H. Zetterberg

Plasma Biomarkers for Neocortical Tau Burden.

Importance Phosphorylated tau-217 (p-tau217) is now an established plasma biomarker for assessing amyloid-β pathology in individuals at risk of Alzheimer disease. However, its performance in identifying advanced neocortical neurofibrillary tangle burden remains suboptimal. Precise assessment of tau pathology is increasingly critical for the rational implementation of anti-amyloid therapies and developing anti-tau interventions. Improved biofluid biomarker-based tau staging could enhance patient stratification and optimize participant selection for clinical care and therapeutic trials. Objective To develop and validate a multiprotein plasma panel to improve identification of neocortical tau pathology beyond p-tau217 alone. Design, Setting, and Participants This multicenter cohort study included 2 independent observational cohorts, Swedish BioFINDER study and Translational Biomarkers in Aging and Dementia (TRIAD). Cross-sectional clinical data and blood samples were collected between 2017 and 2024. Participants included 560 individuals spanning the clinical spectrum from cognitively unimpaired to dementia. These data were analyzed from January 2025 to May 2026. Exposures Plasma concentrations of 125 proteins measured using Nucleic Linked Immuno-Sandwich Assay central nervous system panel. Main Outcome and Measure Advanced tau pathology defined as tau positron emission tomography (PET) uptake within Braak stage V and VI regions. Predictive performance of biomarker models was evaluated using area under the receiver operating characteristic curve (AUC). Results The study included 560 amyloid-positive participants (BioFINDER: n = 431; mean [SD] age, 73.6 [7.0] years; 212 female [49.2%] and 219 male [51.8%]; TRIAD: n = 129; mean [SD] age, 70.4 [8.3] years; 76 female [58.9%] and 53 male [41.1%]). Using multivariable logistic regression approaches, a 7-protein panel was found in BioFINDER to identify tau PET uptake within Braak stage V and VI regions. When compared with p-tau217 (AUC, 0.86-0.88; 95% CI, 0.82-0.94), this multiprotein panel was associated with improved identification in both discovery and validation cohorts (AUC, 0.92-0.94; 95% CI, 0.89-0.98; DeLong P < .001). This reduced the proportion of individuals classified within the intermediate-risk range (between paired sensitivity and specificity thresholds) in the validation cohort by 14.7% to 21.0%. Conclusions and Relevance This multicohort study demonstrated how including additional plasma proteins significantly enhanced the performance of p-tau217 in predicting advanced tau pathology among amyloid-positive individuals. This suggests a multiprotein approach may offer a viable and scalable alternative to tau PET staging in clinical or research settings.

Exploring longitudinal relationships among Alzheimer's disease biomarkers

While most studies of Alzheimer's disease (AD) examine cross‐sectional relationships among biomarkers, longitudinal relationships are also highly relevant.

Predicting continuous amyloid PET levels with CSF and plasma brain‐derived p‐tau217

Staging amyloid beta (Aβ) burden along a continuous spectrum provides clinically relevant information. Conventional phosphorylated tau (p‐tau)217 reliably identifies amyloid positron emission tomography (PET) positivity, but its ability to capture the full Aβ continuum is limited. Recently developed brain‐derived (BD) p‐tau217 assays enrich for central nervous system tau species and may improve specificity.

CSF fibrinogen predicts longitudinal Tau accumulation in cognitively unimpaired older adults

Blood–brain barrier (BBB) dysfunction is an early feature of Alzheimer's disease (AD). Fibrinogen represents a sensitive marker of BBB leakage, but whether it modifies longitudinal tau progression in cognitively unimpaired (CU) individuals remains unknown.

Lifestyle and psychosocial protective factors drive healthy aging and modulate inflammatory and metabolic pathways.

Lifestyle habits, cognitive reserve, and affective reserve (secure attachment, extraversion, psychological resilience) predict resilience in the oldest-old, though the underlying biological mechanisms remain unclear. This study explored relationships between these protective factors, 120 + NULISA CNS blood biomarkers, and multidimensional health outcomes (global cognition, mental health, walking speed) in 401 dementia-free participants (age 83-87) from the InveCe.Ab study. Using sparse partial least squares (sPLS) regression, eight biomarkers were stably associated with the protective factors: HBA1, DDC, IFNG, IL15, GOT1, ACHE, SNAP25, and SNCB. Structural equation modeling (SEM) showed that the three protective factors exerted an independent and domain-specific effect on health outcomes. Moreover, lifestyle habits were associated with ACHE (β = 0.26), IL15 (β = 0.22), and GOT1 (β = 0.28); affective reserve showed inverse associations with IFNG (β = -0.13) and IL15 (β = -0.31), and GOT1 (β = -0.18). Regarding health domains, SNAP25 was inversely related to global cognition (β = -0.10), while SNCB was associated with global cognition (β = 0.16) and walking speed (β = 0.13). Notably, no significant mediated effects were found, suggesting that the clinical benefits observed were not directly driven by the aforementioned biological pathways. The present study paves the way for further investigations on the biological mechanisms underlying resilient aging, while further demonstrating the key protective role of individual habits and psychosocial characteristics during the life course.

Cognitive components derived from traditional neuropsychological tests and their associations with plasma p-tau217 and p-tau181 in mild cognitive impairment: a multisite analysis.

BACKGROUND Currently, no single biomarker can reliably identify preclinical Alzheimer's disease (AD), particularly at or before the mild cognitive impairment (MCI) stage. Given the heterogeneity of MCI, integrative approaches are needed to improve early risk stratification. OBJECTIVES (i) To derive robust latent cognitive components from a multicenter, clinically defined MCI cohort using principal component analysis (PCA); (ii) to investigate the associations between these components and plasma p-tau217 and p-tau181 levels. METHODS Data from 742 MCI participants in the AI-Mind cohort were analyzed. Cognitive domains were derived using PCA with varimax rotation and tested for associations with plasma p-tau biomarkers using site-specific linear regressions, adjusted for age, sex, and education. RESULTS A reproducible four-component cognitive structure emerged (memory, executive/processing speed, verbal fluency, visuospatial ability), with memory as the most p-tau-sensitive domain. The p-tau217 measure showed stronger associations with memory than p-tau181, though effects varied by site. CONCLUSION The findings indicate that a robust four-factor cognitive structure can be identified in clinically defined MCI cohorts without prior biological selection. The association between latent memory factors and plasma p-tau217, observed primarily in cohorts with higher biomarker burden or clearer amnestic profiles, highlights the potential for blood-based biomarkers to refine risk assessment in routine clinical practice.

Blood-based biomarkers of Alzheimer’s disease and neurodegeneration in an indigenous African cohort using both Simoa and NULISA platforms

In low- and middle-income countries, Alzheimer’s disease (AD) constitutes a growing public health burden. However, AD biomarkers research remains underrepresented in African populations. This study assesses core biomarkers of AD and their relevance in the African context as potential aid in clinical diagnosis. Nigerian older adults from VALIANT cohort (n = 967) underwent biomarker quantification in plasma (p-tau217, GFAP, NfL, Aβ42 and Aβ40) employing both the Single Molecule Assay (Simoa, Quanterix) and Nucleic acid-Linked Immuno-Sandwich Assay (NULISA, Alamar). Biomarkers were associated with disease severity in clinical-diagnostic and clinical-biological groups, with stepwise increases of p-tau217, NfL and GFAP from cognitively unimpaired to dementia (p < 0.05). Results were consistent across platforms. Comparison between sexes showed higher biomarker levels in male participants across diagnostic groups. A significant effect of apoE-E4 proteotype on p-tau217 levels, after adjusting for age and sex was identified. These findings support the application of plasma AD biomarkers in the African context and the relevance of further AD biomarker research in diverse populations.

Analytical validation and amyloid-status discrimination of a high-throughput, research-use-only plasma p-Tau217 immunoassay

Blood-based immunophenotyping of T cell profiles in patients with neurodegenerative disorders.

BACKGROUND There is increasing evidence for the role of central and peripheral inflammation across neurodegenerative disorders, with animal models and post-mortem studies identifying T-cell infiltration in the brain associated with pathology and neurodegeneration. Peripheral T-cell changes have been measured in Alzheimer's disease (AD), dementia with Lewy bodies (DLB), frontotemporal dementia (FTD) and progressive supranuclear palsy (PSP). This study examines a unique cohort of blood-based T-cell profiles across a range of neurodegenerative dementias including AD, DLB, FTD, corticobasal syndrome (CBS), PSP, and aged-matched healthy controls. Then it also explores their associations with dementia-relevant plasma biomarkers and clinical outcomes. METHODS Freshly prepared peripheral blood mononuclear cells (PBMCs) from 174 participants (AD = 20, DLB = 24, FTD = 19, CBS = 18, PSP = 58, controls = 35) were studied using a flow-cytometry panel designed to analyse major T-cell subpopulations, including memory and T-helper subtypes. Neurodegeneration-relevant biomarkers (p-tau217, p-tau231, GFAP, NfL, and A-beta42/40) were measured in plasma samples. T-cell populations were compared between groups and in association with biomarkers, and principal components analysis (PCA) was used to identify T-cell profiles and their association with dementia-relevant biomarkers in diagnostic classification and survival prediction. RESULTS There was a significant reduction in the fraction of CD3+ cells in patients with DLB compared to other diagnostic groups, and an increase in relative Th1/17-like cell levels in patients with FTD compared to controls. This increase in Th1/17-like cells correlated with NfL and GFAP plasma levels in patients with FTD. PCA identified five components primarily representing CD4+ memory cell population subsets. After sex and age adjustments, component 4 marked by effector memory types including Th2-like, Th-like1 and Th1/17-like cells was a significant predictor of FTD, however was not as accurate as plasma NfL. Higher scores in specific T-cell components (1 and 3) were associated with reduced mortality across all diseases, with component 3 remaining a significant predictor even when controlling for traditional neurodegenerative biomarkers like NfL and p-tau217. CONCLUSIONS This study provides evidence that T-cell dysregulation is not unified in patients with neurodegenerative diseases. We observe different involvement across different dementia types establishing adaptive immunity as a key contributor to disease heterogeneity. However, although plasma biomarkers such as NfL and p-tau217 exhibit superior diagnostic accuracy for clinical classification, peripheral T-cell signature were associated with survival outcomes across diagnostic groups, highlighting their promise for prognostic applications and disease monitoring. The characterisation of T-cell populations across neurodegenerative conditions may inform target development and patient stratification for new interventional trials.

Educational attainment and sex modulate clinical outcomes in genetic frontotemporal dementia

Sex and educational attainment significantly affect the development and maintenance of cognitive reserve in individuals with genetic FTD, and underscore the importance of identifying disease-modifying interventions since the presymptomatic stages of the disease.

Defining the underlying pathology of corticobasal syndrome using clinical features and biomarkers.

Young onset, less parkinsonism and more cognitive and cortical sensory impairment, along with reduced MRI parietal volumes point to CBS-AD, while limb dystonia, falls and worse verbal fluency relate to CBS-non-AD.

Neurobiological correlates of longitudinal grey matter volume changes in preclinical Alzheimer’s disease

In this large longitudinal sample of asymptomatic individuals, the Aβ-dominant biomarker component showed the strongest association with longitudinal GM atrophy and cognitive decline, beyond the effects of tau pathophysiology and neuroaxonal injury.