APP and Alzheimer disease: Additionally, the mice received the platelets from aged APP/PS1 mice (AD mouse model) through the tail vein injection caused significantly learning and memory deficits and raised Aβ deposition when compared with the mice injected with plasma [31], suggesting that in peripheral blood, Aβ derived from platelets is able to enter into the brain through the BBB and deposits in the hippocampus, playing an crucial role in the pathogenesis of AD [58].