APP and Alzheimer disease: Up to now, several studies have reported significantly lower platelet APP ratio (i.e. the ratio between the upper 130 kDa and the lower 106–110 kDa isoforms) in AD patients correlating positively with cognitive decline (Di Luca et al. 1996, 1998; Borroni et al. 2004; Tang et al. 2006; Zainaghi et al. 2012).