CHARACTERIZATION OF NEUROPSYCHOLOGICAL IMPAIRMENT IN SCHIZOPHRENIA

在过去的一年里，我们试图更全面地描述

For the past year we have attempted to characterize more completely the cognitive impairments in schizophrenia. We have examined working memory using an n back paradigm. We have now developed a computational model of this task using production system if then statements. We have also found a strong relation between performance on the n back and IQ. More specifically this relation was driven by IQ subtests with the greatest working memory demands. We have also begun work on the mechanisms accounting for temporal order failures in working memory in schizophrenia. Last we believe that some components of the CPT might involve working memory and stimulus response mapping as opposed to attention and vigilance as heretofore stressed and are testing this hypothesis. We have used verbal fluency to assess the integrity of the semantic system in schizophrenia. In particular we found that pacing has differential effects on the semantic versus phonologic fluency and that schizophrenia is not associated with category specific impairments. We began an intensive series of studies of the effects of neuroleptics on: a working memory as instantiated in the n back test; b. a wide array of clinical neurocognitive tests. Thought disorder in schizophrenia continued to come under scrutiny. A recent study using a triadic comparisons task found that patients with high levels of thought disorder had disorganized semantic maps. (One possible mechanism for this involved abnormal automatic spreading activation as assessed by semantic priming.) We are beginning to gather data on a nonverbal morphing task to assess where schizophrenic patients delimit semantic boundaries in the same way as do normal controls. We are also looking at this question in a reaction time test to words. Last we are doing a contrast study which compares patients with schizophrenia to patients with Alzheimer's disease and children to find dissociations between the size of the verbal lexicon and its organization. A genetic study of schizophrenia with an emphasis on intermediate phenotypes is ongoing. We are using a large battery of neurocognitive measures to characterize this "intermediate" phenotype. We base this on the rationale that patients do not inherit schizophrenia but a variety of susceptibilities to cognitive impairments and their attendant neurophysiologic abnormalities. We will use extreme discordant pairs (affected unaffected) and affected sib pairs for selected variables and attempt to find linkage between cognitive variables and genetic markers.