On substituting the WAIS-R for the WAIS in neuropsychological assessment: a caution for clinicians.

The Wechsler Adult Intelligence Scale-Revised (WAIS-R) yields lower Full Scale IQs than the Wechsler Adult Intelligence Scale (WAIS). Thus, a prediction about a patient's neuropsychological functioning based on the WAIS-R will differ from that based on the WAIS. The present study compared predicted Halstead Category Test (HCT) error scores based on the WAIS-R with those based on the WAIS. Thirty-five patients with the neurological and/or psychiatric conditions completed the HCT and WAIS-R, while 35 diagnostically similar patients were given HCT and WAIS. Regression equations to estimate HCT error scores were developed with the use of appropriate Full Scale IQs as the predictors. Results indicated that predicted HCT error scores were higher with the WAIS Full Scale IQ than with the WAIS-R. When the WAIS-R is substituted for the WAIS in a neuropsychological battery, the established relationship between IQ and expected neuropsychological performance should not be utilized.