Trait and state aspects of P300 amplitude reduction in schizophrenia: A retrospective longitudinal study

Background: The P300 component of the auditory event-related brain potentia l (ERP) is consistently reduced in schizophrenia, Longitudinal data are exa mined to determine whether P300 amplitude is a trait marker of schizophreni a or a state marker tracking clinical fluctuations over time. Methods: Schizophrenic men (DSM-III-R) (n = 36) received ERP and the Brief Psychiatric Rating Scale (BPRS) assessments on multiple occasions, at varyi ng intervals, under varying medication states. Automatically elicited audit ory P3a and effortfully elicited auditory and visual P3b amplitudes were as sessed Brief Psychiatric Rating Scale scores were regressed on P300 amplitu de within patients using bath multiple regression models and nonparametric analyses of individual patient slopes. Event related brain potentials in pa tients were compared to ERPs from 34 age-matched control men, and stability of P300 over time was estimated with intraclass correlations Results: P300 amplitude, regardless of elicitation method or sensory modali ty, tracked BPRS Total and positive symptom scores over time, decreasing wi th symptom exacerbations and increasing with improvements. In addition, eff ortful auditory and visual P3b amplitudes tracked negative symptoms, and au tomatic auditory P3a tracked depression-anxiety symptoms. When analyses wer e limited to unmedicated occasions, auditory P3a and P3b persisted in hacki ng BPRS Total scores, with additional tracking of positive symptoms by P3b and mood symptoms by P3a. Mean auditory and visual P3bs, averaged over all measurement occasions for each individual were inversely related to mean ne gative symptoms Auditory P3a and P3b, but not visual P3b, amplitudes were s maller in patients than control subjects, even when patients were least sym ptomatic. P300 amplitudes showed high test-retest reliability in control su bjects and patients and moderate stability over time in patients. Conclusions: Auditory and possibly visual P300 amplitudes track fluctuation s in clinical state, but only auditory P300 amplitude is a trait marker of schizophrenia. (C) 2000 Society of Biological Psychiatry.