TAC1 and Alzheimer disease: For this purpose, blood samples of 33 German Holstein (GH) cows with AD, 36 healthy controls (GH), and 32 healthy German Fleckvieh (GF) cows were collected, and concentrations of substance P (SP), vasoactive intestinal polypeptide (VIP), and interleukin1β (IL-1β) were measured via commercially available ELISA kits.