Long-Term Dopamine Transporter Imaging and Clinical Assessment of Parkinson's Disease Progression

All subjects will be imaged at the Institute for Neurodegenerative Disorders. Subjects will be evaluated sequentially with \[123I\]ß-CIT SPECT and standardized clinical rating scales during a sixty month period. The subjects involved in this study will have had \[123I\]ß-CIT and SPECT scans at baseline and return for scanning at week 40 following the start of their participation in the ELLDOPA study. Before each SPECT procedure subjects will be tested to ensure eligibility for the study. They will also have a neurological evaluation including tests of motor function, thinking, memory and handwriting. Some of these tests will be given with the aid of a computer. On the first day participants are injected with \[123I\]ß-CIT, an investigational radioactive material that localizes in the brain. Study participants will also have a thorough neurologic examination and standard neuropsychological testing, including testing of memory, concentration, abstraction and visual spatial functions. Twenty-four hours later study participants return to the Institute for Neurodegenerative Disorders where an investigational scanning procedure will be used to obtain SPECT (single photon emission computed tomography) images of the brain.