Three proteins: NEFL, Aβ38 and CCL2, were associated with the four diseases, and 10 proteins (ANXA5, Aβ40, Aβ42, GOT1, NPY, PRDX6, p-tau217, p-tau231, TEK, VEGFD) were associated with DLB, PD and AD. The gene discussed is PRDX6; the disease is Alzheimer disease.