Crystal R. Blyler

Short form of the WAIS-III for use with patients with schizophrenia

The recent publication of the Wechsler Adult Intelligence Scale (WAIS-III), the most widely used standard test of intelligence, requires the development of a new short form for use with patients with schizophrenia for many clinical and research purposes. We used regression analyses of complete WAIS-III data on 41 outpatients with schizophrenia and 41 education-, and age-matched healthy subjects to determine the best combination of subtests to use as a short form. Excluding three subtests that are time-consuming to administer, and requiring that the solution includes one subtest from each of the four WAIS index scores, the combination that most fully accounted for the variance in full-scale IQ (FSIQ) for both participants with schizophrenia (R(2)=0.90) and healthy controls (R(2)=0.86) included the information, block design, arithmetic, and digit symbol subtests. When the restrictions regarding which subtests could enter were relaxed, the best four-subtest solution included information, block design, comprehension, and similarities. Although the latter explained 95% of the variance in FSIQ for schizophrenia participants and 90% of the variance for healthy controls, it consistently overestimated FSIQ for the schizophrenia group. We recommend the four-factor short form for use in future research and clinical practice in which a quick, accurate IQ estimate is desired.

Line drawing as a possible measure of lateralized motor performance in schizophrenia

In this paper we suggest a new method, conceived by Maher, to assess lateralized motor performance in schizophrenia. Subjects draw two straight lines with each hand. The lines are scanned into a computer, and a regression is run on the points of the line. The root mean squared error (RMS) of the regression equation indicates the deviation from straightness of the line. The average RMS of all four lines is taken as an overall measure of motor disorder, and the difference in performance between the two hands serves as an index of motoric laterality. Scores on the motor disorder index were significantly positively related to clinical ratings of Parkinsonism among schizophrenic inpatients. A marginal relation was found to ratings of voluntary movement disorders, and the task was not associated with dyskinetic movements. Scores on the motor disorder measure were significantly worse for schizophrenic subjects than for staff controls. The laterality index significantly differentiated right- and left-handed subjects, but did not differentiate schizophrenic from control subjects. Mahers simple line drawing task yields objective continuous ratings of motor disorder and handedness and may be a useful tool for examining associations between motor functioning and cognition and symptomatology in schizophrenia.