A Long-term, Extension Study of E2020 in Patients With Dementia With Lewy Bodies

Inclusion criteria: 1. Patients diagnosed as probable Dementia with Lewy Bodies (DLB) according to the diagnostic criteria for DLB. 2. Patients who have completed Phase II double-blind study (E2020-J081-431). 3. Patients having caregivers who submit written consent for cooperative involvement in this study, can routinely stay with patients 3 days a week (at least 4 hours a day), provide patients' information necessary for this study, assist treatment compliance and escort their patients on required visits to study institution. Exclusion criteria: 1. Patients with a complication of serious neuropsychiatric disease(s) such as stroke, brain tumor, schizophrenia, epilepsy, normal pressure hydrocephalus, mental retardation, brain trauma with unconsciousness, and/or who underwent brain surgery causing unsolved deficiency. 2. Patients with severe complication of cardiovascular, hepatic, renal, hematological, or other diseases unable to secure the safety. 3. Pregnant or lactating women, or women who are willing to become pregnant no later than 1 month after the scheduled study completion. 4. Patients with severe extrapyramidal disorders (Hoehn and Yahr staging score is greater than IV). 5. Patients whose systolic blood pressure is less than 90 mmHg or pulse rate is less than 50 beats/min.