The development of biological biomarkers reflecting neuropathology has enhanced the diagnostic precision of Alzheimer's disease over the past decade, compared to the clinical diagnosis that suffers from low specificity. Patients undergoing evaluation in specialized memory clinics suspected of major or minor neurocognitive disorder are notably examined through a lumbar puncture to measure beta-amyloid 42, beta-amyloid 40, total tau, and phosphorylated tau in the cerebrospinal fluid (CSF). The purpose of this clinico-biological collection is to better characterize the existing biomarkers used in clinical practice, as well as the development of new diagnostic or prognostic biomarkers for neurodegenerative diseases causing neurocognitive disorder (Alzheimer's disease, Lewy body disease, frontotemporal lobar degeneration, in particular).

The primary objective is to gain a better understanding of conventional biomarkers and to develop new diagnostic and prognostic biomarkers for neurocognitive diseases: establishing a prospective clinico-biological collection of patients evaluated in clinical practice for a neurocognitive disorder.

Inclusion Criteria:

• Adult patient
• Not under legal guardianship
• Clinical indication for blood and cerebrospinal fluid (CSF) biomarkers measurement during a day hospital stay for Alzheimer's disease (beta-amyloid peptide, tau protein).
• Signature of the research consent form.

Exclusion Criteria:

• Not affiliated with a social security scheme.
• Patient under State Medical Aid (AME).

Patients followed in the memory clinic at the Center for Cognitive Neurology of Lariboisière Hospital (APHP) or at the memory clinic of Bretonneau Hospital (APHP), with a clinical indication for the measurement of blood and cerebrospinal fluid (CSF) biomarkers (day hospital for the diagnosis of a neurocognitive disorder).