The cognitive abilities screening instrument (CASI): data from a cohort of 2524 cognitively intact elderly.

OBJECTIVES: To describe the effects of age and education for the Cognitive Abilities Screening Instrument (CASI), a 25-item test of cognitive function. DESIGN: Cross-sectional descriptive study of the initial enrollment in a community-based prospective cohort study. PARTICIPANTS: A total of 2524 cognitively intact older adults over age 65 who were members of a major health maintenance organization, and who consented to participate in a longitudinal study. MEASUREMENTS: Summary scores for the CASI are given in the form of mean, median and percentile distributions specific for age and educational level. RESULTS: Based upon maximum likelihood analyses, age and education were significant (p<0.0001) predictors of total CASI score. Increased age and lower education were associated with a lower CASI score, as well as an increased spread in score distribution. Gender was also significantly related (p<0.01) to total CASI, with women having a slightly higher distribution of scores. Mean total scores ranged from CASI=82.2 (SD=9.0) in subjects aged 90-95 who had less than a high school degree to CASI=94.8 (SD=3. 8) in subjects aged 65-69 with at least a high school education. CONCLUSIONS: Like most cognitive screening instruments, performance on the CASI in non-demented persons is influenced by age and education. The reference values for 5-year age categories described in this article should be useful for clinicians and research investigators when using the CASI as a measure of cognitive function.