Diagnostic value of cerebro-spinal fluid biomarkers in dementia with lewy bodies.

Dementia with Lewy Bodies (DLB) is the second most common form of dementia after Alzheimer's disease (AD), accounting for 15% to 20% of neuropathologically defined cases. Two-thirds of the patients affected are not or misdiagnosed because of the clinical similarity of these two pathologies. In this review, we evaluate the discriminatory power of cerebrospinal fluid (CSF) biomarkers by focusing more specifically on differential diagnosis between DLB and AD. We focus on the AD biological biomarkers used in clinical routine as well as the biomarkers under study and more particularly the alpha-synuclein assay. Thus, among the AD biomarkers (t-Tau, phospho-Tau181, Aβ42 and Aβ40) used routinely, t-Tau and phospho-Tau181 have shown excellent discrimination whatever the clinical stages severity. Aβ42 level is pathological in DLB patients at the demented stage, but is almost not impacted at the prodromal stage. Alpha-synuclein assay in the CSF has also an interest in the discrimination between DLB and AD but not in segregation between DLB and healthy elderly subjects. Thus, globally the biological diagnosis on CSF basis makes it possible, to separate the DLBs from the ADs. In addition, the development of biomarkers such as phospho-alpha-synuclein and oligomeric alpha-synuclein should help to reinforce this discrimination power.