Background. The stability of the National Adult Reading Test (NART) as a measure of pre-morbid
intelligence in schizophrenia has not yet been satisfactorily established despite the widespread use
of the NART in schizophrenia research.
Method. We examined NART stability in a diverse group of 45 schizophrenic patients in a
prospective longitudinal study over 6·5–7·5 years.
Results. The results showed that NART performance does not decline significantly with increasing
duration of schizophrenic illness and that test–retest reliability, even over 6·5–7·5 years, is extremely
Discussion. Our results provide the necessary evidence that the NART can be used as a stable
measure of pre-morbid intelligence in schizophrenia.