RESUMO
<b>Introduction</b> : To detect major symptoms of dementia, especially symptoms of non-Alzheimer-type dementia, we tried to develop an informant-based questionnaire, the Dementia differentiation questionnaire-41 items (DDQ41).<br><b>Methods</b> : The DDQ41 consisted of 11 questions on symptoms of early dementia (Q-Dementia11), 8 on Alzheimer's disease dementia(Q-ADD8), 9 on dementia with Lewy bodies (Q-DLB9), 8 on vascular dementia (Q-VD8), 5 on frontal lobe signs (Q-Frontal5), and additional 2 questions on urinary incontinence and speech disturbance. Caregivers of the 575 outpatients, who included only 1 diagnosis of dementia disease, checked the DDQ41.<br><b>Results</b> : Mean score of Q-Dementia11 in the MCI group was significantly lower than that in the other dementia groups. Mean score of Q-ADD8 in the ADD group was not significantly different from that in the other dementia groups. Mean score of Q-DLB9 in the DLB group was significantly higher than that in the other dementia groups. Area under the ROC curve of Q-DLB9 was 85.6%, and sensitivity and specificity were 82.6% and 77.7%(cut-off : 3 items/4 items), respectively, for DLB.<br><b>Conclusion</b> : We developed the DDQ41, an informant-based questionnaire sheet, for detecting symptoms of dementia. It may be useful in detecting frontal lobe signs and symptoms of non-Alzheimer-type dementia, especially those of DLB.