• SIB, MMSE, ADCS-ADL, QoL-AD and EQ-5D (quality of life), TOS (treatment outcomes), GAtS [ Time Frame: Every 3 months (+/- 5 days). ] [ Designated as safety issue: Yes ]
  

• Vital signs, weight, complete physical examination, basic neurological examination. [ Time Frame: Every 3 months (+/- 5 days). ] [ Designated as safety issue: Yes ]
  

Inclusion Criteria:

1. Written informed consent will be obtained from the patient (if possible) or from the patient's legal guardian or other representative at the time of the Baseline visit, prior to beginning any assessments or activities. Even if unable to provide written informed consent, the patient must assent verbally to participating in the study and the record should note this assent.
2. Age range: Adult patients, 45 to 91 years of age inclusive.

3. Completion of study E2020-G000-326 with no ongoing SAEs or history of serious adverse drug reactions during this study in its entirety.

   Patients must enroll in the present study within 7 days of completion of study E2020-G000-326.

4. Health: physically healthy and ambulatory or ambulatory-aided (ie, walker or cane); corrected vision and hearing sufficient for compliance with testing procedures.
5. Clinical laboratory values must be within normal limits or, if abnormal, must be judged not clinically significant by the investigator.
6. Patients with risk factors of hypertension and cardiac disease may be enrolled in the study, provided that hypertension is medication controlled (supine diastolic BP < 95 mm Hg) and cardiac disease (eg, angina pectoris, congestive heart failure, right bundle branch block, or arrhythmias) is stable on appropriate medication for 3 months prior to Baseline. Peripheral vascular disease must also have been stable for 3 months prior to Baseline.
7. Patients with diabetes mellitus or risk factors for diabetes mellitus may be enrolled in the study provided that the patient's disease is stable and that there have been no recent (within 3 months) hospitalizations for diabetic ketoacidosis, hyperosmolar coma, or hypoglycemia. Patients with non-insulin-dependent diabetes may enroll in the study if controlled on diet or oral medications.
8. All diabetic patients must have an HbA1c concentration of < 10% and a fasting (8 hours) serum glucose concentration of < 170 mg/dL, or a random serum glucose concentration of < 250 mg/dL at Baseline.
9. Patients undergoing treatment with selective serotonin re-uptake inhibitors (SSRI) (≤ 10 mg daily of escitalopram, ≤ 20 mg daily of citalopram or fluoxetine, ≤ 30 mg daily of paroxetine, < 50 mg daily of sertraline or ≤ 100 mg daily of fluvoxamine) may enter the study provided that the SSRI dose has been stable for at least three months prior to Baseline.

Inclusion Criteria for Caregivers:

Written informed consent will be obtained from the designated caregiver for participation in study assessments. The caregiver must be sufficiently familiar with the patient (as determined by the investigator) to provide accurate data. Specifically, the caregiver must have sufficient contact with the patient to provide accurate reports of the patient's functioning, must be able to observe for possible adverse events, and must be able to accompany the patient to all visits. It is preferable that the caregiver be the same as in study E2020-G000-326. If no replacement caregiver is available who meets the caregiver inclusion/exclusion criteria, the patient must be discontinued from the study

Exclusion Criteria:

1. No caregiver available to meet the inclusion criteria for caregivers
2. Patients with psychiatric disorders affecting the ability to assess cognition such as schizophrenia, bipolar or unipolar depression. Patients with clinically-significant sleep disorders will also be excluded unless these are controlled by treatment and clinically stable for > 3 months.
3. Patients with dementia complicated by other organic disease or Alzheimer's disease with delirium (DSM IV 290.30 or 290.11; Appendix 5)
4. Patients with any active or clinically-significant conditions affecting absorption, distribution, or metabolism of the study medication (eg, inflammatory bowel disease, gastric or duodenal ulcers, hepatic disease, or severe lactose intolerance)
5. Patients with evidence of clinically significant, active gastrointestinal, renal, hepatic, respiratory, endocrine, or cardiovascular system disease
6. Patients with current evidence of malignant neoplasms (does not include basal or squamous cell carcinoma of the skin). Males with localized prostate cancer requiring no treatment would not be excluded.
7. Known plan for elective surgery during the study period that would require general anesthesia and administration of neuromuscular blocking agents, such as succinylcholine, to induce paralysis/muscle relaxation. Minor surgery, such as colonoscopy or cataract surgery, will be permitted as long as it does not require the use of these paralytic agents.
8. Patients who are unwilling or unable to fulfill the requirements of the study
9. Use of any prohibited prior or concomitant medications
10. Any condition that would make the patient, in the opinion of the investigator, unsuitable for the study
11. Patients taking concomitant antidepressant medication known to have significant anticholinergic effects, such as tricyclic antidepressants prescribed at doses recommended for the treatment of major depression.
12. Patients who cannot swallow or who have difficult swallowing whole tablets

Exclusion Criteria for Caregivers:

1. Caregivers who are unwilling or unable to give informed consent or otherwise to fulfill the requirements of the study
2. Any condition that would make the caregiver, in the opinion of the Investigator, unsuitable for the study