Stein, Thor D.

Importance In vivo biomarkers for detecting neuropathologies from repetitive head impacts (RHI), including chronic traumatic encephalopathy (CTE), are needed. Objective To evaluate the utility of plasma phosphorylated tau 217 (p-tau217), assess its performance as a beta-amyloid (Aβ) biomarker in participants with RHI exposure at risk for CTE, and explore concordance with CTE neuropathology in a postmortem subsample. Design, Setting, and Participants This longitudinal, multicenter, case-control study used data from the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of CTE (DIAGNOSE CTE) Research Project, collected from September 2016 to October 2023. Participants were former American football players (case participants) and asymptomatic men unexposed to RHI (control participants). A subsample had available neuropathologic data. Exposures RHI, traumatic encephalopathy syndrome (TES) diagnoses, and levels of CTE certainty. Main Outcomes and Measures Plasma p-tau217 (classified as positive [≥0.63 pg/mL], intermediate [0.40-0.62 pg/mL], and negative [<0.40 pg/mL]), Aβ–positron emission tomography (PET; 18 F-florbetapir; with Aβ-positive defined as a standardized uptake value ratio [SUVR] ≥1.10), and tau-PET ( 18 F-flortaucipir). TES diagnoses were assigned by multidisciplinary consensus conference. Analyses of postmortem brains controlled for age, race, and APOE ε4 status. Results Among 231 participants (mean [SD] age, 57.75 [8.25] years), 177 were former football players (117 professional and 60 college) and 54 were unexposed participants. Former football players had higher baseline mean (SD) p-tau217 concentrations than unexposed participants (0.35 [0.26] pg/mL vs 0.27 [0.14] pg/mL; P = .008), although this was driven by a higher proportion of Aβ-PET–positive participants among former players. Plasma p-tau217 increased over time across the sample (B = 0.207 [95% CI, 0.117-0.298]; P < .001), with no significant time × exposure group interactions. Among football players, p-tau217 showed no time × group interactions with TES diagnosis, TES-CTE certainty, or RHI metrics. Higher p-tau217 concentration correlated with higher global Aβ-PET SUVR (B = 0.058 [95% CI, 0.053-3.501; P = .01), with a few discordant cases (5 participants were p-tau217–negative and Aβ-PET–positive; 7 participants were p-tau217–positive and Aβ-PET–negative). P-tau217 had similar areas under the curve for projecting Aβ-PET positivity as cerebrospinal fluid (CSF) p-tau181/Aβ42 and CSF Aβ40/42 measures (p-tau217: AUC, 0.88 [95% CI, 0.80-0.96]; CSF p-tau181/Aβ42: AUC, 0.89 [95% CI, 0.79-1.00]; CSF Aβ40/42: AUC, 0.85 [95% CI, 0.72-0.98]). Among 9 brain donors, 6 had CTE (stages II-IV; none with Alzheimer disease). Seven had negative or intermediate p-tau217, concordant with Aβ-PET. Two p-tau217 outliers with stage III CTE had normal concentrations upon additional testing. Conclusions and Relevance The findings of this study suggest that plasma p-tau217 concentration is unlikely to be useful for the detection of CTE, but it does show utility for ruling out Aβ pathology in participants at risk for CTE.

Abstract Background Cumulative head trauma, encompassing repetitive head impacts (RHI) and traumatic brain injury (TBI), has been associated with later‐life neurodegenerative disease. Studies on parkinsonism/Parkinson's disease (PD) have evaluated RHI and TBI in isolation, yielding mixed results. Cumulative head trauma may better predict PD risk. Objective To examine independent and cumulative effects of RHI through soccer participation and TBI history on PD diagnosis and age at diagnosis. Methods We used a cross‐sectional cohort design with data from the Fox Insight study. Participants completed self‐report questionnaires on PD diagnosis, TBI (no TBI, TBI with loss of consciousness [LOC], TBI without LOC), and sport participation. Multivariable logistic regressions examined the effects of soccer, TBI group, and their interaction on PD diagnosis. Cox proportional hazards examined associations with time to PD diagnosis. Covariates included age, sex, race, education, income, body mass index, heart disease/diabetes, and family PD history. Results Among 1231 participants (mean[SD] age = 66.12[10.60]), 278 played soccer (953 non–contact and collision sport [CCS] athletes). Participants reported no TBI (390[33%]), TBI without LOC (495[43%]), or TBI with LOC (258[23%]). Overall, 768(62%) reported a PD diagnosis (mean[SD] age at diagnosis = 59.02[9.86]). A significant soccer × TBI interaction indicated that soccer players with TBI with LOC had 2.6× higher odds of PD compared to non‐CCS athletes without TBI (OR [95% CI] = 2.600[1.085–6.305], P = 0.033). Former soccer players with TBI with LOC had a 15.6% higher hazard of early PD diagnosis (HR = 1.469, P = 0.027) compared to non‐CCS athletes with no TBI. Conclusion Cumulative head trauma (RHI + TBI) increased PD risk and lowered age at onset. © 2026 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Abstract INTRODUCTION Repetitive head impacts (RHI) from contact sports may cause a unique pattern of white matter hyperintensities (WMH) on T2‐weighted fluid‐attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI), termed RHI‐associated WMH (RHI‐WMH). These lesions are punctate, circular, and located at the gray–white matter boundary, an area vulnerable to trauma‐related damage. METHODS We investigated the association of RHI with these lesions in two aging cohorts: (1) former American football players versus asymptomatic unexposed men and (2) individuals with RHI from various contact sports versus non‐RHI participants. RHI‐WMH were assessed using visual ratings and a novel automated quantification pipeline. RESULTS Individuals with RHI had greater RHI‐WMH by both detection methods in both cohorts. RHI‐WMH were associated with plasma neurofilament light and p‐tau231, and flortaucipir positron emission tomography (PET) uptake. DISCUSSION RHI‐WMH may represent a new supportive biomarker for the detection of RHI‐related neuropathologies later in life.

Abstract Background In vivo biomarkers that can detect long‐term neuropathologies from repetitive head impact (RHI) exposure are needed, especially for the neurodegenerative tauopathy chronic traumatic encephalopathy (CTE). Here, we evaluated plasma p ‐tau217 as a potential biomarker for CTE p ‐tau pathology, and examined the concordance between plasma p ‐tau217 and Aβ pathology in an at‐risk for CTE sample. Method The sample included 180 male former football players (120 professional, 60 college), and 56 asymptomatic men without RHI (i.e., controls). Participants completed blood draws, 18F‐florbetapir (Aβ+=SUVR≥1.10), and 18F‐flortaucipir PET. Traumatic encephalopathy syndrome (TES) diagnoses were made. Single molecule array for plasma p ‐tau217 (ALZpath) was performed (≥0.6 cutoff used to maximize sensitivity). Nine participants had post‐mortem tissue. ANCOVA examined group differences in p ‐tau217 (football vs controls; TES‐CTE no, TES‐CTE suggestive, TES‐CTE possible/probable). Multivariable regression models tested associations between p ‐tau217 and florbetapir/flortaucipir PET. Covariates included age, race and APOE e4 . Result Sample characteristics are in Table 1. p ‐tau217 concentrations were higher in former football players compared to controls (est. marginal mean difference=‐0.217, p = 0.005). There were no group differences in Aβ‐PET SUVR. No differences were found across TES‐CTE certainty levels. In football players, higher p ‐tau217 was associated with higher Aβ‐PET SUVR (B=1.380, 95%CI[0.597‐2.155], p = 0.001) but not when Aβ+ ( n = 17) participants and those with kidney/liver disease ( n = 5) were excluded. Aβ+ participants had the highest p ‐tau217 (Figure 1). When compared against Aβ‐PET, several false Aβ‐positives (high p ‐tau217, Aβ‐) were identified, including one extreme outlier (assay related) and a cluster of Aβ‐ participants with p ‐tau217 between 0.60–1.0. There were no associations with flortaucipir SUVR (frontal, mesial temporal, left parietal). Two extreme p ‐tau217 outliers had autopsy‐confirmed CTE stage III (AD‐, Table 2). Of the remaining donors, all were AD‐ and four had CTE (stages II‐IV) with ptau217 between 0.125‐0.449. Conclusion Plasma p ‐tau217 has usefulness in quantifying Aβ pathology but restricted utility for detection of CTE. In this at‐risk for CTE sample, p ‐tau217 and Aβ‐PET were associated at the group level. At the individual level, false Aβ‐positives (and negatives) existed, including Aβ‐ participants with high p ‐tau217. We will explore whether this discrepancy is due to disease or peripheral interference with the N‐terminal binding in p ‐tau assays.

Abstract Background Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with repetitive head impacts (RHI). Autopsy studies show that RHI influences risk for other later‐life neuropathologies, particularly white matter and vascular injury. We have observed a unique pattern of white matter hyperintensities (WMH) on FLAIR MRI in people exposed to RHI (RHI‐WMH) characterized by small, discrete lesions near the depths of sulci (Figure 1a). The objective of this study was to characterize this pattern empirically in former American football players and to investigate neuropathology co‐localizing with the WMH. Method The sample included 164 male former football players ( n = 111 professional, n = 53 college) and 55 asymptomatic males without RHI from the DIAGNOSE CTE Project (Table 1). Visual ratings of WMH blind to the participant's RHI and clinical status were conducted to count lesions that were a.) within 1.0cm of the gray/white matter boundary, b.) as bright as the cortex, c.) spherical and d.) <1.0cm in size. ANCOVA compared groups on total number of WMH adjusted for age and vascular risk factors. We selected one individual (former professional player) with the typical RHI‐WMH pattern and who donated their brain for neuropathological examination. Guided by in vivo MRI, ex vivo MRI was done to locate the WMH near the depths of the sulci in the tissue. Tissue sections were tested for phosphorylated tau immunoreactivity and reactive astrocytes and microglia in areas surrounding the lesion seen on MRI. Result Number of RHI‐WMH was greater in football players compared to controls ( p = 0.007) (Figure 1b). Number of RHI‐WMH was greater in former professional players compared to controls ( p = 0.001) but not compared to the college players ( p = 0.983). In the neuropathology case study, we located the punctate RHI‐WMH on ex vivo MRI. Immunostaining revealed that the RHI‐WMH was adjacent to a sulcus with the pathognomonic CTE p ‐tau lesion and was characterized by myelin pallor, dense GFAP‐positive glial scarring, and increased total and activated microglia (Figure 2). Conclusion We provide empirical support for exposure to RHI as potentially leading to a unique pattern of WMH. Importantly, histopathological evidence showed that the RHI‐WMH co‐localized with RHI and CTE‐related neuropathologies at the depths of the sulci.

Abstract INTRODUCTION Few African American (AA) donors have been included in post mortem Alzheimer's disease (AD) studies compared to European‐ancestry (EA) individuals. METHODS We generated transcriptome‐wide bulk pre‐frontal cortex (PFC) gene expression data from 125 AA donors with neuropathologically determined AD and 82 AA controls. RESULTS Transcriptome‐wide significant differential expression was observed with 482 genes. The most significant, ADAMTS2 , showed 1.52 times higher expression in AD cases ( p = 2.96x10 −8 ). Comparison of findings with those from a recent gene expression study of EA brain donors revealed substantial concordance, including ADAMTS2 . Other associations not observed in EA results may be especially relevant to AD risk in the AA population. Examination of AA AD GWAS‐implicated variants identified several expression quantitative trait loci. CONCLUSION This first large‐scale AA brain AD gene expression study identified many differentially expressed genes, including ADAMTS2 , and supports gene expression as a molecular pathway underlying the impact of several AA AD risk variants. Highlights We performed the largest African American brain tissue Alzheimer's disease (AD) gene expression study. Expression differences for 482 genes, notably ADAMTS2 , were study‐wide significant. Many significant differentially expressed genes are involved in energy metabolism. Several previously known AD‐associated variants in African Americans are eQTLs. These results advance knowledge of the genetic basis of AD in the AA population.

AbstractBackgroundAlthough the rate of Alzheimer’s disease (AD) in African‐ancestry (AA) Americans is higher than that of persons from European‐ancestry (EA) populations, AA participants have been underrepresented in AD neuropathological studies.MethodUtilizing the AD Research Centers (ADRC) infrastructure, we obtained AA donor pre‐frontal cortex (PFC) tissue from brain repositories of 12 ADRC and generated bulk RNA sequencing (RNA‐seq) data for 179 samples that met QC and inclusion criteria. Previously generated PFC RNAseq data were obtained for 28 additional AA donors from the Columbia University ADRC. Differential gene expression was evaluated among 125 donors with a neuropathological diagnosis of AD (NIA‐Reagan intermediate or high likelihood) and 82 neuropathologically confirmed controls using regression models including covariates for age at death, sex, cell‐type frequencies, and RNA integrity number (RIN) calculated with Limma. FDR‐corrected p‐values (padj) were calculated to control for the 33,611 genes examined.ResultA total of 482 genes surpassed the multiple‐testing threshold. The most significant, ADAMTS2 (p = 2.96 × 10‐8, padj = 0.001), showed increased expression in AD cases (see Table/Figure). We note that ADAMTS2 was differentially expressed in a prior EA study of neuropathologically confirmed AD cases and controls (Panitch et al. Molecular Psychiatry 2021). Additionally, a recent analysis of cognitive resilience in EA neuropathological AD cases identified a strong association with ADAMTS2 (See Li et al. AAIC2024 abstract). Of the differentially expressed genes observed in the Panitch et al. EA study, 385 (35%) were nominally significant,65 (5.8%) were corrected significant, and most (89%) of these genes had the same effect direction in the AA cohort. Some of the observed associations appear to be AA specific (e.g., EFR3B, IRS4, and CA12; see Table). Additionally, we found nominally significant (p<0.05) associations with expression of APOE (Log2 fold change [L2FC = ‐0.20, p = 0.012) and several other established AD genes including SORL1 (L2FC = ‐0.10, p = 0.014) and IGF1R(L2FC = 0.11, p = 0.0013).ConclusionThis largest‐ever (to our knowledge) gene expression study of AD in postmortem brain tissue from AA donors implicates many more genes as having a role in AD in this population than previously identified in genome‐wide association studies and provides insight into trans‐ancestry differences risk for AD.

AbstractBackgroundRepetitive 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.MethodIn 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 findingsResultNo 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.ConclusionFormer 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.

ImportanceParkinsonism and Parkinson disease (PD) are known to result from repetitive head impacts from boxing. Repetitive head impacts from American football may also be associated with increased risk of neurodegenerative pathologies that cause parkinsonism, yet in vivo research on the association between football play and PD is scarce and limited by small samples and equivocal findings.ObjectiveTo evaluate the association between football participation and self-reported parkinsonism or PD diagnosis.Design, Setting, and ParticipantsThis cross-sectional study leveraged data from the online Fox Insight study. Participants completed online questionnaires and self-reported whether they currently had a diagnosis of Parkinson disease or parkinsonism by a physician or other health care professional. In November 2020, the Boston University Head Impact Exposure Assessment was launched for data collection on repetitive head impacts. Data used for this manuscript were obtained from the Fox Insight database on June 9, 2022. A total of 1875 men who endorsed playing any organized sport were included. Former athletes were divided into those who participated in football (n = 729 [38.9%]) and those who participated in other sports (reference group).ExposuresSelf-reported participation in football, duration and level of football play, age at first exposure.Main Outcomes and MeasuresLogistic regression tested associations between PD status and history of football play, duration of football play, highest level played, and age at first exposure, controlling for age, education, history of diabetes or heart disease, body mass index, history of traumatic brain injury with loss of consciousness, and family history of PD.ResultsIn this sample of 1875 men (mean [SD] age, 67.69 [9.84] years) enriched for parkinsonism or PD (n = 1602 [85.4%]), 729 (38.9%) played football (mean [SD] duration, 4.35 [2.91] years). History of playing football was associated with higher odds of having a parkinsonism or PD diagnosis (odds ratio [OR], 1.61; 95% CI, 1.19-2.17). Among the entire sample, longer duration of play was associated with higher odds of having a parkinsonism or PD diagnosis (OR, 1.12; 95% CI, 1.06-1.19). Among football players, longer duration of football play (OR, 1.12; 95% CI, 1.02-1.23) and higher level of play (OR, 2.93; 95% CI, 1.28-6.73) were associated with higher odds of having parkinsonism or PD.Conclusions and RelevanceIn this cross-sectional study of participants enriched for PD, participation in football was associated with higher odds of having a reported parkinsonism or PD diagnosis.