Imaging Depression in Parkinson's Disease

Eligibility Criteria

• 1. Age 40-80.
• 2. Physically healthy by medical history, physical, ECG and laboratory examinations
• 3. For women of reproductive potential, a negative pregnancy test at screening and scanning
• 4. For PD patients, clinical diagnosis of PD, able to consent and tolerate PET procedures
• 5. For PD depression patients - at least moderate symptom severity as determined by a cut-off of 14 on the HAMD-17, which has shown maximum discrimination between depressed and non-depressed PD patients87.
• 1. Dementia (Montreal Cognitive Assessment (MoCA) score \<21)88
• 2. A significant primary DSM-5 psychiatric disorder except for MDD
• 3. A history of or current significant medical (e.g. cardiovascular, renal), or neurological (e.g. cerebrovascular, seizure, traumatic brain injury) illness other than PD that is unstable and significantly increase their risk and/or might affect the study objectives, as determined by study physicians.
• 4. Prior radiation exposure for research purposes within such that participation in this study would place them over FDA limits for annual radiation exposure
• 5. Medications affecting SV2A availability (e.g. levetiracetam)
• 6. For dPD patients receiving ketamine, blood pressure \>145/90.
• 7. Contraindications to MRI.
• 8. Iodine allergy
• 9. Bleeding disorder or thinning blood medication
• 10. Inability to provide written informed consent according to the Yale Human Investigation Committee (HIC) guidelines in English.