Research Involving Subjects With Parkinson's Disease, Alzheimer Disease and Healthy Controls

PD subject inclusion criteria: * The participant is 30 years or older. * Written informed consent is obtained. * Participants have a diagnosis of PD (based on UK Brain Bank Criteria). * Modified Hoehn and Yahr stage of 1 - 4. * For females, non-child bearing potential or a negative urine or blood pregnancy test on day of \[18F\] CFPyPB injection. PD subject exclusion criteria: * The subject has a clinically significant abnormal laboratory value and/or clinically significant unstable medical or psychiatric illness. * The subject has any disorder that may interfere with drug absorption, distribution, metabolism, or excretion. * The subject has evidence of clinically significant gastrointestinal, cardiovascular, hepatic, renal, hematological, neoplastic, endocrine, neurological, immunodeficiency, pulmonary, or other disorder or disease. * The subject has any contraindication to MRI examination, e.g. metal implants or phobia as determined by the onsite radiologist performing the scan. * The subject is a pregnant or nursing mother AD subject inclusion criteria: * The participant is 50 years or older. * Written informed consent is obtained. * Participants have a clinical diagnosis of probable Alzheimer disease in accordance with the DSM-IV-TR and according to (NINCDS/ADRDA) criteria. * Participants do not fulfill the ICC criteria for probable DLB, the NINDS-AIREN for probable vascular dementia, or the Neary \[Neary, et al. 1998\] criteria for FTD. * Clinical Dementia Rating Scale score 0.5, 1 or 2. * Modified Hachinski Ischemia Scale score of ≤ 4. * Geriatric Depression Scale (GDS) ≤ 10. * For females, non-child bearing potential or a negative urine or blood pregnancy test on day of \[18F\] CFPyPB injection. AD subject exclusion criteria: * The subject has a clinically significant abnormal laboratory value and/or clinically significant unstable medical or psychiatric illness * The subject has any disorder that may interfere with drug absorption, distribution, metabolism, or excretion. * The subject has evidence of clinically significant gastrointestinal, cardiovascular, hepatic, renal, hematological, neoplastic, endocrine, neurological, immunodeficiency, pulmonary, or other disorder or disease. * The subject has any contraindication to MRI examination, e.g. metal implants or phobia as determined by the onsite radiologist performing the scan. * The subject is a pregnant or nursing mother. Healthy volunteer inclusion criteria: * The participant is 18 years or older. * Written informed consent is obtained. * Negative history of neurological or psychiatric illness based on evaluation by a research physician. * For females, non-child bearing potential a negative urine or blood pregnancy test on day of \[18F\] CFPyPB injection. Healthy volunteer exclusion criteria: * The subject has a clinically significant abnormal laboratory value and/or clinically significant unstable medical or psychiatric illness. * The subject has evidence of clinically significant gastrointestinal, cardiovascular, hepatic, renal, hematological, neoplastic, endocrine, neurological, immunodeficiency, pulmonary, or other disorder or disease. * The subject has any disorder that may interfere with drug absorption, distribution, metabolism, or excretion. * The subject has any contraindication to MRI examination, e.g. metal implants or phobia as determined by the onsite radiologist performing the scan. * The subject is a pregnant or nursing mother.