Plasma biomarkers of Alzheimer’s disease predict cognitive decline and could improve clinical trials in the cognitively unimpaired elderly

Plasma biomarkers of amyloid, tau, and neurodegeneration (ATN) need to be characterized in cognitively unimpaired (CU) elderly indviduals. We therefore tested if plasma measurements of amyloid-β (Aβ)42/40, phospho-tau217 (P-tau217), and neurofilament light (NfL) together predict clinical deterioration in 435 CU individuals followed for an average of 4.8 ±1.7 years in the BioFINDER study. A combination of all three plasma biomarkers and basic demographics best predicted change in the cognition (Pre-Alzheimer’s Clinical Composite; R 2 =0.14, 95% CI [0.12-0.17]; P<0.0001) and subsequent AD dementia (AUC=0.82, 95% CI [0.77-0.91], P<0.0001). In a simulated clinical trial, a screening algorithm combining all three plasma biomarkers would reduce the required sample size by 70% (95% CI [54-81]; P<0.001) with cognition as trial endpoint, and by 63% (95% CI [53-70], P<0.001) with subsequent AD dementia as trial endpoint. Plasma ATN biomarkers show usefulness in cognitively unimpaired populations and could make large clinical trials more feasible and cost-effective.