Dementia: case ascertainment in a community survey

Dementia is a general mental deterioration that is associated with a number of diseases which are common in the aged, such as Alzheimer's disease. Its prevalence is expected to increase as the general population ages. Epidemiological studies on the prevalence and causes of dementia are thus of increasing importance. These studies can be difficult to perform because identifying the presence of dementia from records and cases is often difficult. This study examined the prevalence of dementia in a certain population. A detailed survey of a sampling of adults in Baltimore, Maryland was performed. Adults identified as potentially suffering from dementia were asked to take part in differential diagnosis. Results were obtained from 32 of 41 individuals with possible dementia who chose to take part in differential diagnosis. Results of diagnosis were: five receiving no diagnosis of dementia, five receiving a diagnosis of possible dementia, 12 having Alzheimer's disease (AD), seven having multi-infarct dementia (MID), and three with mixed dementia. Of the 12 subjects with AD, 10 were women and all were 73 years of age or older. Of the subjects with MID, four were men and three were women. Prevalence rates for dementia for the population aged 65 years and older in the area were then calculated as 4.5 percent for the population over the age of 65 as a whole, with a prevalence of 1.2 percent in the age 65- to 74-year-old group and 25.6 percent for the age 85 and older group. Males had a slightly higher rate of dementia than females overall, but females had a higher rate of dementia caused by AD (2.9 percent versus 0.8 percent). Non-whites had a higher overall prevalence of dementia than did whites (7.2 percent versus 3.8 percent). The prevalence of AD increased and that of MID decreased as educational level increased. These results show the prevalence of dementia by cause and demographic characteristics in one community. Results are from a small sample, so interpretations and conclusions should be drawn cautiously. (Consumer Summary produced by Reliance Medical Information, Inc.)