Effect of Stimulus Rate on Cognitive and Motor Activity in Young Subjects, Elderly Subjects, and Patients With Parkinson's Disease

INCLUSION CRITERIA: Imaging methods (e.g., structural MRI) may be included as a part of the pre-study evaluation. PD patients should be at a relatively early stage of the disease and must be devoid of any other neuropsychiatric symptoms, especially dementia. To assure this, they are to be rated by UPDRS (motor sub-scale) and standard neuropsychological batteries (e.g., mini-mental test). Thirty PD patients with age 40 and higher will be recruited. Patients may be male or female. Patients will be asked to withhold any medication that can influence central nervous system (e.g. levodopa) at least 8 hours prior to the examination. They will also asked to abstain from alcohol for 24 hours before the study. Sixty normal volunteers ranging from 21-75 will be included. Normal volunteers will be recruited from people who are registered as HMCS Normal Volunteers. Patients would be referred from the HMCS Clinic. All subjects participating in MR studies should have a valid Clinical Center Medical Record Number. Procedures for the fMRI experiment will follow the Standard Operating Procedures of the HMCS Neuroimaging group. EXCLUSION CRITERIA: PD patients younger than 40 years will be excluded from the study since they are considered to be young-onset PD and have slightly different characteristics from typical idiopathic PD. Normal subjects younger than 21 years old will also be excluded. Patients with MRI findings consistent with organic brain lesions such as brain tumors, stroke, trauma or AVM's will be excluded. Patients with progressive neurological disorders other than PD will be excluded. Patients with a history of significant medical disorders such as cancers, or requiring continuous treatment with drugs other than antiparkinsonian medication, will be excluded. Subjects who have any contraindications to MRI will be excluded from the fMRI part of the study. We will not scan pregnant women because safety of high magnetic field to fetus is not established. Therefore, we will administer a urine pregnancy test for any female subjects of childbearing potential prior to functional MRI scan. Patients not capable of giving informed consent will be excluded.