SYN1 and Alzheimer disease: Therefore, in the present study, we have evaluated genetic polymorphisms of the genes BDNF, CREB1, NTRK2, NGFR, ARC, AKT, GSK3B, MAPK1, MTOR, PTEN, and SYN1 involved in several neurotrophic/neuroplasticity pathways with relevance to the mechanism of action of AD.