# Plasma p-tau217 as a biomarker of Alzheimer’s disease pathology in individuals with Down syndrome

## TL;DR

Plasma p-tau217 is a highly accurate blood test for detecting Alzheimer’s disease in people with Down syndrome.

## Contribution

The study shows p-tau217 outperforms other biomarkers in detecting AD in Down syndrome individuals.

## Key findings

- Plasma p-tau217 distinguished AD dementia in DS individuals with an AUC of 0.96.
- It accurately identified amyloid β positivity in DS individuals with an AUC of 0.95.
- p-tau217 predicted clinical progression in DS individuals better than other plasma biomarkers.

## Abstract

Diagnosing Alzheimer’s disease (AD) in adults with Down syndrome (DS), a population with a high genetically determined risk of AD, remains challenging. In this large observational study including n = 2329 samples from the Down Alzheimer Barcelona Neuroimaging Initiative (DABNI) and euploid controls from the Sant Pau Initiative on Neurodegeneration (SPIN) with and without symptomatic AD, we investigate if the strong diagnostic performance of plasma p-tau217 observed in sporadic AD extends to the DS population. Plasma p-tau217 discriminated cognitively stable individuals with DS from those with AD dementia with an AUC of 0.96 (95% CI, 0.95-0.97), and from those with prodromal AD with an AUC of 0.90 (95% CI, 0.87-0.92). Amyloid β (Aβ) positive and Aβ negative individuals with DS were distinguished with an AUC of 0.95 (95% CI, 0.92-0.99). In this study, we demonstrate that plasma p-tau217 is highly accurate in detecting amyloid β positivity and predicting clinical progression in individuals with DS, outperforming other plasma biomarkers. These findings support its use as a reliable, noninvasive tool for early AD detection and management in individuals with DS.

The authors show that phosphorylated tau 217 is an accurate blood-based biomarker to detect Alzheimer’s disease and predict disease progression in individuals with Down syndrome, supporting its use as a reliable, non-invasive tool for early diagnosis and care.