The age-specific prevalence of dementia, its sex difference, and the relative prevalence of important types of dementia were studied in the elderly people in a Korean rural community. A two-stage approach was employed, involving screening and clinical assessment. The prevalence among individuals aged 65 and over was found to be 10.8%, with rates of 7.2% in men and 14.5% in women. The dementia was of the Alzheimer type in 60.0% of cases, multi-infarct dementia in 12.0%, mixed dementia of Alzheimer type and multi-infarct in 10.7%, alcoholic dementia in 8.0%, and others and unclassifiable in 9.3%. The prevalence of dementia of the Alzheimer type was significantly higher in women and rapidly increased with age in both sexes. The prevalence of multi-infarct dementia was not related to sex or age. Alcoholic dementia was identified only in men. These findings indicate that the prevalence of dementia in rural Korea is similar to that reported in Western countries and that the prevalence of dementia of the Alzheimer type in rural Korea is greater than that of multi-infarct dementia.

SUMMARYDiagnostic power of the Korean version of the Mini-Mental State Examination (MMSE-K) (Park and Kwon, 1990) for DSM-111-R dementia was studied in 406 persons aged 60 years or more from three sources. Psychiatric clinic patients (N= 177) were diagnosed using standard clinical procedures, laboratory tests and psychological tests; in residential home elderly (N= 128) consensus diagnoses were reached by two psychiatrists afterjoint interviews using the CAMDEX (Roth et al., 1988) including physical examinations but without laboratory tests; and members of psychiatric patients' families (N= 101) were diagnosed after a brief psychiatric interview and assessment of activities of daily living by one psychiatrist. At the cutoff point of 24/23 of MMSE-K score, sensitivity was 92.0% and specificity 91.5%. 23.9% of demented people and 39.3% of non-demented obtained similar scores between 20 and 26. With the introduction of the arbitrary criteria of 'questionable dementia' (MMSE-K score 21-24) the false positive rate was reduced to 1% and the false negative rate to 3%. 74% of males with 'questionable dementia' scores were clinically demented while only 12% of females with the same scores were demented.KEY woms-Dementia, aged, diagnosis, sensitivity and specificity.It is not easy to evaluate exactly cognitive dysfunction and its severity in the elderly. Of the many brief tests for cognitive function, the Wechsler Adult Intelligence Scale (Dick e t al., 1984). The scores also have a close relationship to lesions on the brain CT (Tsai and Twang, 1979). For these reasons and its brevity in use, the MMSE was employed in the Diagnostic Interview Schedule (Robins e t al., 1984). Satisfactory diagnostic validity of the MMSE was demonstrated in an Australian epidemiological study (Kay et al., 1985).However, its score is much influenced by the educational level of subjects (Magaziner e t al., 1987; O'Connor e t al., 1989a) and there are many problems in its administration to non-English-speaking populations (Escobar e t al., 1986). We developed the Korean version of the MMSE (MMSE-K) for use with the Korean elderly. Details of the test, including test items, instructions, interrater reliability and how to correct raw into corrected scores were described in the first part of this project (Park

The reliability and validity of the Cognitive Impairment Diagnosing Instrument (CIDI) were studied in 67 nursing home elderly subjects and 251 elderly psychiatric patients. Its possible highest score is 77 and covers 10 subscales: short-term memory, long-term memory, concentration/calculation, abstract thinking, judgement, memory registration, higher cortical functions, orientation in time, orientation in place and object naming. Test-retest correlations were between 0.827 and 0.990 for the subscale scores and 0.984 for the total score. Inter-tester kappas for each item ranged from 0.200 to 1.000 with a mean of 0.698. Concordance rates were between 50.0 and 100.0% with a mean of 87.2%. Cronbach's alphas for the items of the individual subscales ranged from 0.702 to 0.915. Inter-subscale and subscale-total correlations ranged from 0.503 to 0.820 with a mean of 0.684 and from 0.721 to 0.883, respectively. Cronbach's alpha of the subscales was 0.934. Sensitivity and specificity were 93.3% and 93.8% at the cut-off point of 57.0/57.5 for dementia. Subscale and total scores were significantly different between the demented and non-demented. The total CIDI score was significantly correlated with scores of the Blessed Dementia Rating Scale and the Korean version of the Mini-Mental State Examination.