Background Differential diagnosis between dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD) is not straightforward, especially in the early stages of disease. We compared AD biomarkers (phospho-Tau181, total-Tau, Aβ42 and Aβ40) in cerebrospinal fluid (CSF) of patients with DLB and AD, focusing especially on the prodromal stage.
Methods A total of 1221 CSF were collected in different memory centres (ePLM network) in France and analysed retrospectively. Samples were obtained from patients with prodromal DLB (pro-DLB; n=57), DLB dementia (DLB-d; n=154), prodromal AD (pro-AD; n=132) and AD dementia (n=783), and control subjects (CS; n=95). These centres use the same diagnostic procedure and criteria to evaluate the patients.
Results In patients with pro-DLB, CSF Aβ42 levels appeared much less disrupted than in patients at the demented stage (DLB-d) (P<0.05 CS>pro-DLB; P<0.001 CS>DLB-d). On average, Aβ40 levels in patients with DLB (pro-DLB and DLB-d) were much below those in patients with pro-AD (P<0.001 DLB groups<pro-AD). The Aβ42/Aβ40 ratio in patients with pro-DLB remained close to that of CS. t-Tau and phospho-Tau181 levels were unaltered in patients with DLB (pro-DLB and DLB-d).
Conclusions Reduced levels of CSF Aβ42 were found in patients with DLB but rather at a later stage, reaching those of patients with AD, in whom Aβ42 levels were decreased even at the prodromal stage. At the prodromal stage of DLB, the majority of patients presented a normal CSF profile. CSF t-Tau and phospho-Tau181 were the best biomarkers to discriminate between AD and DLB, whatever the stage of disease.
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Contributors OB and FB: study concept, design and supervision; FB, NP and PA: selection of patients from Strasbourg; OB and TL: analysis and interpretation of all data. SB: selection of patients from Lille; SS and XD: analysis of CSF assays of patients from Lille; DW: selection of patients from Rouen; MMQ: analysis of CSF assays of patients from Rouen; AG: selection of patients from Montpellier; SL: analysis of CSF assays on patients from Montpellier; CP: selection of patients from Paris; EA-B: analysis of CSF assays of patients from Paris; EM: selection of patients from Besançon; CM-A: analysis of CSF assays of patients from Besançon.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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