 Participants in this study will be screened with medical and psychiatric examinations, an electrocardiogram EKG, and blood and urine tests. This study comprises two parts. During Part 1, participants will undergo a whole-body PET scan. During Part 2, participants will undergo a magnetic resonance imaging MRI scan of the brain. At the next study visit, participants will have one or two PET head scans. If not is not possible to perform both scans on the same day, an additional visit will be scheduled for the second PET scan. 