Les biomarqueurs du LCR et du plasma : utilisation diagnostique et pronostique dans la maladie d'Alzheimer et les syndromes apparentés

Over the last 10 years, there has been a paradigmal shift in the diagnostic field of Alzheimer's disease (AD). Scientific thought has enriched the concept of the pathophysiological continuum of the disease and pointed out the contribution of biomarkers for in vivo diagnosis, specifically during the early stages of the disease. The use of these biomarkers has enabled us to move from a clinic-pathological entity to a clinic-biological entity. Among the three types of biomarkers - biological, morphological and functional brain imaging - CSF biomarkers have the main advantage to reflect the two pathophysiological lesions of the Alzheimer process in a unique in vivo investigation. The relevance of CSF biomarkers is well validated in research but the evaluation of their interest and diagnostic accuracy in routine clinical practice in Memory centers is just beginning. We describe the characteristics of CSF biomarkers and their contributions in terms of positive and differential diagnosis of AD, but also during the early stages of the disease. The PLM study (CMRRs Paris-Nord, Lille and Montpellier), combining data from over 1200 patients included in the three CMRRs bio-banks, will be presented. It allows us to put forward answers about the relevance of using three CSF biomarkers in Memory consultation, but also to propose a consensus for procedures harmonization to reduce the impact of pre-analytical factors. Finally, to overcome the constraints of lumbar puncture, much research focuses on the use of plasma biomarkers. We describe their usefulness and limitations. A specific point will be developed regarding their impact as a prognostic factor for cognitive decline.