CSF diagnosis of Alzheimer's disease and dementia with Lewy bodies.

Differential diagnosis of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) is often crucial. CSF Tau protein and Amyloid-beta (A beta) peptides have shown diagnostic value for the diagnosis of AD, but discrimination from DLB was poor.Herein, we investigate CSF of 18 patients with probable AD, 25 with probable DLB and 14 non-demented disease controls (NDC) by A beta-SDS-PAGE/immunoblot and commercially available ELISAs for A beta1-42 and tau. CSF A beta peptide patterns and tau exhibited disease specific alterations among AD and DLB. The ratio of A beta1-42 to A beta1-38 and A beta1-42 to A beta1-37, respectively, in combination with absolute tau, yielded a sensitivity and specificity of 100 and 92%, respectively. We conclude that CSF A beta peptide patterns and tau levels reflect disease-specific pathophysiological pathways of these dementias as distinct neurochemical phenotypes. Combined evaluation of these biomarkers provides a reasonable accuracy for differential diagnosis of AD and DLB.