Differential frontal activation in schizophrenia and bipolar illness during verbal fluency

Introduction: The precise nature of frontal lobe dysfunction in schizophren ia remains unclear. We have previously demonstrated, using fMRI a task-spec ific attenuation of frontal activation in schizophrenic patients. By using an identical methodology in matched bipolar subjects. we sought to determin e whether this finding is specific to schizophrenia or a correlate of psych osis in general. Method: Five dextral male bipolar patients and matching gr oups of schizophrenic subjects and controls were studied using fMRI. Echopl anar images were acquired while subjects performed two paced tasks: covert verbal fluency and a semantic decision task. Generic brain activation maps were constructed from individual images by sinusoidal regression analysis. Between-group differences in the mean power of experimental response were i dentified on a voxel-wise basis by an analysis of variance (ANOVA). Results : The bipolar patients showed extensive prefrontal activation during verbal fluency which was significantly greater than in controls. There was no dif ference in the prefrontal BOLD response during the semantic decision task, Conclusions: These data indicate that bipolar patients show a strikingly di fferent pattern of frontal responses compared to those with schizophrenia a nd provide further evidence that abnormal frontal activation in psychotic d isorders is more apparent during verbal fluency than semantic decision. (C) 2001 Elsevier Science B.V. All rights reserved.