COGNITIVE IMPAIRMENT IN THE NONDEMENTED ELDERLY - RESULTS FROM THE CANADIAN STUDY OF HEALTH AND AGING

Study Objective: To describe a population that was categorized as ''co gnitively impaired not demented'' (CIND) and to examine the utility of some of the proposed criteria for describing this degree of cognitive impairment. Design: Population-based prevalence study of dementia in those subjects who were 65 years and older. Setting: Community and ins titutional settings in Canada. Subjects: Individuals who underwent a c linical evaluation (N=2914). Intervention: Initial screening with the Modified Mini-Mental State Examination (3MS) to identify potential cog nitive impairment; the 3MS was followed by a detailed clinical examina tion to confirm the presence of dementia and to determine the probable cause. Clinical examinations were performed on all those subjects who were residing in institutions, those in the community with a 3MS scor e less than 78, and a sample of those in the community with a 3MS scor e of 78 or more. Neuropsychological testing was performed as part of t he clinical examination when the 3MS score was 50 or more. At the conc lusion of the assessment, subjects were categorized as being cognitive ly normal, CIND, and demented. Measurements: Frequency of a diagnosis of CIND; demographical, cognitive, and functional characteristics of c ognitively normal and CIND subjects and those with early and late deme ntia; and proportion of subjects who were CIND and met the proposed cr iteria. Results: Subjects who were categorized as CIND were common and fell between cognitively normal subjects and those with dementia in t erms of age, 3MS score, general intellectual function, and performance of daily activities. Because of the restrictive inclusion and exclusi on criteria, the proposed criteria for cognitive impairment described only 30% of our subjects who were CIND. Conclusions: Subjects who were categorized as CIND appeared to be distinct from and intermediate bet ween subjects with dementia and cognitively normal subjects. Most indi viduals did not meet the criteria that were evaluated for describing t his group. While the various criteria that were evaluated may accurate ly define a select subset of cognitively impaired individuals, the nat ural history and prognosis of such groups, currently unknown, may not be generalizable to the larger population of subjects who are CIND. Fu rther work is needed to clearly define this group, and longitudinal st udies are required to determine an outcome.