The validity of psychometric instruments for detection of dementia in the elderly general population

OBJECTIVE: To compare the validity of different instruments for screening and diagnosis of dementia and to provide threshold scores for these purposes, ie screening focusing on a high sensitivity and diagnosis focusing on a high specificity. SETTING: 287 subjects from a general population sample who had completed more than one of these psychometric tests. METHODS: The performances of the Structured Interview for the Diagnosis of Dementia of the Alzheimer Type, Multi-Infarct Dementia and Dementias of Other Aetiology according to ICD-10 and DSM-III-R, the Mini-Mental State Examination, the Blessed Dementia Rating Scale, the Global Deterioration Scale, the Verbal Fluency Test, the Word list Learning Task, the Trail Making Test and the Labyrinth Test were compared using receiver operating characteristics analysis. RESULTS: The validity of composite instruments for the discrimination of dementia and cognitive health was higher than the validity of individual tests. However, some cognitive tests, ie verbal fluency and immediate recall of words, reached a high validity, making them useful and short screening instruments for dementia. CONCLUSION: There is no perfect instrument for screening and diagnosis of dementia. Different threshold scores for different purposes were provided in the present study. Recommendations for improving the validity of the Delayed Word List Learning Task for discriminating dementia and cognitive health include the expansion of list length and shortening of delay.