Risk for Later-Life Cognitive Impairment, Neurobehavioral Dysregulation, and Dementia in Former Soccer and American Football Players: The Head Impact and Trauma Surveillance Study (HITSS)

The project will create the Head Impact and Trauma Surveillance Study (HITSS) by leveraging the Brain Health Registry (BHR) at the University of California, San Francisco. A HITSS Module will be developed and added to BHR to assess contact and collision sports (CCS) history, repetitive head impact (RHI) exposure, and standardized neuropsychiatric measures. Participants will be recruited nationally, enrolling 1800 former soccer players (900 female, 900 male) and 1800 male former American football players, aged 40-75, across various levels of play. Two propensity-matched comparison groups (n=1800 each) without CCS or TBI history will be drawn from existing BHR participants. The study will test the hypothesis that greater cumulative RHI exposure increases risk for cognitive impairment, neurobehavioral dysregulation, and dementia, and that non-RHI factors will modify this effect. Data will be shared with researchers worldwide.