The impact of concussion on the cardiac autonomic nervous system of adolescents: a systematic review

Concussions pose a serious threat to adolescents, with potential long-term effects. This systematic review considers whether cardiac autonomic nervous system dysfunction occurs post-concussion in adolescents. Eight databases were searched on 30/5/24 using terms related to adolescents, concussion, and the cardiac autonomic nervous system. Included were full-text English articles comparing heart rate, blood pressure, or heart rate variability among adolescents with concussion history and controls. JBI critical appraisal tools assessed methodological quality. Meta-analysis was not performed due to inter-study methodological variations. Ten studies met the inclusion criteria. Two studies included participants with longer-term concussion histories. Eight studies involved exertion. Mixed results were found for all metrics. A greater percentage of results was significant during exertion; the lowest percentage was for resting heart rate variability (15%), whilst the highest was for heart rate under exertion (46.15%). Critical appraisal highlights methodological flaws. Studies often inappropriately manage confounding factors, and some selected controls inappropriately, such as using individuals with a history of concussion as controls. Evidence suggests possible cardiac autonomic dysfunction post-concussion, more apparent under exertion. Methodological limitations prevent definitive conclusions. Future research should better manage confounding factors to determine whether cardiac autonomic assessment can assist concussion diagnosis and management.