A comparative validation of sympathetic reactivity in children and adults.

This study provides comparative data on cardiac reactivity to common laboratory tasks in preschool children (ages 4.5-5.5 years) and young adults. We used a series of tasks (an emotionally evocative video, interview, reaction time task, and cold forehead pressor) to examine whether pre-ejection period, a common estimate of sympathetic cardiac activity in adults, provides a comparable measure of sympathetic reactivity to these tasks in preschool children. Our results demonstrate that the cardiac reactivity (pre-ejection period, respiratory sinus arrhythmia, and heart period) to such tasks in children and young adults is similar, but with smaller sympathetic reactivity in children. The consistency of the reactivity across tasks within individuals and consistency of reactivity across children and young adults suggests that pre-ejection period is a reasonable estimate of sympathetic activity in children.