To determine how heart rate variability (HRV) can predict outcomes, such as fear avoidance behaviors, in persistent post-concussion symptoms (PPCS).

Currently concussion science lacks objective biomarkers to evaluate treatment. Autonomic measures, such as HRV remain abnormal in a significant portion of concussed patients. Wearable devices, such as the Oura Ring, that measure nocturnal HRV remotely will drastically expand longitudinal monitoring in concussion.

We are conducting a double-blind, placebo-controlled Phase II clinical trial to extinguish fear avoidance behavior and autonomic reactivity in PPCS. We deliver personalized transcranial magnetic stimulation (TMS) targeting a frontoamygdala circuit in adults with PPCS. Participants undergo 5 brain MRIs (resting-state and task-based fMRI, diffusion, anatomical), 1 pre- and 4 post-treatment, 10 days of TMS treatment with in-lab interbeat interval (IBI) before, during, and after stimulation, and at-home continuous tracking of sleep, activity, and HRV with the Oura Ring. To assess if at-home and in-lab HRV predict fear avoidance behaviors (rated on a published scale from 0-10 where higher scores mean more avoidance), we constructed regression models relating HRV with fear avoidance scores over time for 6 patients.

For the 4 weeks of treatment, participants were over 80% compliant in wearing the device. In 5 out of the first 6 patients in the trial, in-lab and at-home HRV showed weak to moderate negative correlations with fear avoidance scores across the 10 TMS sessions (R² 0.2-0.4). Overall, at-home nocturnal HRV (mean R² 0.4) was a stronger predictor of fear avoidance ratings than in-lab HRV (mean R² 0.2).

Autonomic measurements, such as HRV, collected at home by wearable devices may be useful in tracking fear avoidance. This supports the feasibility and utility of such devices as an adjunct in the clinical monitoring of concussion recovery and risk factors for prolonged symptoms.