Medicine and Health Sciences Commons^™

Resting State Electrophysiological Profiles And Their Relationship With Cognitive Performance In Cognitively Unimpaired Older Adults: A Systematic Review, Brenda Chino, David López-Sanz, Sandra Doval, Lucía Torres-Simón, Jaisalmer De Frutos Lucas, Lydia Giménez-Llort, Jonathan Zegarra-Valdivia, Fernando Maestú

Research outputs 2022 to 2026

Background: Aging is a complex and natural process. The physiological decline related to aging is accompanied by a slowdown in cognitive processes, which begins shortly after individuals reach maturity. These changes have been sometimes interpreted as a compensatory sign and others as a fingerprint of deterioration. Objective: In this context, our aim is to uncover the mechanisms that underlie and support normal cognitive functioning in the brain during the later stages of life. Methods: With this purpose, a systematic literature search was conducted using PubMed, Scopus, and Web of Science databases, which identified 781 potential articles. After applying inclusion and …

The Relationship Between Diet, Depression, And Alzheimer's Disease: A Narrative Review, Hilal Salim Said Al Shamsi, Stephanie R. Rainey-Smith, Samantha L. Gardener, Hamid R. Sohrabi, Rodrigo Canovas, Ralph N. Martins, Warnakulasuriya Mary Ann Dipika Binosha Fernando

Research outputs 2022 to 2026

Purpose of Review: This narrative review evaluates the role of diet in the relationship between depression and Alzheimer's disease (AD). Recent Findings: AD and depression are often comorbid, and depression appears to independently increase the future risk of AD. Evidence suggests diet influences the risk of both conditions directly and indirectly. Diet impacts neurochemical and biological processes that may affect the development and progression of depression and cognitive dysfunction. The dietary components offering the greatest protection against depression and AD are yet to be determined. Current evidence highlights the importance of polyphenolic compounds, folate, B vitamins, and polyunsaturated fatty acids, …

The Crosstalk Between Amyloid-Β, Retina, And Sleep For The Early Diagnosis Of Alzheimer's Disease: A Narrative Review, Isaiah Lorenzo De Guia, Shaun Eslick, Sharon L. Naismith, Swathi Kanduri, Tejal M. Shah, Ralph N. Martins

Research outputs 2022 to 2026

Alzheimer's disease (AD) is the most common type of dementia, which is characterised by progressive memory loss and accumulation of hallmark markers amyloid-β (Aβ) and neurofibrillary tangles in the diseased brain. The current gold standard diagnostic methods have limitations of being invasive, costly, and not easily accessible. Thus, there is a need for new avenues, such as imaging the retina for early AD diagnosis. Sleep disruption is symptomatically frequent across preclinical and AD subjects. As circadian activity, such as the sleep-wake cycle, is linked to the retina, analysis of their association may be useful additions for achieving predictive AD diagnosis. …

Suboptimal Self-Reported Sleep Efficiency And Duration Are Associated With Faster Accumulation Of Brain Amyloid Beta In Cognitively Unimpaired Older Adults, Louise N. Pivac, Belinda M. Brown, Kelsey R. Sewell, James D. Doecke, Victor L. Villemagne, Vincent Doré, Michael Weinborn, Hamid R. Sohrabi, Samantha L. Gardener, Romola S. Bucks, Simon M. Laws, Kevin Taddei, Paul Maruff, Colin L. Masters, Christopher Rowe, Ralph N. Martins, Stephanie R. Rainey-Smith

Research outputs 2022 to 2026

INTRODUCTION: This study investigated whether self-reported sleep quality is associated with brain amyloid beta (AB) accumulation. METHODS: Linear mixed effect model analyses were conducted for 189 cognitively unimpaired (CU) older adults (mean ± standard deviation 74.0 ± 6.2; 53.2% female), with baseline self-reported sleep data, and positron emission tomography-determined brain AB measured over a minimum of three time points (range 33.3–72.7 months). Analyses included random slopes and intercepts, interaction for apolipoprotein E (APOE) 4 allele status, and time, adjusting for sex and baseline age. RESULTS: Sleep duration < 6 hours, in APOE 4 carriers, and sleep efficiency < 65%, in the whole sample and APOE 4 non-carriers, is associated with faster accumulation of brain AB. DISCUSSION: These findings suggest a role for self-reported suboptimal sleep efficiency and duration in the accumulation of Alzheimer's disease (AD) neuropathology in CU individuals. Additionally, poor sleep efficiency represents a potential route via which individuals at lower genetic risk may progress to preclinical AD. Highlights: In cognitively unimpaired older adults self-report sleep is associated with brain amyloid beta (AB) accumulation. Across sleep characteristics, this relationship differs by apolipoprotein E (APOE) genotype. Sleep duration < 6 hours is associated with faster brain AB accumulation in APOE 4 carriers. Sleep efficiency < 65% is associated with faster brain AB accumulation in APOE 4 non-carriers. Personalized sleep interventions should be studied for potential to slow AB accumulation.

The Australian Multidomain Approach To Reduce Dementia Risk By Protecting Brain Health With Lifestyle Intervention Study (Au-Arrow): A Study Protocol For A Single-Blind, Multi-Site, Randomized Controlled Trial, Samantha L. Gardener, Stephanie J. Fuller, Sharon L. Naismith, Laura Baker, Miia Kivipelto, Victor L. Villemagne, Stuart M. Grieve, Paul Yates, Stephanie R. Rainey-Smith, Juliana Chen, Belinda Thompson, Nicola J. Armstrong, Malika G. Fernando, Carolina B. Castro, Silochna Meghwar, Rema Raman, Andrew Gleason, Catriona Ireland, Roger Clarnette, Kaarin J. Anstey, Kevin Taddei, Manohar Garg, Hamid R. Sohrabi, Ralph N. Martins

Research outputs 2022 to 2026

INTRODUCTION: The Finnish Geriatric Intervention Study (FINGER) led to the global dementia risk reduction initiative: World-Wide FINGERS (WW-FINGERS). As part of WW-FINGERS, the Australian AU-ARROW study mirrors aspects of FINGER, as well as US-POINTER. METHOD: AU-ARROW is a randomized, single-blind, multisite, 2-year clinical trial (n = 600; aged 55–79). The multimodal lifestyle intervention group will engage in aerobic exercise, resistance training and stretching, dietary advice to encourage MIND diet adherence, BrainHQ cognitive training, and medical monitoring and health education. The Health Education and Coaching group will receive occasional health education sessions. The primary outcome measure is the change in a …

Editorial: Neurotoxins In Alzheimer's Disease And Other Dementias, Alexandre Henriques, Philippe L. L. Poindron, Binosha Fernando, Kevin N. Hascup

Research outputs 2022 to 2026

Alzheimer's disease (AD) and other dementias are neurodegenerative disorders characterized by a progressive decline in cognition and independence from activities of daily living. Dementia is multifactorial with numerous risk factors including age, genes, molecules, lifestyle, and environmental contributions to disease onset and progression. In recent years, an emerging focus on neurotoxins has added a new layer of complexity to our understanding of dementia. This editorial aims to discuss recent updates regarding the role of neurotoxins in the pathogenesis of dementia.

Nutrients And Polyphenols-Rich Sorghum Bicolor Genotypes As Complementary Therapy For Alzheimer’S Disease, Rasheed A. Abdulraheem, Ralph N. Martins, Prashant Bharadwaj, Zhaoyu Li, Ranil Coorey, Stuart Johnson, W. M. A. D. Binosha Fernando

Research outputs 2022 to 2026

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and most common cause of dementia among older people. The main pathological hallmarks of AD are formation of insoluble amyloid beta senile plaques and paired helical filaments of neurofibrillary tangles. AD features gradual memory decline, mild to severe cognitive impairment, eventually total dependence of patients on caregivers. Currently available drugs have not been able to modify AD pathology. This has drawn increasing attention to plant food materials with high nutritional and bioactive constituents as potential complementary therapy for AD. Sorghum bicolor is a widely available cost-effective source of proteins, fats, crude fibres, …

Cerebrospinal Fluid Proteomics Define The Natural History Of Autosomal Dominant Alzheimer’S Disease, Erik C. B. Johnson, Shijia Bian, Rafi U. Haque, E. Kathleen Carter, Caroline M. Watson, Brian A. Gordon, Lingyan Ping, Duc M. Duong, Michael P. Epstein, Eric Mcdade, Nicolas R. Barthélemy, Celeste M. Karch, Chengjie Xiong, Carlos Cruchaga, Richard J. Perrin, Aliza P. Wingo, Thomas S. Wingo, Jasmeer P. Chhatwal, Gregory S. Day, James M. Noble, Sarah B. Berman, Ralph Martins, Neill R. Graff-Radford, Peter R. Schofield, Takeshi Ikeuchi, Hiroshi Mori, Johannes Levin, Martin Farlow, James J. Lah, Christian Haass, Mathias Jucker, John C. Morris, Tammie L. S. Benzinger, Blaine R. Roberts, Randall J. Bateman, Anne M. Fagan, Nicholas T. Seyfried, Allan I. Levey, Dominantly Inherited Alzheimer Network

Research outputs 2022 to 2026

Alzheimer’s disease (AD) pathology develops many years before the onset of cognitive symptoms. Two pathological processes—aggregation of the amyloid- (A ) peptide into plaques and the microtubule protein tau into neurofibrillary tangles (NFTs)—are hallmarks of the disease. However, other pathological brain processes are thought to be key disease mediators of A plaque and NFT pathology. How these additional pathologies evolve over the course of the disease is currently unknown. Here we show that proteomic measurements in autosomal dominant AD cerebrospinal fluid (CSF) linked to brain protein coexpression can be used to characterize the evolution of AD pathology over a timescale …

Plasma Glial Fibrillary Acidic Protein In Autosomal Dominant Alzheimer's Disease: Associations With Aβ-Pet, Neurodegeneration, And Cognition, Pratishtha Chatterjee, Lisa Vermunt, Brian A. Gordon, Steve Pedrini, Lynn Boonkamp, Nicola J. Armstrong, Chengjie Xiong, Abhay K. Singh, Yan Li, Hamid R. Sohrabi, Kevin Taddei, Mark Molloy, Tammie L. S. Benzinger, John C. Morris, Celeste Karch, Sarah Berman, Jasmeer Chhatwal, Carlos Cruchaga, Neill R. Graff-Radford, Gregory S. Day, Martin Farlow, Nick Fox, Alison Goate, Jason Hassenstab, Jae-Hong Lee, Johannes Levin, Eric Mcdade, Hiroshi Mori, Richard Perrin, Raquel Sanchez-Valle, Peter R. Schofield, Allan Levey, Mathias Jucker, Colin L. Masters, Anne M. Fagan, Randall J. Bateman, Ralph N. Martins, Charlotte Teunissen, Dominantly Inherited Alzheimer Network

Research outputs 2022 to 2026

Background: Glial fibrillary acidic protein (GFAP) is a promising candidate blood-based biomarker for Alzheimer's disease (AD) diagnosis and prognostication. The timing of its disease-associated changes, its clinical correlates, and biofluid-type dependency will influence its clinical utility. Methods: We evaluated plasma, serum, and cerebrospinal fluid (CSF) GFAP in families with autosomal dominant AD (ADAD), leveraging the predictable age at symptom onset to determine changes by stage of disease. Results: Plasma GFAP elevations appear a decade before expected symptom onset, after amyloid beta (A ) accumulation and prior to neurodegeneration and cognitive decline. Plasma GFAP distinguished A -positive from A -negative ADAD …

First Presentation With Neuropsychiatric Symptoms In Autosomal Dominant Alzheimer's Disease: The Dominantly Inherited Alzheimer's Network Study, Antoinette O'Connor, Helen Rice, Josephine Barnes, Natalie S. Ryan, Kathy Y. Liu, Ricardo Francisco Allegri, Sarah Berman, John M. Ringman, Carlos Cruchaga, Martin R. Farlow, Jason Hassenstab, Jae-Hong Lee, Richard J. Perrin, Chengjie Xiong, Brian Gordon, Allan I. Levey, Alison Goate, Neil Graff-Radford, Johannes Levin, Mathias Jucker, Tammie Benzinger, Eric Mcdade, Hiroshi Mori, James M. Noble, Peter R. Schofield, Ralph N. Martins, Stephen Salloway, Jasmeer Chhatwal, John C. Morris, Randall Bateman, Rob Howard, Suzanne Reeves, Nick C. Fox

Research outputs 2022 to 2026

Behavioural changes and neuropsychiatric symptoms (NPS) commonly occur in Alzheimer’s disease (AD) but may not be recognised as AD-related when they are the presenting feature. NPS are important as they are associated with greater functional impairment, poorer quality of life, accelerated cognitive decline and worsened caregiver burden.1 Autosomal dominant AD (ADAD), although < 1% of total AD cases, provides a valuable opportunity to study the clinical heterogeneity of AD. The young age at onset reduces the prevalence of age-related comorbid pathologies and the near 100% penetrance of pathogenic mutations reduces the likelihood of misdiagnosis.2 Anxiety and depression commonly occur in ADAD family members, with increased levels of depression having been found among predementia female mutation carriers.3 Subsequent studies, however, have shown that anxiety and/or depression are common regardless of mutation status, occurring in almost one in three at-risk individuals, with one study reporting a higher rate of depression in non-carriers (17%) than asymptomatic carriers (5%).4 5 Despite the high frequency of NPS in ADAD families, relatively little is known about the proportion of ADAD cases who present with predominantly behavioural symptoms. Our aims were to assess the first reported clinical change in symptomatic ADAD, to compare presentations across genotypes, and to compare cognitive performance between behavioural and cognitive-led presentations.

Discovery Of A Missense Mutation (Q222k) Of The Apoe Gene From The Australian Imaging, Biomarker And Lifestyle Study, Blaine R. Roberts, Scott B. Laffoon, Anne M. Roberts, Tenielle Porter, Chris Fowler, Colin L. Masters, Edward A. Dratz, Simon M. Laws

Research outputs 2022 to 2026

After age, polymorphisms of the Apolipoprotein E (APOE) gene are the biggest risk factor for the development of Alzheimer's disease (AD). During our investigation to discovery biomarkers in plasma, using 2D gel electrophoresis, we found an individual with and unusual apoE isoelectric point compared to APOE ϵ2, ϵ3, and ϵ4 carriers. Whole exome sequencing of APOE from the donor confirmed a single nucleotide polymorphism (SNP) in exon 4, translating to a rare Q222K missense mutation. The apoE ϵ4 (Q222K) mutation did not form dimers or complexes observed for apoE ϵ2 ϵ3 proteins.

Leukocyte Surface Biomarkers Implicate Deficits Of Innate Immunity In Sporadic Alzheimer's Disease, Xin Huang, Yihan Li, Christopher Fowler, James D. Doecke, Yen Ying Lim, Candace Drysdale, Vicky Zhang, Keunha Park, Brett Trounson, Kelly Pertile, Rebecca Rumble, John W. Pickering, Robert A. Rissman, Floyd Sarsoza, Sara Abdel-Latif, Yong Lin, Vincent Doré, Victor Villemagne, Christopher C. Rowe, Jurgen Fripp, Ralph Martins, James S. Wiley, Paul Maruff, Jacobo E. Mintzer, Colin L. Masters, Ben J. Gu

Research outputs 2022 to 2026

Introduction:

Blood-based diagnostics and prognostics in sporadic Alzheimer's disease (AD) are important for identifying at-risk individuals for therapeutic interventions.

Methods:

In three stages, a total of 34 leukocyte antigens were examined by flow cytometry immunophenotyping. Data were analyzed by logistic regression and receiver operating characteristic (ROC) analyses.

Results:

We identified leukocyte markers differentially expressed in the patients with AD. Pathway analysis revealed a complex network involving upregulation of complement inhibition and downregulation of cargo receptor activity and Aβ clearance. A proposed panel including four leukocyte markers – CD11c, CD59, CD91, and CD163 – predicts patients’ PET Aβ status with an …

Impaired Muscle Function, Including Its Decline, Is Related To Greater Long-Term Late-Life Dementia Risk In Older Women, Simone Radavelli-Bagatini, Helen Macpherson, David Scott, Robin M. Daly, Jonathan M. Hodgson, Simon M. Laws, Kun Zhu, Richard L. Prince, Joshua R. Lewis, Marc Sim

Research outputs 2022 to 2026

Background: Impaired muscle function has been identified as a risk factor for declining cognitive function and cardiovascular health, both of which are risk factors for late-life dementia (after 80 years of age). We examined whether hand grip strength and timed-up-and-go (TUG) performance, including their change over 5 years, were associated with late-life dementia events in older women and whether any associations provided independent information to Apolipoprotein E ℇ4 (APOE ℇ4) genotype. Methods: Grip strength and TUG were assessed in community-dwelling older women (mean ± SD; age 75.0 ± 2.6 years) at baseline (n = 1225) and 5 years (n = …

A Potential Role For Sirtuin-1 In Alzheimer's Disease: Reviewing The Biological And Environmental Evidence, Mehrane Mehramiz, Tenielle Porter, Eleanor K. O'Brien, Stephanie R. Rainey-Smith, Simon M. Laws

Research outputs 2022 to 2026

Sirtuin-1 (Sirt1), encoded by the SIRT1 gene, is a conserved Nicotinamide adenine dinucleotide (NAD+) dependent deacetylase enzyme, considered as the master regulator of metabolism in humans. Sirt1 contributes to a wide range of biological pathways via several mechanisms influenced by lifestyle, such as diet and exercise. The importance of a healthy lifestyle is of relevance to highly prevalent modern chronic diseases, such as Alzheimer's disease (AD). There is growing evidence at multiple levels for a role of Sirt1/SIRT1 in AD pathological mechanisms. As such, this review will explore the relevance of Sirt1 to AD pathological mechanisms, by describing the involvement …

Plasma Aβ42/40 Ratio, P-Tau181, Gfap, And Nfl Across The Alzheimer's Disease Continuum: A Cross-Sectional And Longitudinal Study In The Aibl Cohort, Pratishtha Chatterjee, Steve Pedrini, James D. Doecke, Rohith Thota, Victor L. Villemagne, Vincent Doré, Abhay K. Singh, Penghao Wang, Stephanie Rainey-Smith, Christopher Fowler, Kevin Taddei, Hamid R. Sohrabi, Mark P. Molloy, David Ames, Paul Maruff, Christopher C. Rowe, Colin L. Masters, Ralph N. Martins, Aibl Research Group

Research outputs 2022 to 2026

Introduction:

Plasma amyloid beta (Aβ)1-42/Aβ1-40 ratio, phosphorylated-tau181 (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) are putative blood biomarkers for Alzheimer's disease (AD). However, head-to-head cross-sectional and longitudinal comparisons of the aforementioned biomarkers across the AD continuum are lacking.

Methods:

Plasma Aβ1-42, Aβ1-40, p-tau181, GFAP, and NfL were measured utilizing the Single Molecule Array (Simoa) platform and compared cross-sectionally across the AD continuum, wherein Aβ-PET (positron emission tomography)–negative cognitively unimpaired (CU Aβ−, n = 81) and mild cognitive impairment (MCI Aβ−, n = 26) participants were compared with Aβ-PET–positive participants across the AD continuum (CU Aβ+, n = …

Longitudinal Trajectories Of Basal Forebrain Volume In Normal Aging And Alzheimer's Disease, Ying Xia, Paul Maruff, Vincent Doré, Pierrick Bourgeat, Simon M. Laws, Christopher Fowler, Stephanie R. Rainey-Smith, Ralph N. Martins, Victor L. Villemagne, Christopher C. Rowe, Colin L. Masters, Elizabeth J. Coulson, Jurgen Fripp

Research outputs 2022 to 2026

Dysfunction of the cholinergic basal forebrain (BF) system and amyloid- (A ) deposition are early pathological features in Alzheimer's disease (AD). However, their association in early AD is not well-established. This study investigated the nature and magnitude of volume loss in the BF, over an extended period, in 516 older adults who completed A -PET and serial magnetic resonance imaging scans. Individuals were grouped at baseline according to the presence of cognitive impairment (CU, CI) and A status (A −, A +). Longitudinal volumetric changes in the BF and hippocampus were assessed across groups. The results indicated that high A …

Physical Activity And Brain Amyloid Beta: A Longitudinal Analysis Of Cognitively Unimpaired Older Adults, Michael G. Slee, Stephanie R. Rainey-Smith, Victor L. Villemagne, James D. Doecke, Hamid R. Sohrabi, Kevin Taddei, David Ames, Vincent Dore, Paul Maruff, Simon M. Laws, Colin L. Masters, Christopher C. Rowe, Ralph N. Martins, Kirk I. Erickson, Belinda M. Brown

Research outputs 2022 to 2026

Introduction: The current study evaluated the relationship between habitual physical activity (PA) levels and brain amyloid beta (A ) over 15 years in a cohort of cognitively unimpaired older adults. Methods: PA and A measures were collected over multiple timepoints from 731 cognitively unimpaired older adults participating in the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study of Aging. Regression modeling examined cross-sectional and longitudinal relationships between PA and brain A . Moderation analyses examined apolipoprotein E (APOE) 4 carriage impact on the PA-A relationship. Results: PA was not associated with brain A at baseline ( = –0.001, p = 0.72) …

Apoe Ε2 Resilience For Alzheimer’S Disease Is Mediated By Plasma Lipid Species: Analysis Of Three Independent Cohort Studies, Tingting Wang, Kevin Huynh, Corey Giles, Natalie A. Mellett, Thy Duong, Anh Nguyen, Wei L. F. Lim, Alex A. T. Smith, Gavriel Olshansky, Gemma Cadby, Joseph Hung, Jennie Hui, John Beilby, Gerald F. Watts, Pratishtha Chatterjee, Ian Martins, Simon Laws, Ashley I. Bush, Christopher C. Rowe, Victor L. Villemagne, David Ames, Colin L. Masters, Kevin Taddei, Vincent Doré, Jürgen Fripp, Matthias Arnold, Gabi Kastenmüller, Kwangsik Nho, Andrew J. Saykin, Rebecca Baillie, Xianlin Han, Ralph N. Martins, Eric K. Moses, Rima Kaddurah-Daouk, Peter J. Meikle

Research outputs 2022 to 2026

Introduction:

The apolipoprotein E (APOE) genotype is the strongest genetic risk factor for late-onset Alzheimer's disease. However, its effect on lipid metabolic pathways, and their mediating effect on disease risk, is poorly understood.

Methods:

We performed lipidomic analysis on three independent cohorts (the Australian Imaging, Biomarkers and Lifestyle [AIBL] flagship study, n = 1087; the Alzheimer's Disease Neuroimaging Initiative [ADNI] 1 study, n = 819; and the Busselton Health Study [BHS], n = 4384), and we defined associations between APOE ε2 and ε4 and 569 plasma/serum lipid species. Mediation analysis defined the proportion of the treatment effect of the APOE …

Plasma High-Density Lipoprotein Cargo Is Altered In Alzheimer's Disease And Is Associated With Regional Brain Volume, Steve Pedrini, James D. Doecke, Eugene Hone, Penghao Wang, Rohith Thota, Ashley I. Bush, Christopher C. Rowe, Vincent Dore, Victor L. Villemagne, David Ames, Stephanie Rainey-Smith, Giuseppe Verdile, Hamid R. Sohrabi, Manfred R. Raida, Kevin Taddei, Sam Gandy, Colin L. Masters, Pratishtha Chatterjee, Ralph N. Martins, Aibl Research Group

Research outputs 2022 to 2026

Cholesterol levels have been repeatedly linked to Alzheimer's Disease (AD), suggesting that high levels could be detrimental, but this effect is likely attributed to Low-Density Lipoprotein (LDL) cholesterol. On the other hand, High-Density Lipoproteins (HDL) cholesterol levels have been associated with reduced brain amyloidosis and improved cognitive function. However, recent findings have suggested that HDL-functionality, which depends upon the HDL-cargo proteins associated with HDL, rather than HDL levels, appears to be the key factor, suggesting a quality over quantity status. In this report, we have assessed the HDL-cargo (Cholesterol, ApoA-I, ApoA-II, ApoC-I, ApoC-III, ApoD, ApoE, ApoH, ApoJ, CRP, and SAA) …

Understanding The Relationship Between Age-Related Hearing Loss And Alzheimer's Disease: A Narrative Review, Hadeel Y. Tarawneh, Dona M. P. Jayakody, Hamid R. Sohrabi, Ralph N. Martins, Wilhelmina H.A.M. Mulders

Research outputs 2022 to 2026

Evidence suggests that hearing loss (HL), even at mild levels, increases the long-term risk of cognitive decline and incident dementia. Hearing loss is one of the modifiable risk factors for dementia, with approximately 4 million of the 50 million cases of dementia worldwide possibly attributed to untreated HL. This paper describes four possible mechanisms that have been suggested for the relationship between age-related hearing loss (ARHL) and Alzheimer's disease (AD), which is the most common form of dementia. The first mechanism suggests mitochondrial dysfunction and altered signal pathways due to aging as a possible link between ARHL and AD. The …

Systemic Perturbations Of The Kynurenine Pathway Precede Progression To Dementia Independently Of Amyloid-Β, Marcela Cespedes, Kelly R. Jacobs, Paul Maruff, Alan Rembach, Christopher J. Fowler, Brett Trounson, Kelly K. Pertile, Rebecca L. Rumble, Stephanie R. Rainey-Smith, Christopher C. Rowe, Victor L. Villemagne, Pierrick Bourgeat, Chai K. Lim, Pratishtha Chatterjee, Ralph N. Martins, Arne Ittner, Colin L. Masters, James D. Doecke, Gilles J. Guillemin, David B. Lovejoy

Research outputs 2022 to 2026

Increasing evidence suggests that kynurenine pathway (KP) dyshomeostasis may promote disease progression in dementia. Studies in Alzheimer's disease (AD) patients confirm KP dyshomeostasis in plasma and cerebrospinal fluid (CSF) which correlates with amyloid-β and tau pathology. Herein, we performed the first comprehensive study assessing baseline levels of KP metabolites in participants enrolling in the Australian Imaging Biomarkers Flagship Study of Aging. Our purpose was to test the hypothesis that changes in KP metabolites may be biomarkers of dementia processes that are largely silent. We used a cross-sectional analytical approach to assess non-progressors (N = 73); cognitively normal (CN) or mild …

The Association Between Alzheimer's Disease-Related Markers And Physical Activity In Cognitively Normal Older Adults, Steve Pedrini, Pratishtha Chatterjee, Akinori Nakamura, Michelle Tegg, Eugene Hone, Stephanie R. Rainey-Smith, Christopher C. Rowe, Vincent Dore, Victor L. Villemagne, David Ames, Naoki Kaneko, Samantha L. Gardener, Kevin Taddei, Binosha Fernando, Ian Martins, Prashant Bharadwaj, Hamid R. Sohrabi, Colin L. Masters, Belinda Brown, Ralph N. Martins, Aibl Research Group

Research outputs 2022 to 2026

Previous studies have indicated that physical activity may be beneficial in reducing the risk for Alzheimer's disease (AD), although the underlying mechanisms are not fully understood. The goal of this study was to evaluate the relationship between habitual physical activity levels and brain amyloid deposition and AD-related blood biomarkers (i.e., measured using a novel high-performance mass spectrometry-based assay), in apolipoprotein E (APOE) ε4 carriers and noncarriers. We evaluated 143 cognitively normal older adults, all of whom had brain amyloid deposition assessed using positron emission tomography and had their physical activity levels measured using the International Physical Activity Questionnaire (IPAQ). We …

Cerebrospinal Fluid Levels Of Fatty Acid–Binding Protein 3 Are Associated With Likelihood Of Amyloidopathy In Cognitively Healthy Individuals, Kunal Dhiman, Victor L. Villemagne, Christopher Fowler, Pierrick Bourgeat, Qiao-Xin Li, Steven Collins, Christopher C. Rowe, Colin L. Masters, David Ames, Kaj Blennow, Henrik Zetterberg, Ralph N. Martins, Veer Gupta

Research outputs 2022 to 2026

Introduction: Fatty acid–binding protein 3 (FABP3) is a biomarker of neuronal membrane disruption, associated with lipid dyshomeostasis—a notable Alzheimer's disease (AD) pathophysiological change. We assessed the association of cerebrospinal fluid (CSF) FABP3 levels with brain amyloidosis and the likelihood/risk of developing amyloidopathy in cognitively healthy individuals. Methods: FABP3 levels were measured in CSF samples of cognitively healthy participants, > 60 years of age (n = 142), from the Australian Imaging, Biomarkers & Lifestyle Flagship Study of Ageing (AIBL). Results: FABP3 levels were positively associated with baseline brain amyloid beta (Aβ) load as measured by standardized uptake value ratio (SUVR, standardized β …

Plasma P-Tau181/Aβ1-42 Ratio Predicts Aβ-Pet Status And Correlates With Csf-P-Tau181/Aβ1-42 And Future Cognitive Decline, Christopher J. Fowler, Erik Stoops, Stephanie R. Rainey-Smith, Eugeen Vanmechelen, Jeroen Vanbrabant, Nele Dewit, Kimberley Mauroo, Paul Maruff, Christopher C. Rowe, Jurgen Fripp, Qiao-Xin Li, Pierrick Bourgeat, Steven J. Collins, Ralph N. Martins, Colin L. Masters, James D. Doecke

Research outputs 2022 to 2026

Background: In Alzheimer's disease (AD), plasma amyloid beta (Aβ)1-42 and phosphorylated tau (p-tau) predict high amyloid status from Aβ positron emission tomography (PET); however, the extent to which combination of these plasma assays can predict remains unknown. Methods: Prototype Simoa assays were used to measure plasma samples from participants who were either cognitively normal (CN) or had mild cognitive impairment (MCI)/AD in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study. Results: The p-tau181/Aβ1-42 ratio showed the best prediction of Aβ-PET across all participants (area under the curve [AUC] = 0.905, 95% confidence interval [CI]: 0.86–0.95) and in CN (AUC = …

An Il1rl1 Genetic Variant Lowers Soluble St2 Levels And The Risk Effects Of Apoe-Ε4 In Female Patients With Alzheimer’S Disease, Yuanbing Jiang, Xiaopu Zhou, Hiu Yi Wong, Li Ouyang, Fanny C. F. Ip, Vicky M. N. Chau, Shun-Fat Lau, Wei Wu, Daniel Y. K. Wong, Heukjin Seo, Wing-Yu Fu, Nicole C. H. Lai, Yuewen Chen, Yu Chen, Estella P.S. Tong, Alzheimer’S Disease Neuroimaging Initiative, Vincent C. T. Mok, Timothy C. Y. Kwok, Kin Y. Mok, Maryam Shoai, Benoit Lehallier, Patricia Morán Losada, Eleanor O'Brien, Tenielle Porter, Simon Laws, John Hardy, Tony Wyss-Coray, Colin L. Masters, Amy K.Y. Fu, Nancy Y. Ip

Research outputs 2022 to 2026

Changes in the levels of circulating proteins are associated with Alzheimer’s disease (AD), whereas their pathogenic roles in AD are unclear. Here, we identified soluble ST2 (sST2), a decoy receptor of interleukin-33–ST2 signaling, as a new disease-causing factor in AD. Increased circulating sST2 level is associated with more severe pathological changes in female individuals with AD. Genome-wide association analysis and CRISPR–Cas9 genome editing identified rs1921622, a genetic variant in an enhancer element of IL1RL1, which downregulates gene and protein levels of sST2. Mendelian randomization analysis using genetic variants, including rs1921622, demonstrated that decreased sST2 levels lower AD …

Exploring Discordant Low Amyloid Beta And High Neocortical Tau Positron Emission Tomography Cases, Natasha Krishnadas, Vincent Doré, Simon M. Laws, Tenielle Porter, Fiona Lamb, Svetlana Bozinovski, Victor L. Villemagne, Christopher C. Rowe

Research outputs 2022 to 2026

Introduction: Neocortical 3R4R (3-repeat/4-repeat) tau aggregates are rarely observed in the absence of amyloid beta (Aβ). 18F-MK6240 binds specifically to the 3R4R form of tau that is characteristic of Alzheimer's disease (AD). We report four cases with negative Aβ, but positive tau positron emission tomography (PET) findings. Methods: All Australian Imaging, Biomarkers and Lifestyle study of aging (AIBL) study participants with Aβ (18F-NAV4694) and tau (18F-MK6240) PET scans were included. Centiloid < 25 defined negative Aβ PET (Aβ–). The presence of neocortical tau was defined quantitatively and visually. Results: Aβ– PET was observed in 276 participants. Four of these participants (one cognitively unimpaired [CU], two mild cognitive impairment [MCI], one AD) had tau tracer retention in a pattern consistent with Braak tau stages V to VI. Fluid biomarkers supported a diagnosis of AD. In silico analysis of APP, PSEN1, PSEN2, and MAPT genes did not identify relevant functional mutations. Discussion: Discordant cases were infrequent (1.4% of all Aβ– participants). In these cases, the Aβ PET ligand may not be detecting the Aβ that is present.

Plasma P217+Tau Versus Nav4694 Amyloid And Mk6240 Tau Pet Across The Alzheimer's Continuum, Vincent Doré, James D. Doecke, Ziad S. Saad, Gallen Triana-Baltzer, Randy Slemmon, Natasha Krishnadas, Pierrick Bourgeat, Kun Huang, Samantha Burnham, Christopher Fowler, Stephanie R. Rainey-Smith, Ashley I. Bush, Larry Ward, Jo Robertson, Ralph N. Martins, Colin L. Masters, Victor L. Villemagne, Jurgen Fripp, Hartmuth C. Kolb, Christopher C. Rowe

Research outputs 2022 to 2026

Introduction: We evaluated a new Simoa plasma assay for phosphorylated tau (P-tau) at aa217 enhanced by additional p-tau sites (p217+tau). Methods: Plasma p217+tau levels were compared to 18F-NAV4694 amyloid beta (Aβ) positron emission tomography (PET) and 18F-MK6240 tau PET in 174 cognitively impaired (CI) and 223 cognitively unimpaired (CU) participants. Results: Compared to Aβ− CU, the plasma levels of p217+tau increased 2-fold in Aβ+ CU and 3.5-fold in Aβ+ CI. In Aβ− the p217+tau levels did not differ significantly between CU and CI. P217+tau correlated with Aβ centiloids P =.67 (CI, P =.64; CU, P =.45) and tau SUVRMT P …

A Large-Scale Genome-Wide Cross-Trait Analysis Reveals Shared Genetic Architecture Between Alzheimer’S Disease And Gastrointestinal Tract Disorders, Emmanuel O. Adewuyi, Eleanor K. O'Brien, Dale R. Nyholt, Tenielle Porter, Simon Laws

Research outputs 2022 to 2026

Consistent with the concept of the gut-brain phenomenon, observational studies suggest a relationship between Alzheimer’s disease (AD) and gastrointestinal tract (GIT) disorders; however, their underlying mechanisms remain unclear. Here, we analyse several genome-wide association studies (GWAS) summary statistics (N = 34,652–456,327), to assess the relationship of AD with GIT disorders. Findings reveal a positive significant genetic overlap and correlation between AD and gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), gastritis-duodenitis, irritable bowel syndrome and diverticulosis, but not inflammatory bowel disease. Cross-trait meta-analysis identifies several loci (P_{meta-analysis} < 5 × 10⁻⁸) shared by AD and GIT disorders (GERD and PUD) including …