To analyse CSF of patients with AD (n = 45), patients with DLB (n = 29) and control subjects without dementia (n = 36), we used immunoassays to measure levels of IL-6 (multiplex electrochemiluminescence); AD markers phosphorylated tau, total tau and amyloid-β1–42 (enzyme-linked immunosorbent assay [ELISA]); and α-synuclein (ELISA). This evidence concerns the gene MAPT and Alzheimer disease.