Background: Mental well-being and the risk of psychiatric disorders are significantly influenced by stress resilience. Traditional methods of measuring resilience often rely on subjective self-reports, which can be prone to bias. This limitation highlights the critical need for objective, biological, and physiological biomarkers to accurately assess resilience. Heart rate variability (HRV) has emerged as a promising candidate in this domain, potentially serving as a biomarker for mental health resilience (MHR). This article reviews the existing evidence supporting the use of HRV as such a biomarker.
Methods: This review focused on studies investigating the relationship between HRV and responses to laboratory-induced stressors in individuals without pre-existing medical or psychiatric conditions. HRV was measured through the decomposition of RR intervals obtained from electrocardiograms (ECG). A comprehensive bibliographic search was conducted in PubMed for publications within the period of January 2010 to September 2018.
Results: Eight relevant studies met the inclusion criteria for this review. The findings consistently indicated that higher vagally mediated HRV, measured either before or during stressful laboratory tasks, was associated with several indicators of enhanced resilience. These included improved cognitive resilience in the face of competitive or self-control challenges, more effective emotional regulation during emotionally demanding tasks, and better modulation of cortisol, cardiovascular, and inflammatory responses when exposed to psychosocial or mental stressors.
Limitations: It is important to note that all the studies included in this review were cross-sectional in design. This limits the ability to draw definitive conclusions about causality and the temporal relationship between HRV and resilience. Furthermore, the majority of studies focused on young participants, with some samples being limited to either males or females. The range of HRV indexes assessed was also limited across studies. Finally, the ecological validity of stressful laboratory tasks in reflecting real-world stress remains an open question.
Conclusions: The evidence suggests that vagally mediated HRV may serve as a valuable global index of an individual’s capacity for flexibility and adaptation when facing stressors. This supports the concept of HRV as a plausible, non-invasive, and readily applicable biomarker for mental health resilience. Future research should prioritize longitudinal studies, potentially leveraging wearable health devices to record HRV in naturalistic, real-life settings. This approach could yield more robust and ecologically valid insights into the role of HRV as a biomarker for resilience in everyday life.
