Study in Elderly Alzheimer's Patients to Assess Skin Tolerability, Irritation With 3, 7-Day Applications of DTP-System

Inclusion Criteria: * Male or female at least 65 years of age. * Established dose of Aricept 10 mg at least 2 months prior to enrollment. * Established diagnosis of stable Alzheimer's disease treated with oral Aricept * Must be willing to change from oral Aricept to DTP (and placebo patch). * Body mass index of at least 18 and a minimum weight of at least 45 kg. * Blood pressure (sitting) must be diastolic \<95mmHg, and systolic \<145, stable for at least 3 months. Patients with well-controlled hypertension (with medication) may enroll as long as 3-month stability criterion is met. * Those with stable cardiac disease may be enrolled provided the patient has been on appropriate medication for 3 months prior to screening. Those with a pacemaker may be enrolled. * Pulse rate between 45 - 100 bpm; respirations between 8 - 20 per minute. * Those with thyroid disease may enroll if stable on treatment for at least 3 months prior to screening, and maintain the same dose of thyroid medication throughout the study. * Must have a caregiver who is either living with the patient or is in daily contact with the patient, agrees to be present at all visits, provide information as required, and ensure compliance with the medication schedule. * Free from any abnormality at Screening which may compromise the patient's ability to participate. * Free of any dermatologic conditions, excessive hair or skin allergies and sensitivities. * Male patients who have female partners of childbearing potential must use a condom. * Must understand and provide written informed consent (or have a Legally Authorized Representative who is able), prior to the initiation of any protocol-specific procedures. * Must be willing and able to abide by all study requirements and restrictions. * Must be on stable medications for at least 30 days prior to enrollment into the study. Exclusion Criteria: * Use of systemic or topical antihistamines within 72 hours prior to enrollment, or systemic or topical corticosteroids within 3 weeks of study enrollment or foreseen use during the study. * History of allergy to Donepezil hydrochloride or to piperidine derivatives, related drugs, or any of the drug excipients or other drug product components. * Those with a recent (\< 2 years) cancer (except for non-melanoma skin cancers, females with in-situ cancer of the cervix or males with localized prostate cancer requiring no treatment). * Presence of history of a psychiatric disorder, or other seizure disorder deemed clinically significant. * Those with a known plan for elective surgery during the study period. * Those taking antidepressant medication. * Abnormality (e.g., scar, tattoo) or unhealthy skin (e.g., burns, wounds) at the application site; or an existing chronic skin disease or history of skin disease at the application site(s) within the 30 days prior to enrollment. * Treatment with any investigational drug within 30 days prior to enrollment in the study. * Any condition which would make the patient or caregiver, in the opinion of the investigator or designee, not suitable for the study for any reason. * Current or pending legal charges that may affect patient or caregiver compliance. * Treatment with medications contraindicated for use with Aricept