Publications by authors named "Franzmeier N"

Traumatic brain injury is widely viewed as a risk factor for dementia, but the biological mechanisms underlying this association are still unclear. In previous studies, traumatic brain injury has been associated with the hallmark pathologies of Alzheimer's disease, i.e.

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In Alzheimer's disease (AD), amyloid-β (Aβ) triggers the aggregation and spreading of tau pathology, which drives neurodegeneration and cognitive decline. However, the pathophysiological link between Aβ and tau remains unclear, which hinders therapeutic efforts to attenuate Aβ-related tau accumulation. Aβ has been found to trigger neuronal hyperactivity and hyperconnectivity, and preclinical research has shown that tau spreads across connected neurons in an activity-dependent manner.

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Purpose Of The Report: Adults with Down Syndrome (DS) have a substantially increased risk for Alzheimer's disease (AD) due to the triplicated amyloid-precursor-protein gene on chromosome 21, resulting in amyloid and tau accumulation. However, tau PET assessments are not sufficiently implemented in DS-AD research or clinical work-up, and second-generation tau tracers such as [F]PI-2620 have not been thoroughly characterized in adults with DS. We aim at illustrating feasibility and potential diagnostic value of tau PET imaging with [F]PI-2620 for the diagnosis of DS-AD.

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Aim: Standardized evaluation of [F]PI-2620 tau-PET scans in 4R-tauopathies represents an unmet need in clinical practice. This study aims to investigate the effectiveness of visual evaluation of [F]PI-2620 images for diagnosing 4R-tauopathies and to develop a straight-forward reading algorithm to improve objectivity and data reproducibility.

Methods: A total of 83 individuals with [F]PI-2620 PET scans were included.

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Background: The recent Movement Disorders Society (MDS)-progressive supranuclear palsy (PSP) diagnostic criteria conceptualized three clinical diagnostic certainty levels: "suggestive of PSP" for sensitive early diagnosis based on subtle clinical signs, "possible PSP" balancing sensitivity and specificity, and "probable PSP" highly specific for PSP pathology.

Objective: The aim of this study was to prospectively validate the criteria against long-term clinical follow-up and characterize the diagnostic certainty increase over time.

Methods: Patients with "possible PSP" or "suggestive of PSP" diagnosis and clinical follow-up were recruited in two German multicenter longitudinal observational studies (ProPSP and DescribePSP).

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In Alzheimer's disease (AD), Aβ triggers p-tau secretion, which drives tau aggregation. Therefore, it is critical to characterize modulators of Aβ-related p-tau increases which may alter AD trajectories. Here, we assessed whether factors known to alter tau levels in AD modulate the association between fibrillar Aβ and secreted p-tau determined in the cerebrospinal fluid (CSF).

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In early-stage Alzheimer's disease (AD) amyloid-β (Aβ) deposition can induce neuronal hyperactivity, thereby potentially triggering activity-dependent neuronal secretion of phosphorylated tau (p-tau), ensuing tau aggregation and spread. Therefore, cortical excitability is a candidate biomarker for early AD detection. Moreover, lowering neuronal excitability could potentially complement strategies to reduce Aβ and tau buildup.

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Article Synopsis
  • * In studies using a mouse model lacking the NPC1 protein in immune cells, researchers found significant changes in microglial lipid profiles, increased microglial activity, and symptoms resembling NPC disease, such as lifespan reduction and motor issues.
  • * Monitoring translocator protein (TSPO) levels in the blood may be useful for assessing NPC disease progression and treatment response, as shown by changes in TSPO levels following a specific therapy that appeared beneficial for patients.
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Introduction: With the advent of disease-modifying therapies, accurate assessment of biomarkers indicating the presence of disease-associated amyloid beta (Aβ) pathology becomes crucial in patients with clinically suspected Alzheimer's disease (AD). We evaluated Aβ levels in cerebrospinal fluid (Aβ CSF) and Aβ levels in positron emission tomography (Aβ PET) biomarkers in a real-world memory-clinic setting to develop an efficient algorithm for clinical use.

Methods: Patients were evaluated for AD-related Aβ pathology from two independent cohorts (Ludwig Maximilian University [LMU],  = 402, and Medical University of Vienna [MUV],  = 144).

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Tau PET has attracted increasing interest as an imaging biomarker for 4-repeat (4R)-tauopathy progressive supranuclear palsy (PSP). However, the translation of in vitro 4R-tau binding to in vivo tau PET signals is still unclear. Therefore, we performed a translational study using a broad spectrum of advanced methodologies to investigate the sources of [F]PI-2620 tau PET signals in individuals with 4R-tauopathies, including a pilot PET autopsy study in patients.

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Fibrillar tau gradually progresses in the brain during the course of Alzheimer's disease (AD). However, the contribution of tau accumulation in a given brain region to decline in different cognitive domains and thus phenotypic heterogeneity in AD remains unclear. Here, we leveraged the functional connectome to link the locality of tau accumulation to domain-specific cognitive impairment.

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  • White matter hyperintensities (WMH) are linked to cognitive impairment but solely measuring their volume doesn't fully explain the cognitive deficits.
  • Lesion network mapping (LNM) offers a new way to assess how WMH connects with brain networks, potentially improving our understanding of their impact on cognition.
  • In a study of 3,485 patients, LNM scores outperformed WMH volumes in predicting cognitive performance, especially in attention, processing speed, and verbal memory, but not for language functions.
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Background And Objectives: Behavioral and neuropsychiatric symptoms are frequent in patients with genetic frontotemporal dementia (FTD). We aimed to describe behavioral and neuropsychiatric phenotypes in genetic FTD, quantify their temporal association, and investigate their regional association with brain atrophy.

Methods: We analyzed data of pathogenic variant carriers in the chromosome 9 open reading frame 72 (), progranulin (), or microtubule-associated protein tau () gene from the Genetic Frontotemporal dementia Initiative cohort study that enrolls both symptomatic pathogenic variant carriers and first-degree relatives of known carriers.

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Introduction: Recent advances in biomarker research have improved the diagnosis and monitoring of Alzheimer's disease (AD), but in vivo biomarker-based workflows to assess 4R-tauopathy (4RT) patients are currently missing. We suggest a novel biomarker-based algorithm to characterize AD and 4RTs.

Methods: We cross-sectionally assessed combinations of cerebrospinal fluid measures (CSF p-tau and t-tau) and F-PI-2620 tau-positron emission tomography (PET) in patients with AD (n = 64), clinically suspected 4RTs (progressive supranuclear palsy or corticobasal syndrome, n = 82) and healthy controls (n = 19).

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Background: Microglial activation is one hallmark of Alzheimer disease (AD) neuropathology but the impact of the regional interplay of microglia cells in the brain is poorly understood. We hypothesized that microglial activation is regionally synchronized in the healthy brain but experiences regional desynchronization with ongoing neurodegenerative disease. We addressed the existence of a microglia connectome and investigated microglial desynchronization as an AD biomarker.

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Purpose: Current therapy strategies still provide only limited success in the treatment of glioblastoma, the most frequent primary brain tumor in adults. In addition to the characterization of the tumor microenvironment, global changes in the brain of patients with glioblastoma have been described. However, the impact and molecular signature of neuroinflammation distant of the primary tumor site have not yet been thoroughly elucidated.

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Aim: β-amyloid (Aβ) small animal PET facilitates quantification of fibrillar amyloidosis in Alzheimer's disease (AD) mouse models. Thus, the methodology is receiving growing interest as a monitoring tool in preclinical drug trials. In this regard, harmonization of data from different scanners at multiple sites would allow the establishment large collaborative cohorts and may facilitate efficacy comparison of different treatments.

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Background: Preclinical, postmortem, and positron emission tomography (PET) imaging studies have pointed to neuroinflammation as a key pathophysiological hallmark in primary 4-repeat (4R) tauopathies and its role in accelerating disease progression.

Objective: We tested whether microglial activation (1) progresses in similar spatial patterns as the primary pathology tau spreads across interconnected brain regions, and (2) whether the degree of microglial activation parallels tau pathology spreading.

Methods: We examined in vivo associations between tau aggregation and microglial activation in 31 patients with clinically diagnosed 4R tauopathies, using 18F-PI-2620 PET and 18F-GE180 (translocator protein [TSPO]) PET.

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Article Synopsis
  • Four-repeat tauopathies are brain diseases that happen when a protein called 4R tau builds up in certain areas of the brain, affecting how it works.
  • Two main types of these diseases are progressive supranuclear palsy (PSP) and corticobasal degeneration, which both cause problems in brain regions that are important for movement and other functions.
  • The researchers are trying to figure out how the problems in one part of the brain (subcortical) affect other connected areas (cortical) by studying patients and using special brain scans to see how these changes relate to each other.
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Article Synopsis
  • - The study investigates various MRI measures as biomarkers for tracking brain atrophy progression in patients with progressive supranuclear palsy (PSP), focusing on comparing different staging systems and assessing their effectiveness for clinical trials.
  • - 508 participants were analyzed, including PSP patients and healthy controls, with specific attention given to the brainstem and midbrain volumes, which showed the most significant changes over one year.
  • - Results suggest that automated atlas-based volumetry is more sensitive and requires smaller sample sizes than other methods for detecting atrophy progression in PSP, potentially aiding in the evaluation of treatment efficacy in clinical trials.
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Purpose: [F]PI-2620 positron emission tomography (PET) detects misfolded tau in progressive supranuclear palsy (PSP) and Alzheimer's disease (AD). We questioned the feasibility and value of absolute [F]PI-2620 PET quantification for assessing tau by regional distribution volumes (V). Here, arterial input functions (AIF) represent the gold standard, but cannot be applied in routine clinical practice, whereas image-derived input functions (IDIF) represent a non-invasive alternative.

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Introduction: White matter hyperintensities of presumed vascular origin (WMH) are associated with cognitive impairment and are a key imaging marker in evaluating cognitive health. However, WMH volume alone does not fully account for the extent of cognitive deficits and the mechanisms linking WMH to these deficits remain unclear. We propose that lesion network mapping (LNM), enables to infer if brain networks are connected to lesions, and could be a promising technique for enhancing our understanding of the role of WMH in cognitive disorders.

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Article Synopsis
  • White matter hyperintensities (WMH) correlate with major dementia causes, particularly arteriolosclerosis and amyloid pathology; the study aimed to pinpoint specific WMH locations linked to vascular risk and amyloid-β (Aβ42) status.* -
  • Data from 3,132 patients were analyzed, revealing that vascular risk was associated with WMH in the anterior/superior corona radiata and middle cerebellar peduncle, while Aβ42 positivity linked to WMH in the posterior thalamic radiation and splenium.* -
  • The findings suggest WMH patterns differ between vascular risk factors and Aβ42 pathology, indicating the need for further research on how these factors impact white matter
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This paper provides an overview of the role of neuroinflammation in Alzheimer's disease and other neurodegenerative diseases, highlighting the potential of anti-inflammatory treatments to slow or prevent decline. This research focuses on the use of positron emission tomography (PET) imaging to visualize and quantify molecular brain changes in patients, specifically microglial activation and reactive astrogliosis. We discuss the development and application of several PET radioligands, including first-generation ligands like PK11195 and Ro5-4864, as well as second- and third-generation ligands such as [11C]PBR28, [18F]DPA-714, [18F]GE-180, and [11C]ER176.

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Article Synopsis
  • - The study examines the balance between sample size and scan time in neuroimaging, particularly in brain-wide association studies (BWAS) using fMRI, and finds that total scan duration significantly affects prediction accuracy, suggesting they can be interchangeable up to 20-30 minutes.
  • - As scan time increases, its relative benefits diminish compared to sample size, indicating that longer scan times should be considered, especially when accounting for participant-related costs like recruitment and non-imaging measures.
  • - The research highlights that conventional methods prioritize sample size over scan time, potentially leading to poorer prediction accuracies; thus, it provides recommendations for optimizing future study designs to make better resource use.
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