Published online by Cambridge University Press: 19 May 2010
Dementia is characterized by memory and learning impairment as well as deficits in at least one other cognitive domain. These include: impairment in communication (aphasia); impairment in recognition and manipulation of objects (agnosia and apraxia); impairment in reasoning ability; and impairment in handling complex tasks (executive function). These cognitive symptoms must represent a significant decline from a previous level of functioning and interfere with functional status and social activities. The disturbances must be insidious in onset and progressive and must not be better accounted for by another psychiatric diagnosis, such as delirium, or systemic disease.
The prevalence of dementia has been estimated to be approximately 6%–10% of individuals aged 65 years or older. The prevalence of dementia increases with age, rising from 2% among those aged 65 to 74 years to more than 30% of those 85 years and older. Incidence rates of Alzheimer's disease (AD) demonstrate exponential growth, doubling every 5 years after the age of 65 years, at least until the age of 85 years.
The cost of caring for people with dementia is substantial; dementia has been estimated to increase the mean annual health care cost per older patient by $4,134, primarily as a result of increased hospitalization costs and increased expenditures on skilled nursing facilities. The current annual economic cost of dementia is approximately $100 billion. With the anticipated doubling of the population aged 65 years and older by 2030, the financial impact of dementia on our society will be even more dramatic.