P556. N400 Event-Related Brain Potential as a Predictor of Symptomatic Outcome in Persons at Clinical High Risk for Psychosis

Abstract

The N400 event-related potential response to meaningful stimuli (e.g., words, pictures) is smaller for stimuli that are more related to preceding ones. This “N400 semantic priming effect” is thought to reflect greater activation of contextually related concepts in semantic memory. Reduced N400 semantic priming has been found in schizophrenia, suggesting deficiency in using context to pre-activate related concepts. We have found similar N400 semantic priming deficits in patients at clinical high risk (CHR) for developing a schizophrenia-spectrum disorder. In the present study, we examined whether the degree of these deficits in CHR patients predicts symptomatic outcome over two years.