- Subjects currently receiving cholinesterase inhibitors or who have received them in the 3 months prior to screening or with prior use >3 months prior to screening who stopped for lack of efficacy or tolerability or simply to enroll the subject in this study. Also excluded are subjects who participated in the Phase II study E2020-A001-219 (A2501059). In addition, subjects may not have taken any other investigational medications (including memantine) within 3 months prior to screening.