Taking the APP gene-118C/A site CC allele as a reference, the CA and AA genotypes were protective factors for AD (adjusted OR = 0.781, 95% CI: 0.638–0.941, P=0.007; adjusted OR = 0.600, 95% CI: 0.308–0.989, P=0.043), the risk of AD decreased in the dominant model (adjusted OR = 0.757, 95% CI: 0.624–0.906, P=0.002), and there was no risk of AD in the recessive model (adjusted OR = 0.634, 95% CI: 0.326–1.004, P=0.083). Here, APP is linked to Alzheimer disease.