LAUSR

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to repetitive head impacts (RHI) such as those from American football. Our understanding of this association is based on research in autopsied brains since CTE can only be diagnosed postmortem. Such studies are susceptible to selection bias, which needs to be accounted for to ensure a generalizable estimate of the association between RHI and CTE. We evaluated the relationship between level of American football play and CTE diagnosis after adjusting for selection bias. The sample included 290 deceased male former American football players who donated their brain to the Veterans Affairs-Boston University-Concussion Legacy Foundation Brain Bank (VA-BU-CLF) between 2008 and 2019. After adjusting for selection bias, college and professional football players have 2.38 (95% simulation interval (SI): 1.16,5.94) and 2.47 (95% SI: 1.46,4.79) times the risk of being diagnosed with CTE relative to high school players, respectively, which are larger than estimates with no selection bias adjustment. Since CTE is currently diagnosed only post-mortem, we additionally provide plausible scenarios for the risk ratios of these populations where we consider the outcome affecting former players during their lifetime. In conclusion, this study provides further evidence to support a dose-response relationship between football play and CTE.