AIBRIEF
Two tests are now FDA cleared for early symptom use, but the disease modifying drugs they feed into only marginally slow a disease with no cure.
The Alzheimer's Association International Conference (AAIC), the field's main annual meeting, closed in London on July 15 with the clearest picture yet of how a blood test for Alzheimer's actually fits into a clinic visit. Two plasma assays are now FDA-cleared: Roche's Elecsys pTau181 and Fujirebio's Lumipulse, both measuring p-tau protein fragments linked to the brain changes that drive the disease.
The harder question is what comes after a positive result, because the available treatments only marginally slow a disease with no cure. Lecanemab and donanemab, the two lab-made antibody drugs cleared in recent years, modestly delay progression but do not stop it. Earlier diagnosis mainly widens the window for trial enrollment, lifestyle planning, and treatment eligibility.
A Buckley et al. study presented at AAIC 2026 and published in JAMA found that plasma p-tau217 predicted Alzheimer's risk up to a decade before symptoms, the most discriminating single biomarker in head-to-head network meta-analyses. When results land in a gray zone, clinicians add p-tau181 to settle discordant cases. The AAIC 2025 Clinical Practice Guideline is the playbook for who gets tested and how.
For now, the tests are for people with early memory or personality changes, used alongside cognitive exams, not general screening. The next clinic question is direct: is a plasma p-tau test right for your situation.