The autonomic nervous system (ANS) has demonstrated utility for identifying alterations in emotion processing associated with common psychopathology, including depression and anxiety. To date though the majority of this ANS research has several limitations. Most studies have examined parasympathetic and sympathetic branches separately, requiring activity in the other branch be inferred. This is problematic as each branch may function independently. Composite indices such as cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR) which examine the relative input between respiratory sinus arrhythmia (RSA) and pre‐ejection period (PEP) should provide more comprehensive measures of autonomic functioning and thus stronger predictors of psychopathology. However, the sympathetic branch is driven by multiple neurotransmitter systems, thus PEP does not necessarily reflect overall SNS arousal. We propose two new metrics for assessing ANS functioning associated with psychopathology: parasympathetic effects on cardiac control (RSA) relative to sympathetic effects on the eccrine system (electrodermal activity, EDA), which we term cross‐system autonomic balance (CSAB) and regulation (CSAR). Eighty‐five women (18–37) completed a baseline physiological assessment with parasympathetic (RSA) and sympathetic indices (PEP, EDA), along with self‐reported depressive and anxiety symptoms. Lower CSAB, indicating sympathetic dominance driven by cholinergic neurotransmission, was associated with higher depressive and anxiety symptoms. Lower CAB indicating sympathetic dominance driven by beta‐adrenergic neurotransmission was associated specifically with depressive symptoms. CSAB was a more robust index than RSA. Results support the utility of assessing multiple composite ANS indices for identifying physiological substrates of alterations in emotion regulation associated with internalizing disorders.

Background Exposure therapy is the gold standard for treating childhood anxiety, yet not all youth improve. Children do not always have insight on their distress, which can limit the utility of self-reported units of distress (SUDS) during exposures. Physiological assessment provides an objective means of monitoring emotional arousal. Electrodermal activity (EDA) in particular indexes sympathetic nervous system arousal which is heavily linked to anxiety. The aim of the current study was to examine the feasibility and utility of incorporating EDA assessment in an in-session exposure. We examined concordance between EDA and SUDS, and whether either predicted treatment response. Methods Thirty-four youth who met DSM-5 criteria for generalized, separation, and/or social anxiety disorder completed brief CBT (8 sessions) and completed a survey on trait physiological arousal. EDA and SUDS were collected from 18 youth (9 female, ages 9–14) during a mid-treatment exposure. Changes in anxiety severity were examined post-treatment. Results SUDS were not correlated with trait or state physiological arousal. There was a large association between heightened sympathetic arousal and poorer post-treatment response. Similarly, SUDS indices of greater fear activation and habituation were associated with poorer post-treatment response with a small to moderate effect size. Supplemental analyses among the full sample aligned: trait physiological arousal predicted poorer treatment response. Conclusions The lack of concordance between sympathetic arousal and SUDS indices highlights the limitations of relying solely on SUDS with pediatric populations. EDA provided unique data on youth’s distress during exposures. Thus, results indicate that physiological assessment may exhibit clinical utility for aiding clinicians in monitoring youth’s progress in exposure therapy. Trial Registration ClinicalTrials.gov Identifier: NCT02259036.