GSK3B and Alzheimer disease: To date, several key targets regulating the generation and deterioration of AD have been discovered, such as acetylcholinesterase (AChE), monoamine oxidase B (MAO-B), glycogen synthase kinase 3β (GSK-3β), brain metal ions, phosphodiesterases (PDEs), and the N-methyl-D-aspartate (NMDA) receptor [14,15,16].