title: The onset of dementia.
abstract: Epidemiological concepts may contribute to the understanding of dementia of Alzheimer type (DAT). The disease follows a variable clinical course determined only partly by the nature and distribution of the organic damage to the brain. Genetic and environmental factors interact with the organic process to determine the degree of functional (mental) impairment, while yet further interactions with environmental factors determine whether in terms of social function the dementia is compensated or decompensated. Knowledge of disease incidence rates can assist in the differential diagnosis of acquired mental impairment. Systematic data on the natural history of the DAT and its range of variation is valuable in recognising intercurrent, possibly remediable illness, and in planning care.
authors.affiliation: University of Oxford, Radcliffe Infirmary, England.
authors.forename: J G
authors.initials: JG
authors.lastname: Evans
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000209:etiology / Q000523:psychology; D003937:Diagnosis, Differential; D006801:Humans; D008875:Middle Aged