scholarly journals 18F–THK–5351, Fluorodeoxyglucose, and Florbetaben PET Images in Atypical Alzheimer’s Disease: A Pictorial Insight into Disease Pathophysiology

2021 ◽  
Vol 11 (4) ◽  
pp. 465
Author(s):  
Sohee Park ◽  
Minyoung Oh ◽  
Jae Kim ◽  
Jae-Hong Lee ◽  
Young Yoon ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Symptoms ◽  
Primary Progressive Aphasia ◽  
Clinical Findings ◽  
Cortical Atrophy ◽  
Positron Emission ◽  
Clinical Presentations ◽  
Atypical Alzheimer’S Disease ◽  
Insight Into

The recent advance of positron emission tomography (PET) tracers as biomarkers in Alzheimer’s disease (AD) provides more insight into pathophysiology, preclinical diagnosis, and further therapeutic strategies. However, synergistic processes or interactions between amyloid and tau deposits are still poorly understood. To better understand their relationship in focal brain changes with clinical phenotypes, we focused on region-specific or atypical AD characterized by focal clinical presentations: Posterior cortical atrophy (PCA) and logopenic variant of primary progressive aphasia (lpvPPA). We compared three different PET images with 18F–THK–5351 (tau), 18F–Florbetaben (amyloid beta, Aβ), and 18F–Fluorodeoxyglucose (glucose metabolism) to investigate potential interactions among pathologies and clinical findings. Whereas the amyloid accumulations were widespread throughout the neocortex, tau retentions and glucose hypometabolism showed focal changes corresponding to the clinical features. The distinctly localized patterns were more prominent in tau PET imaging. These findings suggest that tau pathology correlates more closely to the clinical symptoms and the neurodegenerative processes than Aβ pathology in AD.

scholarly journals Cryo-EM structures of tau filaments from Alzheimer’s disease with PET ligand APN-1607

2021 ◽  
Vol 141 (5) ◽  
pp. 697-708
Author(s):  
Yang Shi ◽  
Alexey G. Murzin ◽  
Benjamin Falcon ◽  
Alexander Epstein ◽  
Jonathan Machin ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Small Molecules ◽  
Binding Sites ◽  
Binding Activity ◽  
Cortical Atrophy ◽  
Binding Modes ◽  
Major Site ◽  
Age Related ◽  
Positron Emission

AbstractTau and Aβ assemblies of Alzheimer’s disease (AD) can be visualized in living subjects using positron emission tomography (PET). Tau assemblies comprise paired helical and straight filaments (PHFs and SFs). APN-1607 (PM-PBB3) is a recently described PET ligand for AD and other tau proteinopathies. Since it is not known where in the tau folds PET ligands bind, we used electron cryo-microscopy (cryo-EM) to determine the binding sites of APN-1607 in the Alzheimer fold. We identified two major sites in the β-helix of PHFs and SFs and a third major site in the C-shaped cavity of SFs. In addition, we report that tau filaments from posterior cortical atrophy (PCA) and primary age-related tauopathy (PART) are identical to those from AD. In support, fluorescence labelling showed binding of APN-1607 to intraneuronal inclusions in AD, PART and PCA. Knowledge of the binding modes of APN-1607 to tau filaments may lead to the development of new ligands with increased specificity and binding activity. We show that cryo-EM can be used to identify the binding sites of small molecules in amyloid filaments.

Difficulties in diagnosing atypical variants of Alzheimer’s disease

2021 ◽  
Vol 26 (5) ◽  
pp. 16-23
Author(s):  
A. A. Tappakhov ◽  
T. Ya. Nikolaeva ◽  
T. E. Popova ◽  
N. A. Shnayder
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Picture ◽  
Short Term Memory ◽  
Late Onset ◽  
Early Stage ◽  
Primary Progressive Aphasia ◽  
Cortical Atrophy ◽  
Posterior Cortical Atrophy ◽  
Short Term

Alzheimer’s disease (AD) is the most common cause of dementia in the population. Late onset AD has a classic clinical picture with short-term memory deficit, apraxia and agnosia. Patients with early-onset AD may have an atypical clinical picture which complicates diagnosis. Atypical AD variants include the logopenic variant of primary progressive aphasia, posterior cortical atrophy, behavioral, biparietal, and cortico-basal variants. These variants have pathomorphological signs similar to classical AD, but at an early stage they are characterized by focal atrophy which explains their clinical polymorphism. This article provides a review of the current literature on atypical types of AD and presents a clinical case of a 62-year-old patient in whom the disease debuted with prosopagnosia due to focal atrophy of the temporo-occipital regions of the non-dominant hemisphere.

Clinical Characteristic in Primary Progressive Aphasia in Relation to Alzheimer’s Disease Biomarkers

2021 ◽  
pp. 1-13
Author(s):  
Sung Hoon Kang ◽  
Hanna Cho ◽  
Jiho Shin ◽  
Hang-Rai Kim ◽  
Young Noh ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Language Impairment ◽  
Amyloid Β ◽  
Primary Progressive Aphasia ◽  
Cortical Atrophy ◽  
Clinical Feature ◽  
Progressive Aphasia ◽  
Disease Biomarkers ◽  
Primary Progressive

Background: Primary progressive aphasia (PPA) is associated with amyloid-β (Aβ) pathology. However, clinical feature of PPA based on Aβ positivity remains unclear. Objective: We aimed to assess the prevalence of Aβ positivity in patients with PPA and compare the clinical characteristics of patients with Aβ-positive (A+) and Aβ-negative (A–) PPA. Further, we applied Aβ and tau classification system (AT system) in patients with PPA for whom additional information of in vivo tau biomarker was available. Methods: We recruited 110 patients with PPA (41 semantic [svPPA], 27 non-fluent [nfvPPA], 32 logopenic [lvPPA], and 10 unclassified [ucPPA]) who underwent Aβ-PET imaging at multi centers. The extent of language impairment and cortical atrophy were compared between the A+ and A–PPA subgroups using general linear models. Results: The prevalence of Aβ positivity was highest in patients with lvPPA (81.3%), followed by ucPPA (60.0%), nfvPPA (18.5%), and svPPA (9.8%). The A+ PPA subgroup manifested cortical atrophy mainly in the left superior temporal/inferior parietal regions and had lower repetition scores compared to the A–PPA subgroup. Further, we observed that more than 90%(13/14) of the patients with A+ PPA had tau deposition. Conclusion: Our findings will help clinicians understand the patterns of language impairment and cortical atrophy in patients with PPA based on Aβ deposition. Considering that most of the A+ PPA patents are tau positive, understanding the influence of Alzheimer’s disease biomarkers on PPA might provide an opportunity for these patients to participate in clinical trials aimed for treating atypical Alzheimer’s disease.

scholarly journals Combined Study of Cerebral Glucose Metabolism and [11C]Methionine Accumulation in Probable Alzheimer's Disease Using Positron Emission Tomography

1996 ◽  
Vol 16 (3) ◽  
pp. 399-408 ◽  
Author(s):  
E. Salmon ◽  
M. C. Gregoire ◽  
G. Delfiore ◽  
C. Lemaire ◽  
C. Degueldre ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Positron Emission Tomography ◽  
Glucose Metabolism ◽  
Clinical Symptoms ◽  
Synaptic Activity ◽  
Emission Tomography ◽  
Tissue Loss ◽  
Positron Emission

There is a characteristic decrease in glucose metabolism in associative frontal and temporo-parietal cortices of patients suffering from Alzheimer's disease (AD). The decrease in metabolism might result from local neuronal loss or from a decrease of synaptic activity. We measured in vivo [11C]methionine accumulation into proteins with positron emission tomography (PET) to assess cortical tissue loss in AD. Both global regional activity and compartmental analysis were used to express [11C]methionine accumulation into brain tissue. Glucose metabolism was measured with [18F]fluorodeoxyglucose and autoradiographic method. Combined studies were performed in 10 patients with probable AD, compared to age-matched healthy volunteers. There was a significant 45% decrease of temporo-parietal glucose metabolism in patients with AD, and frontal metabolism was lowered in most patients. Temporo-parietal metabolism correlated to dementia severity. [11C]methionine incorporation into temporo-parietal and frontal cortices was not significantly decreased in AD. There was no correlation with clinical symptoms. Data suggest that regional tissue loss, assessed by the decrease of [11C]methionine accumulation, is not sufficient to explain cortical glucose hypometabolism, which reflects, rather, reduced synaptic connectivity.

Molecular Imaging in Alzheimer’s Disease

2011 ◽  
Vol 6 (1) ◽  
pp. 16
Author(s):  
Karl Herholz ◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Imaging ◽  
Clinical Symptoms ◽  
Accurate Method ◽  
Imaging Biomarker ◽  
Pet Tracer ◽  
Specificity And Sensitivity ◽  
Positron Emission ◽  
Dementia Research

The most sensitive and accurate method for molecular imaging in human Alzheimer’s disease (AD) is positron emission tomography (PET). The most widely available PET tracer, which is also used in clinical oncology, is 18F-2-fluoro-2-deoxy-D-glucose (FDG). FDG is an imaging biomarker for early and differential diagnosis of AD. Even higher molecular specificity and sensitivity for detection of AD before dementia onset is provided by high-affinity ligands for fibrillary amyloid. 11C-Pittsburgh Compound B is widely being used in research laboratories, while new 18F-labelled ligands are currently undergoing formal clinical trials as amyloid imaging agents and are expected to become commercially available for clinical use in the near future. A large variety of tracers is being developed and used in dementia research for activated microglia and multiple neurotransmitter systems to study disease pathophysiology, biological correlates of clinical symptoms and new possibilities for treatment. Current studies in humans are investigating cholinergic, serotonergic and dopaminergic neurotransmission.

scholarly journals Behavioral variant of frontotemporal dementia or frontal variant of Alzheimer's disease? A case study

2019 ◽  
Vol 13 (3) ◽  
pp. 356-360
Author(s):  
Leonardo Cruz de Souza ◽  
Luciano Inácio Mariano ◽  
Renata Freire de Moraes ◽  
Paulo Caramelli
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Frontotemporal Dementia ◽  
Csf Biomarkers ◽  
Positron Emission ◽  
Personality Changes ◽  
Clinical Presentations ◽  
History Of ◽  
Executive Deficits

ABSTRACT Alzheimer's disease (AD) has heterogeneous clinical presentations. Amnestic progressive disorder leading to dementia is the most typical, but non-amnestic presentations are also recognized. Here we report a case of frontal variant of AD. A right-handed woman, aged 68 years, was referred for progressive behavioral disorders and personality changes. She had a corroborated history of dietary changes, hyperorality, impulsivity, affective indifference and apathy, with functional impairment. Cognitive assessment yielded severe executive deficits. Positron emission tomography with fluorodeoxyglucose showed marked hypometabolism in frontotemporal regions, with relative preservation of parietal regions. CSF AD biomarkers showed low Aβ42, high Tau and high P-Tau. The patient fulfilled criteria for probable behavioral variant frontotemporal dementia. However, considering the AD pathophysiological signature on CSF biomarkers, a diagnosis of frontal variant of AD was established. In the perspective of disease-modifying therapies, it is important to identify atypical Alzheimer presentations, as these patients may be candidates for specific treatments.

Biomarkers in Alzheimer’s disease

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Manuel H. Janeiro ◽  
Carlos G. Ardanaz ◽  
Noemí Sola-Sevilla ◽  
Jinya Dong ◽  
María Cortés-Erice ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Symptoms ◽  
Biological Fluids ◽  
Pathological Process ◽  
Positron Emission ◽  
Cerebrospinal Fluid Biomarkers ◽  
Novel Biomarkers ◽  
Definition Of ◽  
T Tau

AbstractBackgroundAlzheimer’s disease (AD) is a progressive neurodegenerative disease. AD is the main cause of dementia worldwide and aging is the main risk factor for developing the illness. AD classical diagnostic criteria rely on clinical data. However, the development of a biological definition of AD using biomarkers that reflect the underling neuropathology is needed.ContentThe aim of this review is to describe the main outcomes when measuring classical and novel biomarkers in biological fluids or neuroimaging.SummaryNowadays, there are three classical biomarkers for the diagnosis of AD: Aβ42, t-Tau and p-Tau. The diagnostic use of cerebrospinal fluid biomarkers is limited due to invasive collection by lumbar puncture with potential side effects. Plasma/serum measurements are the gold standard in clinics, because they are minimally invasive and, in consequence, easily collected and processed. The two main proteins implicated in the pathological process, Aβ and Tau, can be visualized using neuroimaging techniques, such as positron emission tomography.OutlookAs it is currently accepted that AD starts decades before clinical symptoms could be diagnosed, the opportunity to detect biological alterations prior to clinical symptoms would allow early diagnosis or even perhaps change treatment possibilities.

P2-169: NEUROFIBRILLARY TANGLES PREDICT IN VIVO CORTICAL ATROPHY IN PRIMARY PROGRESSIVE APHASIA WITH ALZHEIMER'S DISEASE

2006 ◽  
Vol 14 (7S_Part_13) ◽  
pp. P733-P733
Author(s):  
Daniel T. Ohm ◽  
Garam Kim ◽  
Tamar Gefen ◽  
Alfred Rademaker ◽  
Sandra Weintraub ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurofibrillary Tangles ◽  
Primary Progressive Aphasia ◽  
Cortical Atrophy ◽  
Progressive Aphasia ◽  
Primary Progressive

scholarly journals A systematic review of the prevalence of depression, anxiety, and apathy in frontotemporal dementia, atypical and young-onset Alzheimer’s disease, and inherited dementia

2020 ◽  
pp. 1-20
Author(s):  
Jessica D. Collins ◽  
Susie M. D. Henley ◽  
Aida Suárez-González
Keyword(s):  
Systematic Review ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Frontotemporal Dementia ◽  
Neuropsychiatric Symptoms ◽  
Primary Progressive Aphasia ◽  
Small Sample ◽  
Cortical Atrophy ◽  
Sample Sizes ◽  
Young Onset

ABSTRACT Objectives: Depression, anxiety, and apathy are the most commonly reported neuropsychiatric symptoms (NPS) in Alzheimer’s disease (AD). Understanding their prevalence in rarer dementias such as frontotemporal dementia (FTD), primary progressive aphasia (PPA), posterior cortical atrophy (PCA), young-onset AD (YOAD), and inherited dementias has implications for both clinical practice and research. In this study, we aimed to examine the current state of knowledge of the prevalence of these three NPS in less prevalent dementias. Design: We conducted a systematic review based on searches of EMBASE, PsycINFO, and PubMed up to September 2019. Results: 47 articles meeting inclusion criteria were identified. Depression, anxiety, and apathy were commonly reported across the phenotypes studied but their prevalence showed large variation between studies. Apathy showed the highest reported frequency in FTD (50–100% across studies), behavioral variant frontotemporal dementia (bvFTD) (73–100%), and YOAD (44–100%). Anxiety was frequently reported in FTD (0–100%) and bvFTD (19–63%). Depression showed the highest prevalence in FTD (7–69%) and YOAD (11–55%). Among the three variants of PPA, sv-PPA is the one most investigated (seven articles). Three or fewer articles were identified examining NPS in the remaining PPA variants, PCA, familial AD, and familial FTD. Inconsistency in the tools used to measure symptoms and small sample sizes were common methodological limitations. Conclusions: Future studies should consider the inclusion of larger sample sizes (e.g. through multicenter collaborations) and the use of harmonized protocols that include the combination of caregiver and patient-derived measures and symptom-specific questionnaires. More research is needed on the phenotype-specific barriers and facilitators for people living with dementia to successfully engage in self-reports of NPS.

scholarly journals Tau-first subtype of Alzheimer's disease consistently identified across in vivo and post mortem studies

2020 ◽  
Author(s):  
Leon M Aksman ◽  
Neil P Oxtoby ◽  
Marzia A Scelsi ◽  
Peter A Wijeratne ◽  
Alexandra L Young ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Β ◽  
Tau Proteins ◽  
Post Mortem ◽  
Positron Emission ◽  
Soluble Trem2 ◽  
The Brain ◽  
Insight Into

Alzheimer's disease (AD) is marked by the spread of misfolded amyloid-β and tau proteins throughout the brain. While it is commonly believed that amyloid-β abnormality drives the cascade of AD pathogenesis, several in vivo and post mortem studies indicate that in some subjects localized tau-based neurofibrillary tangles precede amyloid-β pathology. This suggests that there may be multiple distinct subtypes of protein aggregation pathways within AD, with potentially different demographic, cognitive and comorbidity profiles. We investigated this hypothesis, applying data-driven disease progression subtyping models to post mortem immunohistochemistry and in vivo positron emission tomography (PET) and cerebrospinal fluid (CSF) based measures of protein pathologies in two large observational cohorts. We consistently identified both amyloid-first and tau-first AD subtypes, where tau-first subjects had higher levels of soluble TREM2 compared to amyloid-first subjects. Our work provides insight into AD progression that may be valuable for interventional trials targeting amyloid-β and tau.

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