Prediction of cognitive damage in patients with schizophrenia: A thirty-one year retrospective

The purpose of this study is to find out which tests from the Wechsler Intelligence Scale define the most detailed cognitive model that is able to predict the relevant cognitive impairment in elderly people with schizophrenia. A group of 30 institutionalised women who were diagnosed with schizophrenia were assessed with MEC-35; they had been previously assessed 31 years before using the WAIS. It was found that 53.3% of the patients showed significant cognitive impairment and 31 years ago their scores were lower in all the subtests from the WAIS. Those differences are significant (p< .05) in all of the IQ measurements. Throughout the logistical regression analysis we found that the cognitive model that made the best prediction was produced from the following subtests: Similarities, Puzzles and Arithmetic, classifying 96.7% of the cases and showing an excellent criterion validity, a sensitivity of 93.8% and a 100% of specificity. We conclude that the increase of the cognitive impairment in elderly patients with schizophrenia seems to be associated with previous low fluid intelligence.