 This follow-up study is designed to obtain longitudinal clinical and MEG scan data to gain information on Alzheimers disease AD progression, the stability of healthy control HC MEG scan data, to enrich the Orasi database of AD and HC subjects, and is intended to extend the capabilities of the Synchronous Neural Interaction SNI test, which is under development by the sponsor, Orasi Medical. The current study is intended to extend the database of AD and HC MEG scans and will include patients who previously enrolled and completed Orasi Protocol ADG 08-01. This study will include MEG scans on up to approximately 50 AD subjects and 70 HC subjects. Additionally, AD subjects will complete 3 standard functional tests while HC subjects will complete 2 standard functional tests. ApoE genotyping also will be determined for all subjects. The results generated in this study will be used to improve the accuracy of the SNI test for diagnosing and tracking the progression of AD. 