scholarly journals Fifteen Years of the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study: Progress and Observations from 2,359 Older Adults Spanning the Spectrum from Cognitive Normality to Alzheimer’s Disease

2021 ◽  
pp. 1-26
Author(s):  
Christopher Fowler ◽  
Stephanie R. Rainey-Smith ◽  
Sabine Bird ◽  
Julia Bomke ◽  
Pierrick Bourgeat ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Age At Onset ◽  
Cognitive Testing ◽  
Imaging Biomarkers ◽  
Positron Emission ◽  
Investigation Methods ◽  
Aβ Amyloid ◽  
Magnetic Resonance Imaging Mri ◽  
A Prospective Study

Background: The Australian Imaging, Biomarkers and Lifestyle (AIBL) Study commenced in 2006 as a prospective study of 1,112 individuals (768 cognitively normal (CN), 133 with mild cognitive impairment (MCI), and 211 with Alzheimer’s disease dementia (AD)) as an ‘Inception cohort’ who underwent detailed ssessments every 18 months. Over the past decade, an additional 1247 subjects have been added as an ‘Enrichment cohort’ (as of 10 April 2019). Objective: Here we provide an overview of these Inception and Enrichment cohorts of more than 8,500 person-years of investigation. Methods: Participants underwent reassessment every 18 months including comprehensive cognitive testing, neuroimaging (magnetic resonance imaging, MRI; positron emission tomography, PET), biofluid biomarkers and lifestyle evaluations. Results: AIBL has made major contributions to the understanding of the natural history of AD, with cognitive and biological definitions of its three major stages: preclinical, prodromal and clinical. Early deployment of Aβ-amyloid and tau molecular PET imaging and the development of more sensitive and specific blood tests have facilitated the assessment of genetic and environmental factors which affect age at onset and rates of progression. Conclusion: This fifteen-year study provides a large database of highly characterized individuals with longitudinal cognitive, imaging and lifestyle data and biofluid collections, to aid in the development of interventions to delay onset, prevent or treat AD. Harmonization with similar large longitudinal cohort studies is underway to further these aims.

scholarly journals Biomarkers for Alzheimer’s Disease Early Diagnosis

2020 ◽  
Vol 10 (3) ◽  
pp. 114 ◽  
Author(s):  
Eva Ausó ◽  
Violeta Gómez-Vicente ◽  
Gema Esquiva
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neuronal Loss ◽  
Diagnostic Tools ◽  
Csf Biomarkers ◽  
Diagnosis And Prognosis ◽  
Positron Emission ◽  
The Central Nervous System ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain

Alzheimer’s disease (AD) is the most common cause of dementia, affecting the central nervous system (CNS) through the accumulation of intraneuronal neurofibrillary tau tangles (NFTs) and β-amyloid plaques. By the time AD is clinically diagnosed, neuronal loss has already occurred in many brain and retinal regions. Therefore, the availability of early and reliable diagnosis markers of the disease would allow its detection and taking preventive measures to avoid neuronal loss. Current diagnostic tools in the brain, such as magnetic resonance imaging (MRI), positron emission tomography (PET) imaging, and cerebrospinal fluid (CSF) biomarkers (Aβ and tau) detection are invasive and expensive. Brain-secreted extracellular vesicles (BEVs) isolated from peripheral blood have emerged as novel strategies in the study of AD, with enormous potential as a diagnostic evaluation of therapeutics and treatment tools. In addition; similar mechanisms of neurodegeneration have been demonstrated in the brain and the eyes of AD patients. Since the eyes are more accessible than the brain, several eye tests that detect cellular and vascular changes in the retina have also been proposed as potential screening biomarkers. The aim of this study is to summarize and discuss several potential markers in the brain, eye, blood, and other accessible biofluids like saliva and urine, and correlate them with earlier diagnosis and prognosis to identify individuals with mild symptoms prior to dementia.

scholarly journals Imaging biomarkers for amyloid: a new generation of probes and what lies ahead

2014 ◽  
Vol 26 (5) ◽  
pp. 703-707 ◽  
Author(s):  
Antoine Leuzy ◽  
Eduardo Rigon Zimmer ◽  
Venkat Bhat ◽  
Pedro Rosa-Neto ◽  
Serge Gauthier
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Work Group ◽  
Imaging Biomarkers ◽  
Amyloid A ◽  
Positron Emission ◽  
Communicative Disorders ◽  
Physiologic Parameters ◽  
New Generation

Since the original 1984 criteria for Alzheimer's disease (AD), put forth by a work group jointly established by the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) and the Alzheimer's Disease and Related Disorders Association (ADRDA) (McKhann et al., 1984), important advances have occurred in our ability to detect AD pathophysiology, with the incorporation of biomarkers – defined as anatomic, biochemical, or physiologic parameters that provide in vivo evidence of AD neuropathology (Cummings, 2011) – that can improve the certainty of AD diagnosis. Use of imaging biomarkers such as positron emission tomography (PET) with amyloid ligands, particularly in asymptomatic and pre-dementia stages of AD, however, has been the subject of debate (Dubois et al., 2013), with arguments both for and against the biomarker driven diagnosis of AD.

AD Resemblance Atrophy Index as a Diagnostic Biomarker for Alzheimer’s Disease: A Retrospective Clinical and Biological Validation

2021 ◽  
Vol 79 (3) ◽  
pp. 1023-1032
Author(s):  
Yingren Mai ◽  
Qun Yu ◽  
Feiqi Zhu ◽  
Yishan Luo ◽  
Wang Liao ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Brain Structure ◽  
Imaging Biomarker ◽  
Imaging Biomarkers ◽  
Clinical Scenario ◽  
Clinical Criteria ◽  
Positron Emission ◽  
And Gender ◽  
Sensitivity Specificity

Background: Magnetic resonance imaging (MRI) provides objective information about brain structural atrophy in patients with Alzheimer’s disease (AD). This multi-structural atrophic information, when integrated as a single differential index, has the potential to further elevate the accuracy of AD identification from normal control (NC) compared to the conventional structure volumetric index. Objective: We herein investigated the performance of such an MRI-derived AD index, AD-Resemblance Atrophy Index (AD-RAI), as a neuroimaging biomarker in clinical scenario. Method: Fifty AD patients (19 with the Amyloid, Tau, Neurodegeneration (ATN) results assessed in cerebrospinal fluid) and 50 age- and gender-matched NC (19 with ATN results assessed using positron emission tomography) were recruited in this study. MRI-based imaging biomarkers, i.e., AD-RAI, were quantified using AccuBrain®. The accuracy, sensitivity, specificity, and area under the ROC curve (AUC) of these MRI-based imaging biomarkers were evaluated with the diagnosis result according to clinical criteria for all subjects and ATN biological markers for the subgroup. Results: In the whole groups of AD and NC subjects, the accuracy of AD-RAI was 91%, sensitivity and specificity were 88% and 96%, respectively, and the AUC was 92%. In the subgroup of 19 AD and 19 NC with ATN results, AD-RAI results matched completely with ATN classification. AD-RAI outperforms the volume of any single brain structure measured. Conclusion: The finding supports the hypothesis that MRI-derived composite AD-RAI is a more accurate imaging biomarker than individual brain structure volumetry in the identification of AD from NC in the clinical scenario.

Standardization of hippocampus volumetry using automated brain structure volumetry tool for an initial Alzheimer’s disease imaging biomarker

2018 ◽  
Vol 60 (6) ◽  
pp. 769-776 ◽  
Author(s):  
Jill Abrigo ◽  
Lin Shi ◽  
Yishan Luo ◽  
Qianyun Chen ◽  
Winnie Chiu Wing Chu ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Intraclass Correlation ◽  
Area Under The Curve ◽  
Imaging Biomarker ◽  
Imaging Biomarkers ◽  
Dice Similarity Coefficient ◽  
Reference Dataset ◽  
Magnetic Resonance Imaging Mri ◽  
Hippocampus Segmentation

Background One significant barrier to incorporate Alzheimer’s disease (AD) imaging biomarkers into diagnostic criteria is the lack of standardized methods for biomarker quantification. The European Alzheimer’s Disease Consortium-Alzheimer’s Disease Neuroimaging Initiative (EADC-ADNI) Harmonization Protocol project provides the most authoritative guideline for hippocampal definition and has produced a manually segmented reference dataset for validation of automated methods. Purpose To validate automated hippocampal volumetry using AccuBrain™, against the EADC-ADNI dataset, and assess its diagnostic performance for differentiating AD and normal aging in an independent cohort. Material and Methods The EADC-ADNI reference dataset comprise of manually segmented hippocampal labels from 135 volumetric T1-weighted scans from various scanners. Dice similarity coefficient (DSC), intraclass correlation coefficient (ICC), and Pearson’s r were obtained for AccuBrain™ and FreeSurfer. The magnetic resonance imaging (MRI) of a separate cohort of 299 individuals (150 normal controls, 149 with AD) were obtained from the ADNI database and processed with AccuBrain™ to assess its diagnostic accuracy. Area under the curve (AUC) for total hippocampal volumes (HV) and hippocampal fraction (HF) were determined. Results Compared with EADC-ADNI dataset ground truths, AccuBrain™ had a mean DSC of 0.89/0.89/0.89, ICC of 0.94/0.96/0.95, and r of 0.95/0.96/0.95 for right/left/total HV. AccuBrain™ HV and HF had AUC of 0.76 and 0.80, respectively. Thresholds of ≤ 5.71 mL and ≤ 0.38% afforded 80% sensitivity for AD detection. Conclusion AccuBrain™ provides accurate automated hippocampus segmentation in accordance with the EADC-ADNI standard, with great potential value in assisting clinical diagnosis of AD.

scholarly journals Metals in Imaging of Alzheimer’s Disease

2020 ◽  
Vol 21 (23) ◽  
pp. 9190
Author(s):  
Olga Krasnovskaya ◽  
Daniil Spector ◽  
Alexander Zlobin ◽  
Kirill Pavlov ◽  
Peter Gorelkin ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Single Photon ◽  
Early Stage ◽  
Photon Emission ◽  
Brain Parenchyma ◽  
Emission Computed Tomography ◽  
Positron Emission ◽  
Magnetic Resonance Imaging Mri ◽  
Photon Emission Computed Tomography

One of the hallmarks of Alzheimer’s disease (AD) is the deposition of amyloid plaques in the brain parenchyma, which occurs 7–15 years before the onset of cognitive symptoms of the pathology. Timely diagnostics of amyloid formations allows identifying AD at an early stage and initiating inhibitor therapy, delaying the progression of the disease. However, clinically used radiopharmaceuticals based on 11C and 18F are synchrotron-dependent and short-lived. The design of new metal-containing radiopharmaceuticals for AD visualization is of interest. The development of coordination compounds capable of effectively crossing the blood-brain barrier (BBB) requires careful selection of a ligand moiety, a metal chelating scaffold, and a metal cation, defining the method of supposed Aβ visualization. In this review, we have summarized metal-containing drugs for positron emission tomography (PET), magnetic resonance imaging (MRI), and single-photon emission computed tomography (SPECT) imaging of Alzheimer’s disease. The obtained data allow assessing the structure-ability to cross the BBB ratio.

Comorbidity of Cerebrovascular and Alzheimer’s Disease in Aging

2020 ◽  
Vol 78 (1) ◽  
pp. 321-334
Author(s):  
Ying Xia ◽  
Nawaf Yassi ◽  
Parnesh Raniga ◽  
Pierrick Bourgeat ◽  
Patricia Desmond ◽  
...  
Keyword(s):  
Risk Factors ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cerebrovascular Disease ◽  
Amyloid Β ◽  
Later Life ◽  
Imaging Biomarkers ◽  
Comorbid Condition ◽  
Cross Sectional ◽  
Positron Emission

Background: Cerebrovascular disease often coexists with Alzheimer’s disease (AD). While both diseases share common risk factors, their interrelationship remains unclear. Increasing the understanding of how cerebrovascular changes interact with AD is essential to develop therapeutic strategies and refine biomarkers for early diagnosis. Objective: We investigate the prevalence and risk factors for the comorbidity of amyloid-β (Aβ) and cerebrovascular disease in the Australian Imaging, Biomarkers and Lifestyle Study of Ageing, and further examine their cross-sectional association. Methods: A total of 598 participants (422 cognitively normal, 89 with mild cognitive impairment, 87 with AD) underwent positron emission tomography and structural magnetic resonance imaging for assessment of Aβ deposition and cerebrovascular disease. Individuals were categorized based on the comorbidity status of Aβ and cerebrovascular disease (V) as Aβ–V–, Aβ–V+, Aβ+V–, or Aβ+V+. Results: Advancing age was associated with greater likelihood of cerebrovascular disease, high Aβ load and their comorbidity. Apolipoprotein E ɛ4 carriage was only associated with Aβ positivity. Greater total and regional WMH burden were observed in participants with AD. However, no association were observed between Aβ and WMH measures after stratification by clinical classification, suggesting that the observed association between AD and cerebrovascular disease was driven by the common risk factor of age. Conclusion: Our observations demonstrate common comorbid condition of Aβ and cerebrovascular disease in later life. While our study did not demonstrate a convincing cross-sectional association between Aβ and WMH burden, future longitudinal studies are required to further confirm this.

scholarly journals Utility of Plasma Neurofilament Light in the 1Florida Alzheimer’s Disease Research Center (ADRC)

2021 ◽  
Vol 79 (1) ◽  
pp. 59-70
Author(s):  
Warren Barker ◽  
Carlos Quinonez ◽  
Maria T. Greig ◽  
Raquel Behar ◽  
Cesar Chirinos ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Decline ◽  
Neuropsychiatric Disorders ◽  
Cognitive Testing ◽  
Imaging Biomarkers ◽  
Hippocampal Atrophy ◽  
Amyloid Pet ◽  
Neurofilament Light ◽  
Hispanic Ethnicity

Background: Plasma NfL (pNfL) levels are elevated in many neurological disorders. However, the utility of pNfL in a clinical setting has not been established. Objective: In a cohort of diverse older participants, we examined: 1) the association of pNfL to age, sex, Hispanic ethnicity, diagnosis, and structural and amyloid imaging biomarkers; and 2) its association to baseline and longitudinal cognitive and functional performance. Methods: 309 subjects were classified at baseline as cognitively normal (CN) or with cognitive impairment. Most subjects had structural MRI and amyloid PET scans. The most frequent etiological diagnosis was Alzheimer’s disease (AD), but other neurological and neuropsychiatric disorders were also represented. We assessed the relationship of pNfL to cognitive and functional status, primary etiology, imaging biomarkers, and to cognitive and functional decline. Results: pNfL increased with age, degree of hippocampal atrophy, and amyloid load, and was higher in females among CN subjects, but was not associated with Hispanic ethnicity. Compared to CN subjects, pNfL was elevated among those with AD or FTLD, but not those with neuropsychiatric or other disorders. Hippocampal atrophy, amyloid positivity and higher pNfL levels each added unique variance in predicting greater functional impairment on the CDR-SB at baseline. Higher baseline pNfL levels also predicted greater cognitive and functional decline after accounting for hippocampal atrophy and memory scores at baseline. Conclusion: pNfL may have a complementary and supportive role to brain imaging and cognitive testing in a memory disorder evaluation, although its diagnostic sensitivity and specificity as a stand-alone measure is modest. In the absence of expensive neuroimaging tests, pNfL could be used for differentiating neurodegenerative disease from neuropsychiatric disorders.

scholarly journals Neuroimaging advances regarding subjective cognitive decline in preclinical Alzheimer’s disease

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Xiaoqi Wang ◽  
Weijie Huang ◽  
Li Su ◽  
Yue Xing ◽  
Frank Jessen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Decline ◽  
Subjective Cognitive Decline ◽  
Imaging Features ◽  
Future Directions ◽  
Positron Emission ◽  
Magnetic Resonance Imaging Mri ◽  
Larger Sample ◽  
Neuroimaging Techniques

Abstract Subjective cognitive decline (SCD) is regarded as the first clinical manifestation in the Alzheimer’s disease (AD) continuum. Investigating populations with SCD is important for understanding the early pathological mechanisms of AD and identifying SCD-related biomarkers, which are critical for the early detection of AD. With the advent of advanced neuroimaging techniques, such as positron emission tomography (PET) and magnetic resonance imaging (MRI), accumulating evidence has revealed structural and functional brain alterations related to the symptoms of SCD. In this review, we summarize the main imaging features and key findings regarding SCD related to AD, from local and regional data to connectivity-based imaging measures, with the aim of delineating a multimodal imaging signature of SCD due to AD. Additionally, the interaction of SCD with other risk factors for dementia due to AD, such as age and the Apolipoprotein E (ApoE) ɛ4 status, has also been described. Finally, the possible explanations for the inconsistent and heterogeneous neuroimaging findings observed in individuals with SCD are discussed, along with future directions. Overall, the literature reveals a preferential vulnerability of AD signature regions in SCD in the context of AD, supporting the notion that individuals with SCD share a similar pattern of brain alterations with patients with mild cognitive impairment (MCI) and dementia due to AD. We conclude that these neuroimaging techniques, particularly multimodal neuroimaging techniques, have great potential for identifying the underlying pathological alterations associated with SCD. More longitudinal studies with larger sample sizes combined with more advanced imaging modeling approaches such as artificial intelligence are still warranted to establish their clinical utility.

The Associations of Serum Valine with Mild Cognitive Impairment and Alzheimer’s Disease

2021 ◽  
Author(s):  
Yong-lan Xiong ◽  
Joseph Therriault ◽  
Shu-jiang Ren ◽  
Xiao-jun Jing ◽  
Hua Zhang
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Glucose Metabolism ◽  
Rate Of Change ◽  
Cerebral Glucose Metabolism ◽  
Csf Biomarkers ◽  
Positron Emission ◽  
Magnetic Resonance Imaging Mri

Abstract The introduction of metabolomics makes it possible to study the characteristic changes of peripheral metabolism in Alzheimer’s disease (AD). Recent studies have found that the levels of valine are related to mild cognitive impairment (MCI) and AD, but its characteristics in MCI and AD need to be further clarified. A total of 786 participants from the Alzheimer’s Disease Neuroimaging Initiative-1 (ADNI-1) cohort were selected to evaluate the relationships between serum valine and cerebrospinal fluid (CSF) biomarkers, brain structure (magnetic resonance imaging, MRI), cerebral glucose metabolism (18F-fluorodeoxyglucose-positron emission tomography, FDG-PET), and cognitive declines, through different cognitive subgroups. We found that (1) serum valine was decreased in patients with AD compared with cognitive normal (CN) and stable MCI (sMCI), and in progressive MCI (pMCI) compared with CN; (2) serum valine was negatively correlated with CSF total tau (t-tau) and phosphorylated tau (p-tau) in pMCI; (3) serum valine significantly predicted conversion from MCI to AD; (4) serum valine was related to the rate of change of cerebral glucose metabolism during the follow-up period in pMCI. We speculated serum valine may be a peripheral biomarker of pMCI and AD, and its level predicts the progression of MCI to AD. Our study may help to reveal the metabolic changes during AD disease trajectory and its relationship to clinical phenotype.

scholarly journals Recent Developments in Positron Emission Tomography Tracers for Proteinopathies Imaging in Dementia

2022 ◽  
Vol 13 ◽  
Author(s):  
Ruiqing Ni ◽  
Roger M. Nitsch
Keyword(s):  
Alzheimer’S Disease ◽  
Parkinson’S Disease ◽  
Alzheimer's Disease ◽  
Positron Emission Tomography ◽  
Parkinson's Disease ◽  
Amyloid Β ◽  
Emission Tomography ◽  
Imaging Biomarkers ◽  
Positron Emission ◽  
Imaging Probes

An early detection and intervention for dementia represent tremendous unmet clinical needs and priorities in society. A shared feature of neurodegenerative diseases causing dementia is the abnormal accumulation and spreading of pathological protein aggregates, which affect the selective vulnerable circuit in a disease-specific pattern. The advancement in positron emission tomography (PET) biomarkers has accelerated the understanding of the disease mechanism and development of therapeutics for Alzheimer’s disease and Parkinson’s disease. The clinical utility of amyloid-β PET and the clinical validity of tau PET as diagnostic biomarker for Alzheimer’s disease continuum have been demonstrated. The inclusion of biomarkers in the diagnostic criteria has introduced a paradigm shift that facilitated the early and differential disease diagnosis and impacted on the clinical management. Application of disease-modifying therapy likely requires screening of patients with molecular evidence of pathological accumulation and monitoring of treatment effect assisted with biomarkers. There is currently still a gap in specific 4-repeat tau imaging probes for 4-repeat tauopathies and α-synuclein imaging probes for Parkinson’s disease and dementia with Lewy body. In this review, we focused on recent development in molecular imaging biomarkers for assisting the early diagnosis of proteinopathies (i.e., amyloid-β, tau, and α-synuclein) in dementia and discussed future perspectives.

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