Children's behavioral inhibition and anxiety disorder symptom severity: The role of individual differences in respiratory sinus arrhythmia.

Although behavioral inhibition (BI) is clearly identified as a temperamental risk factor for childhood anxiety psychopathology, much less is known about whether the strength of this association may vary as a function of parasympathetic nervous system regulation in children with anxiety disorders. To build upon extant research in this area, the present study examined whether respiratory sinus arrhythmia (RSA) can explicate the conditions in which BI is linked to increased symptom severity among anxiety-disordered children (N = 44; M = 9.61 years, SD = 1.63; 52% female and African American, respectively). We examined RSA responding both during a basal period and during a stressor ("challenge" RSA): interacting with a "mystery guest" who was wearing a mask. As hypothesized, the interaction between BI and both basal and challenge RSA was significantly related to anxiety disorder symptom severity, even after controlling for depressive symptoms. The form of the interaction indicated that highest levels of anxiety disorder symptoms were found among children with high levels of BI and low basal and challenge RSA, respectively. These data provide novel empirical evidence of a clinically-relevant interplay between RSA and BI in relation to anxiety disorder symptom severity among clinical youth. Future work is needed to expand on the specific mechanisms that may be responsible e for the interplay between temperamental and psychobiological risks for childhood anxiety.