Diagnostic Performance of Plasma Biomarkers of Alzheimer's Disease Compared With CSF Markers
.The goal of this interventional study is to estimate the diagnostic performance of plasma biomarkers of interest (Aβ40 and Aβ42, P-Tau and NFL), enabling discrimination between patients with and without a pathophysiological AD process. The main questions it aims to answer are:

to define a threshold value for each of the plasma,
to describe the correlations between the plasma biomarkers of interest and the other biological analyses performed as part of care, in particular triglyceridemia, cholesterolemia, glycemia and proteinemia,
to describe biomarker results in relation to comorbidities, in particular dyslipidemia and diabetes
to describe the final diagnosis and results obtained for plasma biomarkers, for patients with intermediate results according to the A/T/N classification (A-/T+ or A+/T-) Participants will be selected among patients undergoing lumbar puncture for the differential diagnosis of AD at Nancy University Hospital.
- EligibilityCriteria: Inclusion Criteria:  Man or woman aged 18 or over Person affiliated to a social security scheme or beneficiary of such a scheme Person who has received full information on the organization of the research and has signed an informed consent form Person whose care requires a lumbar puncture to measure markers of Alzheimer's disease  Exclusion Criteria:  Adult subject to a legal protection measure (guardianship, curatorship, safeguard of justice) An adult unable to give consent Persons deprived of their liberty by judicial or administrative decision Persons under psychiatric care under articles L. 3212-1 and L. 3213-1. Pregnant, parturient or breast-feeding women Persons staying in a health or social establishment for purposes other than research. - HealthyVolunteers: No - Gender: All - MinimumAge: 18 Years - StdAgeList: Adult, Older Adult