Detailed analysis of the Japanese version of the Rapid Dementia Screening Test, revised version.

AIM: The number-transcoding task on the Japanese version of the Rapid Dementia Screening Test (RDST-J) requires mutual conversion between Arabic and Chinese numerals (209 to , 4054 to , to 681, to 2027). In this task, question and answer styles of Chinese numerals are written horizontally. We investigated the impact of changing the task so that Chinese numerals are written vertically.

METHODS: Subjects were 211 patients with very mild to severe Alzheimer's disease and 42 normal controls. Mini-Mental State Examination scores ranged from 26 to 12, and Clinical Dementia Rating scores ranged from 0.5 to 3.

RESULTS: Scores of all four subtasks of the transcoding task significantly improved in the revised version compared with the original version. The sensitivity and specificity of total scores ≥9 on the RDST-J original and revised versions for discriminating between controls and subjects with Clinical Dementia Rating scores of 0.5 were 63.8% and 76.6% on the original and 60.1% and 85.8% on revised version.

CONCLUSIONS: The revised RDST-J total score had low sensitivity and high specificity compared with the original RDST-J for discriminating subjects with Clinical Dementia Rating scores of 0.5 from controls.