Background
•Repetitive head impact (RHI) exposure through contact sports (American football) or other sources (military service) is associated with later-life cognitive decline and neurobehavioral dysregulation
•Understanding the overlapping contributions of multiple RHI exposure sources is critical
Objective
Investigate associations among military history, years of American football play, post-traumatic stress disorder (PTSD) and cognitive and neuropsychiatric function.
Methods
Sample
•Male former American football players (aged ≥40) enrolled in the Head Impact & Trauma Surveillance Study (HITSS)
•Included players with and w/o history of military service
•HITSS: online longitudinal observational study that leverages the Brain Health Registry (BHR)
Measures and Outcome Domains
•Boston University RHI Exposure Assessment (BU-RHIEA)
•(1) Self-Report Cognitive Outcomes: ECog, BRIEF-A MI
•(2) Computerized Cognitive Outcomes: CANTAB PAL (First Attempt Memory Score [FAMS], Total Errors Adj.)
•(3) Self-Report Neuropsychiatric Outcomes: GDS-15, BRIEF-A BRI
Statistical Analyses
•Simultaneous equation modeling (SEM) examined direct and indirect associations of football years of play (primary) and military participation (secondary) with outcome domains.
•PTSD as a correlated intermediate clinical factor
•Covariates: age, self-identified racial group, education, vascular composite
•Models fit across three outcome domains. Z-scores used.
•Follow-Up: military participation replaced with military-related RHI exposure metrics
Results
•Greater years of football play directly associated with higher self-reported cognitive (1), neuropsychiatric (2) scores and PAL FAMS (3).
•Military participation not directly associated with any outcome.
•Military history indirectly associated with self-reported cognitive (1) and neuropsychiatric (2) outcomes.
•Military-related metrics of RHI exposure (combat history, breaching training, combatant training, counter-IED training) mirrored overall military participation.
Conclusions
•Years of football play were directly associated with later-life cognitive and neuropsychiatric outcomes.
•History of military service may contribute to long-term cognitive/neuropsychiatric vulnerability in former football players, potentially through mechanisms involving PTSD
•Helps clarify risk factors and patterns of vulnerability underlying cognitive and neuropsychiatric outcomes.
•Lays the groundwork for future clinician guidance for assessing and managing individuals with complex RHI exposure histories.
