passages.id: split_1_test_3374_passage
passages.type: progene_text
passages.text: The brains of Alzheimer 's disease ( AD ) patients display cerebrovascular and parenchymal deposits of beta - amyloid ( A beta ) peptides , which are derived by proteolytic processing by the beta - site APP - cleaving enzyme 1 ( BACE1 ) of the amyloid precursor protein ( APP ) .