Evaluation of 123-I Iodobenzovesamicol (IBVM) and SPECT Imaging of Healthy Subjects and Patients With Alzheimer Disease

Approximately 25 patients with mild to moderate Alzheimer's disease (AD) and 25 patients Parkinson's disease and 20 healthy controls will be recruited to participate in this study. AD patients will be eligible to participate if they have a diagnosis of AD based on NINCDS-ADRDA criteria. PD patients will be eligible to participate if they have a clinical diagnosis of Parkinson's disease. Healthy controls will be evaluated to ensure that there is no evidence of neurodegenerative changes including cognitive decline. All subjects will undergo written informed consent and a screening evaluation including baseline clinical laboratory testing, a physical and neurological evaluation and cognitive assessment. Subjects will be asked to undergo an injection of 123-I IBVM followed by up to three approximately thirty minute SPECT scans during the next 24 hours. Subjects may be asked to undergo a second imaging visit two-weeks to six months following the initial imaging visit to assess the reproducibility of the imaging outcome and/or the progressive change from baseline in 123-I IBVM binding. The imaging analyses will be performed by an image-processing specialist who will remain masked to clinical diagnosis. The primary imaging outcome measure will be the brain regional distribution volumes expressed as a target region to cerebellar ratio.