Publications by authors named "Melissa E Murray"

190 Publications

Alzheimer's disease and progressive supranuclear palsy share similar transcriptomic changes in distinct brain regions.

J Clin Invest 2021 Nov 23. Epub 2021 Nov 23.

Mayo Clinic Florida, Jacksonville, United States of America.

Vast numbers of differentially expressed genes and perturbed networks have been identified in Alzheimer's disease (AD), however neither disease- nor brain region-specificity of these transcriptome alterations have been explored. Using RNA sequencing data from 231 temporal cortex and 224 cerebellum samples of patients with AD and progressive supranuclear palsy (PSP), a tauopathy, we identify a striking correlation in the directionality and magnitude of gene expression changes between these two neurodegenerative proteinopathies. Further, the transcriptome changes in AD and PSP are highly conserved between the temporal and cerebellar cortices, indicating highly similar transcriptional changes occur in pathologically affected and grossly less affected, albeit functionally connected, areas of the brain. Shared up- or down-regulated genes in AD and PSP are enriched in biological pathways. Many of these genes also have concordant protein changes and evidence of epigenetic control. These conserved transcriptomic alterations of two distinct proteinopathies in brain regions with and without significant gross neuropathology have broad implications. AD and other neurodegenerative diseases are likely characterized by common disease or compensatory pathways with widespread perturbations in the whole brain. These findings can be leveraged to develop multifaceted therapies and biomarkers that address these common, complex and ubiquitous molecular alterations in neurodegenerative diseases.
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http://dx.doi.org/10.1172/JCI149904DOI Listing
November 2021

Genome-wide association study and functional validation implicates JADE1 in tauopathy.

Acta Neuropathol 2021 Nov 1. Epub 2021 Nov 1.

Neumora Therapeutics, South San Francisco, CA, USA.

Primary age-related tauopathy (PART) is a neurodegenerative pathology with features distinct from but also overlapping with Alzheimer disease (AD). While both exhibit Alzheimer-type temporal lobe neurofibrillary degeneration alongside amnestic cognitive impairment, PART develops independently of amyloid-β (Aβ) plaques. The pathogenesis of PART is not known, but evidence suggests an association with genes that promote tau pathology and others that protect from Aβ toxicity. Here, we performed a genetic association study in an autopsy cohort of individuals with PART (n = 647) using Braak neurofibrillary tangle stage as a quantitative trait. We found some significant associations with candidate loci associated with AD (SLC24A4, MS4A6A, HS3ST1) and progressive supranuclear palsy (MAPT and EIF2AK3). Genome-wide association analysis revealed a novel significant association with a single nucleotide polymorphism on chromosome 4 (rs56405341) in a locus containing three genes, including JADE1 which was significantly upregulated in tangle-bearing neurons by single-soma RNA-seq. Immunohistochemical studies using antisera targeting JADE1 protein revealed localization within tau aggregates in autopsy brains with four microtubule-binding domain repeats (4R) isoforms and mixed 3R/4R, but not with 3R exclusively. Co-immunoprecipitation in post-mortem human PART brain tissue revealed a specific binding of JADE1 protein to four repeat tau lacking N-terminal inserts (0N4R). Finally, knockdown of the Drosophila JADE1 homolog rhinoceros (rno) enhanced tau-induced toxicity and apoptosis in vivo in a humanized 0N4R mutant tau knock-in model, as quantified by rough eye phenotype and terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) in the fly brain. Together, these findings indicate that PART has a genetic architecture that partially overlaps with AD and other tauopathies and suggests a novel role for JADE1 as a modifier of neurofibrillary degeneration.
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http://dx.doi.org/10.1007/s00401-021-02379-zDOI Listing
November 2021

Cerebral Amyloid Angiopathy Pathology and Its Association With Amyloid-β PET Signal.

Neurology 2021 Nov 9;97(18):e1799-e1808. Epub 2021 Sep 9.

From the Departments of Neurology (S.M., M.M.M., A.A.R., H.B., D.T.J., V.K.R., R.C.P., D.K., B.F.B., J.G.-R.), Quantitative Health Sciences (T.G.L., M.M.M., S.A.P.), Radiology (V.L., C.R.J., P.V., K.K.), and Pathology and Laboratory Medicine (E.C., R.R.R.), Mayo Clinic, Rochester, MN; and Departments of Neuroscience (M.E.M., D.W.D.) and Pathology and Laboratory Medicine (D.W.D.), Mayo Clinic, Jacksonville, FL.

Background And Objectives: To determine the contribution of cerebral amyloid angiopathy (CAA) to Pittsburgh compound B (PiB)-PET tracer retention.

Methods: Participants from the Mayo Clinic Study of Aging and Mayo Clinic Alzheimer's Disease Research Center with antemortem PiB-PET imaging for β-amyloid (Aβ) who later underwent autopsy were included in this study. Pathologic regional leptomeningeal, parenchymal, capillary CAA, and Aβ plaque burden were calculated from one hemisphere. Regional lobar amyloid standardized uptake value ratio (SUVR) on PET was calculated from the same hemisphere sampled at autopsy. Single- and multiple-predictor linear regression models were used to evaluate the relative contributions of pathologically determined regional CAA and Aβ plaques to antemortem PiB-PET SUVR.

Results: Forty-one participants (30 male, 11 female) with a mean (SD) age at death of 75.7 (10.6) years were included. Twenty-seven (66%) had high PiB signal with a mean (SD) of 2.3 (1.2) years from time of PET scan to death; 24 (59%) had a pathologic diagnosis of Alzheimer disease. On multivariate analysis, CAA was not associated with PiB-PET SUVR, while plaques remained associated with PiB-PET SUVR in all regions (all < 0.05). In patients without frequent amyloid plaques, CAA was not associated with PiB-PET in any region.

Discussion: We did not find evidence that pathologically confirmed regional CAA burden contributes significantly to proximal antemortem regional PiB-PET signal, suggesting that amyloid PET imaging for measurement of cortical amyloid burden is unconfounded by CAA on a lobar level. Whether CAA burden contributes to PiB-PET signal in patients with severe CAA phenotypes, such as lobar hemorrhage, requires further investigation.
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http://dx.doi.org/10.1212/WNL.0000000000012770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8610626PMC
November 2021

Interaction of tau with HNRNPA2B1 and N-methyladenosine RNA mediates the progression of tauopathy.

Mol Cell 2021 Oct 27;81(20):4209-4227.e12. Epub 2021 Aug 27.

Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; Department of Neurology, Boston University School of Medicine, Boston, MA 02118, USA; Center for Neurophotonics, Boston University, Boston, MA 02215, USA; Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA. Electronic address:

The microtubule-associated protein tau oligomerizes, but the actions of oligomeric tau (oTau) are unknown. We have used Cry2-based optogenetics to induce tau oligomers (oTau-c). Optical induction of oTau-c elicits tau phosphorylation, aggregation, and a translational stress response that includes stress granules and reduced protein synthesis. Proteomic analysis identifies HNRNPA2B1 as a principle target of oTau-c. The association of HNRNPA2B1 with endogenous oTau was verified in neurons, animal models, and human Alzheimer brain tissues. Mechanistic studies demonstrate that HNRNPA2B1 functions as a linker, connecting oTau with N-methyladenosine (mA) modified RNA transcripts. Knockdown of HNRNPA2B1 prevents oTau or oTau-c from associating with mA or from reducing protein synthesis and reduces oTau-induced neurodegeneration. Levels of mA and the mA-oTau-HNRNPA2B1 complex are increased up to 5-fold in the brains of Alzheimer subjects and P301S tau mice. These results reveal a complex containing oTau, HNRNPA2B1, and mA that contributes to the integrated stress response of oTau.
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http://dx.doi.org/10.1016/j.molcel.2021.07.038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8541906PMC
October 2021

Genome-wide analysis identifies a novel LINC-PINT splice variant associated with vascular amyloid pathology in Alzheimer's disease.

Acta Neuropathol Commun 2021 05 21;9(1):93. Epub 2021 May 21.

Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA.

Cerebral amyloid angiopathy (CAA) contributes to accelerated cognitive decline in Alzheimer's disease (AD) dementia and is a common finding at autopsy. The APOEε4 allele and male sex have previously been reported to associate with increased CAA in AD. To inform biomarker and therapeutic target discovery, we aimed to identify additional genetic risk factors and biological pathways involved in this vascular component of AD etiology. We present a genome-wide association study of CAA pathology in AD cases and report sex- and APOE-stratified assessment of this phenotype. Genome-wide genotypes were collected from 853 neuropathology-confirmed AD cases scored for CAA across five brain regions, and imputed to the Haplotype Reference Consortium panel. Key variables and genome-wide genotypes were tested for association with CAA in all individuals and in sex and APOEε4 stratified subsets. Pathway enrichment was run for each of the genetic analyses. Implicated loci were further investigated for functional consequences using brain transcriptome data from 1,186 samples representing seven brain regions profiled as part of the AMP-AD consortium. We confirmed association of male sex, AD neuropathology and APOEε4 with increased CAA, and identified a novel locus, LINC-PINT, associated with lower CAA amongst APOEε4-negative individuals (rs10234094-C, beta = -3.70 [95% CI -0.49--0.24]; p = 1.63E-08). Transcriptome profiling revealed higher LINC-PINT expression levels in AD cases, and association of rs10234094-C with altered LINC-PINT splicing. Pathway analysis indicates variation in genes involved in neuronal health and function are linked to CAA in AD patients. Further studies in additional and diverse cohorts are needed to assess broader translation of our findings.
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http://dx.doi.org/10.1186/s40478-021-01199-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8147512PMC
May 2021

The Longitudinal Early-onset Alzheimer's Disease Study (LEADS): Framework and methodology.

Alzheimers Dement 2021 May 21. Epub 2021 May 21.

Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.

Patients with early-onset Alzheimer's disease (EOAD) are commonly excluded from large-scale observational and therapeutic studies due to their young age, atypical presentation, or absence of pathogenic mutations. The goals of the Longitudinal EOAD Study (LEADS) are to (1) define the clinical, imaging, and fluid biomarker characteristics of EOAD; (2) develop sensitive cognitive and biomarker measures for future clinical and research use; and (3) establish a trial-ready network. LEADS will follow 400 amyloid beta (Aβ)-positive EOAD, 200 Aβ-negative EOnonAD that meet National Institute on Aging-Alzheimer's Association (NIA-AA) criteria for mild cognitive impairment (MCI) or AD dementia, and 100 age-matched controls. Participants will undergo clinical and cognitive assessments, magnetic resonance imaging (MRI), [ F]Florbetaben and [ F]Flortaucipir positron emission tomography (PET), lumbar puncture, and blood draw for DNA, RNA, plasma, serum and peripheral blood mononuclear cells, and post-mortem assessment. To develop more effective AD treatments, scientists need to understand the genetic, biological, and clinical processes involved in EOAD. LEADS will develop a public resource that will enable future planning and implementation of EOAD clinical trials.
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http://dx.doi.org/10.1002/alz.12350DOI Listing
May 2021

In Vivo Imaging and Autoradiography in a Case of Autopsy-Confirmed Pick Disease.

Neurol Clin Pract 2021 Feb;11(1):e11-e14

Department of Neurology (RLU, KAJ) and Department of Radiology (CGS, NES, VJL, JLW), Mayo Clinic, Rochester, MN; and Department of Neuroscience (MEM), Mayo Clinic, Jacksonville, FL.

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http://dx.doi.org/10.1212/CPJ.0000000000000755DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8101319PMC
February 2021

Long-read targeted sequencing uncovers clinicopathological associations for C9orf72-linked diseases.

Brain 2021 05;144(4):1082-1088

Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.

To examine the length of a hexanucleotide expansion in C9orf72, which represents the most frequent genetic cause of frontotemporal lobar degeneration and motor neuron disease, we employed a targeted amplification-free long-read sequencing technology: No-Amp sequencing. In our cross-sectional study, we assessed cerebellar tissue from 28 well-characterized C9orf72 expansion carriers. We obtained 3507 on-target circular consensus sequencing reads, of which 814 bridged the C9orf72 repeat expansion (23%). Importantly, we observed a significant correlation between expansion sizes obtained using No-Amp sequencing and Southern blotting (P = 5.0 × 10-4). Interestingly, we also detected a significant survival advantage for individuals with smaller expansions (P = 0.004). Additionally, we uncovered that smaller expansions were significantly associated with higher levels of C9orf72 transcripts containing intron 1b (P = 0.003), poly(GP) proteins (P = 1.3 × 10- 5), and poly(GA) proteins (P = 0.005). Thorough examination of the composition of the expansion revealed that its GC content was extremely high (median: 100%) and that it was mainly composed of GGGGCC repeats (median: 96%), suggesting that expanded C9orf72 repeats are quite pure. Taken together, our findings demonstrate that No-Amp sequencing is a powerful tool that enables the discovery of relevant clinicopathological associations, highlighting the important role played by the cerebellar size of the expanded repeat in C9orf72-linked diseases.
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http://dx.doi.org/10.1093/brain/awab006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8105038PMC
May 2021

Transcriptomic analysis to identify genes associated with selective hippocampal vulnerability in Alzheimer's disease.

Nat Commun 2021 04 19;12(1):2311. Epub 2021 Apr 19.

Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA.

Selective vulnerability of different brain regions is seen in many neurodegenerative disorders. The hippocampus and cortex are selectively vulnerable in Alzheimer's disease (AD), however the degree of involvement of the different brain regions differs among patients. We classified corticolimbic patterns of neurofibrillary tangles in postmortem tissue to capture extreme and representative phenotypes. We combined bulk RNA sequencing with digital pathology to examine hippocampal vulnerability in AD. We identified hippocampal gene expression changes associated with hippocampal vulnerability and used machine learning to identify genes that were associated with AD neuropathology, including SERPINA5, RYBP, SLC38A2, FEM1B, and PYDC1. Further histologic and biochemical analyses suggested SERPINA5 expression is associated with tau expression in the brain. Our study highlights the importance of embracing heterogeneity of the human brain in disease to identify disease-relevant gene expression.
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http://dx.doi.org/10.1038/s41467-021-22399-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055900PMC
April 2021

Visualization of neurofibrillary tangle maturity in Alzheimer's disease: A clinicopathologic perspective for biomarker research.

Alzheimers Dement 2021 09 2;17(9):1554-1574. Epub 2021 Apr 2.

Department of Neuroscience, Mayo Clinic, Jacksonville, Florida, USA.

Neurofibrillary tangles, one of the neuropathologic hallmarks of Alzheimer's disease, have a dynamic lifespan of maturity that associates with progressive neuronal dysfunction and cognitive deficits. As neurofibrillary tangles mature, the biology of the neuron undergoes extensive changes that may impact biomarker recognition and therapeutic targeting. Neurofibrillary tangle maturity encompasses three levels: pretangles, mature tangles, and ghost tangles. In this review, we detail distinct and overlapping characteristics observed in the human brain regarding morphologic changes the neuron undergoes, conversion from intracellular to extracellular space, tau immunostaining patterns, and tau isoform expression changes across the lifespan of the neurofibrillary tangle. Post-translational modifications of tau such as phosphorylation, ubiquitination, conformational events, and truncations are discussed to contextualize tau immunostaining patterns. We summarize accumulated and emerging knowledge of neurofibrillary tangle maturity, discuss the current tools used to interpret the dynamic nature in the postmortem brain, and consider implications for cognitive dysfunction and tau biomarkers.
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http://dx.doi.org/10.1002/alz.12321DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8478697PMC
September 2021

Cerebral Amyloid Angiopathy Burden and Cerebral Microbleeds: Pathological Evidence for Distinct Phenotypes.

J Alzheimers Dis 2021 ;81(1):113-122

Department of Pathology and Laboratory Medicine, Mayo Clinic, Rochester, MN, USA.

Background: The relationship between cerebral microbleeds (CMBs) on hemosiderin-sensitive MRI sequences and cerebral amyloid angiopathy (CAA) remains unclear in population-based participants or in individuals with dementia.

Objective: To determine whether CMBs on antemortem MRI correlate with CAA.

Methods: We reviewed 54 consecutive participants with antemortem T2*GRE-MRI sequences and subsequent autopsy. CMBs were quantified on MRIs closest to death. Autopsy CAA burden was quantified in each region including leptomeningeal/cortical and capillary CAA. By a clustering approach, we examined the relationship among CAA variables and performed principal component analysis (PCA) for dimension reduction to produce two scores from these 15 interrelated predictors. Hurdle models assessed relationships between principal components and lobar CMBs.

Results: MRI-based CMBs appeared in 20/54 (37%). 10 participants had ≥2 lobar-only CMBs. The first two components of the PCA analysis of the CAA variables explained 74% variability. The first rotated component (RPC1) consisted of leptomeningeal and cortical CAA and the second rotated component of capillary CAA (RPC2). Both the leptomeningeal and cortical component and the capillary component correlated with lobar-only CMBs. The capillary CAA component outperformed the leptomeningeal and cortical CAA component in predicting lobar CMBs. Both capillary and the leptomeningeal/cortical components correlated with number of lobar CMBs.

Conclusion: Capillary and leptomeningeal/cortical scores correlated with lobar CMBs on MRI but lobar CMBs were more closely associated with the capillary component. The capillary component correlated with APOEɛ4, highlighting lobar CMBs as one aspect of CAA phenotypic diversity. More CMBs also increase the probability of underlying CAA.
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http://dx.doi.org/10.3233/JAD-201536DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8113155PMC
September 2021

Loss of Tmem106b leads to cerebellum Purkinje cell death and motor deficits.

Brain Pathol 2021 05 11;31(3):e12945. Epub 2021 Mar 11.

Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA.

TMEM106B has been recently implicated in multiple neurodegenerative diseases. Here, Rademakers et al. report a late-onset cerebellar Purkinje cell loss and progressive decline in motor function and gait deficits in a conventional Tmem106b-/- mouse model. By using high-power microscopy and bulk RNA sequencing, the authors further identify lysosomal and immune dysfunction as potential underlying mechanisms of the Purkinje cell loss.
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http://dx.doi.org/10.1111/bpa.12945DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8412084PMC
May 2021

Latent trait modeling of tau neuropathology in progressive supranuclear palsy.

Acta Neuropathol 2021 05 26;141(5):667-680. Epub 2021 Feb 26.

Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.

Progressive supranuclear palsy (PSP) is the second most common neurodegenerative Parkinsonian disorder after Parkinson's disease, and is characterized as a primary tauopathy. Leveraging the considerable clinical and neuropathologic heterogeneity associated with PSP, we measured tau neuropathology as quantitative traits to perform a genome-wide association study (GWAS) within PSP to identify genes and biological pathways that underlie the PSP disease process. In 882 PSP cases, semi-quantitative scores for phosphorylated tau-immunoreactive coiled bodies (CBs), neurofibrillary tangles (NFTs), tufted astrocytes (TAs), and tau threads were documented from 18 brain regions, and converted to latent trait (LT) variables using the R ltm package. LT analysis utilizes a multivariate regression model that links categorical responses to unobserved covariates allowing for a reduction of dimensionality, generating a single, continuous variable to account for the multiple lesions and brain regions assessed. We first tested for association with PSP LTs and the top PSP GWAS susceptibility loci. Significant SNP/LT associations were identified at rs242557 (MAPT H1c sub-haplotype) with hindbrain CBs and rs1768208 (MOBP) with forebrain tau threads. Digital microscopy was employed to quantify phosphorylated tau burden in midbrain tectum and red nucleus in 795 PSP cases and tau burdens were used as quantitative phenotypes in GWAS. Top associations were identified at rs1768208 with midbrain tectum and red nucleus tau burden. Additionally, we performed a PSP LT GWAS on an initial cohort, a follow-up SNP panel (37 SNPs, P < 10) in an extended cohort, and a combined analysis. Top SNP/LT associations were identified at SNPs in or near SPTBN5/EHD4, SEC13/ATP2B2, EPHB1/PPP2R3A, TBC1D8, IFNGR1/OLIG3, ST6GAL1, HK1, CALB1, and SGCZ. Finally, testing for SNP/transcript associations using whole transcriptome and whole genome data identified significant expression quantitative trait loci at rs3088159/SPTBN5/EHD4 and rs154239/GHRL. Modeling tau neuropathology heterogeneity using LTs as quantitative phenotypes in a GWAS may provide substantial insight into biological pathways involved in PSP by affecting regional tau burden.
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http://dx.doi.org/10.1007/s00401-021-02289-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8043857PMC
May 2021

New insights into atypical Alzheimer's disease in the era of biomarkers.

Lancet Neurol 2021 03;20(3):222-234

Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA.

Most patients with Alzheimer's disease present with amnestic problems; however, a substantial proportion, over-represented in young-onset cases, have atypical phenotypes including predominant visual, language, executive, behavioural, or motor dysfunction. In the past, these individuals often received a late diagnosis; however, availability of CSF and PET biomarkers of Alzheimer's disease pathologies and incorporation of atypical forms of Alzheimer's disease into new diagnostic criteria increasingly allows them to be more confidently diagnosed early in their illness. This early diagnosis in turn allows patients to be offered tailored information, appropriate care and support, and individualised treatment plans. These advances will provide improved access to clinical trials, which often exclude atypical phenotypes. Research into atypical Alzheimer's disease has revealed previously unrecognised neuropathological heterogeneity across the Alzheimer's disease spectrum. Neuroimaging, genetic, biomarker, and basic science studies are providing key insights into the factors that might drive selective vulnerability of differing brain networks, with potential mechanistic implications for understanding typical late-onset Alzheimer's disease.
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http://dx.doi.org/10.1016/S1474-4422(20)30440-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8056394PMC
March 2021

TAR DNA-Binding Protein 43 Is Associated with Rate of Memory, Functional and Global Cognitive Decline in the Decade Prior to Death.

J Alzheimers Dis 2021 ;80(2):683-693

Department of Neurology, Mayo Clinic, Rochester, MN, USA.

Background: Transactive response DNA-binding protein of 43 kDa (TDP-43) is associated with memory impairment and overall cognitive decline. It is unclear how TDP-43 contributes to the rate of clinical decline.

Objective: To determine whether cross-sectional and longitudinal cognitive and functional decline are associated with anatomical distribution of TDP-43 in the brain.

Methods: Longitudinal clinical-neuropathologic autopsy cohort study of 385 initially cognitively normal/mildly impaired older adults prospectively followed until death. We investigated how TDP-43, amyloid-β (Aβ), tau neurofibrillary tangles (NFT), Lewy body disease (LBD), age, sex, and genetics are associated with clinical scores and rates of their longitudinal decline.

Results: Of 385 participants, 260 (68%) had no TDP-43, 32 (8%) had TDP-43 limited to amygdala, and 93 (24%) had TDP-43 in the hippocampus and beyond. Higher TDP-43 and Braak NFT stages independently were associated with faster decline in global cognition, functional performance measured by Clinical Dementia Rating scale, and naming and episodic memory, whereas older age was associated with slower rate of cognitive, psychiatric, and functional decline. Cross-sectionally the following associations were found: higher TDP-43 and Braak NFT - worse performance; higher Aβ burden - worse global cognition, more behavioral changes, the latter also with higher LBD; older age - worse naming, lower frequency of behavioral changes; female sex - more impaired naming and better preserved episodic memory. There were no genetic associations.

Conclusion: The association of TDP-43 distribution with decline in cognitive and functional performance suggests that TDP-43 is playing a role in the clinical progression to dementia. Further characterization of clinical features associated with TDP-43 can facilitate establishment of antemortem diagnosis.
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http://dx.doi.org/10.3233/JAD-201166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8020877PMC
September 2021

The mechanistic link between selective vulnerability of the locus coeruleus and neurodegeneration in Alzheimer's disease.

Acta Neuropathol 2021 05 11;141(5):631-650. Epub 2021 Jan 11.

Neuropathology Laboratory, Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.

Alzheimer's disease (AD) is neuropathologically characterized by the intracellular accumulation of hyperphosphorylated tau and the extracellular deposition of amyloid-β plaques, which affect certain brain regions in a progressive manner. The locus coeruleus (LC), a small nucleus in the pons of the brainstem, is widely recognized as one of the earliest sites of neurofibrillary tangle formation in AD. Patients with AD exhibit significant neuronal loss in the LC, resulting in a marked reduction of its size and function. The LC, which vastly innervates several regions of the brain, is the primary source of the neurotransmitter norepinephrine (NE) in the central nervous system. Considering that NE is a major modulator of behavior, contributing to neuroprotection and suppression of neuroinflammation, degeneration of the LC in AD and the ultimate dysregulation of the LC-NE system has detrimental effects in the brain. In this review, we detail the neuroanatomy and function of the LC, its essential role in neuroprotection, and how this is dysregulated in AD. We discuss AD-related neuropathologic changes in the LC and mechanisms by which LC neurons are selectively vulnerable to insult. Further, we elucidate the neurotoxic effects of LC de-innervation both locally and at projection sites, and how this augments disease pathology, progression and severity. We summarize how preservation of the LC-NE system could be used in the treatment of AD and other neurodegenerative diseases affected by LC degeneration.
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http://dx.doi.org/10.1007/s00401-020-02248-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8043919PMC
May 2021

MAPT subhaplotypes in corticobasal degeneration: assessing associations with disease risk, severity of tau pathology, and clinical features.

Acta Neuropathol Commun 2020 12 7;8(1):218. Epub 2020 Dec 7.

Division of Biomedical Statistics and Informatics, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.

The microtubule-associated protein tau (MAPT) H1 haplotype is the strongest genetic risk factor for corticobasal degeneration (CBD). However, the specific H1 subhaplotype association is not well defined, and it is not clear whether any MAPT haplotypes influence severity of tau pathology or clinical presentation in CBD. Therefore, in the current study we examined 230 neuropathologically confirmed CBD cases and 1312 controls in order to assess associations of MAPT haplotypes with risk of CBD, severity of tau pathology (measured as semi-quantitative scores for coiled bodies, neurofibrillary tangles, astrocytic plaques, and neuropil threads), age of CBD onset, and disease duration. After correcting for multiple testing (P < 0.0026 considered as significant), we confirmed the strong association between the MAPT H2 haplotype and decreased risk of CBD (Odds ratio = 0.26, P = 2 × 10), and also observed a novel association between the H1d subhaplotype and an increased CBD risk (Odds ratio = 1.76, P = 0.002). Additionally, although not statistically significant after correcting for multiple testing, the H1c haplotype was associated with a higher risk of CBD (Odds ratio = 1.49, P = 0.009). No MAPT haplotypes were significantly associated with any tau pathology measures, age of CBD onset, or disease duration. Though replication will be important and there is potential that population stratification could have influenced our findings, these results suggest that several MAPT H1 subhaplotypes are primarily responsible for the strong association between MAPT H1 and risk of CBD, but that H1 subhaplotypes are unlikely to play a major role in driving tau pathology or clinical features. Our findings also indicate that similarities in MAPT haplotype risk-factor profile exist between CBD and the related tauopathy progressive supranuclear palsy, with H2, H1d, and H1c displaying associations with both diseases.
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http://dx.doi.org/10.1186/s40478-020-01097-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7720600PMC
December 2020

Protein contributions to brain atrophy acceleration in Alzheimer's disease and primary age-related tauopathy.

Brain 2020 12;143(11):3463-3476

Department of Radiology (Radiology Research) Mayo Clinic, Rochester, MN, USA.

Alzheimer's disease is characterized by the presence of amyloid-β and tau deposition in the brain, hippocampal atrophy and increased rates of hippocampal atrophy over time. Another protein, TAR DNA binding protein 43 (TDP-43) has been identified in up to 75% of cases of Alzheimer's disease. TDP-43, tau and amyloid-β have all been linked to hippocampal atrophy. TDP-43 and tau have also been linked to hippocampal atrophy in cases of primary age-related tauopathy, a pathological entity with features that strongly overlap with those of Alzheimer's disease. At present, it is unclear whether and how TDP-43 and tau are associated with early or late hippocampal atrophy in Alzheimer's disease and primary age-related tauopathy, whether either protein is also associated with faster rates of atrophy of other brain regions and whether there is evidence for protein-associated acceleration/deceleration of atrophy rates. We therefore aimed to model how these proteins, particularly TDP-43, influence non-linear trajectories of hippocampal and neocortical atrophy in Alzheimer's disease and primary age-related tauopathy. In this longitudinal retrospective study, 557 autopsied cases with Alzheimer's disease neuropathological changes with 1638 ante-mortem volumetric head MRI scans spanning 1.0-16.8 years of disease duration prior to death were analysed. TDP-43 and Braak neurofibrillary tangle pathological staging schemes were constructed, and hippocampal and neocortical (inferior temporal and middle frontal) brain volumes determined using longitudinal FreeSurfer. Bayesian bivariate-outcome hierarchical models were utilized to estimate associations between proteins and volume, early rate of atrophy and acceleration in atrophy rates across brain regions. High TDP-43 stage was associated with smaller cross-sectional brain volumes, faster rates of brain atrophy and acceleration of atrophy rates, more than a decade prior to death, with deceleration occurring closer to death. Stronger associations were observed with hippocampus compared to temporal and frontal neocortex. Conversely, low TDP-43 stage was associated with slower early rates but later acceleration. This later acceleration was associated with high Braak neurofibrillary tangle stage. Somewhat similar, but less striking, findings were observed between TDP-43 and neocortical rates. Braak stage appeared to have stronger associations with neocortex compared to TDP-43. The association between TDP-43 and brain atrophy occurred slightly later in time (∼3 years) in cases of primary age-related tauopathy compared to Alzheimer's disease. The results suggest that TDP-43 and tau have different contributions to acceleration and deceleration of brain atrophy rates over time in both Alzheimer's disease and primary age-related tauopathy.
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http://dx.doi.org/10.1093/brain/awaa299DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7719030PMC
December 2020

Association of ABI3 and PLCG2 missense variants with disease risk and neuropathology in Lewy body disease and progressive supranuclear palsy.

Acta Neuropathol Commun 2020 10 22;8(1):172. Epub 2020 Oct 22.

Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA.

Missense variants ABI3_rs616338-T and PLCG2_rs72824905-G were previously associated with elevated or reduced risk of Alzheimer's disease (AD), respectively. Despite reports of associations with other neurodegenerative diseases, there are few studies of these variants in purely neuropathologically diagnosed cohorts. Further, the effect of these mutations on neurodegenerative disease pathologies is unknown. In this study, we tested the effects of ABI3_rs616338-T and PLCG2_rs72824905-G on disease risk in autopsy cohorts comprised of 973 patients diagnosed neuropathologically with Lewy body disease (LBD-NP) and 1040 with progressive supranuclear palsy (PSP), compared to 3351 controls. LBD-NP patients were further categorized as high, intermediate and low likelihood of clinical dementia with Lewy bodies (DLB-CL) based on DLB Consortium criteria. We also tested for association with both Braak neurofibrillary tau tangle (n = 2008, n = 1037, n = 971) and Thal phase amyloid plaque scores (n = 1786, n = 1018, n = 768). Additionally, 841 PSP patients had quantitative tau neuropathology measures that were assessed for genetic associations. There was no statistically significant association with disease risk for either LBD-NP or PSP in our study. LBD intermediate category disease risk was significantly associated with ABI3_rs616338-T (OR = 2.65, 95% CI 1.46-4.83, p = 0.001). PLCG2_rs72824905-G was associated with lower Braak stage (ß = - 0.822, 95% CI - 1.439 to - 0.204, p = 0.009). This effect was more pronounced in the PSP (ß = - 0.995, 95% CI - 1.773 to - 0.218, p = 0.012) than LBD-NP patients (ß = - 0.292, 95% CI - 1.283 to 0.698, p = 0.563). PLCG2_rs72824905-G also showed association with reduced quantitative tau pathology for each lesion type and overall tau burden in PSP (ß = - 0.638, 95% CI - 1.139 to - 0.136, p = 0.013). These findings support a role for PLCG2_rs72824905-G in suppressing tau neuropathology. ABI3_rs616338-T may influence disease risk specifically in the LBD-NP intermediate category comprised of patients with diffuse neocortical or limbic LB, concurrently with moderate or high AD neuropathology, respectively. Our study provides a potential mechanism of action for the missense PLCG2 variant and suggests a differential disease risk effect for ABI3 in a distinct LBD-NP neuropathologic category.
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http://dx.doi.org/10.1186/s40478-020-01050-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7579984PMC
October 2020

Mitophagy alterations in Alzheimer's disease are associated with granulovacuolar degeneration and early tau pathology.

Alzheimers Dement 2020 Oct 8. Epub 2020 Oct 8.

Department of Neuroscience, Mayo Clinic, Jacksonville, Florida, USA.

Introduction: The cytoprotective PTEN-induced kinase 1 (PINK1)-parkin RBR E3 ubiquitin protein ligase (PRKN) pathway selectively labels damaged mitochondria with phosphorylated ubiquitin (pS65-Ub) for their autophagic removal (mitophagy). Because dysfunctions of mitochondria and degradation pathways are early features of Alzheimer's disease (AD), mitophagy impairments may contribute to the pathogenesis.

Methods: Morphology, levels, and distribution of the mitophagy tag pS65-Ub were evaluated by biochemical analyses combined with tissue and single cell imaging in AD autopsy brain and in transgenic mouse models.

Results: Analyses revealed significant increases of pS65-Ub levels in AD brain, which strongly correlated with granulovacuolar degeneration (GVD) and early phospho-tau deposits, but were independent of amyloid beta pathology. Single cell analyses revealed predominant co-localization of pS65-Ub with mitochondria, GVD bodies, and/or lysosomes depending on the brain region analyzed.

Discussion: Our study highlights mitophagy alterations in AD that are associated with early tau pathology, and suggests that distinct mitochondrial, autophagic, and/or lysosomal failure may contribute to the selective vulnerability in disease.
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http://dx.doi.org/10.1002/alz.12198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8048674PMC
October 2020

Sensitivity-Specificity of Tau and Amyloid β Positron Emission Tomography in Frontotemporal Lobar Degeneration.

Ann Neurol 2020 11 12;88(5):1009-1022. Epub 2020 Sep 12.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Objective: To examine associations between tau and amyloid β (Aβ) molecular positron emission tomography (PET) and both Alzheimer-related pathology and 4-repeat tau pathology in autopsy-confirmed frontotemporal lobar degeneration (FTLD).

Methods: Twenty-four patients had [ F]-flortaucipir-PET and died with FTLD (progressive supranuclear palsy [PSP], n = 10; corticobasal degeneration [CBD], n = 10; FTLD-TDP, n = 3; and Pick disease, n = 1). All but 1 had Pittsburgh compound B (PiB)-PET. Braak staging, Aβ plaque and neurofibrillary tangle counts, and semiquantitative tau lesion scores were performed. Flortaucipir standard uptake value ratios (SUVRs) were calculated in a temporal meta region of interest (meta-ROI), entorhinal cortex and cortical/subcortical regions selected to match the tau lesion analysis. Global PiB SUVR was calculated. Autoradiography was performed in 1 PSP patient, with digital pathology used to quantify tau burden.

Results: Nine cases (37.5%) had Aβ plaques. Global PiB SUVR correlated with Aβ plaque count, with 100% specificity and 50% sensitivity for diffuse plaques. Twenty-one (87.5%) had Braak stages I to IV. Flortaucipir correlated with neurofibrillary tangle counts in entorhinal cortex, but entorhinal and meta-ROI SUVRs were not elevated in Braak IV or primary age-related tauopathy. Flortaucipir uptake patterns differed across FTLD pathologies and could separate PSP and CBD. Flortaucipir correlated with tau lesion score in red nucleus and midbrain tegmentum across patients, but not in cortical or basal ganglia regions. Autoradiography demonstrated minimal uptake of flortaucipir, although flortaucipir correlated with quantitative tau burden across regions.

Interpretation: Molecular PET shows expected correlations with Alzheimer-related pathology but lacks sensitivity to detect mild Alzheimer pathology in FTLD. Regional flortaucipir uptake was able to separate CBD and PSP. ANN NEUROL 2020;88:1009-1022.
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http://dx.doi.org/10.1002/ana.25893DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7861121PMC
November 2020

Tau and apolipoprotein E modulate cerebrovascular tight junction integrity independent of cerebral amyloid angiopathy in Alzheimer's disease.

Alzheimers Dement 2020 10 22;16(10):1372-1383. Epub 2020 Aug 22.

Department of Neuroscience, Mayo Clinic, Jacksonville, Florida, USA.

Introduction: Cerebrovascular pathologies including cerebral amyloid angiopathy (CAA) and blood-brain barrier (BBB) dysregulation are prominent features in the majority of Alzheimer's disease (AD) cases.

Methods: We performed neuropathologic and biochemical studies on a large, neuropathologically confirmed human AD cohort (N = 469). Amounts of endothelial tight junction proteins claudin-5 (CLDN5) and occludin (OCLN), and major AD-related molecules (amyloid beta [Aβ40], Aβ42, tau, p-tau, and apolipoprotein E) in the temporal cortex were assessed by ELISA.

Results: Higher levels of soluble tau, insoluble p-tau, and apolipoprotein E (apoE) were independently correlated with lower levels of endothelial tight junction proteins CLDN5 and OCLN in AD brains. Although high Aβ40 levels, APOE ε4, and male sex were predominantly associated with exacerbated CAA severity, those factors did not influence tight junction protein levels.

Discussion: Refining the molecular mechanisms connecting tau, Aβ, and apoE with cerebrovascular pathologies is critical for greater understanding of AD pathogenesis and establishing effective therapeutic interventions for the disease.
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http://dx.doi.org/10.1002/alz.12104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8103951PMC
October 2020

Progressive dysexecutive syndrome due to Alzheimer's disease: a description of 55 cases and comparison to other phenotypes.

Brain Commun 2020 27;2(1):fcaa068. Epub 2020 May 27.

Department of Neurology Mayo Clinic, Rochester, MN 55902, USA.

We report a group of patients presenting with a progressive dementia syndrome characterized by predominant dysfunction in core executive functions, relatively young age of onset and positive biomarkers for Alzheimer's pathophysiology. Atypical frontal, dysexecutive/behavioural variants and early-onset variants of Alzheimer's disease have been previously reported, but no diagnostic criteria exist for a progressive dysexecutive syndrome. In this retrospective review, we report on 55 participants diagnosed with a clinically defined progressive dysexecutive syndrome with F-fluorodeoxyglucose-positron emission tomography and Alzheimer's disease biomarkers available. Sixty-two per cent of participants were female with a mean of 15.2 years of education. The mean age of reported symptom onset was 53.8 years while the mean age at diagnosis was 57.2 years. Participants and informants commonly referred to initial cognitive symptoms as 'memory problems' but upon further inquiry described problems with core executive functions of working memory, cognitive flexibility and cognitive inhibitory control. Multi-domain cognitive impairment was evident in neuropsychological testing with executive dysfunction most consistently affected. The frontal and parietal regions which overlap with working memory networks consistently demonstrated hypometabolism on positron emission tomography. Genetic testing for autosomal dominant genes was negative in all eight participants tested and at least one ε allele was present in 14/26 participants tested. EEG was abnormal in 14/17 cases with 13 described as diffuse slowing. Furthermore, CSF or neuroimaging biomarkers were consistent with Alzheimer's disease pathophysiology, although CSF p-tau was normal in 24% of cases. Fifteen of the executive predominate participants enrolled in research neuroimaging protocols and were compared to amnestic ( = 110), visual ( = 18) and language ( = 7) predominate clinical phenotypes of Alzheimer's disease. This revealed a consistent pattern of hypometabolism in parieto-frontal brain regions supporting executive functions with relative sparing of the medial temporal lobe (versus amnestic phenotype), occipital (versus visual phenotype) and left temporal (versus language phenotype). We propose that this progressive dysexecutive syndrome should be recognized as a distinct clinical phenotype disambiguated from behavioural presentations and not linked specifically to the frontal lobe or a particular anatomic substrate without further study. This clinical presentation can be due to Alzheimer's disease but is likely not specific for any single aetiology. Diagnostic criteria are proposed to facilitate additional research into this understudied clinical presentation.
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http://dx.doi.org/10.1093/braincomms/fcaa068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7325839PMC
May 2020

F-fluorodeoxyglucose positron emission tomography in dementia with Lewy bodies.

Brain Commun 2020 8;2(1):fcaa040. Epub 2020 Apr 8.

Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.

Among individuals with dementia with Lewy bodies, pathologic correlates of clinical course include the presence and extent of coexisting Alzheimer's pathology and the presence of transitional or diffuse Lewy body disease. The objectives of this study are to determine (i) whether F-fluorodeoxyglucose PET signature patterns of dementia with Lewy bodies are associated with the extent of coexisting Alzheimer's pathology and the presence of transitional or diffuse Lewy body disease and (ii) whether these F-fluorodeoxyglucose pattern(s) are associated with clinical course in dementia with Lewy bodies. Two groups of participants were included: a pathology-confirmed subset with Lewy body disease ( = 34) and a clinically diagnosed group of dementia with Lewy bodies ( = 87). A subset of the clinically diagnosed group was followed longitudinally ( = 51). We evaluated whether F-fluorodeoxyglucose PET features of dementia with Lewy bodies (higher cingulate island sign ratio and greater occipital hypometabolism) varied by Lewy body disease subtype (transitional versus diffuse) and Braak neurofibrillary tangle stage. We investigated whether the PET features were associated with the clinical trajectories by performing regression models predicting Clinical Dementia Rating Scale Sum of Boxes. Among autopsied participants, there was no difference in cingulate island sign or occipital hypometabolism by Lewy body disease type, but those with a lower Braak tangle stage had a higher cingulate island sign ratio compared to those with a higher Braak tangle stage. Among the clinically diagnosed dementia with Lewy bodies participants, a higher cingulate island ratio was associated with better cognitive scores at baseline and longitudinally. A higher F-fluorodeoxyglucose PET cingulate island sign ratio was associated with lower Braak tangle stage at autopsy, predicted a better clinical trajectory in dementia with Lewy body patients and may allow for improved prognostication of the clinical course in this disease.
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http://dx.doi.org/10.1093/braincomms/fcaa040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7293797PMC
April 2020

Subtypes of dementia with Lewy bodies are associated with α-synuclein and tau distribution.

Neurology 2020 07 19;95(2):e155-e165. Epub 2020 Jun 19.

From the Departments of Psychiatry and Psychology (T.J.F., O.P.), Neurology (J.A.V.G., N.R.G.-R., R.J.U., Z.K.W.), and Neuroscience (M.E.M., O.A.R., D.W.D.) Mayo Clinic, Jacksonville, FL; Department of Psychiatry (N.A.), Yokohama University Medical Center, Japan; and Departments of Neurology (B.F.B., J.G.-R., D.S.K., R.C.P.), Health Sciences Research (J.A.A.), Radiology (K.K.), Laboratory Medicine and Pathology (J.E.P., R.R.R.), and Psychiatry and Psychology (J.A.F.), Mayo Clinic, Rochester, MN.

Objective: To determine whether Lewy body disease subgroups have different clinical profiles.

Methods: Participants had dementia, autopsy-confirmed transitional or diffuse Lewy body disease (TLBD or DLBD) (n = 244), or Alzheimer disease (AD) (n = 210), and were seen at least twice (mean follow-up 6.2 ± 3.8 years). TLBD and DLBD groups were partitioned based on the presence or absence of neocortical neurofibrillary tangles using Braak staging. Four Lewy body disease subgroups and AD were compared on clinical features, dementia trajectory, and onset latency of probable dementia with Lewy bodies (DLB) or a DLB syndrome defined as probable DLB or dementia with one core feature of parkinsonism or probable REM sleep behavior disorder.

Results: In TLBD and DLBD without neocortical tangles, diagnostic sensitivity was strong for probable DLB (87% TLBD, 96% DLBD) and the DLB syndrome (97% TLBD, 98% DLBD) with median latencies <1 year from cognitive onset, and worse baseline attention-visual processing but better memory-naming scores than AD. In DLBD with neocortical tangles, diagnostic sensitivity was 70% for probable DLB and 77% for the DLB syndrome with respective median latencies of 3.7 years and 2.7 years from cognitive onset, each associated with tangle distribution. This group had worse baseline attention-visual processing than AD, but comparable memory-naming impairment. TLBD with neocortical tangles had 48% diagnostic sensitivity for probable DLB and 52% for the DLB syndrome, with median latencies >6 years from cognitive onset, and were cognitively similar to AD. Dementia trajectory was slowest for TLBD without neocortical tangles, and fastest for DLBD with neocortical tangles.

Conclusions: The phenotypic expression of DLB was associated with the distribution of α-synuclein and tau pathology.
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http://dx.doi.org/10.1212/WNL.0000000000009763DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7455327PMC
July 2020

Clinical and pathologic features of cognitive-predominant corticobasal degeneration.

Neurology 2020 07 9;95(1):e35-e45. Epub 2020 Jun 9.

From the Departments of Neuroscience (N.S., M.E.M., D.W.D.), Psychiatry and Psychology (O.A.S., O.P.), and Neurology (R.J.U., Z.K.W., N.R.G.-R.), Mayo Clinic, Jacksonville, FL; Department of Neurology (I.L.), University of California San Diego, La Jolla; Department of Neurology (R.D.), Mount Sinai Medical Center, Miami Beach, FL; and Department of Neurology (K.A.J.), Mayo Clinic, Rochester, MN.

Objective: To describe clinical and pathologic characteristics of corticobasal degeneration (CBD) with cognitive predominant problems during the disease course.

Methods: In a series of autopsy-confirmed cases of CBD, we identified patients with cognitive rather than motor predominant features (CBD-Cog), including 5 patients thought to have Alzheimer disease (AD) and 10 patients thought to have behavioral variant frontotemporal dementia (FTD). We compared clinical and pathologic features of CBD-Cog with those from a series of 31 patients with corticobasal syndrome (CBD-CBS). For pathologic comparisons between CBD-Cog and CBD-CBS, we used semiquantitative scoring of neuronal and glial lesion types in multiple brain regions and quantitative assessments of tau burden from image analysis.

Results: Five of 15 patients with CBD-Cog never had significant motor problems during their disease course. The most common cognitive abnormalities in CBD-Cog were executive and visuospatial dysfunction. The frequency of language problems did not differ between CBD-Cog and CBD-CBS. Argyrophilic grain disease, which is a medial temporal tauopathy associated with mild cognitive impairment, was more frequent in CBD-Cog. Apathy was also more frequent in CBD-Cog. Tau pathology in CBD-Cog was greater in the temporal and less in perirolandic cortices than in CBD-CBS.

Conclusion: A subset of patients with CBD has a cognitive predominant syndrome than can be mistaken for AD or FTD. Our findings suggest that distribution of tau cortical pathology (greater in temporal and less in perirolandic cortices) may be the basis of this uncommon clinical variant of CBD.
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http://dx.doi.org/10.1212/WNL.0000000000009734DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7371382PMC
July 2020

Utility of FDG-PET in diagnosis of Alzheimer-related TDP-43 proteinopathy.

Neurology 2020 07 9;95(1):e23-e34. Epub 2020 Jun 9.

From the Departments of Neurology (M.B., H.B., D.T.J., D.S.K., B.F.B., R.C.P., K.A.J.), Radiology (C.G.S., M.L.S., C.R.J., V.L., J.L.W.), and Laboratory Medicine and Pathology (J.E.P.), Mayo Clinic, Rochester, MN; and Department of Neuroscience (M.E.M., L.P., D.W.D.), Mayo Clinic, Jacksonville, FL.

Objective: To evaluate FDG-PET as an antemortem diagnostic tool for Alzheimer-related TAR DNA-binding protein of 43 kDa (TDP-43) proteinopathy.

Methods: We conducted a cross-sectional neuroimaging-histologic analysis of patients with antemortem FDG-PET and postmortem brain tissue from the Mayo Clinic Alzheimer's Disease Research Center and Study of Aging with Alzheimer spectrum pathology. TDP-43-positive status was assigned when TDP-43-immunoreactive inclusions were identified in the amygdala. Statistical parametric mapping (SPM) analyses compared TDP-43-positive (TDP-43[+]) with TDP-43-negative cases (TDP-43[-]), correcting for field strength, sex, Braak neurofibrillary tangle, and neuritic plaque stages. Cross-validated logistic regression analyses were used to determine whether regional FDG-PET values predict TDP-43 status. We also assessed the ratio of inferior temporal to medial temporal (IMT) metabolism as this was proposed as a biomarker of hippocampal sclerosis.

Results: Of 73 cases, 27 (37%) were TDP-43(+), of which 6 (8%) had hippocampal sclerosis. SPM analysis showed TDP-43(+) cases having greater hypometabolism of medial temporal, frontal superior medial, and frontal supraorbital (FSO) regions ( < 0.001). Logistic regression analysis showed only FSO and IMT to be associated with TDP-43(+) status, identifying up to 81% of TDP-43(+) cases ( < 0.001). An IMT/FSO ratio was superior to the IMT in discriminating TDP-43(+) cases: 78% vs 48%, respectively.

Conclusions: Alzheimer-related TDP-43 proteinopathy is associated with hypometabolism in the medial temporal and frontal regions. Combining FDG-PET measures from these regions may be useful for antemortem prediction of Alzheimer-related TDP-43 proteinopathy.

Classification Of Evidence: This study provides Class II evidence that hypometabolism in the medial temporal and frontal regions on FDG-PET is associated with Alzheimer-related TDP-43 proteinopathy.
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http://dx.doi.org/10.1212/WNL.0000000000009722DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7371379PMC
July 2020

Loss of TMEM106B leads to myelination deficits: implications for frontotemporal dementia treatment strategies.

Brain 2020 06;143(6):1905-1919

Department of Neuroscience, Mayo Clinic, Jacksonville, Florida 32224, USA.

Genetic variants that define two distinct haplotypes at the TMEM106B locus have been implicated in multiple neurodegenerative diseases and in healthy brain ageing. In frontotemporal dementia (FTD), the high expressing TMEM106B risk haplotype was shown to increase susceptibility for FTD with TDP-43 inclusions (FTD-TDP) and to modify disease penetrance in progranulin mutation carriers (FTD-GRN). To elucidate the biological function of TMEM106B and determine whether lowering TMEM106B may be a viable therapeutic strategy, we performed brain transcriptomic analyses in 8-month-old animals from our recently developed Tmem106b-/- mouse model. We included 10 Tmem106b+/+ (wild-type), 10 Tmem106b+/- and 10 Tmem106-/- mice. The most differentially expressed genes (153 downregulated and 60 upregulated) were identified between Tmem106b-/- and wild-type animals, with an enrichment for genes implicated in myelination-related cellular processes including axon ensheathment and oligodendrocyte differentiation. Co-expression analysis also revealed that the most downregulated group of correlated genes was enriched for myelination-related processes. We further detected a significant loss of OLIG2-positive cells in the corpus callosum of Tmem106b-/- mice, which was present already in young animals (21 days) and persisted until old age (23 months), without worsening. Quantitative polymerase chain reaction revealed a reduction of differentiated but not undifferentiated oligodendrocytes cellular markers. While no obvious changes in myelin were observed at the ultrastructure levels in unchallenged animals, treatment with cuprizone revealed that Tmem106b-/- mice are more susceptible to cuprizone-induced demyelination and have a reduced capacity to remyelinate, a finding which we were able to replicate in a newly generated Tmem106b CRISPR/cas9 knock-out mouse model. Finally, using a TMEM106B HeLa knock-out cell line and primary cultured oligodendrocytes, we determined that loss of TMEM106B leads to abnormalities in the distribution of lysosomes and PLP1. Together these findings reveal an important function for TMEM106B in myelination with possible consequences for therapeutic strategies aimed at lowering TMEM106B levels.
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http://dx.doi.org/10.1093/brain/awaa141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7296855PMC
June 2020

Pick's disease: clinicopathologic characterization of 21 cases.

J Neurol 2020 Sep 21;267(9):2697-2704. Epub 2020 May 21.

Department of Neurology, Mayo Clinic, 200 1st St SW, Rochester, MN, 55905, USA.

Background: Pick's disease (PiD) is a unique subtype of frontotemporal lobar degeneration characterized pathologically by aggregates of 3-Repeat tau. Few studies have examined the clinical variability and disease progression in PiD. We describe the clinical features, neuropsychological profiles and coexistent pathologies in 21 cases of autopsy-confirmed PiD.

Methods: This study was a retrospective analysis of patients with Pick's disease evaluated at Mayo Clinic, Rochester or Jacksonville (1995-2018), and identified through an existing database.

Results: Twenty-one cases with sufficient clinical data were identified. Behavioral variant FTD (bvFTD; 12/21) was the most common phenotype, followed by primary progressive aphasia (PPA; 7/21), corticobasal syndrome (CBS; 1/21) and amnestic dementia (1/21). Median age at disease onset was 54 years, with PPA cases (median = 52 years) presenting earlier than bvFTD (median = 59). Median disease duration (onset-death) overall was 10 years and did not differ significantly between bvFTD (median = 9.5 years) and PPA (median = 13). Age at death was not significantly different in PPA (median = 66) compared to bvFTD (median = 68.5). A third of the cases (n = 7/21) demonstrated pure PiD pathology, while the remainder showed co-existent other pathologies including Alzheimer's type (n = 6), cerebral amyloid angiopathy (n = 3), combined Alzheimer's and amyloid angiopathy (n = 4), and Lewy body disease (n = 1).

Conclusions: Our study shows that bvFTD and PPA are the most common clinical phenotypes associated with PiD, although rare presentations such as CBS were also seen. Coexisting non-Pick's pathology was also present in many cases. Our study highlights the clinical and pathologic heterogeneity in PiD.
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http://dx.doi.org/10.1007/s00415-020-09927-9DOI Listing
September 2020
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