Utility of Amyloid Beta and Tau Positron Emission Tomography Scans for Identifying Early-Stage Neurodegenerative Changes in Former Professional Football Players and Healthy Controls: Results from the Brain Health Initiative.

The aim of this study is to determine if there is a difference in tau and amyloid beta (Aβ) deposition on positron emission tomography (PET) scans between former players and controls, and if there is a differential association of the tau and Aβ deposition with concussion symptom burden. Participants completed the Rivermead Post-Concussion Questionnaire (RPQ) and PET imaging using Pittsburgh Compound B (PiB) and AV1451 ligands to identify uptake of Aβ and tau, respectively. Aβ standardized uptake value ratios (SUVR) and tau SUVR were compared between players and controls using a general linear model including age, race/ethnicity, years of education completed, and total number of prior sport-related traumatic brain injuries (TBIs) as covariates. A series of linear regression models were built to predict RPQ symptom scores including group status (player vs. control), Aβ SUVR and tau SUVR, and the interaction between group status and the Aβ SUVR and tau SUVR. Former players reported 4.9 ± 2.8 and control reported 1.4 ± 1.6 prior sport-related TBIs. Neither group reported any non-sport-related TBIs. Former players had higher RPQ symptom scores (13.3 ± 1.8) compared with controls (4.7 ± 1.8; p = 0.003). Controls had higher uptake for Aβ in the precuneus (1.22 ± 0.02) compared to players (1.14 ± 0.02; corrected p = 0.007). There were no differences between groups in uptake for Aβ in any other region of interest or tau in any region of interest. None of the regression models associating the interaction of group status and uptake with RPQ symptoms were significant. Aβ and tau PET scans may have limited utility for identifying potential neuropathological differences between participants with a career in professional football from controls who did not play football beyond high school. The PET tracer used for tau in the current study (AV1451) is well-suited for Alzheimer's disease-related tau pathology with limited binding for chronic traumatic encephalopathy-type tau proteins. A PET tracer for chronic traumatic encephalopathy-related tau deposition should remain a focus of future research.