Memory medication study: Alzheimer's Drug Duration - Impact on Functionality

INTERVENTION: Continuation arm: Cholinesterase inhibitor used until randomisation will be continued as prescribed by patients' physician according to the following titration pattern. Donepezil at a starting dose of 5 mg daily (2.5 mg if frail) for 4 to 6 weeks, increased by 5 mg as tolerated with an effective range of 5 to 10 mg daily, galantamine at a starting dose of 8 mg ER daily for 4 to 6 weeks, increased by 8 mg as tolerated with an effective range of 16 to 24 mg daily or rivastigmine at a starting dose of 1.5 mg daily for 2 to 4 weeks, increased by 1.5 to 3 mg as tolerated with an effective range of 6 to 12 mg daily. Treatment will be continued from 5 months to 24 months after randomisation. Switching arm: Cholinesterase inhibitor currently used until randomisation will be discontinued and patient will be started on one of the other two according to each physician's practice and experience, within the following guidelines: a washout period of 2 days for galantamine and rivastigmine and 5 to 7 days for donepezil; start of a new cholinersterase inhibitor using the same titration pattern as for new starts (see above). Withdrawal arm: Cholinesterase inhibitor currently used until randomisation will be discontinued and special authority request forms (where the outcome measures of MMSE and OPAR are reported) will continue to be recorded to facilitate restarts if there is a noticeable decline in cognition/function within 7 to 10 days of stopping. Patients will be called one week after discontinuation to detect sudden deterioration. All patients in this arm will be re‐examined by their physician at one month after withdrawal. As of 12/10/2009 this record has been updated due to major problems with physician recruitment. The randomised allocation in this trial has been temporarily eliminated and physicians and patients are only being recruited for a prospective cohort study. This will be a run‐in phase to assess the feasibility of recruitment without randomised allocation, CONDITION: Alzheimer?s Disease ; Nervous System Diseases ; Alzheimer's disease PRIMARY OUTCOME: Physicians assessment of cognitive status and global assessment rating, measured at 6 months, 12 months, 18 months, 24 months.; SECONDARY OUTCOME: 1. Assessment of patients' cognitive status using Telephone Interview of Cognitive Status; 2. Differences in caregiver assessments of the medications effectiveness; 3. Incidence rates of health services use and use of other drugs using Ministry of Health Services central administrative databases; 4. Net cost of health services using Ministry of Health Services central administrative databases and private expenses reported by caregivers in telephone interviews; ; Measured at 6 months, 12 months, 18 months, 24 months. INCLUSION CRITERIA: 1. Policy criteria: The patient is approved at least once for insurance coverage of ChEIs by British Columbia PharmaCare (the publicly financed drug benefit plan), meaning: 1.1. They are residents of British Columbia eligible for PharmaCare coverage 1.2. They are not in a hospital or long‐term care institution (because drugs of such patients are mostly covered by the Health Authorities) 1.3. A physician has reported on a Special‐Authority Request (insurance coverage application) form that the patient has a diagnosis involving Alzheimer's disease, and the severity of dementia was mild‐to‐moderate (scoring greater than 10 but less than 26 on the Standardised Mini‐Mental Status Examination [SMMSE]) when they were first covered by PharmaCare 2. Clinical criteria: At enrolment: 2.1. The patient has taken ChEIs for no longer than 12 months and has not used them for at least 12 months prior to that 12 months 2.2. The patient has tolerated Ch