ABSTRACT
Most of the new cases of dementia which are identified in longitudinal studies arise in the main group of initially unimpaired persons. Despite a large number of epidemiological studies, there is insufficient knowledge about the frequency, course and duration of mild dementia. All those patients who according to the research criteria suffered from severe or moderately severe dementing illness had been correctly classified by the practitioners. Of the milder forms of cognitive disorder, only 18.5 per cent had been missed. The deficits which are of greatest value in identifying mild and early dementia are those involving mnestic, speech and spatial-constructive functions. Below the age of 75, hardly any cases of severe dementia were found, the proportions being only 0.4 and 0.5 per cent respectively. In general, the objective assessment of cognitive performance should make possible a better differentiation of the stages of dementia and closer comparability of research findings from different groups.
