Concussion history in rugby union players is associated with depressed cerebrovascular reactivity and cognition

Recurrent contact and concussion in rugby union remains a significant public health concern given the potential increased risk of neurodegeneration in later life. This study determined to what extent prior‐recurrent contact impacts molecular‐hemodynamic biomarkers underpinning cognition in current professional rugby union players with a history of concussion. Measurements were performed in 20 professional rugby union players with an average of 16 (interquartile range [IQR] 13–19) years playing history reporting 3 (IQR 1–4) concussions. They were compared to 17 sex‐age‐physical activity‐and education‐matched non‐contact controls with no prior history of self‐reported concussion. Venous blood was assayed directly for the ascorbate free radical (A•− electron paramagnetic resonance spectroscopy) nitric oxide metabolites (NO reductive ozone‐based chemiluminescence) and select biomarkers of neurovascular unit integrity (NVU chemiluminescence/ELISA). Middle cerebral artery blood flow velocity (MCAv doppler ultrasound) was employed to determine basal perfusion and cerebrovascular reactivity (CVR) to hyper/hypocapnia (CVRCO2Hyper/Hypo). Cognition was assessed by neuropsychometric testing. Elevated systemic oxidative‐nitrosative stress was confirmed in the players through increased A•− (p