By using autopsy-confirmed cases, we revealed that CSF levels of HVA and 5-HIAA are significant for clinically excluding LB pathology, and that the combination of CSF levels of HVA, 5-HIAA, and brain-specific proteins t-tau, p-tau, and Aβ 1–42 is a strong tool for distinguishing among DLB, DLB with AD, and AD with high diagnostic accuracy. This evidence concerns the gene MAPT and Lewy body dementia.