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

Exclusion Criteria

• •Any other condition (other than the primary diagnosis), which in the opinion of the investigators might contribute to the syndrome of dementia or complicate its assessment.
• •active medical disorder that could preclude participation in this protocol
• •Women who are pregnant or are breast feeding
• •severe renal impairment as defined by glomerular filtration rate (GFR) less than 30 (may have increased radiation exposure with the DaTscan).
• •Subjects in whom English is not the 1st language
• •Subjects with educational level less than 12 years
• •Subjects who have ever participated in an experimental study with an amyloid targeting agent unless it can be documented that the subject received only placebo during the course of the trial.