Discussion
anxiety, traumatic brain injury, brain injury, traumatic, post-concussive symptoms, TBI, depression, non-TBI, injuries
This study was the first randomized control study in support of self-regulation training using a psychophysiological intervention based on HRV-BF for those afflicted with mild traumatic brain injury. The use of HRV-BF was used to improve psychophysiological and neuropsychological functioning in individuals with mild traumatic brain injury. Several studies have demonstrated that HRV is reduced in individuals who have suffered a traumatic brain injury and that improvements in HRV are concurrent with functional recovery. In our results, compared to the psychoeducation group, the HRV-BF group had significant improvements in executive functioning, information processing, verbal memory, and emotional functions (anxiety, depression, and irritability).The current study results are consistent with previous findings in non-TBI populations, showing that a positive effect of HRV-BF may be observed on executive function, including attention, inhibition, and working memory (Bruin et al., In terms of emotional disturbances, our findings are consistent with previous findings and showed that participants in the HRV-BF group had improvement in emotional regulation in patients with TBI, including reducing depression (Lagos et al., The occurrence of PCS is common following a mild traumatic brain injury. Our results indicated that HRV-BF participants displayed significantly lower levels of PCS compared to those in the psychoeducation group between pre- and post-tests, which is consistent with the previous preliminary case study that indicated clinically significant improvements in post-concussive symptoms in a concussed patient (Lagos et al., As for HRV indices, the results of this study were consistent with Lagos et al. and Kim et al. who found increased LF and LF/HF of HRV from pre-and posttest in the HRV-BF group (Kim et al., This study had a relatively small sample size and targeted patients with mild traumatic brain injury (mTBI), so we cannot draw definitive conclusions and/or make suggestions for all forms of brain injury. It is also possible that the dose–response of the study interventions may differ between the psychoeducational group and the HRV-BF group. Each participant met with the researcher during the pre-test and post-test after brain injury. The HRV-BF group also met with the researcher for training sessions during the 10-session period. Participants in the HRV-BF group may be more motivated and more compliant than those in the psychoeducation group, which may affect the effectiveness of the intervention. However, for the purpose of reducing the influence of rapport between researchers and participants on the standardization of pretest and posttest administration, the researchers who administered the pretest or posttest were different from those who conducted the interventions. Future studies would benefit by using a sham biofeedback procedure such as that utilized by Bachman et al., (Despite the limitations of this small sample size study, this study contributes significantly to the mental health field with regard to understanding the benefits of cutting-edge treatment for mild brain injury patients in order to reduce the negative impact of these injuries on public health and patient wellbeing. In regards to the satisfaction of the participants with their treatment, the researchers did not formally ask the participants to provide written feedback, however, many participants in the HRV-BF group provided positive verbal feedback. For example, some participants told researchers and neurosurgeons that after HRV-BF intervention, their post-concussion symptoms significantly improved and helped them to improve their productivity after returning to work.In this study, HRV-BF interventions were found to modulate central-peripheral nervous system function in mTBI patients by enhancing HRV, stimulating the vagal nerve, and balancing sympathetic and parasympathetic activity. Additionally, HRV-BF interventions contributed to improvement in cognitively challenging tasks within a short timeframe. A particular significance of this study is its demonstration of the effectiveness of HRV-BF training in developing physiological and neuropsychological outcomes quickly without requiring significant cognitive effort. The HRV-BF intervention may be clinically feasible for rehabilitation in patients with mTBI. Further study with a larger sample size and long-term follow-up can be conducted to verify whether those with better recovery have better long-term brain injury prognosis, including fewer PCS, better cognitive functions, or higher HRV.