HJNO Jul/Aug 2026

CTE 22 JUL / AUG 2026 I  U.S. HEALTHCARE JOURNALS with outcomes. We hypothesized that the football cohort would perform worse on cognitive and neuropsychiatric measures compared with the controls and that greater RHI exposure from football play would be associated with worse cognitive function, greater subjective cognitive concerns, and greater depressive symptoms. METHODS Study Design The sample included male former Amer- ican football players enrolled in the Head Impact & Trauma Surveillance Study (HITSS). HITSS is a longitudinal, observa- tional, online study of former American football and soccer players 40 years or older from the US. HITSS is an extension of the University of California, San Francisco Brain Health Registry (BHR), an online demen- tia research registry for the longitudinal monitoring of more than 100 000 adults. 35 ,36 HITSS participants were recruited via separate channels than BHR participants (eMethods 1 in Supplement 1). HITSS aims to characterize risks of later-life brain health concerns among former American football and soccer players across all levels of play. HITSS participants complete BHR assess- ments, additional modules measuring RHI and TBI exposure, and cognitive and neu- ropsychiatric assessments. The 90-minute HITSS battery includes self-report ques- tionnaires pertaining to demographics, sports participation, TBI and medical his- tory, health behaviors, neuropsychiatric and neurobehavioral symptoms, and comput- erized cognitive tests. Participants are not compensated for task completion but are entered into a drawing for the opportunity to win a $500 gift card. HITSS participants must be 40 years or older, have played orga- nized soccer or American football at any level, and have computer access. This arti- cle focuses on American football. Partici- pants provided written informed consent. HITSS is approved by the Boston Univer- sity Medical Campus Institutional Review Board. This study includes data collected from participants’ baseline visits between March 7, 2022, andApril 9, 2025. This study adheres to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines. Samples The first substudy assessed HITSS par- ticipants who played football and BHR par- ticipants who denied RHI (Figure 1). Partici- pants were included in the football cohort if they self-identified as male, endorsed foot- ball as their primary sport, and indicated that they were no longer playing football. Many athletes play multiple sports, so to reflect the population of former foot- ball players, we did not exclude individu- als who played other contact sports (eg, soccer and ice hockey) or military service (eTable 1 in Supplement 1). Controls were male BHR participants 40 years or older who answered no to the following ques- tion: “Have you ever had a period of time in which you experienced repeated impacts to your head (eg, history of abuse, contact Derivation of the sample of American football players from the Head Impact & Trauma Surveillance Study (HITSS) and propensity score matched– controls without repetitive head impact (RHI) exposure. BHR indicates Brain Health Registry; ECog, Everyday Cognition Scale; GDS-15, Geriatric Depression Scale-15; PAL, Paired Associates Learning. Figure 1. Participant Flowchart and Sample Derivation