- Estimated premorbid IQ of 70 or greater, consistent with completion of the sixth grade or ability to read at the sixth grade level. Current ability to read and comprehend a newspaper or history of such ability will satisfy this criterion for patients whose formal education stopped before the sixth grade. For patients who are illiterate, ability to make change from a dollar for a combined purchase of two items or the history of such ability will satisfy this criterion. In the absence of a functional definition, an age-correlated scaled score of > 5 on the Vocabulary Subtest of the WAIS-R or WISC-R may be used to establish IQ.