The effect of age and education transformations on neuropsychological test scores of persons with diffuse or bilateral brain damage.

Heaton, Grant, and Matthews (1991) published procedures for adjusting raw scores on various neuropsychological tests according to the individual's age and education. Despite rather widespread use of these score conversions in both clinical work and research publications, there have been very few investigations to evaluate the accuracy or limitations of these score transformations. This study was based on 52 persons with brain damage who had a range of verified brain injuries or disease. Raw scores were transformed according to the Heaton, Grant, and Matthews (HGM) procedure and also according to Reitan and Wolfson's Neuropsychological Deficit Scale (RW NDS) score procedure. The latter method is a straightforward transformation of raw scores and does not adjust for age or education. The number of normal (vs. impaired) scores was 1.74 times greater using the Heaton, Grant, and Matthews method than when using the Reitan and Wolfson method, yielding a chi2 value of 32.66 (p < .001). These results suggest that impairment in this brain-damaged group was identified less often when using the Heaton, Grant, and Matthews procedure than when using a method that represented the raw scores directly. The clinical and forensic implications of these findings are discussed. More research on this issue is needed.