Author: Cindy Birck

“Early detection of Alzheimer’s disease using small RNAs. Results from the EPAD cohort”

Authors: Tobias Sikosek , Marco Heuvelman, Jagoda Mika, Mustafa Kahraman, Julia Jehn, Maurice Frank, Alberto Daniel-Moreno, Jessika Ceiler, Jasmin Skottke, Marta Sanchez-Delgado, Patrick Neubert, Christina Rudolf , Kaja Tikk, Rastislav Horos, Jeffrey L Cummings, Josie Butchart, Craig Ritchie, Jean Manson, Bruno R Steinkraus; EPAD consortium

Abstract:

Background: Alzheimer’s disease (AD) is the most common form of dementia, and early diagnosis is crucial to enable effective interventions. Currently, Alzheimer’s disease is diagnosed through cognitive assessments, brain imaging and fluid biomarkers focused on determining amyloid (A) and, tau (T) protein levels as well as neurodegeneration (N) in the AT(N) framework. Prognostic biomarkers for predicting cognitive decline within the amyloid positive (Aβ+) individuals would further strengthen the framework.

Objectives: This study evaluated small RNAs as novel auxiliary biomarkers, independent of the AT(N) framework, either alone or in combination with established protein markers, for detecting the earliest cognitive decline in AD.

Design: The European Prevention of Alzheimer’s Disease (EPAD) clinical trial platform is a prospective, multi-center study designed to investigate biomarkers for preclinical and prodromal AD.

Setting: Peripheral whole blood RNA sequencing was performed on participants across Europe with no cognitive impairment or very mild cognitive impairment (MCI), stratified by cerebrospinal fluid amyloid levels.

Participants: 1,913 participants, 50 years or older and free of dementia diagnosis at enrollment, were analyzed.

Intervention: (if any) Not applicable.

Measurements: Ultra-deep small RNA sequencing was performed on whole blood samples using a refined blocking protocol to eliminate highly abundant erythroid small RNAs, and thereby to open sequencing bandwidth for the discovery of less abundant biomarker RNAs. Biomarker RNAs were deconvolved into plasma or blood cell origin and analyzed for functional relevance. We define high and low amyloid groups based on a cutoff on the p-tau₁₈₁/Aβ_1-42 ratio as determined from cerebrospinal fluid.

Results: We identified a combination of small RNAs that predicted early cognitive decline (Clinical Dementia Rating of 0.5) with an area under the receiver-operator curve of ∼0.7. Notably, when focusing on individuals with cognitive decline and high amyloid burden (Aβ+), the predictive accuracy improved to an AUC of 0.77. This performance could be extended to the entire cohort when combining blood RNA and CSF amyloid markers (AUC 0.76). We conducted bioinformatic analyses to interrogate the likely functional relevance of these small RNAs, uncovering several links to dementia-relevant pathways, including neuronal, cardiovascular, and inflammatory activities. Our findings also suggest that small nucleolar RNAs warrant further investigation as potential disease-relevant markers, in addition to microRNAs.

Conclusions: Integrating small RNA biomarkers with protein-based assays offers preliminary evidence for stratifying MCI, particularly within the amyloid positive continuum. Small nucleolar RNAs and microRNAs warrant further exploration as complementary diagnostic tools, and their use may enable more precise and effective interventions.

DOI:https://doi.org/10.1016/j.tjpad.2025.100257

Published online: September 2025 in the journal of Prevention of Alzheimer’s disease

“Brain MRI signatures across sex and CSF Alzheimer’s disease biomarkers”

Authors: You Cheng, Yingnan He Karthik Gopinath, Benjamin Billot, Juan Eugenio Iglesias, Chao-Yi Wu, Hiroko Dodge, Anne-Marie Will, Becky Carlyle, Pia Kivisäkk, Bradley T Hyman, Steven E Arnold, Sudeshna Das; for the Alzheimer’s Disease Neuroimaging Initiative and for the European Prevention of Alzheimer’s Disease (EPAD) Consortium

Abstract:

The relationship between cerebrospinal fluid (CSF) biomarkers of Alzheimer’s disease and neurodegenerative effects is not fully understood. This study investigates neurodegeneration patterns across CSF Alzheimer’s disease biomarker groups, the association of brain volumes with CSF amyloid and tau status and sex differences in these relationships in a clinical neurology sample. MRI and CSF Alzheimer’s disease biomarkers data were analysed in 306 patients of the Mass General Brigham healthcare system aged 50+ (mean age = 68.4 ± 8.8 years; 43.1% female), who had lumbar punctures within 1 year of clinical MRI scans. We first analysed neurodegeneration patterns across four biomarker groups: 60 controls (A−T−&CU; amyloid negative, tau negative, cognitively unimpaired), 25 A+T− (amyloid positive, tau negative), 121 A+T+ (amyloid positive, tau positive) and 100 other dementia (A−T−&CI; amyloid negative, tau negative, cognitively impaired). Second, we examined volumetric associations with amyloid (amyloid positive, tau negative versus control) and tau in the presence of amyloid (amyloid positive, tau positive versus amyloid positive, tau negative) across 52 brain areas. Third, we examined sex differences in these relationships. Finally, we validated core analyses across three independent datasets—NACC (National Alzheimer’s Coordinating Center), ADNI (Alzheimer’s Disease Neuroimaging Initiative) and EPAD (European Prevention of Alzheimer’s Dementia)—totalling 3137 participants, and performed meta-analyses to obtain more robust estimates. We observed distinct neurodegeneration patterns across biomarker groups, with disrupted connectivity (brain volume covariance networks) in amyloid positive and other dementia groups, while amyloid and tau negative, cognitively unimpaired controls exhibited the most connected network. Amyloid was associated with subcortical, cerebellar and brainstem atrophy, with consistent association observations in the thalamus and amygdala across all four datasets. Tau in the presence of amyloid demonstrated general brain shrinkage through enlargement of extracerebral CSF, alongside unexpected ventricle shrinkages. Sex-based analyses revealed that A+T+ (amyloid positive, tau positive) had lower sex differences in connectivity patterns compared with other groups. Sex differences were also noted in amyloid-related ventricular volume changes. This study reveals how amyloid and tau affect brain connectivity and volume across sex and CSF biomarker groups, emphasizing global brain changes and sex differences. By leveraging automated pipelines and advanced MRI and biomarker analyses, we extracted meaningful and replicable findings from heterogeneous clinical samples from real-world data. The meta-analyses across four datasets enhance the generalizability of our results.

DOI: 10.1093/braincomms/fcaf210

Published online: 30 May 2025 in the journal Brain Communications

“Accrual of Alzheimer’s disease pathology as a function of proximity to parental dementia onset”

Authors: Elina T. Ziukelis, Elijah Mak, Craig Ritchie, John T. O’Brien, Dag Aarsland, for the European Prevention of Alzheimer’s Disease (EPAD) Consortium

Abstract:

Introduction: Whether temporal proximity to parental onset of dementia (PPO) can be used to estimate timing of the preclinical stage of sporadic Alzheimer’s disease (AD) remains uncertain.

Methods: We investigated cross-sectionally adults aged > 50 without dementia included in the European Prevention of Alzheimer’s Dementia (EPAD) study. PPO was tested as a predictor of quantitative levels of cerebrospinal fluid (CSF) β-amyloid (1-42) (Aβ1-42) in those with a parental history of dementia (n = 688) and of phosphorylated tau (p-tau) and EPAD neuropsychological examination (ENE) subscores in an amyloid positive subgroup (n = 226). Possible interactions were explored.

Results: Shorter PPO predicted lower CSF Aβ1-42 level (β = 9.357; T = 4.161; p < 0.001), interacting with apolipoprotein E (APOE) -𝜀4 carriage in a dose-dependent manner. Concomitant APOE-𝜀2 carriage appeared to provide protection. PPO did not predict p-tau levels or cognitive performance.

Discussion: PPO may provide a valid method of stratifying risk of early AD pathologic change in APOE-𝜀4 carriers, with empirical and clinical applications.

Highlights:

• Proximity to age of parental dementia onset can predict amyloid accrual
• The effect is APOE-𝜀4 dose-dependent and APOE-𝜀2 appears to provide protection
• PPO does not appear to predict further advancement along the AD continuum
• In the era of anti-amyloid treatments, this may inform timing of amyloid screening
• Used as an empirical metric, PPO could help elucidate the natural history of LOAD

DOI: 10.1002/dad2.70092

Published online: 30 May 2025 in the journal Alzheimer’s & Dementia

“Facilitating clinical use of the Amsterdam Instrumental Activities of Daily Living Questionnaire: Normative data and a diagnostic cutoff value”

Authors: Merel C. Postema, Mark A. Dubbelman, Jürgen Claesen, Craig Ritchie, Merike Verrijp, Leonie Visser, Pieter-Jelle Visser, Marissa D. Zwan, Wiesje M. van der Flier and Sietske A.M. Sikkes

Abstract:

Objective:The Amsterdam Instrumental Activities of Daily Living Questionnaire (A-IADL-Q) is well validated and commonly used to assess difficulties in everyday functioning regarding dementia. To facilitate interpretation and clinical implementation across different European countries, we aim to provide normative data and a diagnostic cutoff for dementia.

Methods: Cross-sectional data from Dutch Brain Research Registry (N = 1,064; mean (M) age = 62 ± 11 year; 69.5% female), European Medial Information Framework-Alzheimer’s Disease 90 + (N = 63; Mage = 92 ± 2 year; 52.4% female), and European Prevention of Alzheimer’s Dementia Longitudinal Cohort Study (N = 247; Mage = 63 ± 7 year; 72.1% female) were used. The generalized additive models for location, scale, and shape framework were used to obtain normative values (Z-scores). The beta distribution was applied, and combinations of age, sex, and educational attainment were modeled. The optimal cutoff for dementia was calculated using area under receiver operating curves (AUC-ROC) and Youden Index, using data from Amsterdam Dementia Cohort (N = 2,511, Mage = 64 ± 8 year, 44.4% female).

Results: The best normative model accounted for a cubic-like decrease of IADL performance with age that was more pronounced in low compared to medium/high educational attainment. The cutoff for dementia was 1.85 standard deviation below the population mean (AUC = 0.97; 95% CI [0.97–0.98]).

Conclusion:We provide regression-based norms for A-IADL-Q and a diagnostic cutoff for dementia, which help improve clinical assessment of IADL performance across European countries.

DOI: https://doi.org/10.1017/S1355617724000031

Published online: 8 March 2024 in the Journal of the International Neuropsychological Society

“Validation of the brain health index in the European Prevention of Alzheimer’s Dementia cohort”

Authors: Jodi K. Watt, David Alexander Dickie, Frederick K. Ho, Donald M. Lyall, Jesse Dawson, Terence J. Quinn, European Prevention of Alzheimer’s Disease (EPAD) Consortium

Abstract:

Background: Brain Health Index (BHI) assimilates various MRI sequences, giving a quantitative measure of brain health. To date, BHI validation has been cross-sectional and limited to selected populations. Further large-scale validation and assessment of temporal change is required to understand its clinical utility.

Aim: Assess 1) relationships between variables associated with cognitive decline and BHI 2) associations between BHI and measures of cognition and 3) longitudinal changes in BHI and relationship with cognitive function.

Methods: BHI computation involved Gaussian mixture-model cluster analysis of T1, T2, T2*, and T2 FLAIR MRI data from participants within the European Prevention of Alzheimer’s Dementia (EPAD) cohort. Group differences (gender- and health-based) were evaluated using independent samples Welch’s t-tests. Relationships between BHI, age and cognitive tests used linear regression. Longitudinal analysis (12/24 months) utilised mixed linear regression models to examine BHI changes, and paired BHI/cognition associations.

Results: Data from N = 1496 predominantly Caucasian participants (50–88 years old, 43.32% male) were used. BHI scores were lower in those with diabetes (p < 0.001, d = 0.419), hypertension (p < 0.001, d = 0.375), hypercholesterolemia (p < 0.001, d = 0.193) and stroke (p < 0.05, d = 0.512). APOE was not significantly related to BHI scores. After correction for age, cross-sectional BHI scores were significantly associated with all measures of cognitive function in males, but only the Four Mountains Test (4MT) in females. Longitudinal change in BHI and cognition were not consistently related.

Conclusions: BHI is a valid marker of cognitive decline and relatively stable over 1-2 year follow-up periods. Further work should assess temporal changes over a longer duration and determine relationships between BHI and cognition in more diverse populations.

DOI: https://doi.org/10.1016/j.cccb.2024.100214

Published online: 5 April 2024 in the Journal Cerebral Circulation – Cognition and Behavior

“Modifiable dementia risk factors and AT(N) biomarkers: findings from the EPAD cohort”

Authors: Eddy Roccati, Aidan David Bindoff, Jessica Marie Collins, Joshua Eastgate, Jay Borchard, Jane Alty, Anna Elizabeth King, James Clement Vickers, Margherita Carboni, Chad Logan, EPAD Consortium

Abstract:

Introduction: Modifiable risk factors account for a substantial proportion of Alzheimer’s disease (AD) cases and we currently have a discrete AT(N) biomarker profile for AD biomarkers: amyloid (A), p-tau (T), and neurodegeneration (N). Here, we investigated how modifiable risk factors relate to the three hallmark AT(N) biomarkers of AD.

Methods: Participants from the European Prevention of Alzheimer’s Dementia (EPAD) study underwent clinical assessments, brain magnetic resonance imaging, and cerebrospinal fluid collection and analysis. Generalized additive models (GAMs) with penalized regression splines were modeled in the AD Workbench on the NTKApp.

Results: A total of 1,434 participants were included (56% women, 39% APOE ε4+) with an average age of 65.5 (± 7.2) years. We found that modifiable risk factors of less education (t = 3.9, p < 0.001), less exercise (t = 2.1, p = 0.034), traumatic brain injury (t = −2.1, p = 0.036), and higher body mass index (t = −4.5, p < 0.001) were all significantly associated with higher AD biomarker burden.

Discussion: This cross-sectional study provides further support for modifiable risk factors displaying neuroprotective associations with the characteristic AT(N) biomarkers of AD.

DOI: https://doi.org/10.3389/fnagi.2024.1346214

Published online: 7 February 2024 in the Journal Frontiers in Aging Neuroscience

“The European Prevention of Alzheimer’s Dementia Programme: An Innovative Medicines Initiative-funded partnership to facilitate secondary prevention of Alzheimer’s disease dementia”

Authors: Stina Saunders, Sarah Gregory, Matthew H S Clement, Cindy Birck, Serge van der Geyten, Craig W Ritchie

Abstract:

Introduction: Tens of millions of people worldwide will develop Alzheimer’s disease (AD), and only by intervening early in the preclinical disease can we make a fundamental difference to the rates of late-stage disease where clinical symptoms and societal burden manifest. However, collectively utilizing data, samples, and knowledge amassed by large-scale projects such as the Innovative Medicines Initiative (IMI)-funded European Prevention of Alzheimer’s Dementia (EPAD) program will enable the research community to learn, adapt, and implement change.

Method: In the current article, we define and discuss the substantial assets of the EPAD project for the scientific community, patient population, and industry, describe the EPAD structure with a focus on how the public and private sector interacted and collaborated within the project, reflect how IMI specifically supported the achievements of the above, and conclude with a view for future.

Results: The EPAD project was a €64-million investment to facilitate secondary prevention of AD dementia research. The project recruited over 2,000 research participants into the EPAD longitudinal cohort study (LCS) and included over 400 researchers from 39 partners. The EPAD LCS data and biobank are freely available and easily accessible via the Alzheimer’s Disease Data Initiative’s (ADDI) AD Workbench platform and the University of Edinburgh’s Sample Access Committee. The trial delivery network established within the EPAD program is being incorporated into the truly global offering from the Global Alzheimer’s Platform (GAP) for trial delivery, and the almost 100 early-career researchers who were part of the EPAD Academy will take forward their experience and learning from EPAD to the next stage of their careers.

Discussion: Through GAP, IMI-Neuronet, and follow-on funding from the Alzheimer’s Association for the data and sample access systems, the EPAD assets will be maintained and, as and when sponsors seek a new platform trial to be established, the learnings from EPAD will ensure that this can be developed to be even more successful than this first pan-European attempt.

DOI: 10.3389/fneur.2022.1051543

Published online: 22 November 2022 in the Journal Frontiers in Neurology