CEREBROSPINAL FLUID (CSF) AND BLOOD SAMPLING AND ANALYZES Lumbar CSF samples will be collected according to a standardized protocol and will follow the principles of the Alzheimer's Association Flow Chart for CSF biomarkers. In short, lumbar puncture will be done between 9-12 am. 20-30 ml of CSF will be collected in Low Binding polypropylene tubes, which are stored on ice for 5-20 min until the CSF samples will be centrifuged (2000g, +4°C, 10 min). Thereafter, the CSF will be aliquoted in ca 1 ml portions into Low Binding polypropylene tubes followed by storage at -80°C until batch analyses.