[Cognitive dysfunction among the elderly evaluated by the cognitive abilities screening instrument (CASI)]

The Cognitive Abilities Screening Instrument (CASI) was developed by Japanese and American researchers, including the authors, to examine cognitive functions, based on previous neuropsychological tests, such as Hasegawa's Dementia Scale and the MMSE. From the Adult Health Study (AHS) population of the Radiation Effects Research Foundation, 2052 men and women aged 60 or over and living in Hiroshima were evaluated for their cognitive functions using the CASI. Dementia was diagnosed in 93 and 1,959 were considered not to suffer from dementia based on the DSM-III-R criteria using neurological examination and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) completed by caregivers. Multivariate regression analysis not only indicated that total score was higher with lower age and higher education but that the slope of its decrease is steeper with higher age and fewer years of education. The slope of score decrease with increase of age was steeper for women than for men. Furthermore, CASI items were categorized by domains of cognitive function. Multivariate regression analysis for each cognitive domain showed clear effects of age and level of education. The effect of age for the nondementia subjects was large in cognitive domains dealing with temporal orientation, short-term memory, and list-generating fluency. The most useful cognitive domains for diagnosing dementia were temporal orientation, short-term memory, and list-generating fluency, as was indicated by high sensitivity and specificity.