Implications of respiratory sinus arrhythmia (RSA) inertia for child psychopathology: Direct effect and interaction with between-task RSA reactivity.

Respiratory sinus arrhythmia (RSA) inertia is the temporary dependency of RSA levels between consecutive epochs, which captures the epoch-to-epoch stickiness of RSA reactivity. Previous studies examining the developmental function of between-task RSA reactivity have yielded mixed findings and have often overlooked RSA reactivity within the task. The present study examined whether RSA inertia during a stress task was associated with subsequent changes in child psychopathology symptoms. To have a comprehensive understanding of the function of RSA reactivity, we tested whether RSA inertia interacted with between-task RSA reactivity to jointly predict changes in child psychopathology symptoms. Eighty-nine middle-to-high income Chinese parent-child dyads were recruited. Children ( = 8.77 years, = 1.80 years, 41 girls) participated in a 2-min and then a 4-min (a public speaking task), during which RSA was continuously recorded in the lab. Parents ( = 39.27 years, = 3.53 years, 67 mothers) reported on children's psychopathology symptoms in the lab and again 9 months later. Children with heightened RSA inertia tended to exhibit increased externalizing symptoms 9 months later. Moreover, RSA inertia interacted with between-task RSA reactivity to predict subsequent changes in externalizing symptoms. Children with the combination of lower RSA inertia and larger between-task RSA decreases had the lowest externalizing symptoms, suggesting an adaptive RSA reactivity pattern. Heightened within-task RSA inertia as well as reduced between-task RSA reactivity may help to identify children at risk for subsequent psychopathology symptoms, aiding in early intervention efforts. (PsycInfo Database Record (c) 2025 APA, all rights reserved).