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  • 1
    In: European Journal of Neurology, Wiley, Vol. 28, No. 5 ( 2021-05), p. 1479-1489
    Abstract: Various blood biomarkers reflecting brain amyloid‐β (Aβ) load have recently been proposed with promising results. However, to date, no comparative study amongst blood biomarkers has been reported. Our objective was to examine the diagnostic performance and cost effectiveness of three blood biomarkers on the same cohort. Methods Using the same cohort ( n  = 68), the performances of the single‐molecule array (Simoa) Aβ40, Aβ42, Aβ42/Aβ40 and the amplified plasmonic exosome (APEX) Aβ42 blood biomarkers were compared using amyloid positron emission tomography (PET) as the reference standard. The extent to which these blood tests can reduce the recruitment cost of clinical trials was also determined by identifying amyloid positive (Aβ+) participants. Results Compared to Simoa biomarkers, APEX‐Aβ42 showed significantly higher correlations with amyloid PET retention values and excellent diagnostic performance (sensitivity 100%, specificity 93.3%, area under the curve 0.995). When utilized for clinical trial recruitment, our simulation showed that pre‐screening with blood biomarkers followed by a confirmatory amyloid PET imaging would roughly half the cost (56.8% reduction for APEX‐Aβ42 and 48.6% for Simoa‐Aβ42/Aβ40) compared to the situation where only PET imaging is used. Moreover, with 100% sensitivity, APEX‐Aβ42 pre‐screening does not increase the required number of initial participants. Conclusions With its high diagnostic performance, APEX is an ideal candidate for Aβ+ subject identification, monitoring and primary care screening, and could efficiently enrich clinical trials with Aβ+ participants whilst halving recruitment costs.
    Type of Medium: Online Resource
    ISSN: 1351-5101 , 1468-1331
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2020241-6
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  • 2
    In: Alzheimer's & Dementia, Wiley, Vol. 16, No. S6 ( 2020-12)
    Abstract: Neuropsychiatric symptoms (NPS) affect quality of life for both patients and caregivers, worsen cognitive and functional impairment in elderly, and are associated with the development of dementia. Manifestations of neurodegenerative and vascular pathologies including abnormal amyloid deposition and cerebrovascular disease (CeVD) often co‐exist in both cognitively normal and impaired elderly. However, the impact of co‐occurrence of amyloid and CeVD on major clinical outcomes, such as neurocognition and neuropsychiatric disorders, have not been extensively explored. Hence, the present study aimed to determine the neuropsychiatric correlates of cerebral amyloid burden amongst patients across a spectrum of cognitive impairment, adjusting for significant CeVD. We hypothesized that amyloid burden is independently associated with NPS severity. Method Participants with or without cognitive impairment from the memory clinic underwent [ 11 C]PiB‐PET and MRI scans between April 2016 and September 2018. NPS were assessed using the 12‐item neuropsychiatric inventory. CeVD markers (cortical infarcts, stenosis, white matter hyperintensities, lacunes, and microbleeds) were graded and significant CeVD was defined following previously validated criteria. The association of NPS severity with global standardized uptake value ratio (SUVR) was analyzed using generalized linear models, controlling for demographics, diagnosis, cognitive function, depression status, and significant CeVD. Possible interactions between amyloid and CeVD were evaluated. The correlations between NPS subsyndromes and regional amyloid uptake were also explored. Holm‐Bonferroni correction was applied to adjust for multiple comparisons. Results Data for 168 participants [age=75.6 (7.3); female=93 (55.4%); MMSE=22.3 (5.7)] were analyzed, including 24 cognitively normal, 89 MCI, and 55 with dementia. Global SUVR was associated with higher total NPS score [β (CI)=0.67 (0.15‐1.18), p =0.011], driven by hyperactivity subsyndrome [β (CI)=0.96 (0.15‐1.11), p =0.002] and apathy subsyndrome [β (CI)=0.90 (0.34‐1.45), p =0.002]. Apathy subsyndrome was positively correlated with amyloid uptake in the thalamus ( r =0.25, p =0.002) and parietal region ( r =0.224, p =0.002). There was no significant interaction between global SUVR and significant CeVD on NPS. Conclusion Neuropsychiatric manifestations reflect underlying neurodegenerative pathology independent of vascular burden, suggesting that amyloid and CeVD may exert their effects through different pathways. This finding contributes to the neuropathological understanding of neuropsychiatric disorders, thus informs future development of novel treatment and monitoring of disease progression.
    Type of Medium: Online Resource
    ISSN: 1552-5260 , 1552-5279
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2201940-6
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  • 3
    In: European Journal of Nuclear Medicine and Molecular Imaging, Springer Science and Business Media LLC, Vol. 47, No. 2 ( 2020-02), p. 319-331
    Type of Medium: Online Resource
    ISSN: 1619-7070 , 1619-7089
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2098375-X
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  • 4
    In: European Journal of Neurology, Wiley, Vol. 29, No. 7 ( 2022-07), p. 1922-1929
    Abstract: The underlying cause of cognitive decline in individuals who are positive for biomarkers of neurodegeneration (N) but negative for biomarkers of amyloid‐beta (A), designated as Suspected non‐Alzheimer's pathophysiology (SNAP), remains unclear. We evaluate whether cerebrovascular disease (CeVD) is more prevalent in those with SNAP compared to A−N− and A+N+ individuals and whether CeVD is associated with cognitive decline over time in SNAP patients. Methods A total of 216 individuals from a prospective memory clinic cohort (mean [SD] age, 72.7 [7.3] years, 100 women [56.5%]) were included and were diagnosed as no cognitive impairment (NCI), cognitive impairment no dementia (CIND), Alzheimer's dementia (AD) or vascular dementia (VaD). All individuals underwent clinical evaluation and neuropsychological assessment annually for up to 5 years. Carbon 11‐labeled Pittsburgh Compound B ([ 11 C]‐PiB) or [ 18 F]‐flutafuranol‐positron emission spectrometry imaging was performed to ascertain amyloid‐beta status. Magnetic resonance imaging was performed to assess neurodegeneration as measured by medial temporal atrophy ≥2, as well as significant CeVD (sCeVD) burden, defined by cortical infarct count ≥1, Fazekas score ≥2, lacune count ≥2 or cerebral microbleed count ≥2. Results Of the 216 individuals, 50 (23.1%) A−N+ were (SNAP), 93 (43.1%) A−N−, 36 (16.7%) A+N− and 37 (17.1%) A+N+. A+N+ individuals were significantly older, while A+N+ and SNAP individuals were more likely to have dementia. The SNAP group had a higher prevalence of sCeVD (90.0%) compared to A−N−. Moreover, SNAP individuals with sCeVD had significantly steeper decline in global cognition compared to A−N− over 5 years ( p  = 0.042). Conclusions These findings suggest that CeVD is a contributing factor to cognitive decline in SNAP. Therefore, SNAP individuals should be carefully assessed and treated for CeVD.
    Type of Medium: Online Resource
    ISSN: 1351-5101 , 1468-1331
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2020241-6
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  • 5
    In: Neurology, Ovid Technologies (Wolters Kluwer Health), Vol. 95, No. 21 ( 2020-11-24), p. e2845-e2853
    Abstract: To evaluate the association between brain amyloid β (Aβ) and cerebral small vessel disease (CSVD) markers, as well as their joint effect on cognition, in a memory clinic study. Methods A total of 186 individuals visiting a memory clinic, diagnosed with no cognitive impairment, cognitive impairment no dementia (CIND), Alzheimer dementia (AD), or vascular dementia were included. Brain Aβ was measured by [ 11 C] Pittsburgh compound B–PET global standardized uptake value ratio (SUVR). CSVD markers including white matter hyperintensities (WMH), lacunes, and cerebral microbleeds (CMBs) were graded on MRI. Cognition was assessed by neuropsychological testing. Results An increase in global SUVR is associated with a decrease in Mini-Mental State Examination (MMSE) in CIND and AD, as well as a decrease in global cognition Z score in AD, independent of age, education, hippocampal volume, and markers of CSVD. A significant interaction between global SUVR and WMH was found in relation to MMSE in CIND ( P for interaction: 0.009), with an increase of the effect size of Aβ (β = −6.57 [−9.62 to −3.54], p 〈 0.001) compared to the model without the interaction term (β = −2.91 [−4.54 to −1.29], p = 0.001). Conclusion Higher global SUVR was associated with worse cognition in CIND and AD, but was augmented by an interaction between global SUVR and WMH only in CIND. This suggests that Aβ and CSVD are independent processes with a possible synergistic effect between Aβ and WMH in individuals with CIND. There was no interaction effect between Aβ and lacunes or CMBs. Therefore, in preclinical phases of AD, WMH should be targeted as a potentially modifiable factor to prevent worsening of cognitive dysfunction.
    Type of Medium: Online Resource
    ISSN: 0028-3878 , 1526-632X
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2020
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  • 6
    In: Alzheimer's & Dementia, Wiley, Vol. 17, No. 10 ( 2021-10), p. 1649-1662
    Abstract: There is increasing evidence that phosphorylated tau (P‐tau181) is a specific biomarker for Alzheimer's disease (AD) pathology, but its potential utility in non‐White patient cohorts and patients with concomitant cerebrovascular disease (CeVD) is unknown. Methods Single molecule array (Simoa) measurements of plasma P‐tau181, total tau, amyloid beta (Aβ)40 and Aβ42, as well as derived ratios were correlated with neuroimaging modalities indicating brain amyloid (Aβ+), hippocampal atrophy, and CeVD in a Singapore‐based cohort of non‐cognitively impaired (NCI; n  = 43), cognitively impaired no dementia (CIND; n = 91), AD ( n  = 44), and vascular dementia (VaD; n  = 22) subjects. Results P‐tau181/Aβ42 ratio showed the highest area under the curve (AUC) for Aβ+ (AUC = 0.889) and for discriminating between AD Aβ+ and VaD Aβ− subjects (AUC = 0.903). In addition, P‐tau181/Aβ42 ratio was associated with hippocampal atrophy. None of the biomarkers was associated with CeVD. Discussion Plasma P‐tau181/Aβ42 ratio may be a noninvasive means of identifying AD with elevated brain amyloid in populations with concomitant CeVD.
    Type of Medium: Online Resource
    ISSN: 1552-5260 , 1552-5279
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2201940-6
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  • 7
    In: Journal of Alzheimer's Disease, IOS Press, Vol. 86, No. 3 ( 2022-04-05), p. 1093-1105
    Abstract: Background: P-wave terminal force in lead V1 (PTFV1) on electrocardiography has been associated with atrial fibrillation and ischemic stroke. Objective: To investigate whether PTFV1 is associated with cerebral small vessel disease (CSVD) markers and etiological subtypes of cognitive impairment and dementia. Methods: Participants were recruited from ongoing memory clinic study between August 2010 to January 2019. All participants underwent physical and medical evaluation along with an electrocardiography and 3 T brain magnetic resonance imaging. Participants were classified as no cognitive impairment, cognitive impairment no dementia, vascular cognitive impairment no dementia, and dementia subtypes (Alzheimer’s disease and vascular dementia). Elevated PTFV1 was defined as 〉  4,000μV×ms and measured manually on ECG. Results: Of 408 participants, 78 (19.1%) had elevated PTFV1 (37 women [47%]; mean [SD] age, 73.8 [7.2] years). The participants with elevated PTFV1 had higher burden of lacunes, cerebral microbleeds (CMB), and cortical microinfarcts. As for the CMB location, persons with strictly deep CMB and mixed CMB had significantly higher PTFV1 than those with no CMB (p = 0.005, p = 0.007). Regardless of adjustment for cardiovascular risk factors and/or heart diseases, elevated PTFV1 was significantly associated with presence of CMB (odds ratio, 2.26; 95% CI,1.33–3.91). Conclusion: Elevated PTFV1 was associated with CSVD, especially deep CMB. PTFV1 in vascular dementia was also higher compared to Alzheimer’s disease. Thus, PTFV1 might be a potential surrogate marker of brain-heart connection and vascular brain damage.
    Type of Medium: Online Resource
    ISSN: 1387-2877 , 1875-8908
    Language: Unknown
    Publisher: IOS Press
    Publication Date: 2022
    detail.hit.zdb_id: 2070772-1
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  • 8
    Online Resource
    Online Resource
    Ovid Technologies (Wolters Kluwer Health) ; 2022
    In:  Alzheimer Disease & Associated Disorders Vol. 36, No. 4 ( 2022-10), p. 327-334
    In: Alzheimer Disease & Associated Disorders, Ovid Technologies (Wolters Kluwer Health), Vol. 36, No. 4 ( 2022-10), p. 327-334
    Abstract: Intracranial stenosis (ICS) and brain amyloid-beta (Aβ) have been associated with cognition and dementia. We aimed to investigate the association between ICS and brain Aβ and their independent and joint associations with cognition. Methods: We conducted a cross-sectional study of 185 patients recruited from a memory clinic. ICS was measured on 3-dimensional time-of-flight magnetic resonance angiography and defined as stenosis ≥50%. Brain Aβ was measured with [ 11 C] Pittsburgh compound B–positron emission tomography imaging. Cognition was assessed with a locally validated neuropsychological battery. Results: A total of 17 (9.2%) patients had ICS, and the mean standardized uptake value ratio was 1.4 (±0.4 SD). ICS was not significantly associated with brain Aβ deposition. ICS was significantly associated with worse global cognition (β: −1.26, 95% CI: −2.25; −0.28, P =0.013), executive function (β: −1.04, 95% CI: −1.86; −0.22, P =0.015) and visuospatial function (β: −1.29, 95% CI: −2.30; −0.27, P =0.015). Moreover, in ICS patients without dementia (n=8), the presence of Aβ was associated with worse performance on visuomotor speed. Conclusions: ICS was significantly associated with worse cognition and showed interaction with brain Aβ such that patients with both pathologies performed worse on visuomotor speed specifically in those without dementia. Further studies may clarify if ICS and brain Aβ deposition indeed have a synergistic association with cognition.
    Type of Medium: Online Resource
    ISSN: 0893-0341
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2022
    detail.hit.zdb_id: 2048789-7
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  • 9
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2021
    In:  European Journal of Nuclear Medicine and Molecular Imaging Vol. 48, No. 6 ( 2021-06), p. 1842-1853
    In: European Journal of Nuclear Medicine and Molecular Imaging, Springer Science and Business Media LLC, Vol. 48, No. 6 ( 2021-06), p. 1842-1853
    Abstract: Standardized uptake value ratio (SUVr) used to quantify amyloid-β burden from amyloid-PET scans can be biased by variations in the tracer’s nonspecific (NS) binding caused by the presence of cerebrovascular disease (CeVD). In this work, we propose a novel amyloid-PET quantification approach that harnesses the intermodal image translation capability of convolutional networks to remove this undesirable source of variability. Methods Paired MR and PET images exhibiting very low specific uptake were selected from a Singaporean amyloid-PET study involving 172 participants with different severities of CeVD. Two convolutional neural networks (CNN), ScaleNet and HighRes3DNet, and one conditional generative adversarial network (cGAN) were trained to map structural MR to NS PET images. NS estimates generated for all subjects using the most promising network were then subtracted from SUVr images to determine specific amyloid load only (SAβ L ). Associations of SAβ L with various cognitive and functional test scores were then computed and compared to results using conventional SUVr. Results Multimodal ScaleNet outperformed other networks in predicting the NS content in cortical gray matter with a mean relative error below 2%. Compared to SUVr, SAβ L showed increased association with cognitive and functional test scores by up to 67%. Conclusion Removing the undesirable NS uptake from the amyloid load measurement is possible using deep learning and substantially improves its accuracy. This novel analysis approach opens a new window of opportunity for improved data modeling in Alzheimer’s disease and for other neurodegenerative diseases that utilize PET imaging.
    Type of Medium: Online Resource
    ISSN: 1619-7070 , 1619-7089
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2098375-X
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  • 10
    In: Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring, Wiley, Vol. 15, No. 1 ( 2023-01)
    Abstract: Plasma neurofilament light chain (NfL) is a potential biomarker for neurodegeneration in Alzheimer's disease (AD), ischemic stroke, and non‐dementia cohorts with cerebral small vessel disease (CSVD). However, studies of AD in populations with high prevalence of concomitant CSVD to evaluate associations of brain atrophy, CSVD, and amyloid beta (Aβ) burden on plasma NfL are lacking. Methods Associations were tested between plasma NfL and brain Aβ, medial temporal lobe atrophy (MTA) as well as neuroimaging features of CSVD, including white matter hyperintensities (WMH), lacunes, and cerebral microbleeds. Results We found that participants with either MTA (defined as MTA score ≥2; neurodegeneration [N]+WMH−) or WMH (cut‐off for log‐transformed WMH volume at 50th percentile; N−WMH+) manifested increased plasma NfL levels. Participants with both pathologies (N+WMH+) showed the highest NfL compared to N+WMH−, N−WMH+, and N−WMH− individuals. Discussion Plasma NfL has potential utility in stratifying individual and combined contributions of AD pathology and CSVD to cognitive impairment.
    Type of Medium: Online Resource
    ISSN: 2352-8729 , 2352-8729
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 2832898-X
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