Tobias M, Yeh LC, Johnson E. Burden of Alzheimer's disease: population-based estimates and projections for New Zealand, 2006-2031. Aust N Z J Psychiatry. 2008 Sep;42(9):828-36.

OBJECTIVE: To estimate the burden of Alzheimer's disease (AD, including 'mixed' dementia) in New Zealand in 2006, and project this burden out to 2031. METHOD: An incidence to prevalence methodology was utilized, the foundation of which is a discrete time Markov model allowing for multiple stages of disease (early vs late). Population estimates and projections, and all-cause mortality rates, were obtained from Statistics New Zealand. In the absence of usable New Zealand data, data on disease incidence and progression were obtained from systematic reviews of the international (mainly European, Australian and North American) literature. Projection scenarios included a demographic scenario in which change resulted only from increases in population size and ageing; a prevention scenario in which incidence rates were reduced by 25% from 2011; a treatment scenario in which disease progression rates were likewise reduced by 25% from 2011; and a combined scenario capturing both interventions. RESULTS: The model estimated that approximately 28000 people are currently living with AD (whether formally diagnosed or not), approximately 55% in the early and 45% in the late stage of the disease; approximately 6600 people newly develop AD each year; and approximately 2300 people die from (as opposed to with) this condition. The model projected that the prevalence of AD will increase approximately 2.5-fold (to approx. 70,000 people) by 2031, if demographic drivers are unopposed. Plausible improvements in prevention and treatment, however, acting together, could reduce this growth by up to 50%, so that the prevalence of AD only doubles. CONCLUSION: Even this more optimistic projection has profound implications for the funding and provision of dementia care services, as well as for patients, their families, informal carers and the psychogeriatric workforce. New service configurations and models of care will be necessary. Access, quality and coordination standards for home care, day care, respite care, residential care and specialist services (including memory clinics) will need to respond accordingly.

Campbell AJ, McCosh LM, Reinken J, Allan BC. Dementia in old age and the need for services. Age Ageing. 1983 Feb;12(1):11-6.

A randomly selected sample of subjects aged 65 years and over was investigated to determine the prevalence of dementia. The sample, which was stratified by age, consisted of 559 subjects living in the community and institutions. It was estimated that 7.7% of those aged 65 years and over suffered from dementia. The disorder affected both sexes equally. There was a marked increase in the prevalence with age so that in those 80 years and over the prevalence rate of dementia was found to be 19%. Those suffering from dementia were significantly more likely to be receiving institutional care than those with normal intellectual function. Those with dementia used significantly more domiciliary services than did those with normal mental function and were more likely to require additional services not already provided. There was a particular need for district nursing supervision, day care and relief admissions. The high prevalence rate of dementia in the elderly, and the high use those suffering from the disorder make of both domiciliary and institutional services, should be appreciated in the planning of services for the elderly.

Foster RH, Plosker GL. Donepezil. Pharmacoeconomic implications of therapy. Pharmacoeconomics. 1999 Jul;16(1):99-114.

Donepezil is a specific acetylcholinesterase inhibitor that can improve symptoms in patients with mild-to-moderate Alzheimer's disease; cognitive function is maintained above baseline levels for up to 1 year and normal decline of cognitive function is slowed. The ability of the patient to perform daily activities and neuropsychiatric symptoms may also be improved by donepezil, but data are limited. Donepezil is not expected to alter the underlying neurodegenerative process, and the response to the drug varies between individuals. In the absence of validated instruments to measure quality of life, it is not clear how donepezil affects this parameter. In a US survey of caregivers of patients with Alzheimer's disease who were being cared for at home at the start of the 6-month study period, treatment with donepezil did not increase overall direct medical costs. The acquisition cost of the drug was balanced by reduced institutionalisation costs. Economic analyses using Markov models from the US, UK and Canada suggest that donepezil initiated in the early stages of disease may be effectively cost neutral as a result of patients remaining in a nonsevere state of disease for a longer time.