UCLA

Persistent post-concussion symptoms (PPCS) extend well beyond the typical time course for concussion recovery and result in ongoing disability and suffering. For individuals who experience PPCS, little is known about what is causing their persistent symptoms and no gold standard treatment exists. The present study builds off the literature connecting autonomic nervous system (ANS) dysfunction and fear-avoidance to PPCS. In this study we propose a theoretical biopsychosocial model of PPCS and test the efficacy of a novel six-week home-based Cognitive Behavior Therapy (CBT) plus a biofeedback breathing training called Capnometry Assisted Respiratory Training (CART) for PPCS. We used a multiple baseline design (MBD) to examine treatment effects on avoidance, catastrophic thinking, ANS dysregulation, as measured by EtCO2 and pulse rate (PR), and post-concussion symptoms in a sample of 9 individuals with PPCS. MBD visual inspection and nonparametric randomization tests were used to examine changes in levels of activity engagement, pain catastrophizing and post-concussion symptoms between the baseline and treatment phases. Paired samples t-tests examined changes in a battery of self-report measures from pre- to post-treatment and at 6-weeks follow-up. Lastly multilevel mixed effects models examined how activity engagement, pain catastrophizing, EtCO2 and PR changed over the course of treatment, and whether these changes mediated treatment effects on post-concussion symptoms. Results revealed significant reductions in post-concussion sleep symptoms and trend-level reductions in post-concussion physical symptoms from the baseline to treatment phase; significant reductions in behavioral avoidance and distress, pain catastrophizing, and illness-related beliefs from pre- to post-treatment that were maintained at follow-up; and significant reductions in pain catastrophizing and post-concussion physical symptoms during the treatment phase. Further, tests of mediation suggest that targeting pain catastrophizing may help to resolve physical symptoms of PPCS, although results must be interpreted with caution as the indirect effect did not meet statistical significance. Our findings provide support for a fear-avoidance model of PPCS and suggest that CBT may be beneficial for reducing avoidance, unhelpful injury- and pain-related cognitions, and post-concussion symptoms in individuals experiencing PPCS. Data collected during CART add to the literature of ANS dysregulation in PPCS by demonstrating hypocapnia at rest in most of our sample. Our findings have potential implications for identifying patients most likely to respond to CBT, helping patients with PPCS return to prior functioning and reducing the economic burden of PPCS by offering an accessible and scalable intervention.