Additional Study Information: The purpose of this study is to test whether an investigational drug called solanezumab can slow the progression of memory problems associated with brain amyloid. The study will also test 1) whether the anti-amyloid treatment can slow evidence of AD-related brain injury on imaging tests to look at brain structure and function and 2) the effect of solanezumab on cerebrospinal fluid (CSF) biomarkers and blood biomarkers. Solanezumab is an investigational drug which means that it has not been approved for routine clinical use or for the use described in this study by the U.S. Food and Drug Administration (FDA).