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Background: Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease thought to be caused, in part, by repetitive head impact (RHI) exposure and characterized by phosphorylated tau deposition with varying patterns in the cerebral cortex. Flortaucipir tau PET data from the DIAGNOSE CTE Research Project was examined to investigate tau PET patterns and its relation to RHI exposure in former professional and college American football players. Method: In this study, 218 DIAGNOSE CTE participants, ages 45‐74, with flortaucipir PET were included; 104 were former National Football League players (PRO), 58 were former college football players (COL), and 56 had no history of contact sports, other exposure to RHI, or traumatic brain injury (UE). Regional flortaucipir uptake was quantified using established procedures for three previously defined statistical regions (superior frontal, left parietal, and medial temporal) and compared across the three groups. Association analyses were also performed to examine the relationship between flortaucipir uptake and exposure to RHI using the cumulative head impact index for linear acceleration g‐force (CHII‐G). The potential clinical utility of flortaucipir PET for CTE was also investigated by examining its ability to differentiate participants meeting criteria for traumatic encephalopathy syndrome (TES) and probable or possible level of certainty for CTE pathology from those who do not meet those criteria. Result: Significantly higher flortaucipir uptake was observed in former football players than in participants without RHI exposure, controlling for age and race for the superior frontal region (Fig. 1A), left parietal, and medial temporal regions. Association between regional flortaucipir uptake and CHII‐G was only observed in the superior frontal region in former players (PRO+COL) 60 years and older (Fig. 1B) and no association was observed in the full PRO+COL group. Flortaucipir PET was not able to differentiate TES groups in former football players (Fig. 1C). Conclusion: Elevated flortaucipir uptake was observed in former American football players to a group of unexposed men. The association between flortaucipir uptake and exposure to RHI may require a long latent period to manifest. Further investigation of more sensitive tau PET tracers and quantification techniques is warranted to better characterize CTE related tau pathology. [ABSTRACT FROM AUTHOR]

Background: Repetitive head impact (RHI) exposure from the routine play of American football increases the risk of later‐life cognitive impairment and dementia from the neurodegenerative disease, chronic traumatic encephalopathy (CTE). Although neuropathological studies of CTE have found comorbid neurodegenerative and other pathologies, neuritic Aβ plaques are infrequent, particularly in early stages. However, amyloid PET imaging has not been fully characterized in cognitively impaired former American football players. Method: In this cross‐sectional, observational cohort study from the DIAGNOSE CTE Research Project, florbetapir PET mean cortical standard uptake value ratios (SUVR) and positivity (defined by average SUVR >1.10, indicative of moderate‐to‐frequent neuritic Aβ plaques), were analyzed in 119 former professional (PRO) National Football League players, 60 former college football players (COL), and 58 men unexposed (UE) to RHI who were cognitively asymptomatic. Former players were categorized into one of four diagnostic groups: cognitively normal (CN), subjective memory complaints (SMC), mild cognitive impairment (MCI), and dementia (DEM). All participants were 45‐74 yo. Multivariable linear and logistic regressions were conducted, with race, education, age, and APOE4 genotype included as covariates. A priori power calculations demonstrated adequate power to detect significant findings Result: No differences between the three exposure groups in average florbetapir SUVR or proportion of elevated florbetapir uptake were found. Pairwise group comparisons resulted in no differences in average SUVR between PRO and COL (‐0.01, 95% CI [‐0.033, 0.025], p = 0.95), PRO and UE (0.02, 95% CI [‐0.010, 0.029], p = 0.41), and COL and UE (0.02, 95% CI [0.0004, 0.039], p = 0.36). Analysis of covariance resulted in no differences among diagnostic groups (F = 0.94, p = 0.43). Neither years of playing football nor measures of cognition and daily functioning showed significant associations with florbetapir SUVR. Conclusion: Former professional and college American football players with cognitive impairment and dementia did not have elevated florbetapir amyloid PET compared to a group of men without RHI exposure. Their rates of florbetapir positivity in the football players were lower than expected for a group of men this age. These findings suggest that cognitive impairment in former elite football players may not be due to Alzheimer's disease pathology. [ABSTRACT FROM AUTHOR]

Introduction: The presentation, risk factors, and etiologies of white matter hyperintensities (WMH) in people exposed to repetitive head impacts are unknown. We examined the burden and distribution of WMH, and their association with years of play, age of first exposure, and clinical function in former American football players. Methods: A total of 149 former football players and 53 asymptomatic unexposed participants (all men, 45–74 years) completed fluid‐attenuated inversion recovery magnetic resonance imaging, neuropsychological testing, and self‐report neuropsychiatric measures. Lesion Segmentation Toolbox estimated WMH. Analyses were performed in the total sample and stratified by age 60. Results: In older but not younger participants, former football players had greater total, frontal, temporal, and parietal log‐WMH compared to asymptomatic unexposed men. In older but not younger former football players, greater log‐WMH was associated with younger age of first exposure to football and worse executive function. Discussion: In older former football players, WMH may have unique presentations, risk factors, and etiologies. Highlights: Older but not younger former football players had greater total, frontal, temporal, and parietal lobe white matter hyperintensities (WMH) compared to same‐age asymptomatic unexposed men.Younger age of first exposure to football was associated with greater WMH in older but not younger former American football players.In former football players, greater WMH was associated with worse executive function and verbal memory. [ABSTRACT FROM AUTHOR]

Background: Inflammatory cytokines and chemokines related to the innate and adaptive immune system have been linked to neuroinflammation in Alzheimer's Disease (AD) dementia. We hypothesized that individual blood‐based inflammatory biomarkers would associate with cognitive function, brain magnetic resonance imaging (MRI) volumes, and risk for dementia in Framingham Heart Study (FHS) participants. Method: Protein biomarkers related to immune cells or associated with inflammatory responses including CD14, CD163, CD5L, CD56, CD40L, CXCL16, SDF1, DPP4, SGP130, sRAGE, and MPO were measured at FHS Offspring exam 7. We identified FHS Offspring participants who underwent neuropsychological (NP) testing (n = 2394) or brain MRI (n = 2135) within five years of the examination; and who were followed up 10 years after age 60 for incident all‐cause dementia (n = 1650). We used linear mixed effect models accounting for family relationships to investigate the associations between the protein biomarkers and NP test performance and brain MRI volumes and Cox proportional hazards models to examine the association with incident dementia. A false discovery rate (FDR) within each outcome set was computed to adjust for multiple testing and FDR ≤ 0.1 indicated significance. Result: Participants from the NP and MRI samples were on average 61 years old and 54% female. Participants from the incident dementia sample (mean age 68 years) included 126 incident dementia cases within 10 years. In addition to CD14 which has an established association, we observed significant associations between higher CD40L and MPO with poorer NP performance from the executive function domain. Higher CD5L levels were significantly associated with smaller total brain volumes (TCBV), whereas higher sRAGE was associated with larger TCBV. Associations persisted after further adjusting for APOE ϵ4 carrier status and cardiovascular risk factors. None of the protein biomarkers included were significantly associated with risk of incident dementia, with trend towards an association for CD5L. Conclusion: Since the proinflammatory factors CD5L, CD40L, sRAGE and MPO are associated with immune cells and are involved in vascular pathology, our study suggests the immune‐vascular axis is associated with cognitive and brain aging. If confirmed in other samples, our findings may provide informative biomarkers of abnormal brain aging. [ABSTRACT FROM AUTHOR]

Introduction: Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with repetitive head impacts (RHI) typically sustained by contact sport athletes. Post‐translation modifications to tau in CTE have not been well delineated or compared to Alzheimer's disease (AD). Methods: We measured phosphorylated tau epitopes within dorsolateral frontal cortex from post mortem brains with neither CTE nor AD (n = 108), CTE (n = 109), AD (n = 223), and both CTE and AD (n = 33). Results: Levels of hyperphosphorylated tau (p‐tau)202, p‐tau231, and p‐tau396 were significantly increased in CTE. Total years of RHI exposure was significantly associated with increased p‐tau202 levels (P =.001), but not p‐tau396. Instead, p‐tau396 was most closely related to amyloid beta (Aβ)1‐42 levels (P <.001). The p‐tau202:p‐tau396 ratio was significantly increased in early and late CTE compared to AD. Discussion: In frontal cortex, p‐tau202 is the most upregulated p‐tau species in CTE, while p‐tau396 is most increased in AD. p‐tau202 and p‐tau396 measurements may aid in developing biomarkers for disease. [ABSTRACT FROM AUTHOR]