Nonlinear Moderation Effect of Vagal Regulation on the Link between Childhood Trauma and Adolescent Internalizing and Externalizing Symptoms.

Childhood trauma is a leading early adverse environment that increases psychopathological symptoms. Respiratory sinus arrhythmia (RSA) suppression to challenges as a marker of self-regulation is found to linearly moderate the link between early adverse experiences and psychopathological symptoms, but yielding mixed findings. The present study examined the relationships between childhood trauma and internalizing and externalizing symptoms via a 1.5-year longitudinal design and the quadratic moderation effect of RSA suppression on these relationships among adolescents. In November 2021 (T1), the final sample of 275 Chinese adolescents (Mage = 12.94, SDage = 0.79; 49.82% females) completed the short form of Childhood Trauma Questionnaire and the Achenbach Youth Self-Report-2001 and underwent a speech task during which their baseline RSA and stress exposure RSA were obtained. In June 2023 (T2), 251 adolescents completed the Achenbach Youth Self-Report-2001. Results showed that childhood trauma at T1 was positively correlated with internalizing and externalizing symptoms at T1 and T2. RSA suppression to stress quadratically moderated these associations, such that adolescents with moderate rather than higher or lower RSA suppression had the least internalizing and externalizing symptoms at T1 and T2 when exposed to childhood trauma. The findings suggest that moderate RSA suppression to stress as a marker of optimal vagal regulation buffers the risk of developmental psychopathology from early adverse experiences.