B-105: Autonomic Reactivity in Concussed Adolescents: Heart Rate Variability Changes From Baseline to Post-Stress Recovery
Abstract
Objective: Autonomic nervous system (ANS) dysfunction may mediate concussion recovery. Using heart rate variability (HRV) as an index of ANS responses to stress, we examined autonomic recovery to cognitive and physical stressors in adolescents with post-acute concussion. We also explored the relationship of working memory performance and post-stress HRV recovery. Method/Data Selection: Adolescents aged 11–17.99 years within 7–35 days post-concussion (n=305) completed ECG at baseline and for 5-minute recovery following the Paced Auditory Serial Addition Test (PASAT) and hand grip (HG) challenge. Root mean square of successive differences (RMSSD), respiratory sinus arrhythmia (RSA), low-frequency HRV (LF-HRV), and mean HR were computed. Linear mixed-effects models with FDR-corrected correlation analyses evaluated longitudinal change. Results/Data Synthesis: HR and most HRV metrics significantly increased compared to baseline following both the PASAT and HG task (ps<.001). RMSSD was only significantly increased following HG compared to baseline (b=4.04, t=4.37, p<.001). HR decreased significantly from post-PASAT to post-HG (p<.001), while RMSSD (p<.001) and RSA (p=.04) increased over the same interval. Despite robust autonomic reactivity, no HRV variables were associated with PASAT performance after FDR correction; however, HR demonstrated a small, positive association between HR and PASAT omissions following HG (rho=0.14, p=.02), which was not significant after correction. Conclusions: HR and HRV response to cognitive and physical stressors indicate dynamic ANS engagement following concussion. However, these dynamics were not significantly related to working memory performance. Small effect sizes suggest that autonomic reactivity and working memory may represent partially independent dimensions of post-concussion recovery. Future studies should compare to control groups and covary for sex and age effects.