All procedures will be performed on a single visit. The subjects will undergo a Mini-Mental Status Examination (MMSE) performed by a qualified examiner. In addition, a blood sample will be obtained for measurements of basic blood chemistry (electrolytes, creatinine, glucose, total protein, and albumin), hematology, thyroid function, metabolic function (e.g. fasting plasma glucose and insulin levels) and for proteomic analysis. The APOE genotype will be determined from the blood samples, if it has not been assessed earlier. A lumbar puncture will be performed to obtain CSF samples that will be used to determine concentrations of biomarkers of AD pathology and to find out new biomarkers that may reflect AD pathology.