A large part of early cognitive decline appears to occur within the hippocampal and prefrontal cortex areas (174, 175), and may involve: (1) the acute activation of the phagocyte NADPH oxidase (PHOX) found in microglia, (2) expression of the inducible nitric oxide synthase (iNOS) in glia, and (3) microglial phagocytosis of neurons (176). The gene discussed is NOS2; the disease is Mental deterioration.