Imaging Inflammation in Alzheimer's Disease With 11C-ER176

Inflammation likely plays a role in the damage to the brain caused by Alzheimer's disease. Accurately measuring inflammation in the brain could provide new information about the mechanisms that cause Alzheimer's disease, and could help identify new treatments that reduce inflammation. Positron emission tomography (PET) imaging is a type of brain scanning method that allows investigators to measure small molecules in the brain. ER176-PET was recently developed as an improved method for measuring brain inflammation. However, ER176-PET has not yet been used in patients with Alzheimer's disease. The investigators propose to use ER176-PET imaging in subjects with mild cognitive impairment (a very early stage of Alzheimer's disease) or mild Alzheimer's disease to compare the amount of inflammation with that seen in older control subjects. The investigators will first use a "gold standard" method of measuring ER176 in brain that requires sampling arterial blood during the scan. The investigators will compare these results to those obtained using novel methods that don't require blood sampling. The investigators hope to show that ER176 is a useful tool for measuring inflammation in Alzheimer's disease, and that the investigators can develop a way to obtain ER176 PET scans that don't require arterial blood sampling. This study uses a special type of scan called a PET scan to take pictures of the brain. During the PET scan, a special dye is injected into the body. Two types of dye will be used in this study: Florbetaben and 11C-ER176. Florbetaben sticks to amyloid plaques, which are in the brain in Alzheimer's disease. Florbetaben has been approved by the Food and Drug Administration to help diagnose Alzheimer's disease. 11C-ER176 sticks to parts of the brain where there is inflammation. Past studies have shown that inflammation is present in the brains of patients with Alzheimer's disease.