 Expanded Access Extension: This is an open label 10 visit extension for up to 5 subjects who have completed the T3D959-201 protocol and whose caregivers and physician requested their continued treatment in an expanded access protocol. All subjects enrolled in this study will be treated with a 15mg q.d. dose of T3D959 for six months, regardless of their assigned dose level from the main study. A continued riskbenefit assessment by the investigator will be conducted at each visit to determine the need for treatment continuation. Subjects will be assessed for safety and tolerability to T3D-959 and evaluated for changes from baseline cognitive function via ADAS-Cog11 and DSST testing and global change via CIBIC-plus testing. 