A Randomized Controlled Trial of Heart Rate Variability Biofeedback Explores Cardiac Autonomic Control as a...

Cardiac autonomic regulation has been proposed as a critical psychophysiological linkage supporting cognitive and social cognition. While heart rate variability biofeedback (HRVB) has demonstrated robust effects on stress reduction, its potential role in supporting social cognition-particularly theory of mind (ToM)-and the underlying psychophysiological mechanisms remain unclear. This randomized controlled trial examined the effects of a six-session HRVB intervention with preset-paced breathing on social cognition and executive functions in young adults with high perceived stress, and explored whether HRVB-induced changes in cardiac autonomic activity may serve as a psychophysiological mechanism linking the intervention to improvements in social cognition beyond executive function changes. As a manipulation check, participants receiving HRVB (n = 32) showed significant reductions in heart rate, respiratory rate, and perceived stress, accompanied by increased cardiac parasympathetic activity and decreased cardiac sympathetic activity, compared with the control group (n = 32). Significant group × time interaction effects were observed for distinct ToM performances, as well as for executive functions. Importantly, exploratory parallel mediation analyses further revealed that HRVB-induced changes in cardiac autonomic activity mediated improvements in overall ToM performance, whereas changes in cardiac sympathetic activity uniquely mediated improvements in cognitive ToM, even after controlling for executive function changes. Together, these findings provide intervention-based evidence suggesting that HRVB-induced modulation of cardiac autonomic activity is associated with a psychophysiological mechanism preferentially supporting social-cognitive function-particularly ToM-beyond executive control. HRVB may therefore represent a promising psychophysiological intervention for enhancing social-cognitive function in stress-vulnerable and high-arousal populations.