Distinguishing Between Alzheimer's Disease, Lewy Body Dementia, and Parkinson's Disease

The study will use structural and functional MRIs, daTscans, fluorodeoxyglucose (FDG) PET scans, Amyvid PET scans, polysomnographs, neuropsychological testing, cerebrospinal fluid in willing participants to distinguish between a diagnosis of Alzheimer's disease, Lewy Body dementia, and Parkinson's Disease. All subjects will have a clinical evaluation, physical examination including vital signs and orthostatic blood pressures and pulses, neurological examination including UPDRS evaluation, genetic blood sample collection, neuropsychological testing, polysomnogram, and neuroimaging. The study partner will also be interviewed for completion of all of the behavioral and functional measures.