Several downregulated genes, such as APP, MAPT, SNCA, VDAC1, BDNF, SNAP25, GAPDH, and SYT1 were implicated in AD-related pathological processes, including amyloid plaques, tau tangles, mitochondrial dysfunction, synaptic abnormalities, and impaired protein degradation. This evidence concerns the gene GAPDH and Alzheimer disease.