Exploratory Open Label Study for Development of a Method To Detect Dendritic Cells

Inclusion Criteria: All Healthy Subjects: * Subjects are determined by the investigator to be medically stable and expected to complete the trial as designed. * Subjects have adequate hearing, vision, and language skills to perform neuropsychiatric testing and interviews as specified in the protocol. * Subjects are able to understand and agree to comply with the study procedures and report for scheduled office visits. * Subjects are able to reliably communicate with study personnel about adverse events (AEs) and concomitant medications. * Signed written informed consent according to institutional guidelines. * Healthy Adult subjects: Male or female and between the ages of 21 to 55 inclusive. * Healthy Elderly subjects: Male or female and between the ages of 65 to 90 inclusive MMSE score between 15 and 26. * Alzheimer's Subjects: Male or female and between the ages of 50 to 90 inclusive. Patients satisfying the criteria for the clinical diagnosis of probable AD based on National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) . OR 6 months documented cognitive decline by physician OR Amyloid or Tau pathology confirmed by PET scan with ligand. MMSE score between 16 and 25 and Modified Hachinski Ischemia Scale (MHIS) score of ≤ 4. Exclusion Criteria: Sex and Reproductive Status: * Women who test positive for pregnancy. * Pre-menopausal women who are not practicing two methods of bi…