Mild traumatic brain injuries (mTBIs) are usually accompanied by post-concussion syndrome (PCS). Heart rate variability biofeedback (HRV-BF) has been shown to validate the neuro-peripheral relationship and enhance the interaction between top-down and bottom-up processes. A few studies have investigated the PCS treatment effects of HRV-BF in traumatic brain injury, but none have examined the treatment effect for each symptom of post-concussion syndrome. This study aimed to investigate the effectiveness of HRV-BF intervention for 16 commonly reported symptoms associated with mTBI and three PCS domains.

Forty-one participants with mTBI were referred from the neurosurgery outpatient clinic and randomly assigned to a psychoeducation group or an HRV-BF intervention group. The psychoeducation group received standard medical care and one 60-minute psychoeducation session. The HRV-BF group received standard medical care and one 60-minute session of the HRV-BF intervention weekly for 10 weeks. All participants completed a pre-, mid-, and post-test of the PCS self-reported measure at week 1 (pre-test), week 4 (mid-test), and week 12 (post-test), and generalized estimating equations (GEE) for repeated measures were used to estimate the intervention effects of the two groups.

Participants in the HRV-BF group experienced greater reduction in headache (β = -1.21, p < .001; β = -1.16, p < .001), dizziness (β = -.83, p = .003; β = -.83, p = .01), fatigue (β = -.88, p = .002; β = -1.07, p < .001), vomiting (β = -.45, p = .045; β = -.65, p = .039), insomnia (β = -.79, p = .003; β = -.89, p = .009), loss of energy (β = -.91, p < .001; β = -.96, p = .001), memory impairment (β = -.84, p < .001; β = -1.04, p < .001), psychomotor slowing (β = -.90, p < .001; β = -.80, p = .005), attention deficit (β = -.89, p < .001; β = -1.29, p < .001), depression (β = -.54, p = .009; β = -.78, p < .001), anxiety (β = -.55, p = .048; β = -.75, p = .009), and irritability (β = -.50, p = .049; β = -.54, p = .027) compared to the psychoeducation group at week 4 and week 10. Further subdividing symptoms into three domains, the HRV-BF group experienced greater reduction in physical (β = -.607, p < .001; β = -6.82, p < .001), cognitive (β = -2.62, p < .001; β = -3.13, p < .001), and emotional symptoms (β = -1.58, p < .001; β = -2.07, p < .001) compared to the psychoeducation group at week 4 and week 10.

The HRV-BF intervention was found to be more effective and efficient in reducing most post-concussion symptoms for participants with mTBI, and the improvement of physical symptoms was greater than that for cognitive and emotional symptoms.