The levels of neuropathological biomarkers of AD, including Aβ1–42, P-tau (T181), P-tau (S199), P-tau (T231), P-tau (S396), and T-tau, and BBB factors, including MMP-2, MMP-3, MMP-9, RAGE, GFAP, and LRP1 in cerebrospinal fluid (CSF) from patients with AD were measured by enzyme-linked immunosorbent assay (ELISA). The gene discussed is MMP9; the disease is Alzheimer disease.