The platelet protein biomarkers that have been studied to diagnose dementia (especially Alzheimer's disease) include amyloid protein precursor (A β PP), A β PP secretase (BACE1 and β 10), α-synuclein, tau protein, 5-hydroxytryptamine, cholesterol, phospholipase, aggregin, immunoglobulin, surface receptor, MAO-B, and coated platelet. The gene discussed is APP; the disease is Alzheimer disease.