Enhancing the brain's emotion regulation capacity with a randomised trial of a 5-week heart rate variability biofeedback intervention

Heart rate variability is a robust biomarker of emotional well-being, consistent with the shared brain networks regulating emotion regulation and heart rate. While high heart rate oscillatory activity clearly indicates healthy regulatory brain systems, can increasing this oscillatory activity also enhance brain function? To test this possibility, we randomly assigned 106 young adult participants to one of two 5-week interventions involving daily biofeedback that either increased heart rate oscillations (Osc+ condition) or had little effect on heart rate oscillations (Osc- condition) and examined effects on brain activity during rest and during regulating emotion. In this healthy cohort, the two conditions did not differentially affect anxiety, depression or mood. However, the Osc+ intervention increased low-frequency heart rate variability and increased brain oscillatory dynamics and functional connectivity in emotion-related resting-state networks. It also increased down-regulation of activity in somatosensory brain regions during an emotion regulation task. The Osc- intervention did not have these effects. These findings indicate that heart rate oscillatory activity not only reflects the current state of regulatory brain systems but also changes how the brain operates beyond the moments of high oscillatory activity.