NOS3 and Alzheimer disease: eNOS deficiency was described as the principal factor contributing to neurodegenerative processes, including AD, predominantly by facilitating the cerebral accumulation of amyloid-β peptides (Aβ) and the microtubule-associated protein tau, leading to the formation of extracellular amyloid plaques and intracellular neurofibrillary tangles [55,56].