Since the identification of robust, psychophysiological markers of trauma-related distress is critical for developing comprehensive, trauma-informed, mental health assessments for youth, the current study examined the clinical utility of cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR), two composite indices of the sympathetic and parasympathetic nervous system.
The study hypothesized that CAB/CAR would more reliably index post-traumatic stress (PTS) responses compared to measuring the parasympathetic (i.e., respiratory sinus arrhythmia; RSA) and sympathetic (i.e., pre-ejection period; PEP) nervous systems in isolation. The study sample was composed of 88 diverse, low-income youth (40.9 percent African-American and 36.4 percent White; 60.5 percent girls; Mage = 12.05 years; SDage = 1.57) who were at increased risk for adversity-exposure. RSA and PEP were measured during a 5-minute baseline period and 5-minute parent-child conflict discussion task. Adolescent-caregiver dyads completed a clinician-administered measure of the youth's lifetime trauma-exposure and current PTS. CAB represented the difference between RSA and PEP, and CAR was the summation of RSA and PEP. Analyses revealed that sympathetically oriented CAB reactivity uniquely (a) indexed PTS, especially in the context of elevated trauma, and (b) distinguished between those with and without PTSD. Findings highlight the translational promise of using physiological markers that account for the balance between the parasympathetic and sympathetic nervous system. (publisher abstract modified)