The National Adult Reading Test as a measure of premorbid IQ in schizophrenia

Objectives. To investigate the validity of the NART as an estimate of premo rbid IQ in schizophrenia. Design. ii within-in participants, follow-back design was adopted. Methods. A sample of adults with schizophrenia who had presented to psychia tric services and had a measure of IQ routinely taken during childhood were traced and subject to follow-up WAIS-R and NART IQ assessment (N = 24). Me asures of current IQ and NART estimated premorbid IQ were compared with the measure of IQ taken 'premorbidly', i.e. in childhood. Results. There were no significant differences between childhood and adult measures of IQ. However there were significant differences between these tw o indices and NART estimated IQ, particularly where IQ deviated from genera l population means. The Vocabulary subtest of the WAIS-R performed better a s an estimate of both premorbid and current IQ in the sample. Conclusion. Use of a word-reading rest such as the NART to predict past lev els of intellectual function should proceed with caution, particularly wher e IQ doss not fail in the 'average' category. Use of more than one index of prior level of function is recommended.