Heart rate variability as a predictor of future depressive symptoms: A systematic review and meta-analysis.

Depression has limited early detection strategies. Heart rate variability (HRV), an indicator of autonomic regulation, has been linked to depression cross-sectionally, but its prospective value remains uncertain. We performed a meta-analysis and systematic review examining whether HRV is prospectively associated with later depressive symptom levels. PubMed, Embase, Cochrane, and PsycINFO (inception November 3, 2024) were searched for longitudinal studies of initially non-depressed baseline HRV and at least one-month follow-up assessing depressive or internalizing symptoms. Meta-analyses used multilevel random-effects models; prediction models were synthesized by HRV's statistical role. From 12,023 records, 56 studies entered the meta-analysis, and 62 the qualitative synthesis. HRV showed small but significant negative correlations with later depressive symptoms for frequency-domain indices (HF-HRV (r = -0.16, 95% CI -0.22 to -0.11), LF-HRV (r = -0.19, 95% CI -0.27 to -0.10), and VLF-HRV (r = -0.19, 95% CI -0.28 to -0.11)), and time-domain indices (RMSSD (r = -0.17, 95% CI -0.28 to -0.05) and SDNN (r = -0.15, 95% CI -0.26 to -0.03)). Across prediction-models, HRV showed direct effects in 43% and conditional effects in 57%, involving RSA and nonlinear patterns. HRV reflects psychophysiological mechanisms of depression vulnerability, but its prospective effects are small and context-dependent. Clinically, HRV may function as an adjunctive tool for identifying individuals who are more vulnerable to adversity and for informing preventive strategies, including the personalization of biofeedback and other regulation-focused interventions.