The validity of the national adult reading test in estimating premorbid intellectual ability in long‐term survivors of hemispheric glioma and whole brain irradiation—a pilot study

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Abstract
We have examined the validity of using the National Adult Reading Test (NART) to estimate premorbid intellectual levels in long‐term survivors of glioma who had received whole brain prophylactic irradiation. Sixteen controls matched for age, sex, education and social class were compared with 16 patients. Patients made significantly more errors in the NART than controls, even after controlling for demographic variables. NART errors were compared with demographically predicted NART errors and NART‐predicted Wechsler Adult Intelligence Scale‐Revised (WAIS‐R) with pro‐rated WAIS‐R scores. While predicted and measured error scores were similar for the controls, for patients NART errors were higher than those predicted by demographic variables, while NART‐predicted WAIS‐R scores were higher than pro‐rated WAIS‐R. NART performance, therefore, appears to be detrimentally affected by brain changes due to the primary tumour or received treatment. This conclusion was supported by the finding that, in patients, NART errors were correlated with current IQ, but not with IQ predicted by socio‐demographic variables. After excluding four demented patients, this pattern of results was largely preserved. After excluding four patients with left temporal lobe involvement, the correlation of NART errors with current IQ disappeared, whereas that with NART errors predicted by socio‐demographic variables became significant. These results suggest that the NART can only be used with caution in survivors of malignant primary brain tumors, particularly if left temporal lobe structures are involved.