Development of the Cambridge Contextual Reading Test for improving the estimation of premorbid verbal intelligence in older persons with dementia

Abstract

Objectives: The Cambridge Contextual Reading Test (CCRT), which sets the NART words within semantic and syntactic context, has been shown to yield a higher prediction of premorbid intelligence than the National Adult Reading Test (NART) for patients with mild/moderate dementia (Beardsall & Huppert, 1994). This study validates and standardizes the CCRT in a sample of healthy older persons.

Design: The CCRT was validated against WAIS-R verbal IQ (VIQ) and the Mill Hill Vocabulary Test (MHVT). Regression equations were used to compare predictions of WAIS-R VIQ from CCRT and demographic variables. A conversion table was constructed for predicted VIQ from the equation derived from CCRT scores.

Methods: Seventy-three healthy British older persons aged over 70 years completed the CCRT, NART, WAIS-R verbal subtests and MHVT.

Results: The benefit of context was greatest for those with lowest word reading ability. The CCRT was satisfactorily correlated with VIQ and the MHVT. Whereas the regression equation predicting VIQ using CCRT alone accounted for 61 per cent of the variance, 68 per cent was accounted for when demographic variables were included.

Conclusions: The CCRT is a valid measure of verbal ability for older persons. When accurate information about years of full-time education is available, prediction of verbal intelligence should be made combining CCRT with demographic variables. Otherwise, prediction should be made using CCRT alone. The CCRT may be used in preference to NART in neuropsychological batteries with older persons provided caution is exercised when language difficulties are indicated.