bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alzheimer’s disease biomarker‐related phospho‐tau 181 signals localize to demyelinated axons of parvalbumin‐positive GABAergic interneurons in App knock‐in mouse
Authors: Hirota Yu , Sakakibara Yasufumi , Takei Kimi , Nishijima Risa , Iijima Koichi M. , Sekiya Michiko 
Published: December 2023

AbstractBackgroundTau proteins phosphorylated at Thr181 (p‐tau 181) in cerebrospinal fluid and blood is a sensitive biomarker for Alzheimer’s disease (AD). An increase in p‐tau 181 level well correlates with Aβ pathology and precedes neurofibrillary tangle formation in the early stage of AD, though the relationship between p‐tau 181 and Aβ‐mediated pathology is less well understood. We have recently reported that p‐tau 181 signals are detected in the axonal structures and represent axonal abnormality around Aβ plaques in the cortex of App knock‐in mouse model of Aβ amyloidosis (AppNLGF
mice). However, from which neuronal subtype(s) these p‐tau 181‐positive axons are originated remains elusive. In this study, we aimed to determine which neuronal subtype(s) express p‐tau 181 in the axons.MethodTo investigate the localization of p‐tau 181 signals in the brains of aged (24‐month‐old) AppNLGF
and wild‐type mice, we prepared frozen brain sections and co‐immunostained with antibodies against p‐tau 181 and myeline basic protein (MBP), the glutamatergic neuronal vesicle marker vesicular glutamate transporter 1 (VGLUT1), the GABAergic neuronal vesicle marker vesicular GABA transporter (VGAT), the inhibitory neuron marker parvalbumin, the cholinergic neuronal vesicle marker vesicular acetylcholine transporter (VAChT), or the noradrenergic neuronal vesicle marker norepinephrine transporter (NET).ResultHistochemical analyses revealed that p‐tau 181 signals were not overlapped with axons of unmyelinated cholinergic nor noradrenergic neurons, but well colocalized with myelinated axons of parvalbumin‐positive GABAergic interneurons, but not of glutamatergic neurons. Interestingly, the density of unmyelinated axons was significantly decreased in AppNLGF
mice, while that of glutamatergic, GABAergic or p‐tau 181‐positive axons was less affected. Instead, myelin sheaths surrounding p‐tau 181‐positive axons were significantly reduced in AppNLGF
mice.ConclusionThis study suggests that p‐tau 181 signals may represent axonal abnormality of parvalbumin‐positive GABAergic interneurons with disrupted myelin sheaths in brains of mouse model of Aβ pathology.
Insulin resistance, vascular dysfunction and inflammation biomarkers associations with an increased CAIDE risk score in APOE‐ε4 carriers with subjective cognitive decline from the PENSA study
Authors: Puig‐Pijoan Albert , Soldevila‐Domenech Natalia , Lorenzo Thais , Pizarro Nieves , Boronat Anna , Cuenca Aida , Gomis Maria , Sánchez‐Benavides Gonzalo , Grau‐Rivera Oriol , Suarez‐Calvet Marc , Minguillón Carolina , Fauria Karine , Gispert Juan Domingo , Forcano Laura , Molinuevo Jose Luis , de la Torre Rafael ,   PENSA Study Group
Published: December 2023

AbstractBackgroundThe CAIDE (Cardiovascular Risk Factors –CVRF‐, Aging, and Incidence of Dementia) Dementia Risk Score is a validated tool to predict late‐life dementia risk based on midlife CVRF. Sex differences in metabolic pathways related to cognitive decline have been described. The aim of this study was to explore associations between measures of insulin resistance, biomarkers of endothelial activation and peripheral inflammation and an increased CAIDE risk score (CAIDE‐rs) in individuals at higher risk of Alzheimer’s disease (AD). Sex differences in these associations were explored.MethodA total of 129 participants of the PENSA study were recruited. Participants were categorized into high (≥ 9 points) or low CAIDE‐rs groups (HR and LR respectively). Homeostatic model assessment was calculated (HOMA IR = fasting insulin (μIU/ml) × fasting glucose (mmol/ml)/22.5). The following biomarkers were analyzed: soluble intercellular adhesion molecule‐1 (ICAM‐1, ng/ml), vascular cell activation molecule‐1 (VCAM‐1, ng/ml), C‐reactive protein (CRP, mg/dl) and fibrinogen (mg/dl), using ELISA and Clauss method assays.ResultParticipants were 67.2 ±4.8 years, 65.1% were women and 32.6% were classified into the HR group. The HR group was older (68.5 vs. 66.5 years, P = 0.026) and presented higher levels of CRP (median of 0.08 vs. 0.06 mg/dL; P = 0.037) and HOMA‐IR (2.1 vs. 1.6; P = <.001). No differences were found for ICAM‐1, VCAM‐1 or fibrinogen.Comparisons between sex groups showed higher fibrinogen median values in women both among the HR group and in the global sample (HR 372 vs. 327mg/dl; P = 0.011; GS 350.5 vs. 340.5mg/dl; P = 0.032). Higher HOMA‐IR and VCAM‐1 median values in men were found in the global sample (2.13 vs. 1.65; P = 0.006 and 495.8 vs. 434.5 ng/ml; P = 0.028). The HR female group showed higher HOMA‐IR and fibrinogen median values than the LR female group (2.06 vs. 1.58; p = <.001 and 372 vs. 343 mg/dl; P = 0.029 respectively). HR male group showed higher CRP values compared to LR male group (0.03 vs. 0.12 mg/dl; p = 0.026).ConclusionAssociations of metabolic alterations and an increased CAIDE‐rs were found in individuals at higher risk of AD. Moreover, sex differences in metabolic alterations were also found. These results highlight the necessity of personalizing preventive interventions for AD taking into account sex‐related profiles.
Routes to standardisation for tau protein measurement in CSF
Authors: Giangrande Chiara , Vaneeckhoutte Hélène , Hirtz Christophe , Lehmann Sylvain , Jeromin Andreas , Delatour Vincent 
Published: December 2023

AbstractBackgroundCSF biomarkers are the target of several commercially available in vitro diagnostic (IVD) kits allowing an early diagnosis of Alzheimer’s disease (AD) and eventually the monitoring of treatment effects in clinical trials. Tau hyper‐phosphorylation is one of the main hallmarks of AD and its measurement provides higher accuracy to stratify patients at an early‐stage.Due to the rapid advancements in proteomics, standardisation of measurements can be achieved through the development of reference measurement procedures (RMPs) and certified reference materials (CRMs).MethodSI‐traceable protein and peptide primary calibrators were developed for t‐tau and p‐tau: mass fraction was determined by amino acid analysis and purity was assessed by LC‐MS at high resolution. CSF pools at different tau concentration were used for the development and validation of LC‐IDMS candidate RMP and their commutability was assessed.ResultAn LC‐IDMS candidate reference method was develop and validated in CSF for t‐tau using a SI‐traceable candidate protein primary calibrator. Three different CSF pools (low, medium, high) were successfully quantified with a relative expanded uncertainty below 10%. The commutability of 13 matrix‐based CRMs was assessed involving 8 immunoassays from 5 IVD providers by measuring 40 single CSF donations.According to the AT(N) classification, high levels of p‐tau(181) are highly correlated to tau pathology and commercially available immunoassays are able to target this specific epitope. We conducted a feasibility study on the development of a candidate reference method for p‐tau(181) in CSF relying on a SI‐traceable peptide primary calibrator and an antibody‐free sample preparation workflow.New assays targeting p‐tau(217) in CSF and plasma were also developed, making it necessary the organisation of standardisation initiatives. We sourced and characterised multiple phosphopeptide primary calibrators as well as a GSK3beta‐phosphorylated protein primary calibrator for the development of an LC‐MS RMP including an immunoprecipitation step in the sample preparation workflow.Conclusiontau is considered as a priority for the IFCC WG on NDD and the development of SI traceable RMPs and CRMs is essential to underpin a worldwide standardisation of results. This will help IVD providers to address the traceability requirements of the IVDR thus facilitating regulatory approvals of the kits.
Dissecting the role of GGGGCC repeat RNA secondary structure in cellular toxicity associated with C9 FTD/ALS
Authors: Malik Indranil 
Published: December 2023

AbstractBackgroundAberrant expansions of simple nucleotide repeat sequences can cause more than fifty human diseases. For example, the most common genetic cause of Frontotemporal dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS) is the expansion of an intronic GGGGCC hexanucleotide repeat sequence in C9orf72 gene (C9 FTD/ALS). Transcribed GGGGCC repeat RNAs can form complex secondary structures, which facilitate unusual interactions with cellular RNA‐binding proteins (RBPs). Sequestration of crucial RBPs into nuclear foci can inhibit the normal functions of those proteins. In addition, expanded GGGGCC repeat RNAs can support the translation of highly toxic repetitive peptides through a non‐canonical process known as repeat associated non‐AUG translation (RAN translation), which may require some specialized factors. Here we sought to understand how RNA secondary structure influence GGGGCC RAN translation and repeat elicited toxicity in C9 FTD/ALS.MethodWe used chemical modification coupled with traditional high‐throughput sequencing and nano‐pore sequencing approaches to probe GGGGCC repeat RNA secondary structures inside cells. We further use in vitro and in vivo RAN translation assays to determine whether repeat RNA secondary structures influence RAN translation efficiency.ResultOur RNA structural studies revealed that GGGGCC repeat RNAs form primarily form hairpin structures in cells. With nanopore sequencing, we were also able to detect the possible presence of unfolded and/or g‐quadruplex folded GGGGCC repeat RNAs in cells. Folding GGGGCC RNAs into hairpins supports RAN translation whereas folding repeat RNAs into g‐quadruplex structures strongly inhibits RAN translation in both in vitro and in vivo assays. Our results suggest that RNA secondary structure can affect the RAN translation elongation efficiency and g‐quadruplex structures may lead to the termination of elongating ribosomes.ConclusionWe present a deep sequencing‐based chemical probing technique to evaluate the roles of repeat RNA secondary structures in RNA toxicity underlying dementia‐associated repeat expansion disorders. Repeat RNA structural information can be used to identify chemical compounds that can bind to the RNA and prevent cytotoxicity in cells.
Plasma biomarkers as prognostic markers in Alzheimer’s disease: Influence of age at onset
Authors: Guillén Núria , Tort‐Merino Adrià , Falgàs Martínez Neus , Esteller Diana , Sarto Jordi , Castellví Magdalena , Juncà‐Parella Jordi , Borrego‐Écija Sergi , Bosch‐Capdevila Beatriz , González Yolanda , Fernandez‐Villullas Guadalupe , Ruiz‐García Raquel , Naranjo Laura , Antonell Anna , Balasa Mircea , Sanchez‐Valle Raquel , Lladó Albert 
Published: December 2023

AbstractBackgroundLittle is known about the influence of age at onset (AAO) on plasma biomarkers and their use as prognostic biomarkers in Alzheimer’s disease (AD).MethodWe selected patients with AD diagnosis with available neuropsychological testing (NPS) at time of diagnosis and two years later, and plasma biomarkers at baseline.NPS battery included Free and Cued Selective Reminding Test (FCSRT), Landscape test (visual memory), Boston Naming Test, Semantic Fluency, BDAE auditory comprehension, Constructional and Ideomotor Praxis, Visual Object and Space Perception (VOSP) Incomplete Letters and Number Location subtests, Trail Making Test (TMT) A and B, Phonemic Fluency, and Digit Span Forward and Backward. NPS scores were compared by AAO: early‐onset AD (EOAD; <65 years) vs. late onset AD (LOAD; >65y).We analyzed plasma biomarkers phosphorilated‐tau181 (p‐tau181), total tau (t‐tau), neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP) and ubiquitin C‐terminal hydrolase L1 (UCHL‐1) using the Quanterix Simoa p‐tau181 Advantage V2 and Neurology 4‐Plex A assays. Group comparisons and linear regressions adjusted by years of education (YOE) were performed in Stata/IC 16.1.ResultForty‐two participants were included, 23 LOAD and 19 EOAD. Plasma p‐tau181 and GFAP levels were higher in LOAD (Table 1). We did not find differences between LOAD and EOAD in NPS tests at baseline or +2 years (Table 2).Plasma ptau‐181 was associated with progression in MMSE globally, VOSP‐Incomplete letters globally and in EOAD. Plasma NfL were associated to Boston Naming test globally and in EOAD, Semantic fluency test globally, VOSP‐incomplete letters in EOAD, and Free and Total Learning of FCSRT in LOAD. Plasma GFAP was associated to MMSE globally and in EOAD, Free learning of FCSRT in LOAD and VOSP‐Incomplete letters and number location globally. Plasma UCHL‐1 was associated to Semantic fluency test in LOAD (Table 3). Praxis and attention and executive function tests loss were not associated to plasma biomarkers.ConclusionPlasma p‐tau18, NfL, GFAP and UCHL‐1 were associated to pogression in memory, language and visual tests. They were predominantly associated to memory loss in LOAD and language and visual function loss in EOAD. Results need to be interpreted cautiously due to small sample size.
Associations between blood‐based biomarkers and cognitive decline among participants at risk of Alzheimer’s disease: the Memento cohort
Authors: Grasset Leslie , Bouteloup Vincent , Pellegrin Isabelle , Planche Vincent , Chêne Geneviève , Dufouil Carole ,   the Memento Study Group
Published: December 2023

AbstractBackgroundBlood‐based biomarkers for Alzheimer’s disease (AD) pathology and neurodegeneration are promising biomarkers due to their lower cost, accessibility, and minimally invasive nature. Higher levels of AD blood‐based biomarkers have been shown to be associated with the risk of AD and cognitive decline. Yet, the specific cognitive domains involved need to be further investigated. We thus aimed at estimating the association between levels of baseline AD blood‐based biomarkers with cognitive trajectories over 5 years of follow‐up across different domains in a large clinical based cohort.MethodWe selected the 2060 dementia‐free individuals aged 60 years and older included in the Memento study, a French nationwide cohort, following patients from 28 memory clinics with either isolated cognitive complaints or mild cognitive impairment. Amyloid‐β 40 and 42, P‐tau181, and Neurofilament Light Chain (NfL) concentrations were measured at baseline using Simoa HD‐X analyzer. Global cognition, episodic memory, semantic memory, and executive functioning were assessed every year up to 5 years using the Mini Mental State Examination, the Free and Cued Reminding test, the Animal fluency test, and the Trail Making Test B respectively. Linear mixed models adjusted for sex, education level, APOE‐ε4 status, and practice effect, with age as time scale and quadratic slopes were performed to examine how AD blood‐based biomarkers relate to longitudinal cognitive trajectories by domain.ResultMean age was 72.8 years, 62% were women, 28% were APOE‐ε4 carriers, and 58% had a Clinical Dementia Rating score of 0.5. Higher baseline plasma P‐tau181 was associated with significantly faster nonlinear cognitive decline in all four cognitive domains (p<0.001). On the opposite, baseline plasma Aβ42/40 ratio and NfL were not associated with cognitive decline whatever the domain. Associations between AD blood‐based biomarkers and faster cognitive decline were not modified by APOE‐ε4, sex, nor education level (p value for interaction > 0.05).ConclusionIn a memory clinic population, plasma P‐tau181 is a marker of future cognitive decline. This marker is a good candidate for additional studies assessing biomarkers relevant for the identification of individuals who may benefit from treatment early in the disease course.
Atypical presentations of autosomal dominant familial Alzheimer’s disease: insights into genetic, neuropathological and clinical heterogeneity
Authors: Ryan Natalie S , Willumsen Nanet , Nicholas Jennifer M , Poole Teresa , Pavisic Ivanna M , Walsh Phoebe , Rice Helen , Lu Kirsty , O'Connor Antoinette , Weston Philip SJ , Abel Emily , Barkhof Frederik , Barnes Jo , Lashley Tammaryn , Fox Nick C 
Published: December 2023

AbstractBackgroundAutosomal dominant familial Alzheimer’s disease (ADAD), caused by APP, PSEN1 and PSEN2 mutations, is clinically and pathologically similar to sporadic AD, with both typically presenting with memory impairment. However as in sporadic AD, atypical phenotypes and neuropathological heterogeneity occur, including variable vascular Aβ deposition as cerebral amyloid angiopathy (CAA). Investigating relationships between clinical, genetic and neuropathological heterogeneity in ADAD may provide insights into pathophysiological pathways relevant to AD in general.Methods256 symptomatic individuals from ADAD families seen at our Centre were included in a survival analysis, with detailed clinical phenotype data available for 138 (101 PSEN1, 37 APP). 33 of these individuals underwent brain donation (24 PSEN1, 9 APP), all demonstrating end‐stage AD pathology. Frontal and occipital cortex sections were stained immunohistochemically for Aβ and vessel counts used to determine the proportion of cortical and leptomeningeal blood vessels affected by CAA.ResultsAge at onset was, on average, seven years younger for PSEN1 than APP mutations and was influenced by mutation much more than survival was. Atypical (non‐amnestic) cognitive presentations with initial behavioral, language, dyscalculic or dysexecutive symptoms, and atypical clinical features (pyramidal, extrapyramidal and cerebellar signs) were more common in PSEN1 than APP cases, particularly those with post‐codon 200 mutations. Atypical cognitive presentations were associated with longer survival. There was some indication that APOE4 carriers had longer survival and that this effect may be restricted to PSEN1. In the post‐mortem cohort, atypical cognitive presentations occurred in 15%. Additional neurological features comprised myoclonus (45%), seizures (21%), pyramidal signs (21%) and extrapyramidal signs (15%), one individual had cerebellar signs. Increased frontal cortical and leptomeningeal CAA occurred in individuals with pyramidal and extrapyramidal signs, and in PSEN1 post‐codon 200 compared to pre‐codon 200 mutations. Atypical cognitive presentations were associated with increased frontal cortical CAA.ConclusionsPhenotypic heterogeneity in ADAD is influenced by causative gene and mutation type, and atypical clinical presentations are associated with increased CAA. Exploring mechanisms by which certain mutations drive Aβ deposition towards the vasculature, and how these may be impacted by other genetic factors and by therapies targeting Aβ, is an important direction for future research.
Parkinson’s Disease Genetic Variants in Sporadic Early Onset Dementia: Results from the Longitudinal Early Onset Alzheimer’s Disease Study
Authors: Nudelman Kelly N. H. , Jackson Trever , Rumbaugh Malia C. , Eloyan Ani , Faber Kelley M. , Snoddy Casey , Foroud Tatiana M. , Carrillo Maria C. , Dickerson Brad C. , Rabinovici Gil D. , Apostolova Liana G. ,   the LEADS Consortium
Published: December 2023

AbstractBackgroundMuch of the genetic etiology of sporadic early onset Alzheimer’s disease and frontotemporal dementia is largely unknown. Genetic investigation using whole exome sequencing (WES) data in the Longitudinal Early Onset Alzheimer’s Disease Study (LEADS) aims to address this gap, with the hypothesis that some individuals with early onset cognitive impairment may carry pathogenic, potentially causative variants in Parkinson’s disease (PD) genes.MethodsWhole exome sequencing data for cognitively impaired LEADS participants (N = 301) was processed using the GATK best practices pipeline with Sentieon software; joint‐called VCFs were annotated with Annovar, and the results were filtered to prioritize amino acid code‐altering variants with minor allele frequencies <1% that have not been reported as benign or likely benign in ClinVar. Variants in the acid beta‐glucocerebrosidase (GBA), leucine‐rich repeat kinase 2 (LRRK2), Parkin RBR E3 ubiquitin protein ligase (PRKN), PTEN‐induced putative kinase 1 (PINK1), protein kinase, interferon‐inducible double‐stranded rna‐dependent activator (PRKRA), and Parkinson disease 7, autosomal recessive early‐onset (PARK7) were reviewed. Heterozygous or homozygous carriers of variants meeting these criteria in GBA and LRRK2, as well as homozygous or potentially compound heterozygous variant carriers in the other genes, were reviewed for the presence of PD‐related symptoms documented with the National Alzheimer’s Coordinating Center (NACC) Uniform Data Set (UDS) collected at baseline (N = 283).ResultsThere were no variants meeting inclusion criteria for PINK1, PARK7, PRKN, or PRKRA. However, we observed 21 individuals with predicted or reported functional variant(s) in GBA or LRRK2. The mean screening visit age for these carriers was 59 (range 53‐64), and all but two were amyloid positive. While only one case was documented with motor symptoms, several participants had peripheral nervous symptoms such as neuropathy. 17 carriers had amnestic‐type dementia, with similar frequency to non‐carriers.ConclusionsWhile there are a small subset of individuals carrying functional variants in PD genes, they do not appear to substantially influence the phenotype of most cases at baseline. Future planned research efforts include assessing alpha synuclein pathology via alpha synuclein seeding assays, which will help clarify the potential role of mixed genetic etiology and pathology in risk for non‐familial early onset dementia.