Subtypes of Schizophrenia: ERPs During Memory Processing

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DESCRIPTION (provided by applicant): Working memory and episodic memory impairments are present in patients with schizophrenia and their relatives, suggesting that it may represent a "cognitive phenotype" of schizophrenia. This project proposes to use brain event-related potentials (ERPs) and behavioral measures to study both working memory and recognition memory for words and faces in patients with schizophrenia. The fine temporal resolution of ERPs will aid in determining the specific stages of processing (encoding, storage and retrieval) associated with abnormalities on these memory tests. Preliminary ERP findings during a word serial position test suggest that a left-frontal slow wave associated with short-term storage of words is reduced in schizophrenia patients, and abnormalities during a word recognition memory test are evident as early as 100 to 200 milliseconds after stimulus onset. Recording ERPs to both words and faces will provide additional information concerning material-specificity of abnormalities of memory function and cerebral laterality in schizophrenia. ERPs of 60 unmedicated schizophrenic patients, 60 patients receiving an atypical antipsychotic, and 60 healthy controls will be recorded during serial position tests and recognition memory tests with word and face stimuli. Patients and controls will also be tested on standard neurocognitive tests of attention (CPT), learning and memory (WMS-R), and problem solving (WCST). Unmedicated patients, medicated patients and healthy controls will be compared to determine whether differences in their performance and brain ERPs on these tests are related to medication status. In addition, ERP and behavioral data for patient subgroups and controls will be compared so as to contribute toward the identification and validation of "cognitive subtypes" with more homogeneous clinical and biological characteristics. A series of studies has identified a subgroup of patients who perform as well as healthy adults on a screening test of attention and tonal perception, but who have a selective deficit in verbal memory (discriminators, Dsz), while a second subgroup of patients, who perform poorly on the screening test, show evidence of a generalized cognitive deficit (non-discriminators, NDsz). The project aims to further validate these subgroups by testing hypothesized differences in their material-specific memory function, ERP abnormalities during different phases of memory processing, deficits on standard neurocognitive tests, and symptom features.