Alzheimer Gut Microbiome Project Note: An Official Proposal has not been Submitted to NACC. Lead Investigator: Rima Kaddurah-Daouk Institution : Duke University E-Mail : rima.kaddurahdaouk@duke.edu Proposal ID : 1788 Proposal Description: Aim 1: Define compositional and functional changes in gut microbiome across AD stages of disease. Aim 2. Define metabolome differences in blood and feces related to gut microbiome differences and link to cognitive and brain imaging differences. We are collecting fecal and blood samples in collaboration with eight Alzheimer's Disease Research Centers across the US. Data will be used to inform the analysis of data generated by our consortium.