Tc99m HMPAO brain SPECT with visuospatial and verbal activation in normal subjects

Abstract

The P300 component of the event-related brain potential (ERP) is reduced in schizophrenia. Cross--sectional analyses suggest smaller P300 amplitudes are associated with worse clinical status. We used a longitudinal design to ask if P300 is a stable reflection of chronic severity or if it tracks short-term clinical fluctuations. Thirty-six male veterans with schizophrenia (DSM-III-R) participated in as many as seven ERP sessions, under various medication regimens, and sometimes over multiple hospitalizations. ERPs were collected during auditory and visual paradigms in which frequent events occurred on 80% of the trials, and rare events on 20%. Subjects pressed a button in response to rare events. The clinical status of the subject was assessed within several days of each ERP session using the Brief Psychiatric Rating Scale (BPRS). Relationships between P300 and clinical status were addressed using hierarchical multiple regression analyses in which BPRS scores were regressed on Subject, P300 (amplitude or latency), and their interaction. In no case was the interaction term significant, allowing a common slope of the BPRS-P300 regression lines to be assumed across subjects. The Subject effect was entered into the regression analysis at the first step, controlling for BPRS variation associated with intersubject differences, leaving only within-subject variation over time as the source of BPRS variance available for prediction. At the second step, P300 measures were entered and the increment in R 2 tested. Auditory and visual P300 amplitude, but not latency, significantly predicted total BPRS scores, but not positive or negative symptom subscores. Thus, within an individual patient over time, increases in both auditory and visual P300 amplitude track clinical improvement. (Supported by NIMH (MH30854) & Department of Veterans Affairs.) 285. Tc99m HMPAO BRAIN SPECT WITH VISUOSPATIAL AND VERBAL ACTIVATION IN NORMAL SUBJECTS