Blood-based multimodal biomarker models for differentiating early-onset Alzheimer’s disease from frontotemporal dementia: a longitudinal study of early-onset dementia and family members (LEAF) study

Predictive value of plasma p-tau217 for Alzheimer’s dementia compared to other blood-based biomarkers

P-tau217, NfL and GFAP showed strong associations with AD risk, especially within the first 9 years of follow-up, outperforming p-tau181, and over the later years of follow-up, the predictive accuracy of p-tau217 was significantly reduced.

Changes in five cerebrospinal fluid and three plasma Alzheimer’s disease biomarkers across increasing brain amyloid-beta and tau pathology burden

Neuropathological validation studies of pathology-specific biomarkers for neurodegenerative diseases are essential but are often limited by long sampling-to-death intervals and the lack of semi-quantitative pathology measures. We assessed the associations of five cerebrospinal fluid (CSF) (Aβ42/Aβ40, p-tau181, p-tau217, Aβ42/p-tau181 and Aβ42/p-tau217) and three plasma (p-tau217, p-tau217/Aβ42 and Aβ42/Aβ40) biomarkers with post-mortem Aβ and tau pathology burden in 250 participants with ante-mortem CSF (n=230) and/or plasma (n=101), affected by prion (n=162) or non-prion diseases (n=88). Aβ and tau burden were scored across nine and six brain areas, respectively. We assessed the earliest biomarker changes across quartiles of Aβ and tau pathology burden and the discriminatory performance at progressively higher pathology thresholds using multivariable linear regression and sequential ROC analyses. Analyses on p-tau markers were restricted to non-prion participants. The median sampling-death interval was 1.5 months for CSF and 1 month for plasma. CSF Aβ42/Aβ40 decreased at the second quartile of Aβ burden (p<0.001), whereas p-tau181 (p<0.01) and p-tau217 (p<0.001) increased only from the third quartile. CSF Aβ42/Aβ40 achieved its highest accuracy at low/intermediate Aβ burden (AUC 0.984), while CSF p-tau and derived ratios performed best at advanced Aβ (AUCs 0.889 to 0.980) and intermediate tau pathology stages (AUCs 0.949 to 0.995). CSF p-tau217 and Aβ42/p-tau217 consistently showed higher accuracy than their p-tau181 counterparts across Aβ and tau pathology scores. Plasma p-tau217 and p-tau217/Aβ42 significantly increased in the highest Aβ and tau burden quartiles, where they achieved their best performance (AUCs 0.893 to 0.928). These findings support a sequential model of biomarker changes across the Alzheimer’s disease neuropathological continuum. CSF Aβ42/Aβ40 best reflects low/intermediate Aβ burden, while CSF p-tau markers are more closely related to high Aβ and intermediate tau load. Plasma markers primarily identify advanced Aβ and tau pathology burden. Notably, current fluid biomarkers do not capture the earliest phases of Aβ deposition.

Cross-Sectional and Longitudinal Diagnostic Performance of Plasma p-tau217 and p-tau217/Aβ42 in Alzheimer's Disease.

OBJECTIVE Recent studies suggest that combining plasma phosphorylated tau (p-tau) with β-amyloid (Aβ) may improve diagnosis accuracy for Alzheimer's disease (AD). However, the cross-sectional and longitudinal concordance of these markers with Aβ positron emission tomography (PET) positivity remains incompletely understood. This study aimed to evaluate the diagnostic performance of plasma p-tau, alone and in combination with plasma Aβ, in AD. METHODS We included 326 participants from the Alzheimer's Disease Neuroimaging Initiative and 357 Chinese older adults from the Greater-Bay-Area Healthy Aging Brain Study who underwent Aβ-PET imaging. Longitudinal data were available for 285 Alzheimer's Disease Neuroimaging Initiative participants. Plasma p-tau181, p-tau217, Aβ42, and Aβ40 were measured on different analytical platforms. Diagnostic performance for Aβ-PET positivity was assessed using a two-cutoff approach. RESULTS Combining plasma p-tau with Aβ42 or the Aβ42/40 ratio reduced the intermediate zone. Notably, p-tau217/Aβ42 showed stronger agreement with Aβ-PET positivity than p-tau217 alone. Among individuals classified as p-tau217/Aβ42 positive but p-tau217 intermediate, 57.1 to 83.3% were Aβ-PET positive. Longitudinally, most Stable Positive (88.0-96.1%) and Stable Negative (89.4-90.9%) cases defined by p-tau217 or p-tau217/Aβ42 were Aβ-PET positive and Aβ-PET negative, respectively. Critically, 69.7 to 75.8% of Non-positive to Positive cases defined by p-tau217/Aβ42 were Aβ-PET positive. INTERPRETATION These findings provide novel insights into the cross-sectional and longitudinal diagnostic performance of plasma p-tau217/Aβ42 in AD. To be specific, plasma p-tau217/Aβ42 can reduce the intermediate zone and improve agreement with Aβ-PET positivity, and longitudinal p-tau217/Aβ42 monitoring is particularly informative for identifying Aβ-PET-positive patients who were p-tau217/Aβ42 negative or intermediate at baseline and were misclassified as low risk of AD. ANN NEUROL 2026.

Association of total and brain-derived Alzheimer's disease plasma biomarkers with brain amyloid deposition in a community-based sample

Relative importance of blood-based biomarkers for Alzheimer’s disease-specific neurodegeneration and cognitive decline

A stratified approach based on amyloid status is essential for the optimal application of blood-based biomarkers in monitoring disease progression and evaluating therapeutic efficacy in future clinical trials and precision medicine.

Serum p-Tau217 and apolipoprotein E as potential biomarkers for Alzheimer's disease severity: a case-control study

Increased serum p-tau217 and decreased ApoE levels were significantly associated with greater AD severity, suggesting that both biomarkers may serve as complementary noninvasive indicators of disease severity in Alzheimer’s disease.