Postmortem tau in the CA2 region of the hippocampus in older adult men who participated in youth amateur American-style football

BackgroundResearchers have reported that hyperphosphorylated tau (p-tau) accumulates in the Cornu Ammonis 2 subfield (CA2) of the hippocampus with age, preferentially in primary age-related tau astrogliopathy, in association with early Alzheimer's disease, and preferentially in chronic traumatic encephalopathy neuropathologic change.ObjectiveExamine the possible association between preferential p-tau in the CA2 region of the hippocampus and history of playing high school American-style football.MethodsPostmortem brain tissue samples were obtained from the Lieber Institute for Brain Development for 174 men (median age at death = 65 years; range = 50-96). There were 126 with no known history of participation in contact or collision sports and 48 (27.6%) who participated in football.ResultsApproximately half were rated modified Braak stage I (47.1%) and modified CERAD stage 0 (52.0%). Preferential CA2 p-tau was present in 29.9%. The average age for those with versus without preferential CA2 p-tau was 75 and 63, respectively (Cohen's d = -1.27, large effect).The sport history groups did not differ in age (p = 0.607). In both univariate and multivariate logistic regressions, older age groups (odds ratio [OR] = 3.42 and 3.23) and those with greater modified CERAD scores (OR = 1.78 and 1.48) were significantly more likely to have preferential CA2 p-tau. There was not a significant association between football participation and preferential CA2 p-tau.ConclusionsThere was not a significant association between participation in high school football and preferential CA2 p-tau identified after death. These results support other theories in the literature-that preferential CA2 p-tau is associated with aging and with Alzheimer's disease neuropathologic change.