| 1. |
- Berron, David, et al.
(författare)
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Hippocampal subregional thinning related to tau pathology in early stages of Alzheimer’s disease
- 2022
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 18:S1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Subregions in the medial temporal lobe (MTL) are affected early by Alzheimer’s disease (AD) pathology and subject to grey matter atrophy. Measuring the earliest AD-related atrophy in the hippocampus is challenging as region-of-interest (ROI) analyses of hippocampal subregional volumes collapse across voxels within anatomical subregions. PET imaging studies, however, report accumulation of tau pathology between anatomical subregions in the earliest disease stages (Berron et al., 2021) fitting reports from the neuropathological literature (Lace et al., 2019; Ravikumar et al., 2021). Thus, sensitive in vivo methods of point-wise structural measures are needed in order to detect the earliest hippocampal thinning in AD along the anterior-posterior as well as the medial-lateral hippocampal axis. Method: Here we analyzed data from 76 amyloid-beta negative (Ab-) cognitively normal (CN), 46 Ab+ CN individuals and 25 Ab+ patients with mild cognitive impairment (MCI) from the BioFINDER-2 study, who underwent 7 Tesla T2-weighted structural magnetic resonance imaging, tau positron emission tomography imaging (using 18F-RO-948) and cognitive assessments. First, we segmented hippocampal subfields and extrahippocampal subregions. Second, we calculated point-wise hippocampal thickness estimates (Diers et al.) of hippocampal subfields subiculum, cornu ammonis (CA)1, CA2 and CA3 on the level of the hippocampal body. Thirdly, we extracted local tau-PET SUVR from Area 35 (A35), entorhinal cortex and amygdala. Finally, we assessed relationships between hippocampal local thickness and tau accumulation as well as cognitive performance. Result: Our analyses revealed earliest hippocampal thinning associated with tau accumulation in an area spanning the boundary of subiculum and CA1 at the level of the anterior hippocampal body. Ab+ MCI patients showed more posterior thinning in comparison to Ab- CU participants. Median thickness in an ROI comprising vertices with A35 tau-related thinning (A35-TauThinning-ROI) was significantly lower in MCI Ab+ and tended to be lower in CU Ab+ compared to CU Ab-. Higher median thickness in the hippocampal A35-TauThinning-ROI, but not whole CA1 nor subiculum thickness, was associated with better 10-Word-Delayed-Recall and higher PACC scores. Conclusion: Our results suggest that tau-related thinning of hippocampal subregions can be observed already in early disease stages. Tau-related point-wise thickness measures were more sensitive compared to volumetric measures of anatomical subregions.
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| 2. |
- Binette, Alexa Pichet, et al.
(författare)
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Amyloid-associated increases in soluble tau is a key driver in accumulation of tau aggregates and cognitive decline in early Alzheimer
- 2022
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 18:S1
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Tidskriftsartikel (refereegranskat)abstract
- Background: For optimal design of anti-amyloid-β (Aβ) and anti-tau clinical trials, it is important to understand how Aβ and soluble phosphorylated tau (p-tau) relate to the accumulation of tau aggregates assessed with positron emission tomography (PET) and subsequent cognitive decline across the Alzheimer's disease (AD) continuum. Method: We included 327 participants from the Swedish BioFINDER-2 cohort with cerebrospinal fluid (CSF) p-tau217, Aβ-PET, longitudinal tau-PET, and longitudinal cognition. The main groups of interest were Aβ-positive non-demented participants and AD dementia patients (Table 1 and Figure 1), and analyses were conducted separately in each group. First, we investigated how soluble p-tau217 and regional Aβ-PET were associated with tau-PET rate of change across the 200 brain parcels from the Schaefer atlas. We also tested the mediating effect of p-tau217 between Aβ-PET and tau-PET change. Second, we investigated how soluble p-tau217 and tau-PET change related to change in cognition, and mediation between these variables. Result: In early AD stages (non-demented participants), increased concentration of soluble p-tau217 was the main driver of accumulation of insoluble tau aggregates across the brain (measured as tau-PET rate of change), beyond the effect of regional Aβ-PET and baseline tau-PET (Figure 2A-C). Further, averaged across all regions, soluble p-tau217 mediated 54% of the association between Aβ and tau aggregation (Figure 2D). Higher soluble p-tau217 concentrations were also associated with cognitive decline, which was mediated by faster increase of tau aggregates (Figure 3). Repeating the same analyses in the AD dementia group, results were different. In late stage of AD, when Aβ fibrils and soluble p-tau levels have plateaued, soluble p-tau217 was not associated with accumulation of tau aggregates beyond baseline tau-PET (Figure 4A), and cognitive decline was driven by the accumulation rate of insoluble tau aggregates and not soluble p-tau217 (Figure 4B-C). Conclusion: Soluble p-tau is a main driver of tau aggregation and future cognitive decline in earlier stages of AD, whereas tau aggregation accumulation is more likely an important driver of disease in later stages. Overall, our data suggest that therapeutic approaches reducing soluble p-tau levels might be most favorable in early AD.
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| 3. |
- Franzmeier, Nicolai, et al.
(författare)
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Earlier Alzheimer's disease onset is associated with a shift of tau pathology towards brain hubs which facilitates tau spreading
- 2022
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 18:S1
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Tidskriftsartikel (refereegranskat)abstract
- Background: In Alzheimer’s disease (AD), younger symptom onset is associated accelerated cognitive decline and tau spreading, yet the drivers of faster disease manifestation in patients with earlier symptom onset are unknown. Earlier symptom onset is associated with stronger tau pathology in fronto-parietal regions which typically harbor globally connected hubs that are central for cognition. Since tau spreads across connected regions, globally connected hubs may accelerate tau spreading due to their large number of connections to other brain regions. Thus, we hypothesized that a pattern shift of tau pathology towards globally connected brain hubs may facilitate tau spreading and earlier symptom manifestation in AD. Method: We included two independent samples with longitudinal Flortaucipir tau-PET covering the AD spectrum (ADNI: n(controls/AD-preclinical/AD-symptomatic)=93/60/89, BioFINDER, n(controls/AD-preclinical/AD-symptomatic)=16/16/25). In addition, we included resting-state fMRI from human connectome project participants (n=1000), applying a 200-ROI brain atlas to obtain a global connectivity map for assessing brain hubs (Fig.1A-D). Applying the same atlas to tau-PET we transformed SUVRs to tau positivities using a pre-established gaussian-mixture modeling approach (Fig.1E-F). By mapping tau-PET positivities to the fMRI-derived global connectivity map (Fig.1G-L), we assessed the degree to which subject specific tau-PET patterns were shifted towards globally connected hubs or non-hubs, while adjusting for global tau levels. Using linear regression, we then tested whether a stronger shift of tau towards hubs was associated with earlier symptom manifestation and faster longitudinal tau accumulation. Result: In symptomatic AD patients, younger age was associated with a stronger shift of tau-PET towards globally connected brain hubs (p[ADNI/BiOFINDER]=0.024/0.018, Fig.2A&B), and with higher global connectivity of epicenters with highest tau pathology (p[ADNI/BiOFINDER]<0.001/0.001, Fig.2C&D). In symptomatic AD, younger age (p[ADNI/BiOFINDER]=0.009/0.001) and a stronger shift of tau-PET towards hubs predicted faster subsequent tau accumulation (p[ADNI/BiOFINDER]=0.004/0.002), supporting the view that that hubs facilitate tau spreading (Fig.3). Further, a stronger shift of tau-PET towards globally connected brain hubs mediated the association between younger age and faster tau accumulation in symptomatic AD patients (p[ADNI/BiOFINDER]=0.039/0.046). Conclusion: Younger AD symptom onset is associated with stronger tau pathology in globally connected brain hubs, which facilitates faster tau spreading.
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| 4. |
- Franzmeier, Nicolai, et al.
(författare)
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The BIN1 rs744373 Alzheimer's disease risk SNP is associated with faster Aβ-associated tau accumulation and cognitive decline
- 2022
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 18:1, s. 103-115
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The BIN1 rs744373 single nucleotide polymorphism (SNP) is a key genetic risk locus for Alzheimer's disease (AD) associated with tau pathology. Because tau typically accumulates in response to amyloid beta (Aβ), we tested whether BIN1 rs744373 accelerates Aβ-related tau accumulation. Methods: We included two samples (Alzheimer's Disease Neuroimaging Initiative [ADNI], n = 153; Biomarkers for Identifying Neurodegenerative Disorders Early and Reliably [BioFINDER], n = 63) with longitudinal 18F-Flortaucipir positron emission tomography (PET), Aβ biomarkers, and longitudinal cognitive assessments. We assessed whether BIN1 rs744373 was associated with faster tau-PET accumulation at a given level of Aβ and whether faster BIN1 rs744373-associated tau-PET accumulation mediated cognitive decline. Results: BIN1 rs744373 risk-allele carriers showed faster global tau-PET accumulation (ADNI/BioFINDER, P <.001/P <.001). We found significant Aβ by rs744373 interactions on global tau-PET change (ADNI: β/standard error [SE] = 0.42/0.14, P = 0.002; BioFINDER: β/SE = –0.35/0.15, P =.021), BIN1 risk-allele carriers showed accelerated tau-PET accumulation at higher Aβ levels. In ADNI, rs744373 effects on cognitive decline were mediated by faster global tau-PET accumulation (β/SE = 0.20/0.07, P =.005). Discussion: BIN1-associated AD risk is potentially driven by accelerated tau accumulation in the face of Aβ.
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| 5. |
- Groot, Colin, et al.
(författare)
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A biomarker profile of elevated CSF p-tau with normal tau PET is associated with increased tau accumulation rates on PET in early Alzheimer’s disease
- 2022
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 18:S1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Different tau biomarkers become abnormal at different stages of Alzheimer’s disease (AD), with CSF p-tau typically being elevated at subthreshold levels of tau-PET binding. To capitalize on the temporal order of tau biomarker-abnormality and capture the earliest changes of tau accumulation, we selected a group of amyloid-β-positive (A+) individuals with elevated CSF p-tau levels but negative tau-PET scans and assessed longitudinal changes in tau-PET, cortical thickness and cognitive decline. Method: Individuals without dementia (i.e., cognitively unimpaired (CU) or mild cognitive impairment, n=231) were selected from the BioFINDER-2 study. These subjects were categorized into biomarker groups based on Gaussian mixture modelling to determine cut-offs for abnormal CSF Aβ42/40 (A; <0.078), CSF p-tau217 (P; >110 pg/ml) and [18F]RO948 tau-PET SUVR within a temporal meta-ROI (T; SUVR >1.40). Resulting groups were: A+P-T- (concordant, n=30), A+P+T- (discordant, n=48) and A+P+T+ (concordant, n=18). We additionally used 135 A- CU individuals (A- CU) as a reference group (Tables 1 and 2). Differences in annual change in regional tau-PET SUVR, cortical thickness and cognition between the A+P+T- group and the other groups were assessed using general linear models, adjusted for age, sex, clinical diagnosis and (for cognitive measures) education. Result: Longitudinal change in tau-PET was faster in the A+P+T- group than in the A- CU and A+P-T- groups across medial temporal and neocortical regions, with the medial temporal increases being more pronounced. The A+P+T- group showed slower rate of increases in tau-PET compared to the A+P+T+ group, primarily in neocortical regions (Figures 1 and 2). We did not detect differences in yearly change in cortical thickness (Figure 3) or in cognitive decline (Figure 3) between the A+P+T- and A+P-T- groups. The A+P+T+ group, however, showed faster cognitive decline compared to all other groups. Conclusion: These findings suggest that the A+P+T- biomarker profile is associated with early tau accumulation, and with relative sparing of cortical thinning and cognitive decline compared to A+P+T+ individuals. Therefore, the A+P+T- group represents an interesting target-group for early anti-tau interventions and for examining the emergence of tau aggregates in early AD.
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| 6. |
- Hansson, Oskar, et al.
(författare)
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Cerebral hypoperfusion is not associated with an increase in amyloid β pathology in middle-aged or elderly people
- 2018
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5279 .- 1552-5260. ; 14:1, s. 54-61
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: It is hypothesized that cerebral hypoperfusion promotes the development of Alzheimer pathology. We therefore studied whether longstanding cerebral hypoperfusion is associated with Alzheimer pathology in nondemented humans.METHODS: Cerebral blood flow and amyloid β ((18)F-Flutemetamol) positron emission tomography retention were assessed in eleven patients with unilateral occlusion of precerebral arteries resulting in chronic and uneven hypoperfusion. A subset of patients underwent tau ((18)F-AV-1451) positron emission tomography.RESULTS: The blood flow was significantly reduced on the affected side of the brain in patients with unilateral occlusion of the internal carotid artery or stenosis of the middle cerebral artery. However, the cortical uptake of (18)F-Flutemetamol or (18)F-AV-1451 was not altered.DISCUSSION: Our results suggest that longstanding cerebral hypoperfusion in humans does not result in accumulation of amyloid β fibrils or tau aggregates.
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| 7. |
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| 8. |
- Mattsson, Niklas, et al.
(författare)
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Predicting diagnosis and cognition with 18F-AV-1451 tau PET and structural MRI in Alzheimer's disease
- 2019
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 15:4, s. 570-580
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The relative importance of structural magnetic resonance imaging (MRI) and tau positron emission tomography (PET) to predict diagnosis and cognition in Alzheimer's disease (AD) is unclear. Methods: We tested 56 cognitively unimpaired controls (including 27 preclinical AD), 32 patients with prodromal AD, and 39 patients with AD dementia. Optimal classifiers were constructed using the least absolute shrinkage and selection operator with 18F-AV-1451 (tau) PET and structural MRI data (regional cortical thickness and subcortical volumes). Results: 18F-AV-1451 in the amygdala, entorhinal cortex, parahippocampal gyrus, fusiform, and inferior parietal lobule had 93% diagnostic accuracy for AD (prodromal or dementia). The MRI classifier involved partly the same regions plus the hippocampus, with 83% accuracy, but did not improve upon the tau classifier. 18F-AV-1451 retention and MRI were independently associated with cognition. Discussion: Optimized tau PET classifiers may diagnose AD with high accuracy, but both tau PET and structural brain MRI capture partly unique information relevant for the clinical deterioration in AD.
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| 9. |
- Ossenkoppele, Rik, et al.
(författare)
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Distinct tau PET patterns in atrophy-defined subtypes of Alzheimer's disease
- 2020
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 16:2, s. 335-344
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Differential patterns of brain atrophy on structural magnetic resonance imaging (MRI) revealed four reproducible subtypes of Alzheimer's disease (AD): (1) “typical”, (2) “limbic-predominant”, (3) “hippocampal-sparing”, and (4) “mild atrophy”. We examined the neurobiological characteristics and clinical progression of these atrophy-defined subtypes. Methods: The four subtypes were replicated using a clustering method on MRI data in 260 amyloid-β–positive patients with mild cognitive impairment or AD dementia, and we subsequently tested whether the subtypes differed on [18F]flortaucipir (tau) positron emission tomography, white matter hyperintensity burden, and rate of global cognitive decline. Results: Voxel-wise and region-of-interest analyses revealed the greatest neocortical tau load in hippocampal-sparing (frontoparietal-predominant) and typical (temporal-predominant) patients, while limbic-predominant patients showed particularly high entorhinal tau. Typical patients with AD had the most pronounced white matter hyperintensity load, and hippocampal-sparing patients showed the most rapid global cognitive decline. Discussion: Our data suggest that structural MRI can be used to identify biologically and clinically meaningful subtypes of AD.
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| 10. |
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