The effects of non-pharmacological interventions on vagally-mediated heart rate variability (vmHRV) in individuals with depression: A systematic review and meta-analysis

Objectives: This study seeks to explore the impact of non-pharmacological interventions (NPIs) on vagally-mediated heart rate variability (vmHRV) in subjects experiencing depression. Additionally, it aims to delineate the relationship between vmHRV alterations and the severity of depressive symptoms. Methods: Search was systematically performed on RCTs studies across various databases. These included Embase, the Cochrane Central Register of Controlled Trials, Medline via EBSCO, PsycINFO accessed through ProQuest, and the Web of Science, capturing all entries until March 11, 2024. Results: The analysis revealed that NPIs generally exerted small to moderate beneficial effects on cardiac parasympathetic nervous system (PNS) markers such as the root mean square of successive differences (RMSSD) ([SMD] = 0.266, 95 % confidence interval [CI] 0.029–0.503) and high-frequency power (HF) (SMD = 0.178, 95 % CI 0.018–0.337). Specifically, mind-body exercises demonstrated moderate to large enhancements in RMSSD (SMD = 0.689, 95 % CI 0.265–1.112) and a moderate improvement in HF (SMD = 0.498, 95 % CI 0.134–0.863) immediately following the interventions. Conversely, psychological interventions did not show significant immediate post-intervention vmHRV enhancements; however, subsequent assessments revealed a moderate increase in HF (SMD = 0.477, 95 % CI 0.177–0.786) during short-term follow-ups. Moreover, substantial correlations were observed between vmHRV improvements and reductions in depression severity. Conclusions: Our findings indicated that NPIs effectively enhance vmHRV and reduce depressive symptoms. This underscores the effectiveness of both mind-body exercises and psychological interventions. Furthermore, alterations in vmHRV may serve as viable predictors for the success of depression treatments.