APLP1 and Alzheimer disease: The proteins active at the synaptic terminals were also at variance, being down-regulated in iNPH compared to C and upregulated in AD compared to C. The substrates of beta-secretase 1 (BACE1), amyloid precursor protein (APP), seizure 6-like protein (SEZ6L) and seizure-related 6 homolog-like 2 (SEZ6L2) were statistically lower in iNPH than in C. Conversely, in AD, APP and SEZ6L levels were statistically upregulated, as amyloid-like protein 1 (APLP1) and amyloid-like protein 2 (APLP2).