Effects of heart rate variability biofeedback training on anxiety reduction and brain activity: A randomized active control study using EEG

Heart rate variability biofeedback (HRVBF) is a promising anxiety-reducing intervention that activates the autonomic nervous system through paced breathing, using feedback from heart rate variability (HRV). Many studies have reported the anxiety-reducing effects of HRVBF; however, reports on the effectiveness of training have been negative. Furthermore, the effects of training and the underlying brain activity changes remain unclear. This study aimed to examine the anxiety-reducing effects of HRVBF training and related brain activity changes, by randomly assigning participants, employing an active control group, and measuring anxiety-related attentional bias using the emotional Stroop task and EEG. Fifty-five right-handed healthy young students with anxiety were randomly assigned: finally, 21 to the HRVBF group and 19 to the control group. Both groups performed 10 training sessions of 20 minutes per day within three weeks and were assessed using HRV, EEG, attentional bias, and the State-Trait Anxiety Inventory-JYZ (STAI-JYZ), before and after training. Results showed increased HRV in the HRVBF group compared with the control group, but no differences in EEG, attentional bias, and STAI-JYZ. Further analyses revealed that participants with higher pre-training HRV achieved higher heart rhythm coherence in HRVBF training and had reduced attentional bias. This study suggests that individuals with higher HRV are more likely to be proficient in HRVBF training and benefit from its anxiety-reducing effects. The findings contribute to an understanding of participant selection and modification of HRVBF training protocols for non-responders.