scholarly journals Aβ deposition is associated with increases in soluble and phosphorylated tau that precede a positive Tau PET in Alzheimer’s disease

2020 ◽  
Vol 6 (16) ◽  
pp. eaaz2387 ◽  
Author(s):  
Niklas Mattsson-Carlgren ◽  
Emelie Andersson ◽  
Shorena Janelidze ◽  
Rik Ossenkoppele ◽  
Philip Insel ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Pet ◽  
Phosphorylated Tau ◽  
Positron Emission ◽  
Aβ Aggregation ◽  
Tau Pet ◽  
5Xfad Mice ◽  
Tau Aggregation ◽  
T Tau

The links between β-amyloid (Aβ) and tau in Alzheimer’s disease are unclear. Cognitively unimpaired persons with signs of Aβ pathology had increased cerebrospinal fluid (CSF) phosphorylated tau (P-tau181 and P-tau217) and total-tau (T-tau), which increased over time, despite no detection of insoluble tau aggregates [normal Tau positron emission tomography (PET)]. CSF P-tau and T-tau started to increase before the threshold for Amyloid PET positivity, while Tau PET started to increase after Amyloid PET positivity. Effects of Amyloid PET on Tau PET were mediated by CSF P-tau, and high CSF P-tau predicted increased Tau PET rates. Individuals with MAPT mutations and signs of tau deposition (but without Aβ pathology) had normal CSF P-tau levels. In 5xFAD mice, CSF tau increased when Aβ aggregation started. These results show that Aβ pathology may induce changes in soluble tau release and phosphorylation, which is followed by tau aggregation several years later in humans.

scholarly journals Contribution of genetic and environmental factors to the onset of preclinical Alzheimer’s disease - a monozygotic twin study

2020 ◽  
Author(s):  
Elles Konijnenberg ◽  
Jori Tomassen ◽  
Anouk den Braber ◽  
Mara ten Kate ◽  
Maqsood M. Yaqub ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Environmental Factors ◽  
Random Effect ◽  
Monozygotic Twin ◽  
Amyloid Pet ◽  
Positron Emission ◽  
Aβ Aggregation ◽  
T Tau ◽  
Aβ Production

AbstractObjectiveTo study the genetic contribution to the start of Alzheimer’s disease as signified by abnormalities in amyloid and tau biomarkers in cognitively intact older identical twins.MethodsWe studied in 96 monozygotic twin-pairs relationships between Aβ aggregation as measured by the ratio Aβ1-42/1-40 in cerebrospinal fluid (CSF) and positron emission tomography (PET), and CSF markers for Aβ production (BACE1, Aβ1-40 and 1-38) and tau. Associations amongst markers were tested with Generalized Estimating Equations including a random effect for twin status, adjusted for age, gender, and APOE ε4 genotype. We used twin analyses to determine relative contributions of genetic and/or environmental factors to AD pathophysiological processes.ResultsTwenty-seven individuals (14%) had an abnormal amyloid-PET, and 14 twin-pairs (15%) showed discordant amyloid status. Within twin-pairs, Aβ production markers and total-tau (t-tau) levels strongly correlated (r range 0.76, 0.88; all p<0.0001), and Aβ aggregation markers and 181-phosphorylated-tau (p-tau) levels correlated moderately strong (r range 0.49, 0.52; all p<0.0001). Cross-twin cross-trait analysis showed that Aβ1-38 in one twin correlated with Aβ1-42/1-40 ratios, t-tau and p-tau levels in their co-twins (r range 0.18, 0.58; all p<.07). Within-pair differences in Aβ production markers related to differences in tau levels (r range 0.49, 0.61; all p<0.0001). Twin discordance analyses suggest that Aβ production and tau levels show coordinated increases in very early AD.InterpretationOur results suggest a substantial genetic/shared environmental background contributes to both Aβ and tau increases, suggesting that modulation of environmental risk factors may aid in delaying the onset of AD pathophysiological processes.

scholarly journals Prospective longitudinal atrophy in Alzheimer’s disease correlates with the intensity and topography of baseline tau-PET

2020 ◽  
Vol 12 (524) ◽  
pp. eaau5732 ◽  
Author(s):  
Renaud La Joie ◽  
Adrienne V. Visani ◽  
Suzanne L. Baker ◽  
Jesse A. Brown ◽  
Viktoriya Bourakova ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Pet ◽  
Specific Distribution ◽  
Positron Emission ◽  
Pet Radiotracers ◽  
Β Amyloid ◽  
Tau Pet ◽  
Prospective Longitudinal

β-Amyloid plaques and tau-containing neurofibrillary tangles are the two neuropathological hallmarks of Alzheimer’s disease (AD) and are thought to play crucial roles in a neurodegenerative cascade leading to dementia. Both lesions can now be visualized in vivo using positron emission tomography (PET) radiotracers, opening new opportunities to study disease mechanisms and improve patients’ diagnostic and prognostic evaluation. In a group of 32 patients at early symptomatic AD stages, we tested whether β-amyloid and tau-PET could predict subsequent brain atrophy measured using longitudinal magnetic resonance imaging acquired at the time of PET and 15 months later. Quantitative analyses showed that the global intensity of tau-PET, but not β-amyloid–PET, signal predicted the rate of subsequent atrophy, independent of baseline cortical thickness. Additional investigations demonstrated that the specific distribution of tau-PET signal was a strong indicator of the topography of future atrophy at the single patient level and that the relationship between baseline tau-PET and subsequent atrophy was particularly strong in younger patients. These data support disease models in which tau pathology is a major driver of local neurodegeneration and highlight the relevance of tau-PET as a precision medicine tool to help predict individual patient’s progression and design future clinical trials.

A Japanese Multicenter Study on PET and Other Biomarkers for Subjects with Potential Preclinical and Prodromal Alzheimer’s Disease

2021 ◽  
pp. 1-8
Author(s):  
M. Senda ◽  
K. Ishii ◽  
K. Ito ◽  
T. Ikeuchi ◽  
H. Matsuda ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Multicenter Study ◽  
Fdg Pet ◽  
Structural Mri ◽  
Amyloid Pet ◽  
Positron Emission ◽  
Prodromal Alzheimer’S Disease ◽  
T Tau

BACKGROUND: PET (positron emission tomography) and CSF (cerebrospinal fluid) provide the “ATN” (Amyloid, Tau, Neurodegeneration) classification and play an essential role in early and differential diagnosis of Alzheimer’s disease (AD). OBJECTIVE: Biomarkers were evaluated in a Japanese multicenter study on cognitively unimpaired subjects (CU) and early (E) and late (L) mild cognitive impairment (MCI) patients. MEASUREMENTS: A total of 38 (26 CU, 7 EMCI, 5 LMCI) subjects with the age of 65-84 were enrolled. Amyloid-PET and FDG-PET as well as structural MRI were acquired on all of them, with an additional tau-PET with 18F-flortaucipir on 15 and CSF measurement of Aβ1-42, P-tau, and T-tau on 18 subjects. Positivity of amyloid and tau was determined based on the positive result of either PET or CSF. RESULTS: The amyloid positivity was 13/38, with discordance between PET and CSF in 6/18. Cortical tau deposition quantified with PET was significantly correlated with CSF P-tau, in spite of discordance in the binary positivity between visual PET interpretation and CSF P-tau in 5/8 (PET-/CSF+). Tau was positive in 7/9 amyloid positive and 8/16 amyloid negative subjects who underwent tau measurement, respectively. Overall, a large number of subjects presented quantitative measures and/or visual read that are close to the borderline of binary positivity, which caused, at least partly, the discordance between PET and CSF in amyloid and/or tau. Nine subjects presented either tau or FDG-PET positive while amyloid was negative, suggesting the possibility of non-AD disorders. CONCLUSION: Positivity rate of amyloid and tau, together with their relationship, was consistent with previous reports. Multicenter study on subjects with very mild or no cognitive impairment may need refining the positivity criteria and cutoff level as well as strict quality control of the measurements.

scholarly journals The Clinical Use of Alzheimer’s Biomarkers in Patients With Mild Cognitive Impairment: A European Alzheimer’s Disease Consortium Survey

2021 ◽  
Author(s):  
Camilla Caprioglio ◽  
Valentina Garibotto ◽  
Frank Jessen ◽  
Lutz Frölich ◽  
Gilles Allali ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Fdg Pet ◽  
Diagnostic Process ◽  
Amyloid Pet ◽  
Clinical Use ◽  
Tau Pet ◽  
T Tau

Abstract Background. This study aims to investigate the clinical use of the main Alzheimer’s disease (AD) biomarkers in patients with mild cognitive impairment (MCI) by examining the beliefs and preferences of clinicians and biomarker experts of the European Alzheimer’s Disease Consortium (EADC).Methods. Out of 306 contacted EADC professionals, 150 (101 clinicians, 43 biomarker experts, and 6 falling into other categories) filled in an online survey from May to September 2020. The investigated biomarkers were: medial temporal lobe atrophy score (MTA) on structural MRI, typical AD (i.e. temporoparietal and posterior cingulate) hypometabolism on FDG-PET, CSF (Aβ42, p-tau, t-tau), amyloid-PET and tau-PET.Results. Despite the abnormal accumulation of amyloid rather than tau was deemed by the majority of responders as the initial cause of AD, responders did not show a clear preference for amyloid-PET. The most widely used biomarker is MTA (77% of responders reported to use it at least frequently), followed by Aβ42, p-tau, t-tau levels in CSF (45%), typical AD hypometabolism on FDG-PET (32%), amyloid-PET (8%), and tau-PET (2%). Imaging and CSF biomarkers were found to be widely used to support the etiological diagnostic process in MCI, while APOE genotyping was performed only in a minority of patients. CSF is considered the most valuable biomarker in terms of additional diagnostic value, followed by amyloid-PET, tau-PET, and typical AD hypometabolism on FDG-PET. The combination of amyloidosis and neuronal injury biomarkers is associated with the highest diagnostic confidence in an etiological diagnosis of AD in MCI, while MTA alone was perceived as the less reliable biomarker.Conclusions. Biomarkers are widely used across Europe for the diagnosis of MCI. Overall, we observed that CSF is currently considered as the most useful biomarker, followed by amyloid-PET. Moreover, the use of molecular imaging (i.e. amyloid-PET and tau-PET) in the diagnostic work-up of MCI patients is increasing over time.

scholarly journals “Don’t Phos Over Tau”: recent developments in clinical biomarkers and therapies targeting tau phosphorylation in Alzheimer’s disease and other tauopathies

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yuxing Xia ◽  
Stefan Prokop ◽  
Benoit I. Giasson
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cerebrospinal Fluid ◽  
Kinase Inhibitors ◽  
Tau Phosphorylation ◽  
Phosphorylated Tau ◽  
Clinical Biomarkers ◽  
Early Results ◽  
Recent Developments ◽  
Tau Aggregation

AbstractPhosphorylation is one of the most prevalent post-translational modifications found in aggregated tau isolated from Alzheimer’s disease (AD) patient brains. In tauopathies like AD, increased phosphorylation or hyperphosphorylation can contribute to microtubule dysfunction and is associated with tau aggregation. In this review, we provide an overview of the structure and functions of tau protein as well as the physiologic roles of tau phosphorylation. We also extensively survey tau phosphorylation sites identified in brain tissue and cerebrospinal fluid from AD patients compared to age-matched healthy controls, which may serve as disease-specific biomarkers. Recently, new assays have been developed to measure minute amounts of specific forms of phosphorylated tau in both cerebrospinal fluid and plasma, which could potentially be useful for aiding clinical diagnosis and monitoring disease progression. Additionally, multiple therapies targeting phosphorylated tau are in various stages of clinical trials including kinase inhibitors, phosphatase activators, and tau immunotherapy. With promising early results, therapies that target phosphorylated tau  could be useful at slowing tau hyperphosphorylation and aggregation in AD and other tauopathies.

scholarly journals Soluble P-tau217 reflects amyloid and tau pathology and mediates the association of amyloid with tau

2021 ◽  
Author(s):  
Niklas Mattsson-Carlgren ◽  
Shorena Janelidze ◽  
Randall Bateman ◽  
Ruben Smith ◽  
Erik Stomrud ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Medial Temporal Lobe ◽  
Amyloid Plaques ◽  
Amyloid Plaque ◽  
Amyloid Pet ◽  
Tau Pathology ◽  
Β Amyloid ◽  
Tau Pet ◽  
Disease Stages

Abstract Alzheimer’s disease is characterized by β-amyloid plaques and tau tangles. Plasma levels of phospho-tau217 (P-tau217) accurately differentiate Alzheimer’s disease dementia from other dementias, but it is unclear to what degree this reflects β-amyloid plaque accumulation, tau tangle accumulation, or both. In a cohort with post-mortem neuropathological data (N=88), both plaque and tangle density contributed independently to higher P-tau217. Several findings were replicated in a cohort with PET imaging (“BioFINDER-2”, N=426), where β-amyloid and tau PET were independently associated to P-tau217. P-tau217 correlated with β-amyloid PET (but not tau PET) in early disease stages, and with both β-amyloid and (more strongly) tau PET in late disease stages. Finally, P-tau217 mediated the association between β-amyloid and tau in both cohorts, especially for tau outside of the medial temporal lobe. These findings support the hypothesis that plasma P-tau217 is increased by both β-amyloid plaques and tau tangles and is congruent with the hypothesis that P-tau is involved in β-amyloid-dependent formation of neocortical tau tangles.

scholarly journals Efficacy and Limitations of rCBF-SPECT in the Diagnosis of Alzheimer’s Disease With Amyloid-PET

2019 ◽  
Vol 34 (5) ◽  
pp. 314-321
Author(s):  
Miwako Takahashi ◽  
Tomoko Tada ◽  
Tomomi Nakamura ◽  
Keitaro Koyama ◽  
Toshimitsu Momose
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Rating Scale ◽  
Single Photon ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Amyloid Pet ◽  
Clinical Dementia Rating ◽  
Positron Emission ◽  
Rcbf Spect

This study aimed to assess efficacy and limitations of regional cerebral blood flow imaging using single-photon emission computed tomography (rCBF-SPECT) in the diagnosis of Alzheimer’s disease (AD) with amyloid-positron emission tomography (amyloid-PET). Thirteen patients, who underwent both rCBF-SPECT and amyloid-PET after clinical diagnosis of AD or mild cognitive impairment, were retrospectively identified. The rCBF-SPECTs were classified into 4 grades, from typical AD pattern to no AD pattern of hypoperfusion; amyloid-beta (Aβ) positivity was assessed by amyloid-PET. Four patients were categorized into a typical AD pattern on rCBF-SPECT, and all were Aβ+. The other 9 patients did not exhibit a typical AD pattern; however, 4 were Aβ+. The Mini-Mental State Examination score and Clinical Dementia Rating scale were not significantly different between Aβ+ and Aβ– patients. A typical AD pattern on rCBF-SPECT can reflect Aβ+; however, if not, rCBF-SPECT has a limitation to predict amyloid pathology.

IC-P-156: Baseline amyloid PET imaging, longitudinal amyloid accumulation, and Tau PET imaging in preclinical Alzheimer's disease

2015 ◽  
Vol 11 (7S_Part_2) ◽  
pp. P105-P105
Author(s):  
Aaron P. Schultz ◽  
Elizabeth C. Mormino ◽  
Jasmeer P. Chhatwal ◽  
Molly LaPoint ◽  
Alex S. Dagley ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Pet Imaging ◽  
Amyloid Pet ◽  
Preclinical Alzheimer’S Disease ◽  
Amyloid Accumulation ◽  
Tau Pet ◽  
Tau Pet Imaging ◽  
Amyloid Pet Imaging

Amyloid imaging in Alzheimer’s disease: a potential new era of personalized medicine?

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Antoine Leuzy ◽  
Eduardo Zimmer ◽  
Serge Gauthier ◽  
Pedro Rosa-Neto
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Personalized Medicine ◽  
Amyloid Imaging ◽  
Phase Iii ◽  
Diagnostic Process ◽  
European Medicines Agency ◽  
Amyloid Pet ◽  
Positron Emission

AbstractRecent advances along clinical and neuropathological lines, as well as in our ability to detect the deposition of β-amyloid (Aβ) in vivo using positron emission tomography (PET), have helped redefine Alzheimer’s disease (AD) as a dynamic clinicobiological entity. On the basis of these advances, AD is now conceptualized as a continuum comprising asymptomatic, minimally symptomatic, and dementia phases, with detection of brain Aβ — in particular, via PET amyloid imaging — central to the diagnostic process. In this respect, [18F]florbetapir (Amyvid™) and [18F]flutemetamol (Vizamyl™) have recently received approval for clinical use from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA), with additional radiofluorinated tracers for detection of Aβ in phase III trials. Recent initiatives such as the Alzheimer’s Disease Neuroimaging Initiative (ADNI) suggest that Aβ production, oligomerization and aggregation begins many years, possibly decades, before detectable cognitive impairment, with Aβ shown to associate with cognitive decline and conversion to dementia. While personalized medicine has now emerged as a prospect for the field, the recent decision by the Centers for Medicare & Medicaid Services (CMS) — who declined to cover the cost of amyloid PET imaging citing insufficient evidence to support its clinical utility — highlights that such a move may be premature.

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