Intervention methods for improving reduced heart rate variability in patients with major depressive disorder: A systematic review and meta-analysis

INTRODUCTION: Several studies have demonstrated that patients with major depressive disorder (MDD) commonly show reductions in heart rate variability (HRV) parameters. Thus, interventions for the improvement of low HRV may be advantageous in treating MDD. This systematic review and meta-analysis aimed to explore the improvement effects of current clinical treatments on low HRV in patients with MDD. METHODS: Based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the PubMed, EMBASE, PsycINFO, and CNKI databases were searched for relevant literature. Interventional studies of patients with confirmed MDD, which included baseline and post-intervention data and at least one HRV parameter as an outcome indicator, were included for meta-analysis. RESULTS: Twenty-one studies were included in the review. Several studies affirmed the role of psychotherapy in improving low HRV in patients with MDD showing a significant increase in high-frequency and low-frequency power after psychotherapy in the meta-analysis. However, both pharmacotherapy studies and physiotherapy studies included in the meta-analysis showed significant heterogeneity. LIMITATIONS: The main limitation of this study was the relatively small samples for the meta-analysis, and more high-quality randomized controlled trials in this field are wanted. CONCLUSIONS: Psychotherapy was effective for improving low HRV in patients with MDD. However, the effect of pharmacotherapy or physical therapy on low HRV in MDD remains unclear. Regarding research methods, it is necessary to formulate and standardize operational guidelines for future HRV measurements.