PEP reward reactivity moderates the effects of RSA reactivity on antisocial behavior and substance use.

Integrating Polyvagal Theory and Reinforcement Sensitivity Theory (RST), we examined pre-ejection period (PEP) reward reactivity, which was suggested to index trait impulsivity, as a moderator between respiratory sinus arrhythmia (RSA) reactivity and antisocial behavior (ASB), and substance use in an urban male, adult sample. To understand the inconsistent findings between RSA reactivity and externalizing problems, we proposed to study both negatively and positively valenced tasks for RSA reactivity and to include PEP reward reactivity as a moderator for the RSA-behavior link. Data were collected from an urban sample of 131 male adults (active offenders, demographic controls, and college students). ICG (impedance cardiography) and ECG (electrocardiogram) were recorded, computing PEP (sympathetic nervous system activity marker) and RSA (parasympathetic nervous system activity marker), while participants completed the modified Trier Social Stress Test and a simple reward task. Reactivity was calculated by subtracting the baseline from the task activity. Consistent with prior studies, more RSA withdrawal to stress and less PEP shortening to reward predicted the most ASB and substance use. Less RSA withdrawal to reward and more PEP shortening to reward predicted the most ASB and substance use. We incorporated autonomic space, RST, and Polyvagal Theory to discuss our findings, and specifically highlight how clarifying what each reactivity captures based on the task demand (e.g., presence of social threat, need for vagal-mediated social affiliative behavior) can illuminate our understanding of the result patterns.