Keck School of Medicine of USC Apr 27 2026 Cognitive decline in Alzheimer's disease differs substantially from one person to the next and is not well predicted by existing medical tests. Among people with preclinical Alzheimer's disease who began one of two related studies with no symptoms, researchers from the Keck School of Medicine of USC found three distinct patterns: stable, slow cognitive decline and fast cognitive decline. About 70% of participants remained stable over the study period