A comparison of three measures of estimating premorbid intellectual level in dementia of the Alzheimer type.
Estimation of premorbid intellectual function is becoming increasingly recognized as a crucial component of neuropsychological assessment in both research and clinical practice. Estimation based on accuracy of pronunciation of irregular words via the National Adult Reading Test (NART) has become popular. However, alternative methods have recently been developed, including the Cambridge Contextual Reading Test (CCRT) and the Spot-the-Word Test (STW). In the present study, the three methods were compared in 21 elderly patients with dementia of the Alzheimer type (DAT), relative to a large sample of healthy controls. Performance on all three measures was relatively unaffected by DAT, and in the controls, both the NART and the CCRT correlated relatively well with current verbal intelligence. However, the correlation between the STW and current verbal intelligence was disappointingly low. The DAT subjects showed a significantly greater improvement in performance (relative to controls) when the irregular words were placed in context (meaningful sentences). The results suggest that the CCRT may provide the fairest estimate of premorbid verbal intelligence in DAT.
Law
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Department of Psychiatry, Edinburgh University, UK.
O'Carroll
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D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D015999:Multivariate Analysis; D011594:Psychometrics; D012044:Regression Analysis; D015203:Reproducibility of Results