypothalamus pituitary adrenal axis (HPA) response before and after mental stress test in healthy adolescents and adults, is the aim of this study. Twenty healthy adults (aged 23-46 years) entered the Trier Social Stress Test (TSST), after informed consent signing. The procedure was modified: (a) the participants' position was supine as ANS system changes were to be assessed, (b) the interviewers were entering and departing from the session room. Salivary cortisol (marker of HPA axis response) samples were collected at the end of the baseline and 20 min after TSST. ANS of the heart was measured with CNS Task Force Monitor in supine position and was recorded during relaxation (15 min) and after TSST. The sympathovagal balance (LF/HF ratio) for each phase was computed. Evaluations were conducted with R. The HPA axis disturbance between baseline and 20 min after TSST was significant (g = 0.545 [0.092, 0.999]) and in adolescents (whereas, the mean intervals of the sinus rhythm RR parameter were found largely changed (g = 0.834 [0.340, 1.327]). The sympathovagal balance component of heart rate variability LF/HF ratio was founded unchanged (g = 0.215 [-0.211, 0.641]). RR changes were not correlated to salivary cortisol concentrations at any phase. Mean RRIs and salivary cortisol levels were significantly increased, although HPA axis showed medium size effect. However, the systems effectively counterbalance the perturbation, since the LF/HF ratio does not change. Our findings suggest further research in stress effect on HPA and ANS cross-talk and dynamics.