Altered hemispheric functional dominance during word generation in negative schizophrenia

Functional brain imaging studies have reported decreased frontal activation s in schizophrenia, but hemispheric dominance for language has rarely been assessed. To Investigate regional activation and lateralization during word production, we determined normalized regional cerebral blood flow (rCBF) v ariations with positron emission tomography (PET) and (H2O)-O-15 (water lab eled with the isotope oxygen 15) in 14 negative schizophrenia patients and 14 volunteers. Subjects were scanned during two trials of three conditions: rest, vocalized verbal fluency, and spontaneous word production. Images we re analyzed using an anatomical volumes of interest method, and the two gro ups' changes were compared, using rest as a baseline. Differences in the la teralization of changes were detected in homologous frontal and inferior pa rietal regions. The lateralization effects in patients arose from lower act ivations in the left frontal regions, abnormal right inferior frontal activ ations, and weaker right inferior parietal deactivation, during the word pr oduction tasks. The right hemisphere changes correlated negatively with the performance in verbal fluency. Thus in negative schizophrenia patients, wh ile the activations were less focused on the left hemisphere regions usuall y engaged in word generation, rCBF changes in the right hemisphere might re flect a compensatory functional pattern.