Military history and post-traumatic stress in former American football players: Modeling contributions to clinical outcomes.
Abstract
Background
Repetitive head impacts (RHIs) from American football or history of military service are associated with later-life cognitive decline and neurobehavioral dysregulation. However, contributions from cumulative exposures and associated susceptibility factors to outcomes are poorly understood. We investigated associations among years of football, history of military service, post-traumatic stress disorder (PTSD) and cognitive and neuropsychiatric function.
Methods
The sample included male former American football players enrolled in the online Head Impact & Trauma Surveillance Study (HITSS). Participants completed contact sport and history of military service questionnaires, and self-reported cognitive (ECog, BRIEF-A MI), computerized cognitive (CANTAB PAL) and self-reported neuropsychiatric measures (GDS-15, BRIEF-A BRI). Simultaneous equation modeling examined direct/indirect associations of football years and history of military service with outcomes, with PTSD as a correlated intermediate factor. Covariates included age, race, education and vascular composite score.
Results
Of 3055 participants, 2680 reported no history of military service and 375 reported history of military service. Greater years of football showed direct (ECog: β = 0.08; p < 0.001; BRIEF-A MI: β = 0.05; p = 0.006; GDS-15: β = 0.06, p = 0.001; BRIEF-A BRI: β = 0.09, p < 0.001) and indirect (ECog: β = 0.01; p = 0.025; BRIEF-A MI: β = 0.01; p = 0.025; GDS-15: β = 0.01, p = 0.027; BRIEF-A BRI: β = 0.01, p = 0.024) associations with self-reported outcomes, and direct associations with worse computerized PAL First Attempt Memory scores (β = -0.07; p = 0.025). In contrast, military participation was only associated with worse self-reported outcomes through indirect associations involving PTSD (ECog: β = 0.04; p < 0.001; BRIEF-A MI: β = 0.04; p < 0.001; GDS-15: β = 0.03, p < 0.001; BRIEF-A BRI: β = 0.04, p < 0.001).
Conclusions
Years of football play were directly associated with cognitive and neuropsychiatric outcomes, whereas history of military service contributed primarily through indirect pathways involving PTSD. Findings help clarify exposure-related risk and may inform clinical interpretation of RHI history.