Each evaluable subject involved in this study must fulfill all the inclusion and exclusion criteria according the subject grouping, healthy subjects, PD, PDD, and AD patients will have 4 visits in this study ,as one screening visit, one florbetapir F-18 imaging visit, one 18F-DTBZ imaging visit, and one safety evaluation.PDI patients will have 3 visits in this study, as one screening visit, one 18F-DTBZ imaging visit, and one safety evaluation. Safety measurement will be evaluated by medical history, vital signs, physical examinations, laboratory examinations and collecting of adverse events.