PON1 and Alzheimer disease: The research is primarily justified by three main sets of findings: (1) Serum PON1 has been widely found to be altered in neurodegenerative diseases, including AD, and this was attributed to the antioxidant capacity of the protein [16,18,36,37,38,39]; (2) both PON1 and PON3 protect LDL from oxidative modification, with the latter being more efficient in this biological activity [1,3]; (3) both PON1 and PON3 are altered in the brain of an AD mice model [27].