Predicting premorbid functioning in crack-cocaine abusers.

The Wide Range Achievement Test (Revised) (WRAT-R) reading test, demographic variables and drug use severity were used to develop prediction equations to estimate premorbid ability in 92 cocaine abusers. WRAT-R reading was correlated significantly with full scale, verbal and performance IQ. Stepwise regression indicated that only WRAT-R reading score and age accounted for 23% of the variance in Full Scale IQ (FSIQ) and 28% in Verbal IQ (VIQ). Abstinence and severity of use variables did not correlate with nor predict IQ. Actual and predicted IQ scores were correlated significantly and did not differ based on within group t-tests. Thus, these formulas accurately estimate premorbid functioning in cocaine-dependent research patients with FSIQs in the average to low average range, replicating the results in normal adults with average IQs.