Longitudinal Imaging of Microglial Activation in Different Clinical Variants of 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. The purpose of this study is to determine if 11C-ER176 is able to accurately measure inflammation in patients with Alzheimer's disease. 11C-ER176 will be administered at activity up to 20 millicurie (mCi) per injection.

MK-6240 measures a protein called in the brain. MK-6240 is experimental but has been used in several human studies before and has been proven to accurately measure tau in the brain.

Florbetaben has been approved by the FDA to help diagnose Alzheimer's disease. florbetaben measures amyloid in the brain.

Inflammation can also be measured by looking at certain proteins in the spinal fluid. In order to measure these proteins in the spinal fluid, the investigators will perform a lumbar puncture (spinal tap).