Several researchers have indicated that individuals with mild cognitive impairment (MCI) develop Alzheimer's disease at a rate of 10-15% per year [1] , and in some vascular dementia, particularly in the small vessels disease subtype, dementia may be preceded by MCI [2] . The evaluation of MCI in the elderly has been receiving more attention recently [3] , and the definition of MCI has been reached by common consent. Meanwhile, how MCI is defined has a direct impact on its prevalence and

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... and various criteria have been proposed according to different clinical applications [4] . A simple, timesaving, and convenient screening parameter that is practical is indispensable for screening or in a large field study of a community population. A highly significant correlation exists between mean plaque counts in pathologic findings and Blessed Dementia Rating Scale (BDRS) test scores in dementia [5] . This pathology-based BDRS has been used to detect or rate dementia for decades, and provides an informant-based simple daily functional scale with the advantage of evaluating over a longer period than the cross-sectional observations in cognitive tests such as the Mini Mental State Examination (MMSE) [6] . A few studies with small sample sizes have proposed Although the Blessed Dementia Rating Scale (BDRS), a clinical screening instrument, has been applied extensively, no suitable cut-off values and clinical application have been proposed, particularly in mild cognitive impairment (MCI), the precursor of dementia. The BDRS, Mini Mental State Examination (MMSE), and Clinical Dementia Rating Scale (CDR) were administrated in people aged 65 years and above, who were enrolled from southern Taiwan with multistep stratified random sampling and followed-up for 2 years. All subjects (total number = 3,027), with new onset of MCI (defined as CDR = 0.5) in the first year and dementia (defined as CDR ≥ 1) in the second and third years were subjected to statistical analysis. In distinguishing normal from MCI, except in the literate group aged 65-74 years, MMSE was superior to BDRS, with cut-off values of 1 in both literate groups aged 65-74 years and ≥ 75 years, and 1.5 and 2 in less educated groups aged 65-74 and ≥ 75 years, respectively. In distinguishing MCI from dementia, BDRS had cut-off values of 2.5 in both literate groups aged 65-74 and ≥ 75 years, and 2.5 and 3 in less educated groups aged 65-74 and ≥ 75 years, respectively. These values were better than those for MMSE in all groups. BDRS might be considered as a better tool than MMSE to screen for MCI and dementia in the increasing proportion of literate elderly aged 65-74 years in the aging population.