Abstract
Schizophrenia causes cognitive dysfunction. The assessment of cognitive function is important in the treatment of schizophrenia. The Wechsler Adult Intelligence Scale (WAIS) is used to assess cognitive function in patients with psychiatric disorders. For clinical use, a short form of the WAIS-III was developed in Japan specifically for patients with schizophrenia, allowing the estimation of IQ using the Similarities and Symbol Search. In the present study, we examined whether the same tasks could be used on the short form of the WAIS-IV. The subjects were 110 patients with schizophrenia. Using methods consistent with those employed in developing the WAIS-III short form, exploratory factor analysis was conducted to confirm the factor structure of intelligence in patients with schizophrenia. Regression analysis demonstrated that the Similarities and Symbol Search had sufficient explanatory power for estimating full-scale IQ. Additionally, correlation analysis revealed a positive relationship between estimated IQ, and social functioning. These findings indicate that the short form of the WAIS-IV, consisting of the Similarities and Symbol Search, meets the necessary criteria for practical use. This short form provides an efficient alternative for estimating cognitive function in patients with schizophrenia while maintaining enough validity.