Braak Neurofibrillary Tangle Stage Research Articles

Role of GBA variants in Lewy body disease neuropathology.

Rare and common GBA variants are risk factors for both Parkinson's disease (PD) and dementia with Lewy bodies (DLB). However, the degree to which GBA variants are associated with neuropathological features in Lewy body disease (LBD) is unknown. Herein, we assessed 943 LBD cases and examined associations of 15 different neuropathological outcomes with common and rare GBA variants. Neuropathological outcomes included LBD subtype, presence of a high likelihood of clinical DLB (per consensus guidelines), LB counts in five cortical regions, tyrosine hydroxylase immunoreactivity in the dorsolateral and ventromedial putamen, ventrolateral substantia nigra neuronal loss, Braak neurofibrillary tangle (NFT) stage, Thal amyloid phase, phospho-ubiquitin (pS65-Ub) level, TDP-43 pathology, and vascular disease. Sequencing of GBA exons revealed a total of 42 different variants (4 common [MAF > 0.5%], 38 rare [MAF < 0.5%]) in our series, and 165 cases (17.5%) had a copy of the minor allele for ≥ 1 variant. In analysis of common variants, p.L483P was associated with a lower Braak NFT stage (OR = 0.10, P < 0.001). In gene-burden analysis, presence of the minor allele for any GBA variant was associated with increased odds of a high likelihood of DLB (OR = 2.00, P < 0.001), a lower Braak NFT stage (OR = 0.48, P < 0.001), a lower Thal amyloid phase (OR = 0.55, P < 0.001), and a lower pS65-Ub level (β: -0.37, P < 0.001). Subgroup analysis revealed that GBA variants were most common in LBD cases with a combination of transitional/diffuse LBD and Braak NFT stage 0-II or Thal amyloid phase 0-1, and correspondingly that the aforementioned associations of GBA gene-burden with a decreased Braak NFT stage and Thal amyloid phase were observed only in transitional or diffuse LBD cases. Our results indicate that in LBD, GBA variants occur most frequently in cases with greater LB pathology and low AD pathology, further informing disease-risk associations of GBA in PD, PD dementia, and DLB.

Multiple system atrophy with amyloid-β-predominant Alzheimer's disease neuropathologic change.

Multiple system atrophy is a neurodegenerative disease with α-synuclein pathology predominating in the striatonigral and olivopontocerebellar systems. Mixed pathologies are considered to be of low frequency and mostly comprise primary age-related tauopathy or low levels of Alzheimer's disease-related neuropathologic change. Therefore, the concomitant presence of different misfolded proteins in the same brain region is less likely in multiple system atrophy. During the neuropathological evaluation of 21 consecutive multiple system atrophy cases, we identified four cases exhibiting an unusual discrepancy between high Thal amyloid-β phase and low transentorhinal Braak neurofibrillary tangle stage. We mapped α-synuclein pathology, measured the size and number of glial cytoplasmic inclusions and compared the amyloid-β peptides between multiple system atrophy and Alzheimer's disease. In addition, we performed α-synuclein seeding assay from the affected putamen samples. We performed genetic testing for APOE, MAPT, PSEN1, PSEN2 and APP. We refer to the four multiple system atrophy cases with discrepancy between amyloid-β and tau pathology as 'amyloid-β-predominant Alzheimer's disease neuropathologic change-multiple system atrophy' to distinguish these from multiple system atrophy with primary age-related tauopathy or multiple system atrophy with typical Alzheimer's disease neuropathologic change. As most multiple system atrophy cases with mixed pathologies reported in the literature, these cases did not show a peculiar clinical or MRI profile. Three amyloid-β-predominant Alzheimer's disease neuropathologic change-multiple system atrophy cases were available for genetic testing, and all carried the APOE ɛ4 allele. The extent and severity of neuronal loss and α-synuclein pathology were not different compared with typical multiple system atrophy cases. Analysis of amyloid-β peptides revealed more premature amyloid-β plaques in amyloid-β-predominant Alzheimer's disease neuropathologic change-multiple system atrophy compared with Alzheimer's disease. α-Synuclein seeding amplification assay showed differences in the kinetics in two cases. This study highlights a rare mixed pathology variant of multiple system atrophy in which there is an anatomical meeting point of amyloid-β and α-synuclein, i.e. the striatum or cerebellum. Since biomarkers are entering clinical practice, these cases will be recognized, and the clinicians have to be informed that the prognosis is not necessarily different than in pure multiple system atrophy cases but that the effect of potential α-synuclein-based therapies might be influenced by the co-presence of amyloid-β in regions where α-synuclein also aggregates. We propose that mixed pathologies should be interpreted not only based on differences in the clinical phenotype but also on whether protein depositions regionally overlap, potentially leading to a different response to α-synuclein-targeted therapies.

Toward a generalizable machine learning workflow for neurodegenerative disease staging with focus on neurofibrillary tangles

Machine learning (ML) has increasingly been used to assist and expand current practices in neuropathology. However, generating large imaging datasets with quality labels is challenging in fields which demand high levels of expertise. Further complicating matters is the often seen disagreement between experts in neuropathology-related tasks, both at the case level and at a more granular level. Neurofibrillary tangles (NFTs) are a hallmark pathological feature of Alzheimer disease, and are associated with disease progression which warrants further investigation and granular quantification at a scale not currently accessible in routine human assessment. In this work, we first provide a baseline of annotator/rater agreement for the tasks of Braak NFT staging between experts and NFT detection using both experts and novices in neuropathology. We use a whole-slide-image (WSI) cohort of neuropathology cases from Emory University Hospital immunohistochemically stained for Tau. We develop a workflow for gathering annotations of the early stage formation of NFTs (Pre-NFTs) and mature intracellular (iNFTs) and show ML models can be trained to learn annotator nuances for the task of NFT detection in WSIs. We utilize a model-assisted-labeling approach and demonstrate ML models can be used to aid in labeling large datasets efficiently. We also show these models can be used to extract case-level features, which predict Braak NFT stages comparable to expert human raters, and do so at scale. This study provides a generalizable workflow for various pathology and related fields, and also provides a technique for accomplishing a high-level neuropathology task with limited human annotations.

Associations of Antemortem Cerebrospinal Fluid Biomarkers with Alzheimer’s Disease Neuropathologic changes at Autopsy

AbstractBackgroundCerebrospinal fluid (CSF) amyloid‐beta 42 (Aβ42) and tau phosphorylated at threonine 181 (p‐tau181) have been widely used as biomarkers for Alzheimer’s disease (AD). AT(N) classification even proposes each substance as a direct biomarker of amyloid (A) and tau (T) pathologies, respectively. However, recent studies suggest that increased CSF p‐tau181 may rather be associated with amyloid pathology. Although neuropathological evaluation at autopsy is the gold standard for assessing these changes, studies evaluating the association between CSF biomarkers and AD neuropathologic changes are limited.MethodWe retrospectively studied patients who underwent antemortem CSF AD biomarker measurement and neuropathological evaluation at autopsy at our institution from 1995 to 2021. CSF biomarkers were measured by ELISA (Fujirebio, Belgium). Neuropathological evaluation of AD was performed routinely regardless of diagnosis and Thal phase, Braak neurofibrillary tangle (NFT) stage, and CERAD score were assessed according to current guidelines.ResultThe mean age of the 119 patients was 76.2 ± 8.9 years; 49 were women. The duration from lumbar puncture to autopsy was median 2 years (0‐13 years). AD pathology was observed in 29 patients (24%). Other common pathologies were Lewy body disease and frontotemporal lobar degeneration. Antemortem CSF Aβ42 and p‐tau181 results were obtained in 119 and 68 patients, respectively. As expected, CSF Aβ42 decreased with increasing Thal phase and CERAD score. CSF p‐tau181 increased with increasing Thal phase, Braak NFT stage, and CERAD score. Even when the analysis was restricted to patients with Braak NFT stage 3 or less (n = 48), CSF p‐tau181 increased mildly with increasing Thal phase and CERAD score. In patients with moderate or severe amyloid pathology by Thal phase or CERAD score (n = 34), CSF p‐tau181 increased more highly at Braak NFT stage 5 or more.ConclusionThe results of this study, which directly compared antemortem CSF biomarkers with AD neuropathologic changes at autopsy, support the current theories that increased CSF p‐tau181 is caused by both amyloid and tau pathology related to AD while decreased CSF Aβ42 is associated with amyloid pathology.

White matter hyperintensities associate with pathological stages of neurodegenerative disease.

AbstractBackgroundWhite matter hyper‐intensities (WMH) are observed on FLAIR MRI, increase with age and are more prominent in neurodegenerative diseases such as in Alzheimer’s disease (AD) and Parkinson’s disease (PD). The aim of this study was to assess the association between WMH and neuropathological staging of amyloid‐beta, neurofibrillary tangles (NFT) and α‐synuclein (α‐syn).MethodIn‐situ 3T‐MRI 3DT1‐weighted and 3D‐FLAIR data were collected for 77 clinically defined and pathologically‐confirmed brain donors; 31 AD, 21 PD and PD dementia (PDD), and 25 controls. WMH were segmented on FLAIR using an in‐house developed multiview convolutional neural network, followed by manual checking, and volume was obtained with FSL. Fifteen brain regions were dissected at autopsy, immunostained and evaluated for neuropathological diagnosis, including Thal amyloid phase, CAA type, and Braak stages for NFT and α‐syn. Group differences were assessed with linear models (corrected for age, gender, post‐mortem delay), and associations with Spearman and Pearson partial correlations.ResultCompared to controls, WMH load was higher in AD (p&lt;0.001), specifically amnestic AD (p = 0.003) rather than non‐amnestic AD (p = 0.053), and higher in PD (p = 0.016), specifically non‐demented PD (p = 0.015) rather than PDD (p = 1.0). No difference in gender was observed (p = 0.38). Without the influence of pathology (in controls), WMH was associated with age (r = 0.49,p = 0.016).In the whole cohort, WMH was associated with Fazekas score (r = 0.67; p&lt;0.001), normalized brain volume (NBV; r = ‐0.31,p = 0.007), gray matter volume (NGMV; r = ‐0.36,p = 0.002), Thal phase (r = 0.24,p0.034), Braak NFT stage (r = 0.33,p = 0.004), and Braak α‐syn stage (r = 0.27, p0.018).Across controls and AD, WMH associated with NBV (r = ‐0.39,p = 0.004), NGMV (r = ‐0.42,p = 0.002), left and right hippocampal volume (r = ‐0.36,p = 0.008 and r = ‐0.32,p = 0.022), Braak NFT (r = 0.41,p&lt;0.001), Thal phase (r = 0.41,p = 0.002), and CAA (r = 0.34,p = 0.01). Amnestic and non‐amnestic AD showed similar results, except for CAA, which was associated with WMH in non‐amnestic AD only (r = 0.33,p = 0.04).Across controls and PD(D), WMH associated with Braak NFT stage (r = 0.39,p = 0.008) and Braak α‐syn stage (r = 0.60,p&lt;0.001), but not with MRI outcome measures. In this respect PD and PDD showed different results; in PD WMH associated with NGMV (r = ‐0.37,p = 0.031), in PDD with left and right hippocampal volume (r = ‐0.44,p = 0.014 and r = ‐0.44,p = 0.015).ConclusionWMH associate with pathological stages of AD and PD(D), and contributes to MRI atrophy.

Single nucleotide polymorphisms linked to Alzheimer’s disease are associated with distinct neuropathological phenotypes

AbstractBackgroundNeurodegenerative brain diseases (NBDs) ultimately result in neuronal loss and subsequent cognitive decline. In Alzheimer’s disease, tau neurofibrillary tangles (NFT) and amyloid plaques are considered as the hallmark lesions, but there are a number of other distinct features that are not exclusive to AD and do occur to a certain extent in other NBDs.MethodWe extracted DNA from a cohort of 382 post‐mortem brains of NBD patients and controls with detailed neuropathological characterization. Genotyping of 85 genetic loci, previously found to be associated with AD, is ongoing using an in‐house developed oxford nanopore technologies (ONT) multiplex assay, allowing simultaneous sequencing of all variants on an ONT Flongle platform. Base‐ calling, alignment to Hg38 and variant calling were performed followed by QC on the data and regression analysis.ResultAssociation testing has currently been performed for 59 of the total 85 SNPs in the assay using either linear or logistic regression. This revealed significant association for an AD risk variant in the SIGLEC11 locus and Braak NFT staging (p = 0.003) and NIA_AA score (p = 0.002). Significance was also found for a risk variant in the EPHA1 locus and Hirano body score (p = 0.008). Furthermore, we found numerous nominally significant associations between risk loci and TDP43 LATE, granulovacuolar degeneration, phases of amyloid plaque distribution and CAA severity.ConclusionThese results possibly highlight biological pathways involved in generating these additional features. Our ongoing work is currently focusing on increasing our sample size to further validate the associations we discovered and optimizing our ONT assay.

Spatiotemporal characterization of tau pathology and dendritic atrophy in the human locus coeruleus

AbstractBackgroundTau pathology of the noradrenergic locus coeruleus (LC) is a hallmark of several age‐related neurodegenerative disorders, including Alzheimer’s disease. However, comprehensive neuropathological examination of the LC is difficult due to its small size and rod‐like shape.MethodTo investigate the LC cytoarchitecture and tau cytoskeletal pathology in relation to possible propagation patterns of disease‐associated tau in a large‐scale and high resolution three‐dimensional view, we applied the state‐of‐the‐art volume immunostaining and optical clearing technology iDISCO+, combined with light sheet fluorescence microscopy. We examined AT8+ pathological tau in the LC/pericoerulear region of 20 brains from Braak neurofibrillary tangle (NFT) stage 0 to 6.ResultWe demonstrate a high morphological complexity of AT8+ cellular structures in the LC, representing various intracellular stages of NFT maturation and their diverse transition forms. We describe novel morphologies of neuronal tau pathology such as AT8+ cells with fine filamentous somatic protrusions or with disintegrating soma. We show that gradual dendritic atrophy is the first morphological sign of the degeneration of tangle‐bearing neurons. Irrespective of the Braak NFT stage, tau pathology is more advanced in the dorsal LC that preferentially projects to vulnerable forebrain regions in Alzheimer’s disease, like the hippocampus or neocortical areas. Moreover, already in the precortical Braak 0 stage, 3D analysis reveals clustering tendency and dendro‐dendritic close appositions of AT8+ LC neurons, AT8+ long axons of NFT‐bearing cells that join the ascending dorsal noradrenergic bundle after leaving the LC, as well as AT8+ processes of NFT‐bearing LC neurons that target the 4th ventricle wall.ConclusionOur study suggests that the unique cytoarchitecture, comprised of a densely packed and dendritically extensively interconnected neuronal network with long projections, makes the human LC to be an ideal anatomical template for early accumulation and trans‐neuronal spreading of hyperphosphorylated tau.

The limbic‐predominant hypometabolic subtype of AD is not enriched for comorbid TDP‐43 pathology or hippocampal sclerosis

AbstractBackgroundPrevious research has identified distinct subtypes of AD that differed with respect to the distribution of neurofibrillary tangles (NFT). One of them, a limbic‐predominant subtype, was enriched for comorbid TDP‐43 pathology. Our previous data‐driven analysis used FDG‐PET to identify a limbic‐predominant subtype of AD that may correspond to the limbic‐predominant NFT subtype. In the current study, we tested the expected associations between measures of neuropathology such as TDP‐43 pathology, hippocampal sclerosis, and Braak stages of NFT accumulation, and the limbic‐predominant hypometabolic subtype.MethodWe analyzed ante‐mortem FDG‐PET and neuropathological data of 74 individuals from the autopsy cohort of the Alzheimer’s Disease Neuroimaging Initiative (ADNI), including 7 cognitively normal participants, 12 participants with MCI, and 55 with dementia (as assessed at the last available clinical evaluation). Severity of TDP‐43 pathology was operationalized as the number of brain areas with TDP‐43 immunoreactive inclusions (including amygdala, hippocampus, entorhinal/inferior temporal cortex and neocortex). Hippocampal sclerosis was operationalized as a binary variable. We measured similarity of individual FDG‐PET profiles to the limbic‐predominant subtype. For that, we used Euclidean distances from each individual profile to the mean profile of the limbic‐predominant AD subtype identified previously in a larger ADNI sample using a data‐driven hierarchical clustering approach (Fig.1). Lower Euclidean distances indicated higher similarity to the subtype. Bayesian linear regressions in JASP were used to assess associations between neuropathological markers and similarity to the limbic‐predominant FDG‐PET pattern, controlling for Thal phase of amyloid accumulation, age, sex, and time delay between the FDG‐PET scan and death in the null model. We assessed Bayes factors representing evidence for a given model in comparison to the null model (BF10).ResultOur results suggest that similarity of individual FDG‐PET profiles to the limbic‐predominant FDG‐PET pattern was not related to severity of TDP‐43 pathology (BF10 = 0.449), presence of hippocampal sclerosis (BF10 = 0.544), or Braak NFT stages (BF10 = 0.525).ConclusionContrary to the expected effects, our current analysis indicates a lack of reliable associations between neuropathological markers such as TDP‐43 pathology, hippocampal sclerosis, or global NFT accumulation and the limbic‐predominant hypometabolic subtype. Future analyses will assess potential alternative contributors, such as region‐specific patterns of NFT distribution.

Genetic associations with mixed neuropathologies in the aging brainGenetic associations with mixed neuropathologies in the aging brain

AbstractBackground““Mixed” neuropathologies (NPs) are common in aged brains. Classic Alzheimer’s disease neuropathologic change (ADNC) proteinopathies are amyloid‐β plaques and tau neurofibrillary tangles (NFTs). In addition, α‐synuclein and TDP‐43 are also key proteinaceous disease markers, and cerebrovascular diseases (CVDs) often coexist. Although the scientific problems regarding mixed NPs are increasingly recognized, genetic associations with mixed NPs have not been well‐investigated. In this study, we applied item response theory (IRT) to optimize the clustering and combination of mixed NPs and examined the genetic associations.MethodNP data were drawn from the National Alzheimer’s Coordinating Center (NACC) NP v10‐11 forms through the March 2022 data freeze, including Thal phase ratings (A score); Braak NFT stage (B score); CERAD neuritic plaque scores (C score); Lewy bodies (LBs); TDP‐43; hippocampal sclerosis (HS); cerebral amyloid angiopathy (CAA); infarct and lacunes; microinfarcts; atherosclerosis of the circle of Willis; and brain arteriolosclerosis. We determined dominant pathology patterns in 1,228 participants who had no missing data using a multidimensional graded response model within the IRT framework. The NACC NP data were linked to the U.S. Alzheimer’s Disease Research Centers genetic data provided by the Alzheimer’s Disease genetic Consortium.ResultFrom the leave one out cross validation simulation, the model fitness tests showed that the 4‐factor model had fewer differences from the data than the other models. As shown in Figure, the predominant NPs were TDP‐43 and HS for factor 1 (F1), CVDs other than CAA for factor 2 (F2), A, B, and C scores and CAA for factor 3 (F3), and LBs for factor 4 (F4). The TMEM106B locus was genome‐wide significant with F1 (TDP‐43/HS) and the APOE locus was genome‐wide significant with F3 (ADNC/CAA) after adjusted for age at death, sex, and other factor scores. The SDK1 and FMNL2 loci were not genome‐wide significant, but had noteworthy associations with F2 (CVDs).ConclusionOur new approach to create mixed NP scores could detect the TMEM106B and APOE loci as TDP‐43/HS related and ADNC related regions, respectively. Although previous studies reported SDK1 as an ADNC related gene, we showed that the gene may be associated with CVDs.

Predictors of Successful Brain Aging: An Autopsy Study

AbstractBackgroundThe neuropathological hallmarks of Alzheimer’s disease (AD), including amyloid plaques and neurofibrillary tangles, also accumulate in the brains of aging individuals. However, some individuals are able to age successfully without significant degenerative neuropathology or cognitive impairment, a phenomenon referred to as “successful aging”. The predictors of successful “neuropathologic” and “cognitive” aging are not fully understood, creating a critical knowledge gap. Factors such as resistance, resilience, and reserve are believed to play important roles. Furthermore, the relationship between neuropathological changes, such as tau pathology and amyloid pathology, and cognitive impairment in the oldest old population remains unclear, and the concept of amyloid plaques causing tau pathology may not be universally valid. The association between amyloid plaques and dementia also continues to be debated.MethodsIn this study, we utilized a collection of 414 post‐mortem brain tissues (171 female, 241 male) from aged individuals (average age 90, range 80‐108) with neuropathological and clinical data (215 without cognitive impairment and 161 with cognitive impairment) to perform a cross‐sectional analysis. Our cohort included subjects who had cognitive assessments available and included those with no amyloid plaque pathology or mild burden based on neuropathological criteria. Variables (including new traits derived from A.I. based feature extraction) associated with the cognitive measures were determined using multivariable logistic regression.ResultsOur results revealed that age of death and Braak neurofibrillary tangle stage were significant predictors of cognitive impairment (p&lt;0.05), while amyloid positivity was not. These findings suggest that tau pathology may have a stronger association with cognitive impairment in the oldest old population compared to amyloid plaques.ConclusionUnderstanding the neuropathological factors associated with successful brain and cognitive aging will contribute to our knowledge of the underlying mechanisms and may pave the way for the development of interventions to promote successful aging and prevent cognitive decline in old age. Further research in this area is warranted to elucidate the complex relationship between neuropathology, cognitive function, and aging in the oldest old population.

An Epigenome‐wide association study of psychosis in Alzheimer’s disease dorsolateral prefrontal cortex

AbstractBackgroundPsychosis is a debilitating syndrome occurring in 40‐60% of people with Alzheimer’s disease (AD) and corresponds with a more severe disease course. Evidence suggests that psychosis in AD (AD+P) is associated with a distinct profile of neurobiological changes, but little is known about the molecular processes driving aetiology. In this study, we performed an epigenome‐wide association study (EWAS) to investigate DNA methylation associated with AD+P in the dorsolateral prefrontal cortex of post‐mortem brain samples.MethodBrain samples were obtained from the University of Pittsburgh Alzheimer’s disease Research Centre (PITT‐ADRC). AD pathology was assessed and classified using CERAD neurotic plaque density score, Braak neurofibrillary tangle stages and NIA‐RI criteria. We used the presence or absence of delusions and hallucinations, Mini‐Mental State Exam (MMSE) and Clinical Dementia Rating (CDR) to categorise our samples into AD with Psychosis (AD+P) and AD without Psychosis (AD‐P) groups. DNA was extracted, bisulfite‐treated and profiled on the Illumina Methylation EPIC Array and genotyping was carried out on the Illumina Global Screening Array (GSA).ResultAfter data quality control, 153 samples (40 AD‐P, 113 AD+P) remained for further analysis. The normalized beta values and the effect estimate values were used to extract Differentially Methylated positions (DMP) and differentially methylated regions (DMRs), respectively. To identify methylation quantitative trait loci (mQTLs) in both cis and trans, SNP‐CpG pairs with a p‐value threshold of &lt;1e‐5 were calculated. We performed a colocalization analysis for the most significant DMPs and mQTLs, using publicly available summary statistics of relevant genome‐wide association studies (GWAS).ConclusionThe development of effective therapies for AD+P is an urgent priority and requires a better understanding of the molecular mechanisms underlying this syndrome. To address this, we have collated a well‐powered study cohort to interrogate the epigenetic basis of AD+P in the brain and have identified several loci of interest that require further study.

ASSOCIATION BETWEEN ALZHEIMER DISEASE AND CANCER: A POSTMORTEM CROSS‐SECTIONAL STUDY IN BRAZIL

AbstractBackgroundA biological mechanism in cancer promotion may have a protective role against AD1. Although disparities between the clinical and the anatomopathological postmortem diagnoses related to the etiology of dementia and cancer were described2, most previous studies were based only on the clinical diagnoses for both diseases. Therefore, we aimed to investigate the association between AD and cancer in a large autopsy study from a racially diverse sample.MethodThis cross‐sectional study analyzed data with postmortem brain tissue from participants over 55 years of age from the Biobank for Aging Studies. Data from the full‐body autopsy reports and a Functional Clinical Questionnaire (FCQ) applied to an informant were used to determine the presence of cancer. The association between AD and cancer was investigated using logistic and linear models adjusted for sociodemographic and clinical variables and APOE allele 4.Result689 subjects were included (mean age 74.2 ± 10.8 years old, 47.5% women, 68% White) (Table 1). 18% of the sample had cancer. The frequencies of cancer types and neuropathological post‐mortem diagnoses are shown in Figure 1. Cancer was not associated with AD (OR = 0.56, 95% CI = 0.21;1.39), or CERAD neuritic plaque score [ b = 0.057, 95% CI = ‐0.31; 0.41], but was associated with lower Braak neurofibrillary tangle staging (b = ‐0.49, 95% CI = ‐0.98; ‐0.03] (Table 2).ConclusionIn a large autopsy study, we found an association between cancer and Braak neurofibrillary tangle staging, which is in accordance with previous research suggesting a protective role of cancer in AD risk3.1. Ospina‐Romero M, Glymour MM, Hayes‐Larson E, Mayeda ER, Graff RE, Brenowitz WD, Ackley SF, Witte JS, Kobayashi LC. Association Between Alzheimer Disease and Cancer With Evaluation of Study Biases: A Systematic Review and Metaanalysis. JAMA Netw Open. 2020 Nov 2;3(11):e2025515.2. Landefeld CS, Chren MM, Myers A, et al. Diagnostic yield of the autopsy in a university hospital and a community hospital. The New England Journal of Medicine. 1988 May;318(19):1249‐1254.3. Nakamura M, Kaneko S, Dickson DW, Kusaka H. Aberrant Accumulation of BRCA1 in Alzheimer Disease and Other Tauopathies. J Neuropathol Exp Neurol. 2020 Jan 1;79(1):22‐33.

Omics analysis of Alzheimer’s disease stratified by the microglial polygenic effect

AbstractBackgroundRecent single‐cell omics analyses have revealed that microglia change into reactive microglia when Aβ accumulates in the brain and exhibit Aβ phagocytosis. However, reactive microglia are less likely to be induced in TREM2 mutation carriers. This microglia‐centred pathological mechanism may be considered one of the pathologies of Alzheimer’s disease (AD). However, a single gene mutation, such as a TREM2 mutation, can rarely explain the pathology of AD. Therefore, polygenic effects involving multiple gene mutations have been proposed. In this study, we propose a polygenic risk score (PRS) to quantify the microglial polygenic effect. We stratified patient groups by this PRS and examined differences in pathogenesis based on omics analysis using postmortem brains.MethodWhole‐genome sequencing and bulk brain tissue RNA‐seq of the frontal cortex were performed using postmortem brain samples from 100 subjects with Braak senile plaque (SP) and neurofibrillary tangle (NFT) staging information. In addition, single‐nuclei RNA‐seq (snRNA‐seq) was performed on 15 of these subjects (healthy subjects: 8 subjects, AD patients: 7 subjects).ResultWe divided AD patients into low and high groups by microglial PRS and performed bulk brain tissue RNA‐seq analysis. We identified 112 differentially expressed genes and found that those genes were related to autophagy and inflammation. To further validate these findings at the single‐cell level, we identified cell clusters containing microglia based on snRNA‐seq. Gene expression analysis of microglia in 3 AD patients with low PRS and 4 AD patients with high PRS suggested altered transcriptional profiles of immune cells and phagocytosis. The expression of APOE and TYROBP, signature genes of reactive microglia, was significantly upregulated in the AD patients with low PRS compared to the AD patients with high PRS and healthy subjects. In contrast, CX3CR1 and P2RY12, signature genes of homeostatic microglia, were downregulated.ConclusionThe stratification analysis of AD by PRS suggests that microglial reactivity differs among AD patient groups. Future detailed microglial observations in postmortem brains from AD patients with low PRS and those with high PRS will further elaborate our results.

Hyperspectral analysis of amyloid beta (Aβ) evolutional changes in preclinical to late‐stage Alzheimer’s disease using matched brain and retinal tissue

AbstractBackgroundAlzheimer’s disease (AD) is a progressive, degenerative brain disorder that leads to cognitive impairment and eventually death. It is marked by buildup of abnormal amyloid aggregates (Aβ) in the brain. This study aimed to elucidate the neuropathologic sequence and corresponding [RetiSpec] hyperspectral signals of Aβ evolutional changes in preclinical to late‐stage AD using retinal and brain samples.MethodWe used brain‐ and retina‐matched human tissue samples from the NIH Brain Bank at Johns Hopkins. Study groups included: No AD neuropathologic change with negative AD neuropathology (n = 15); Low‐level AD neuropathologic change with positive AD neuropathology (n = 15); High level AD neuropathologic change with positive AD neuropathology (n = 15). To validate retinal hyperspectral imaging (rHSI) detection of Aβ in these retinal samples, we quantified Aβ oligomers (AβOs) in human retinal tissue. Immunohistochemistry was performed. We used humanized, affinity‐matured, IgG2 mAβ selective biotinylated antibody (ACU‐193) to detect soluble AβOs in retinal and brain tissues followed by objective quantification of ACU193 retinal staining by performing annotations and data extraction using QuPath software. One‐way ANOVA and t‐tests were performed to compare between controls and AD stages.ResultWhen assessing ACU193 staining present from retinal tissue samples, we observed 29‐53% retinal tissue area positivity in controls and 15‐72% retinal tissue area positivity in the AD group. Level of AD pathology demonstrated an effect on the rHSI spectra (450‐600nm) in regions near the optic disc and the ventral periphery: intermediate AD pathology showed the strongest rHSI signature (decrease in optical transmittance) followed by high, then low AD pathology samples. Correlation of the Braak neurofibrillary tangle stage and ΔOD offered a Pearson r score of 0.79 (p = 0.004).ConclusionThis study was the first to assess and quantify AβOs in clinically, neuropathologically, and hyperspectrally characterized postmortem matched brain and retinal tissues. Progression of well‐established neuropathologically classified AD stages (e.g Braak) may correlate with retinal AβO levels measured using rHSI. Certain retina regions that share nervous tissue with the brain (optic disc, periphery) are likely more sensitive to rHSI‐mediated detection of AD pathology. Larger samples are needed to comprehensively assess and quantify retinal AβOs.

TDP-43 pathology is associated with increased tau burdens and seeding

BackgroundMost Alzheimer’s Disease (AD) cases also exhibit limbic predominant age-related TDP-43 encephalopathy neuropathological changes (LATE-NC), besides amyloid-β plaques and neurofibrillary tangles (NFTs) containing hyperphosphorylated tau (p-tau). LATE-NC is characterized by cytoplasmic aggregates positive for pathological TDP-43 and is associated with more severe clinical outcomes in AD, compared to AD cases lacking TDP-43 pathology TDP-43: AD(LATE-NC-). Accumulating evidence suggests that TDP-43 and p-tau interact and exhibit pathological synergy during AD pathogenesis. However, it is not yet fully understood how the presence of TDP-43 affects p-tau aggregation in symptomatic AD.MethodsIn this study, we investigated the impact of TDP-43 proteinopathy on p-tau pathology with different approaches: histologically, in a human post-mortem cohort (n = 98), as well as functionally using a tau biosensor cell line and TDP-43A315T transgenic mice.ResultsWe found that AD cases with comorbid LATE-NC, AD(LATE-NC+), have increased burdens of pretangles and/or NFTs as well as increased brain levels of p-tau199, compared to AD(LATE-NC-) cases and controls. The burden of TDP-43 pathology was also correlated with the Braak NFT stages. A tau biosensor cell line treated with sarkosyl-insoluble, brain-derived homogenates from AD(LATE-NC+) cases displayed exacerbated p-tau seeding, compared to control and AD(LATE-NC-)-treated cells. Consistently, TDP-43A315T mice injected with AD(LATE-NC+)-derived extracts also exhibited a more severe hippocampal seeding, compared to the remaining experimental groups, albeit no TDP-43 aggregation was observed.ConclusionsOur findings extend the current knowledge by supporting a functional synergy between TDP-43 and p-tau. We further demonstrate that TDP-43 pathology worsens p-tau aggregation in an indirect manner and increases its seeding potential, probably by increasing p-tau levels. This may ultimately contribute to tau-driven neurotoxicity and cell death. Because most AD cases present with comorbid LATE-NC, this study has an impact on the understanding of TDP-43 and tau pathogenesis in AD and LATE, which account for the majority of dementia cases worldwide. Moreover, it highlights the need for the development of a biomarker that detects TDP-43 during life, in order to properly stratify AD and LATE patients.

Neuropathological analysis of cognitive impairment in progressive supranuclear palsy

BackgroundCognitive impairment is an important symptom in progressive supranuclear palsy (PSP), but the pathological changes underlying the cognitive impairment are unclear. This study aimed to elucidate relationships between the severity of cognitive impairment and PSP-related pathology. MethodsWe investigated the clinicopathological characteristics of 10 autopsy cases of PSP, including neuronal loss/gliosis and the burden of PSP-related tau pathology by using a semiquantitative score in 17 brain regions. Other concurrent pathologies such as Braak neurofibrillary tangle stage, Thal amyloid phase, Lewy-related pathology, argyrophilic grains, and TDP-43–related pathology were also assessed. We retrospectively divided the patients into a normal cognition group (PSP-NC) and cognitive impairment group (PSP-CI) based on antemortem clinical information about cognitive impairment and compared the pathological changes between these groups. ResultsSeven patients were categorized into the PSP-CI group (men = 4) and three into the PSP-NC group (men = 3). The severity of neuronal loss/gliosis and concurrent pathologies were not different between the two groups. However, the total load of tau pretangles/neurofibrillary tangles was higher in the PSP-CI group than in the PSP-NC group. In addition, the burden of tufted astrocytes in the subthalamic nucleus and medial thalamus was higher in the PSP-CI group than in the PSP-NC group. ConclusionCognitive impairment in PSP may be associated with the amount of tufted astrocyte pathology in the subthalamic nucleus and medial thalamus.

Alzheimer's disease pathogenetic progression is associated with changes in regulated retained introns and editing of circular RNAs.

The molecular changes leading to Alzheimer's disease (AD) progression are poorly understood. A decisive factor in the disease occurs when neurofibrillary tangles (NFT) composed of microtubule associated protein tau (MAPT) form in the entorhinal cortex and then spread throughout the brain. We therefore determined mRNA and circular RNA changes during AD progression, comparing Braak NFT stages I-VI. Total RNA was isolated from human brain (entorhinal and frontotemporal cortex). Poly(A)+ RNA was subjected to Nanopore sequencing, and total RNA was analyzed by standard Illumina sequencing. Circular RNAs were sequenced from RNase R treated and rRNA depleted total RNA. The sequences were analyzed using different bioinformatic tools, and expression constructs for circRNAs were analyzed in transfection experiments. We detected 11,873 circRNAs of which 276 correlated with Braak NFT stages. Adenosine to inosine RNA editing increased about threefold in circRNAs during AD progression. Importantly, this correlation cannot be detected with mRNAs. CircMAN2A1 expression correlated with AD progression and transfection experiments indicated that RNA editing promoted its translation using start codons out of frame with linear mRNAs, which generates novel proteins. Thus, we identified novel regulated retained introns that correlate with NFT Braak stages and provide evidence for a role of translated circRNAs in AD development.

Voxel-Based and Surface-Based Morphometry Analysis in Patients with Pathologically Confirmed Argyrophilic Grain Disease and Alzheimer's Disease.

Due to clinicoradiological similarities, including amnestic cognitive impairment and limbic atrophy, differentiation of argyrophilic grain disease (AGD) from Alzheimer's disease (AD) is often challenging. Minimally invasive biomarkers, especially magnetic resonance imaging (MRI), are valuable in routine clinical practice. Although it is necessary to explore radiological clues, morphometry analyses using new automated analytical methods, including whole-brain voxel-based morphometry (VBM) and surface-based morphometry (SBM), have not been sufficiently investigated in patients with pathologically confirmed AGD and AD. This study aimed to determine the volumetric differences in VBM and SBM analyses between patients with pathologically confirmed AGD and AD. Eight patients with pathologically confirmed AGD with a lower Braak neurofibrillary tangle stage (<III), 11 patients with pathologically confirmed AD without comorbid AGD, and 10 healthy controls (HC) were investigated. Gray matter volumetric changes in VBM and cortical thickness changes in SBM were compared between the two patient groups (i.e., AGD and AD) and the HC group. In contrast to widespread gray matter volume or cortical thickness loss in the bilateral limbic, temporoparietal, and frontal lobes of the AD group, these were limited, especially in the limbic lobes, in the AGD group, compared with that of the HC group. Although bilateral posterior dominant gray matter volume loss was identified in the AD group compared with the AGD group on VBM, there was no significant cluster between these patient groups on SBM. VBM and SBM analyses both showed a different distribution of atrophic changes between AGD and AD.

Effect of APOE ɛ4 genotype on age at onset and comorbid pathologies in multiple system atrophy (P8-11.004)

<h3>Objective:</h3> To elucidate the effect of apolipoprotein (APOE) ɛ4 genotype on age at onset and comorbid pathologies in multiple system atrophy (MSA). <h3>Background:</h3> APOE ɛ4 increases risk of Alzheimer’s disease (AD) and lowers age of onset of late-onset AD. In synucleinopathy, APOE ɛ4 has been reported to correlate with the severity of Lewy body pathology in Lewy body disease and to lower the age of onset of Parkinson’s disease. The association of APOE E4 with MSA is not well understood. <h3>Design/Methods:</h3> This study included 145 pathologically confirmed MSA patients (female 43%) in the Mayo Clinic Brain Bank. We reviewed the medical records to identify the age at onset at which motor or autonomic symptoms presented. MSA patients were divided into two groups: APOE ɛ4 carriers and non-carriers. We examined comorbid pathologies, including AD pathology, Lewy-related pathology, TDP-43 proteinopathy, argyrophilic grains, cerebral amyloid angiopathy (CAA), and aging-related tau astrogliopathy (ARTAG). We defined the presence of AD pathology based on the Braak neurofibrillary tangle stage and the Thal amyloid phase if both were equal or greater than 3. We compared the frequency of each pathology between APOE ɛ4 carriers and non-carriers. <h3>Results:</h3> Among 145 MSA patients, 26% (37/145) had APOE ɛ4 (female 41%) and 74% (108/145) had non-ɛ4 (female 44%). Age at onset was significantly younger in MSA with APOE ɛ4 than non-ɛ4 (P = 0.028, 56 ± 6 vs. 60 ± 10 years old). The frequency of CAA was significantly greater in MSA with APOE ɛ4 than non-ɛ4 (P = 0.0032, 43% vs. 18%); however, there was no significant difference in the frequency of AD pathology, Lewy-related pathology, TDP-43 proteinopathy, argyrophilic grains, and ARTAG. <h3>Conclusions:</h3> Our results indicate that APOE ɛ4 is associated with CAA in MSA, as well as lower age at onset, but not AD or Lewy-related pathologies. <b>Disclosure:</b> Dr. Sekiya has nothing to disclose. Dr. Koga has nothing to disclose. Dr. Ross has nothing to disclose. Dr. Dickson has nothing to disclose.

Primary progressive apraxia of speech: Clinico-pathological associations of left-right hemispheric dominance (S8.008)

<h3>Objective:</h3> To determine whether there are differences in in demographics, clinicopathologic-neuroimaging or survival, between left-dominant, right-dominant, and symmetric PPAOS. <h3>Background:</h3> Primary progressive apraxia of speech (PPAOS) is a neurodegenerative syndrome associated with neuroimaging abnormalities affecting the lateral premotor cortex (LPC) and supplementary motor area (SMA). It is unclear whether relative greater damage to premotor regions in left/right hemisphere is associated with differences in baseline and/or longitudinal features. <h3>Design/Methods:</h3> Fifty-one prospectively recruited PPAOS patients who completed [¹⁸F]-fluorodeoxyglucose PET scanning were classified as left-dominant, right-dominant, or symmetric, based on visual assessment of the LPC and SMA on FDG-PET by independent raters. Statistical analyses were utilized to compared baseline and longitudinal features. Kaplan-Meyer curves and Cox proportional hazards were used to evaluate survival differences across groups. <h3>Results:</h3> 49% of PPAOS patients were identified as left-dominant, 31% as right-dominant, and 20% as symmetric. At baseline, there were no differences between groups. On longitudinal rates of clinical change, left-dominant PPAOS displayed a slower progression of Parkinsonian symptoms on the Unified Parkinson Disease Rating Scale-III (p=0.047), with a trend for slowest rates of progression in ideomotor apraxia (p=0.06) and motor speech severity (p=0.09) relative to other groups. Right-dominant PPAOS demonstrated the most rapid rates of progression of behavioral disturbances on the Frontal Behavioral Inventory (p=0.02), including disinhibition symptoms (p=0.02) and negative behaviors (p=0.05). The symmetric group had fastest worsening of dysarthria. There were no differences in survival, although a five-year increase in age at onset, but not group classification, was associated with shorter survival (Hazard Ratio = 1.32; p=0.007). Braak neurofibrillary tangle stage differed across groups (p=0.01). While not statistically significant, right-dominant PPAOS tended to have corticobasal degeneration (CBD) and left-dominant PPAOS had progressive supranuclear palsy (PSP) pathology at autopsy. <h3>Conclusions:</h3> Patients with PPAOS and a left-dominant pattern of hypometabolism on FDG-PET have the slowest rate of decline of clinical features. <b>Disclosure:</b> Miss Robinson has nothing to disclose. The institution of Joseph Duffy has received research support from NIH. Joseph Duffy has received publishing royalties from a publication relating to health care. Heather Clark has received personal compensation for serving as an employee of Mayo Clinic. The institution of Heather Clark has received research support from NIH. Heather Clark has received publishing royalties from a publication relating to health care. The institution of Rene Utianski has received research support from NIH. The institution of Dr. Machulda has received research support from NIH. Dr. Botha has received research support from NIH. Dr. Singh has nothing to disclose. Nha Trang Thu Pham has received personal compensation for serving as an employee of Mayo Clinic. Mr. Martin has nothing to disclose. The institution of Dr. Taner has received research support from NIH. Dr. Dickson has nothing to disclose. Dr. Lowe has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for AVID Radiopharmaceutical. Dr. Lowe has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Eisai Inc. The institution of Dr. Lowe has received research support from AVID Radiopharmaceuticals. Dr. Whitwell has nothing to disclose. Dr. Josephs has nothing to disclose.