Cardiorespiratory Stress-Response in Youth with Persistent Post-Concussion Symptoms

Abstract

ObjectiveTo evaluate cardiorespiratory response to a cognitive/emotional stressor in youth with persistent post-concussion symptoms (PPCS).BackgroundThe mechanisms of PPCS (symptoms lasting > 2 months) are poorly understood, but recent studies have emphasized the interactive effect of biopsychosocial factors during recovery. In particular, emerging evidence points to anomalies in autonomic functioning as a key player in PPCS. Autonomic functioning is best measured under conditions of stress; however, there are no current studies that examine autonomic functioning in response to cognitive/emotional stressors in youth with PPCS. Therefore, the present study sought to examine the autonomic response to a cognitive/emotional stressor as measured by a cardiorespiratory outcome (end-tidal CO2 fraction [ETCO2]) as well as cognitive performance metrics in youth with PPCS.Design/MethodsParticipants included 7 patients diagnosed with concussion and 7 non-injured controls between the ages of 13–25. Participants were administered a modified version of the Paced Auditory Serial Addition Test (PASAT), a neuropsychological task that is known to induce autonomic arousal. ETCO2 data were collected via continuous capnometry recording throughout the task and for 10 minutes after.ResultsAfter the PASAT, PPCS patients’ ETCO2 concentration remained stable over the 10’ post-stress period compared to controls who demonstrated a significant increase in ETCO2 (p < 0.05) after the cognitive/emotional stressor. In general, patients with PPCS performed more poorly on the middle trials of the PASAT compared to controls but comparisons were not significant.ConclusionsPPCS patients demonstrate abnormal cardiorespiratory functioning following a cognitive/emotional stressor in that their ETCO2 concentrations remain chronically low after stress. Results suggest autonomic dysregulation is a promising avenue for future research into the etiology of PPCS.