Regulation of arousal and heart rate variability via biofeedback in severe traumatic brain injury.

• ¹ University of New South Wales, Psychology, Australia

Background: Severe traumatic brain injury (TBI) is known to result in impaired emotion regulation and arousal. Heart rate variability (HRV) is an index of autonomic (dys)regulation, reflecting the balance between sympathetic and parasympathetic influences on the central nervous system. Biofeedback techniques have been found to regulate disrupted HRV and alleviate symptoms in disorders associated with impaired arousal. The present study aimed to examine, whether adults with severe TBI show: i) HRV dysregulation at rest; ii) improved HRV regulation via a biofeedback intervention; as well as how these relate to aspects of emotion regulation. Methods: Thirty adults with severe TBI (Mean posttraumatic amnesia = 49.10 days; Range: 2.00 - 180) and 30 age-, education-, and gender-matched controls participated. Participants completed self-report measures of mood, emotional and cognitive empathy, and trait alexithymia. Relative reports of emotion regulation were also provided for TBI participants. Participants’ HRV and skin conductance levels (SCL) were measured under two 5-minute conditions: i) ’free-breathing’ (resting baseline); ii) ‘biofeedback’ (paced at 6 breaths per minute). Results: Among TBI participants, emotional empathy levels (p = .026), cognitive empathy levels (p < 0.01), and ability to identify and describe one’s own feelings, were all significantly lower compared to controls (p < 0.01). On the autonomic measures, HRV and SCL, there were no differences between the TBI and Control groups, either at rest or during biofeedback (all p > 0.05). Biofeedback training lead to significant increases (improvement) on all HRV measures (p < 0.05) and SCL (p = 0.014) for both groups. Higher HRV during biofeedback, and higher SCLs at rest and during biofeedback, correlated negatively with trait alexithymia subscales in both the overall sample and separate groups (p < 0.05), but not empathy, nor relative reports of emotion regulation (p > 0.05). Conclusion: These results suggest that HRV shows promise as an index of impaired autonomic regulation in severe TBI. Biofeedback training may help normalise HRV in severe TBI; improved autonomic regulation may ameliorate impairments on emotional self-awareness.