REN and Alzheimer disease: For the 3 pathways that presented only in the AD-HC group (Renin secretion, corrected p-value = 2.4 × 10−4; Apelin signaling pathway, corrected p-value = 3.29 × 10−4; Adrenergic signaling in cardiomyocytes, corrected p-value = 4.04 × 10−4) only in the AD-HC group, hypertension was associated with AD, and renin secretion was a pathway that regulated cerebral blood flow [60].