# Respiratory Sinus Arrhythmia—Common and Distinct Mechanisms of Emotional Adjustment in the Depressive and Anxiety Disorders Spectrum?

## TL;DR

The study explores how heart rate variability, measured by RSA, relates to emotional regulation in depression and anxiety disorders, finding stronger links with depression.

## Contribution

The study is the first to show that RSA indices can serve as biomarkers for common and distinct mechanisms in depression and anxiety.

## Key findings

- Lower resting RSA is associated with both depression and anxiety, but RSA reactivity is more strongly linked to depression.
- Better RSA reactivity predicts better treatment outcomes in depression, not anxiety.
- RSA indices may help assess shared and unique mechanisms in depression and anxiety.

## Abstract

Respiratory sinus arrhythmia (RSA) reflects the activity of a cortico‐limbic control system, enabling the flexible regulation of cardiac output via the parasympathetic nervous system. We assessed two markers of RSA, that is resting RSA (rRSA) and RSA reactivity (ΔRSA) and evaluated their common and distinct role for regulating emotional reactivity across depressive and anxiety disorders and their treatments. We recruited samples of healthy controls and patients with anxiety and depressive disorders, assessed rRSA during baseline and ΔRSA as RSA change from baseline to viewing emotional films. Patients then underwent disorder‐specific cognitive behavior therapy. Although both patient groups exhibited lower rRSA than controls, depression—but not anxiety—symptomatology was transdiagnostically associated with less rRSA and ΔRSA. Complementing these depression‐specific results, better ΔRSA predicted better treatment outcome in depression, but not anxiety. Our data confirm RSA as a transdiagnostic marker for mood and anxiety, support recent attempts toward transdiagnostic, dimensional classification systems (HiToP, RDoC) and provide evidence for a more robust association of RSA with depression symptomatology and treatment. This renders rRSA and ΔRSA potential markers to assess common and distinct mechanisms associated with depression and anxiety.

On the one hand, our data confirm previous findings on a relationship between low resting RSA and depression and anxiety. On the other hand, our data provide compelling new evidence for a more robust association of flattened RSA reactivity with depression symptomatology and depression treatment as compared to anxiety. Our study is thus the first to demonstrate that different indices of RSA (resting RSA, RSA reactivity) constitute potential biomarkers to assess common and distinct emotion‐related mechanisms underlying depression and anxiety and their treatments.