Features of Autonomic and Hormonal Reactivity during Mental Activity in Children and Teenagers

Abstract

The autonomic and hormonal reactivity in the conditions of mental stress was studied in 248 children and adolescents aged 9–10 to 14–16 years. Changes in functional load level were evaluated based on the dynamics of heart rate variability (HRV) and the salivary cortisol level. A centile table was composed using the changes in these parameters during mental arithmetic tasks. Based on the table, six types of autonomic and hypothalamic-pituitary-adrenal reactivity were determined and gradations of deviations in various parts of the autonomic nervous system (ANS) refined. The reactivity of the ANS and hypothalamic-pituitary-adrenal axis (HPA-axis) was found to depend on the initial functional state and the age of subjects. In early adolescence, an increased level of psychoemotional stress associated with increased activity of the HPA-axis leads to a decrease in the reaction to mental stress. By an age of 14–16 years, the initial functional state of the ANS and HPA-axis tends to improve and, consequently, the reaction to mental stress is normalized.