The problem of assessing brain damage in psychiatric samples: Use of personality variables in prediction of WAIS-R scores

Detection of IQ decrements due to brain injury in patients with preexisting psychiatric disorders was examined. Subjects included 280 male and female adult psychiatric patients who were free of identified neurological disorders. Subjects were administered the MMPI and WAIS-R. Original (Barona, Reynolds, & Chastain, 1984) and revised (Barona & Chastain, 1986) Barona formulae were used to calculate premorbid IQ based on demographic variables. Multiple regression analyses were utilized to predict Wechsler IQ scores from the predicted Barona (original and revised) IQ scores along with MMPI clinical and validity scale raw scores for the experimental group (N = 186). The Barona equations overpredicted current IQ scores. The addition of MMPI variables when predicting current IQs resulted in significant increments in R2(p < .01). Cross-validation on a second sample (N = 94) yielded similar results when MMPI variables were added to all the original Barona formulae and the Barona PIQ revised formula. The MMPI may provide a means of incorporating pathology and personality characteristics into the detection of brain damage in psychiatric patients.