Beyond Memory Loss: Reframing Alzheimer Disease in the Biomarker era- a systematic review.

Abstract

Background: Alzheimer disease is now recognized as a biologically defined neurodegenerative disorder marked by amyloid-β deposition, tau aggregation, synaptic failure, and progressive cognitive decline. Over the past 50 years, the field has shifted from a purely clinical syndrome model to a biomarker-based framework that distinguishes amyloid  pathology, tau pathology, and downstream neurodegeneration