A Transdiagnostic Pilot Study of the Efficacy of Respiratory Rate–Based Biofeedback in the Treatment of Depressive Symptoms

The goal of this study is to evaluate the efficacy of respiratory rate-based biofeedback as an adjunctive intervention for depressive symptoms in hospitalized patients with affective and anxiety disorders. This prospective pilot study will include 80 inpatients with clinically significant depressive symptoms (MADRS ≥ 10). Participants will be allocated in alternating order to either (1) standard pharmacotherapy combined with 10 sessions of respiratory biofeedback delivered via the ReviSide virtual reality system over two weeks, or (2) standard pharmacotherapy alone. Depressive and anxiety symptoms will be assessed using the Montgomery–Åsberg Depression Rating Scale (MADRS) and the Hamilton Anxiety Rating Scale (HARS) at baseline and after 20–27 days (or at discharge). The primary outcome is the between-group difference in MADRS score at follow-up, adjusted for baseline severity and covariates using ANCOVA. Secondary outcomes include treatment response rates (≥50% MADRS reduction), changes in HARS scores, tolerability, and exploratory predictors of treatment response. This study aims to determine whether respiratory biofeedback can serve as a feasible, safe, and effective adjunctive treatment in routine inpatient psychiatric care.