Diagnosis of dementia. Methods for interpretation of scores of 5 neuropsychological tests

N. Meiran, D. T. Stuss, D. A. Guzman, G. Lafleche and J. Willmer
Rotman Research Institute of Baycrest Centre, Ontario.

OBJECTIVE: To provide methods to interpret and compare different neurobehavioral screening tests for the diagnosis of dementia. DESIGN: Five mental-status neuropsychological tools for dementia screening were administered to patients in a memory disorder clinic. These included the Mini-Mental State Examination, the Dementia Rating Scale, the 6-item derivative of the Orientation-memory-Concentration Test, a short Mental Status Questionnaire, and a composite tool we labeled the Ottawa Mental Status Examination, which assessed orientation, memory, attention, language, and visual-constructive functioning. RESULTS: To obtain z and percentile scores, norms are for the different tests, computed separately for patients with dementia of the Alzheimer type, vascular dementia, or no dementia. Another set of norms is reported in which a test score is translated directly into the posttest probability of dementia. Translation formulas are given to allow the estimation of the score on one test from the result on another test. CONCLUSION: The interpretation of tests used to diagnose dementia must be based on an understanding of the meaning of an individual score, which is based on the question asked and the population to which the patient is referenced.