Changes in Phasic Heart Rate Variability Predict Clinical Outcomes Following Emotion Regulation Therapy for...

Generalized anxiety disorder (GAD) and major depressive disorder (MDD) frequently co-occur and are marked by greater chronicity, severity, and poorer treatment response. Perseverative negative thinking (e.g., worry, rumination) is a transdiagnostic mechanism implicated in both disorders and linked to disruptions in large-scale neural networks, threat and reward processing, and vagal modulation. Heart rate variability (HRV)-particularly phasic HRV (vagal reactivity/recovery)-is a peripheral marker of autonomic flexibility and dynamic emotion regulation that may be sensitive to therapeutic change. Yet few studies have tested whether evidence-based treatments modify phasic HRV and whether such changes predict clinical outcomes. Twenty-four adults with GAD ± MDD completed 20 sessions of Emotion Regulation Therapy. At pre- and midtreatment, participants completed laboratory emotion inductions (baseline, fear, sadness, recovery) while cardiac activity was recorded; community controls (n = 28) completed the same paradigm once. Patients self-reported anxiety, depression, worry, rumination, functional impairment, and quality of life at pre-, mid-, and posttreatment. Relative to controls, patients exhibited lower tonic HRV and marginally blunted phasic HRV during a sadness induction. During fear, patients showed decreased HRV from fear to recovery, whereas controls remained stable. From pre- to midtreatment, patients demonstrated improved vagal fear recovery, and greater improvements predicted lower posttreatment GAD severity, worry, and functional impairment, accounting for 12-29% of the variance. These findings preliminarily support vagal fear recovery as a modifiable, objective marker of treatment response in patients with GAD ± MDD. Limitations include small, demographically homogeneous samples and the absence of a midtreatment control group. Future work should incorporate ambulatory physiological monitoring to assess whether these effects generalize to daily life.