Performance of Part I of the study has been completed (15 subjects received a single administration of Aftobetin HCL followed by Sapphire II measurements) and indicated that 3 administrations of Aftobetin-HCl are necessary. For Part II, a second group of up to 30 subjects (CN =10 and mild AD or MCI =20) will receive three Aftobetin HCL administrations. If three administrations of Aftobetin HCL are optimal, up to an additional 30 MCI and 30 mild AD subjects will be entered.