Paradigm shift: semantic memory decline as a biomarker of preclinical Alzheimer’s disease

Uncovering the presence of Alzheimer's disease (AD) in routine neurological management of middle-aged/elderly adults, and differentiating its combination of symptoms from those induced by the processes of normal aging, neurovascular disease or psychiatric conditions (e.g., depression), are challenges of primary importance. Usually, it is the onset of behavioral symptoms that encourages patients with AD and caregivers to seek medical attention for the first time. Research evidence, however, shows that the earliest changes triggered by the disease on the biology of the brain occur several decades prior to any behavioral change of clinical relevance [1]. Based on this large preclinical-stage/symptomatic-stage temporal...